cmake-commands(7)
*****************

Scripting Commands
==================

These commands are always available.

block
-----

.. versionadded:: 3.25

Evaluate a group of commands with a dedicated variable and/or policy scope.

 block([SCOPE_FOR [POLICIES] [VARIABLES] ] [PROPAGATE <var-name>...])
   <commands>
 endblock()

All commands between ``block()`` and the matching ``endblock()`` are
recorded without being invoked.  Once the ``endblock()`` is evaluated, the
recorded list of commands is invoked inside the requested scopes, then the
scopes created by the ``block()`` command are removed.

``SCOPE_FOR``
  Specify which scopes must be created.

  ``POLICIES``
    Create a new policy scope. This is equivalent to
    ``cmake_policy(PUSH)`` with an automatic
    ``cmake_policy(POP)`` when leaving the block scope.

  ``VARIABLES``
    Create a new variable scope.

  If ``SCOPE_FOR`` is not specified, this is equivalent to:

  .. code-block:: cmake

    block(SCOPE_FOR VARIABLES POLICIES)

``PROPAGATE``
  When a variable scope is created by the ``block()`` command, this
  option sets or unsets the specified variables in the parent scope. This is
  equivalent to ``set(PARENT_SCOPE)`` or ``unset(PARENT_SCOPE)``
  commands.

  .. code-block:: cmake

    set(var1 "INIT1")
    set(var2 "INIT2")

    block(PROPAGATE var1 var2)
      set(var1 "VALUE1")
      unset(var2)
    endblock()

    # Now var1 holds VALUE1, and var2 is unset

  This option is only allowed when a variable scope is created. An error will
  be raised in the other cases.

When the ``block()`` is inside a ``foreach()`` or ``while()``
command, the ``break()`` and ``continue()`` commands can be used
inside the block.

 while(TRUE)
   block()
      ...
      # the break() command will terminate the while() command
      break()
   endblock()
 endwhile()

See Also
^^^^^^^^

* ``endblock()``
* ``return()``
* ``cmake_policy()``

break
-----

Break from an enclosing foreach or while loop.

 break()

Breaks from an enclosing ``foreach()`` or ``while()`` loop.

See also the ``continue()`` command.

cmake_host_system_information
-----------------------------

Query various host system information.

Synopsis
^^^^^^^^

 Query host system specific information
   cmake_host_system_information(RESULT <variable> QUERY <key> ...)

 Query Windows registry
   cmake_host_system_information(RESULT <variable> QUERY WINDOWS_REGISTRY <key> ...)

Query host system specific information
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 cmake_host_system_information(RESULT <variable> QUERY <key> ...)

Queries system information of the host system on which cmake runs.
One or more ``<key>`` can be provided to select the information to be
queried.  The list of queried values is stored in ``<variable>``.

``<key>`` can be one of the following values:

``NUMBER_OF_LOGICAL_CORES``
  Number of logical cores

``NUMBER_OF_PHYSICAL_CORES``
  Number of physical cores

``HOSTNAME``
  Hostname

``FQDN``
  Fully qualified domain name

``TOTAL_VIRTUAL_MEMORY``
  Total virtual memory in MiB [#mebibytes]_

``AVAILABLE_VIRTUAL_MEMORY``
  Available virtual memory in MiB [#mebibytes]_

``TOTAL_PHYSICAL_MEMORY``
  Total physical memory in MiB [#mebibytes]_

``AVAILABLE_PHYSICAL_MEMORY``
  Available physical memory in MiB [#mebibytes]_

``IS_64BIT``
  .. versionadded:: 3.10

  One if processor is 64Bit

``HAS_FPU``
  .. versionadded:: 3.10

  One if processor has floating point unit

``HAS_MMX``
  .. versionadded:: 3.10

  One if processor supports MMX instructions

``HAS_MMX_PLUS``
  .. versionadded:: 3.10

  One if processor supports Ext. MMX instructions

``HAS_SSE``
  .. versionadded:: 3.10

  One if processor supports SSE instructions

``HAS_SSE2``
  .. versionadded:: 3.10

  One if processor supports SSE2 instructions

``HAS_SSE_FP``
  .. versionadded:: 3.10

  One if processor supports SSE FP instructions

``HAS_SSE_MMX``
  .. versionadded:: 3.10

  One if processor supports SSE MMX instructions

``HAS_AMD_3DNOW``
  .. versionadded:: 3.10

  One if processor supports 3DNow instructions

``HAS_AMD_3DNOW_PLUS``
  .. versionadded:: 3.10

  One if processor supports 3DNow+ instructions

``HAS_IA64``
  .. versionadded:: 3.10

  One if IA64 processor emulating x86

``HAS_SERIAL_NUMBER``
  .. versionadded:: 3.10

  One if processor has serial number

``PROCESSOR_SERIAL_NUMBER``
  .. versionadded:: 3.10

  Processor serial number

``PROCESSOR_NAME``
  .. versionadded:: 3.10

  Human readable processor name

``PROCESSOR_DESCRIPTION``
  .. versionadded:: 3.10

  Human readable full processor description

``OS_NAME``
  .. versionadded:: 3.10

  See ``CMAKE_HOST_SYSTEM_NAME``

``OS_RELEASE``
  .. versionadded:: 3.10

  The OS sub-type e.g. on Windows ``Professional``

``OS_VERSION``
  .. versionadded:: 3.10

  The OS build ID

``OS_PLATFORM``
  .. versionadded:: 3.10

  See ``CMAKE_HOST_SYSTEM_PROCESSOR``

``MSYSTEM_PREFIX``
  .. versionadded:: 3.28

  Available only on Windows hosts.  In a MSYS or MinGW development
  environment that sets the ``MSYSTEM`` environment variable, this
  is its installation prefix.  Otherwise, this is the empty string.

``DISTRIB_INFO``
  .. versionadded:: 3.22

  Read :file:`/etc/os-release` file and define the given ``<variable>``
  into a list of read variables

``DISTRIB_<name>``
  .. versionadded:: 3.22

  Get the ``<name>`` variable (see man 5 os-release) if it exists in the
  :file:`/etc/os-release` file

  Example:

  .. code-block:: cmake

      cmake_host_system_information(RESULT PRETTY_NAME QUERY DISTRIB_PRETTY_NAME)
      message(STATUS "${PRETTY_NAME}")

      cmake_host_system_information(RESULT DISTRO QUERY DISTRIB_INFO)

      foreach(VAR IN LISTS DISTRO)
        message(STATUS "${VAR}=`${${VAR}}`")
      endforeach()


  Output::

 -- Ubuntu 20.04.2 LTS
 -- DISTRO_BUG_REPORT_URL=`https://bugs.launchpad.net/ubuntu/`
 -- DISTRO_HOME_URL=`https://www.ubuntu.com/`
 -- DISTRO_ID=`ubuntu`
 -- DISTRO_ID_LIKE=`debian`
 -- DISTRO_NAME=`Ubuntu`
 -- DISTRO_PRETTY_NAME=`Ubuntu 20.04.2 LTS`
 -- DISTRO_PRIVACY_POLICY_URL=`https://www.ubuntu.com/legal/terms-and-policies/privacy-policy`
 -- DISTRO_SUPPORT_URL=`https://help.ubuntu.com/`
 -- DISTRO_UBUNTU_CODENAME=`focal`
 -- DISTRO_VERSION=`20.04.2 LTS (Focal Fossa)`
 -- DISTRO_VERSION_CODENAME=`focal`
 -- DISTRO_VERSION_ID=`20.04`

If :file:`/etc/os-release` file is not found, the command tries to gather OS
identification via fallback scripts.  The fallback script can use `various
distribution-specific files`_ to collect OS identification data and map it
into man 5 os-release variables.

Fallback Interface Variables
""""""""""""""""""""""""""""

.. variable:: CMAKE_GET_OS_RELEASE_FALLBACK_SCRIPTS

  In addition to the scripts shipped with CMake, a user may append full
  paths to his script(s) to the this list.  The script filename has the
  following format: ``NNN-<name>.cmake``, where ``NNN`` is three digits
  used to apply collected scripts in a specific order.

.. variable:: CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname>

  Variables collected by the user provided fallback script
  ought to be assigned to CMake variables using this naming
  convention.  Example, the ``ID`` variable from the manual becomes
  ``CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID``.

.. variable:: CMAKE_GET_OS_RELEASE_FALLBACK_RESULT

  The fallback script ought to store names of all assigned
  ``CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname>`` variables in this list.

Example:

 # Try to detect some old distribution
 # See also
 # - http://linuxmafia.com/faq/Admin/release-files.html
 #
 if(NOT EXISTS "${CMAKE_SYSROOT}/etc/foobar-release")
   return()
 endif()
 # Get the first string only
 file(
     STRINGS "${CMAKE_SYSROOT}/etc/foobar-release" CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT
     LIMIT_COUNT 1
   )
 #
 # Example:
 #
 #   Foobar distribution release 1.2.3 (server)
 #
 if(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT MATCHES "Foobar distribution release ([0-9\.]+) .*")
   set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME Foobar)
   set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME "${CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT}")
   set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID foobar)
   set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION ${CMAKE_MATCH_1})
   set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID ${CMAKE_MATCH_1})
   list(
       APPEND CMAKE_GET_OS_RELEASE_FALLBACK_RESULT
       CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME
       CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME
       CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID
       CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION
       CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID
     )
 endif()
 unset(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT)

Query Windows registry
^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.24

::

 cmake_host_system_information(RESULT <variable>
                               QUERY WINDOWS_REGISTRY <key> [VALUE_NAMES|SUBKEYS|VALUE <name>]
                               [VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
                               [SEPARATOR <separator>]
                               [ERROR_VARIABLE <result>])

Performs query operations on local computer registry subkey. Returns a list of
subkeys or value names that are located under the specified subkey in the
registry or the data of the specified value name. The result of the queried
entity is stored in ``<variable>``.

.. note::

  Querying registry for any other platforms than ``Windows``, including
  ``CYGWIN``, will always returns an empty string and sets an error message in
  the variable specified with sub-option ``ERROR_VARIABLE``.

``<key>`` specify the full path of a subkey on the local computer. The
``<key>`` must include a valid root key. Valid root keys for the local computer
are:

* ``HKLM`` or ``HKEY_LOCAL_MACHINE``
* ``HKCU`` or ``HKEY_CURRENT_USER``
* ``HKCR`` or ``HKEY_CLASSES_ROOT``
* ``HKU`` or ``HKEY_USERS``
* ``HKCC`` or ``HKEY_CURRENT_CONFIG``

And, optionally, the path to a subkey under the specified root key. The path
separator can be the slash or the backslash. ``<key>`` is not case sensitive.
For example:

 cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM")
 cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")
 cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKCU\\SOFTWARE\\Kitware")

``VALUE_NAMES``
  Request the list of value names defined under ``<key>``. If a default value
  is defined, it will be identified with the special name ``(default)``.

``SUBKEYS``
  Request the list of subkeys defined under ``<key>``.

``VALUE <name>``
  Request the data stored in value named ``<name>``. If ``VALUE`` is not
  specified or argument is the special name ``(default)``, the content of the
  default value, if any, will be returned.

  .. code-block:: cmake

     # query default value for HKLM/SOFTWARE/Kitware key
     cmake_host_system_information(RESULT result
                                   QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")

     # query default value for HKLM/SOFTWARE/Kitware key using special value name
     cmake_host_system_information(RESULT result
                                   QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware"
                                   VALUE "(default)")

  Supported types are:

  * ``REG_SZ``.
  * ``REG_EXPAND_SZ``. The returned data is expanded.
  * ``REG_MULTI_SZ``. The returned is expressed as a CMake list. See also
    ``SEPARATOR`` sub-option.
  * ``REG_DWORD``.
  * ``REG_QWORD``.

  For all other types, an empty string is returned.

``VIEW``
  Specify which registry views must be queried. When not specified, ``BOTH``
  view is used.

  ``64``
    Query the 64bit registry. On ``32bit Windows``, returns always an empty
    string.

  ``32``
    Query the 32bit registry.

  ``64_32``
    For ``VALUE`` sub-option or default value, query the registry using view
    ``64``, and if the request failed, query the registry using view ``32``.
    For ``VALUE_NAMES`` and ``SUBKEYS`` sub-options, query both views (``64``
    and ``32``) and merge the results (sorted and duplicates removed).

  ``32_64``
    For ``VALUE`` sub-option or default value, query the registry using view
    ``32``, and if the request failed, query the registry using view ``64``.
    For ``VALUE_NAMES`` and ``SUBKEYS`` sub-options, query both views (``32``
    and ``64``) and merge the results (sorted and duplicates removed).

  ``HOST``
    Query the registry matching the architecture of the host: ``64`` on ``64bit
    Windows`` and ``32`` on ``32bit Windows``.

  ``TARGET``
    Query the registry matching the architecture specified by
    ``CMAKE_SIZEOF_VOID_P`` variable. If not defined, fallback to
    ``HOST`` view.

  ``BOTH``
    Query both views (``32`` and ``64``). The order depends of the following
    rules: If ``CMAKE_SIZEOF_VOID_P`` variable is defined. Use the
    following view depending of the content of this variable:

    * ``8``: ``64_32``
    * ``4``: ``32_64``

    If ``CMAKE_SIZEOF_VOID_P`` variable is not defined, rely on
    architecture of the host:

    * ``64bit``: ``64_32``
    * ``32bit``: ``32``

``SEPARATOR``
  Specify the separator character for ``REG_MULTI_SZ`` type. When not
  specified, the character ``\0`` is used.

``ERROR_VARIABLE <result>``
  Returns any error raised during query operation. In case of success, the
  variable holds an empty string.

cmake_language
--------------

.. versionadded:: 3.18

Call meta-operations on CMake commands.

Synopsis
^^^^^^^^

 cmake_language(CALL <command> [<arg>...])
 cmake_language(EVAL CODE <code>...)
 cmake_language(DEFER <options>... CALL <command> [<arg>...])
 cmake_language(SET_DEPENDENCY_PROVIDER <command> SUPPORTED_METHODS <methods>...)
 cmake_language(GET_MESSAGE_LOG_LEVEL <out-var>)
 cmake_language(EXIT <exit-code>)

Introduction
^^^^^^^^^^^^

This command will call meta-operations on built-in CMake commands or
those created via the ``macro()`` or ``function()`` commands.

``cmake_language`` does not introduce a new variable or policy scope.

Calling Commands
^^^^^^^^^^^^^^^^

.. signature::
  cmake_language(CALL <command> [<arg>...])

  Calls the named ``<command>`` with the given arguments (if any).
  For example, the code:

  .. code-block:: cmake

    set(message_command "message")
    cmake_language(CALL ${message_command} STATUS "Hello World!")

  is equivalent to

  .. code-block:: cmake

    message(STATUS "Hello World!")

  .. note::
    To ensure consistency of the code, the following commands are not allowed:

    * ``if`` / ``elseif`` / ``else`` / ``endif``
    * ``block`` / ``endblock``
    * ``while`` / ``endwhile``
    * ``foreach`` / ``endforeach``
    * ``function`` / ``endfunction``
    * ``macro`` / ``endmacro``

Evaluating Code
^^^^^^^^^^^^^^^

.. signature::
  cmake_language(EVAL CODE <code>...)
  :target: EVAL

  Evaluates the ``<code>...`` as CMake code.

  For example, the code:

  .. code-block:: cmake

    set(A TRUE)
    set(B TRUE)
    set(C TRUE)
    set(condition "(A AND B) OR C")

    cmake_language(EVAL CODE "
      if (${condition})
        message(STATUS TRUE)
      else()
        message(STATUS FALSE)
      endif()"
    )

  is equivalent to

  .. code-block:: cmake

    set(A TRUE)
    set(B TRUE)
    set(C TRUE)
    set(condition "(A AND B) OR C")

    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/eval.cmake "
      if (${condition})
        message(STATUS TRUE)
      else()
        message(STATUS FALSE)
      endif()"
    )

    include(${CMAKE_CURRENT_BINARY_DIR}/eval.cmake)

Deferring Calls
^^^^^^^^^^^^^^^

.. versionadded:: 3.19

.. signature::
  cmake_language(DEFER <options>... CALL <command> [<arg>...])

  Schedules a call to the named ``<command>`` with the given arguments (if any)
  to occur at a later time.  By default, deferred calls are executed as if
  written at the end of the current directory's ``CMakeLists.txt`` file,
  except that they run even after a ``return()`` call.  Variable
  references in arguments are evaluated at the time the deferred call is
  executed.

  The options are:

  ``DIRECTORY <dir>``
    Schedule the call for the end of the given directory instead of the
    current directory.  The ``<dir>`` may reference either a source
    directory or its corresponding binary directory.  Relative paths are
    treated as relative to the current source directory.

    The given directory must be known to CMake, being either the top-level
    directory or one added by ``add_subdirectory()``.  Furthermore,
    the given directory must not yet be finished processing.  This means
    it can be the current directory or one of its ancestors.

  ``ID <id>``
    Specify an identification for the deferred call.
    The ``<id>`` may not be empty and may not begin with a capital letter ``A-Z``.
    The ``<id>`` may begin with an underscore (``_``) only if it was generated
    automatically by an earlier call that used ``ID_VAR`` to get the id.

  ``ID_VAR <var>``
    Specify a variable in which to store the identification for the
    deferred call.  If ``ID <id>`` is not given, a new identification
    will be generated and the generated id will start with an underscore (``_``).

  The currently scheduled list of deferred calls may be retrieved:

  .. code-block:: cmake

    cmake_language(DEFER [DIRECTORY <dir>] GET_CALL_IDS <var>)

  This will store in ``<var>`` a :ref:`semicolon-separated list <CMake Language
  Lists>` of deferred call ids.  The ids are for the directory scope in which
  the calls have been deferred to (i.e. where they will be executed), which can
  be different to the scope in which they were created.  The ``DIRECTORY``
  option can be used to specify the scope for which to retrieve the call ids.
  If that option is not given, the call ids for the current directory scope
  will be returned.

  Details of a specific call may be retrieved from its id:

  .. code-block:: cmake

    cmake_language(DEFER [DIRECTORY <dir>] GET_CALL <id> <var>)

  This will store in ``<var>`` a :ref:`semicolon-separated list <CMake Language
  Lists>` in which the first element is the name of the command to be
  called, and the remaining elements are its unevaluated arguments (any
  contained ``;`` characters are included literally and cannot be distinguished
  from multiple arguments).  If multiple calls are scheduled with the same id,
  this retrieves the first one.  If no call is scheduled with the given id in
  the specified ``DIRECTORY`` scope (or the current directory scope if no
  ``DIRECTORY`` option is given), this stores an empty string in the variable.

  Deferred calls may be canceled by their id:

  .. code-block:: cmake

    cmake_language(DEFER [DIRECTORY <dir>] CANCEL_CALL <id>...)

  This cancels all deferred calls matching any of the given ids in the specified
  ``DIRECTORY`` scope (or the current directory scope if no ``DIRECTORY`` option
  is given).  Unknown ids are silently ignored.

Deferred Call Examples
""""""""""""""""""""""

For example, the code:

 cmake_language(DEFER CALL message "${deferred_message}")
 cmake_language(DEFER ID_VAR id CALL message "Canceled Message")
 cmake_language(DEFER CANCEL_CALL ${id})
 message("Immediate Message")
 set(deferred_message "Deferred Message")

prints::

 Immediate Message
 Deferred Message

The ``Canceled Message`` is never printed because its command is
canceled.  The ``deferred_message`` variable reference is not evaluated
until the call site, so it can be set after the deferred call is scheduled.

In order to evaluate variable references immediately when scheduling a
deferred call, wrap it using ``cmake_language(EVAL)``.  However, note that
arguments will be re-evaluated in the deferred call, though that can be
avoided by using bracket arguments.  For example:

 set(deferred_message "Deferred Message 1")
 set(re_evaluated [[${deferred_message}]])
 cmake_language(EVAL CODE "
   cmake_language(DEFER CALL message [[${deferred_message}]])
   cmake_language(DEFER CALL message \"${re_evaluated}\")
 ")
 message("Immediate Message")
 set(deferred_message "Deferred Message 2")

also prints::

 Immediate Message
 Deferred Message 1
 Deferred Message 2

Dependency Providers
^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.24

.. note:: A high-level introduction to this feature can be found in the
          :ref:`Using Dependencies Guide <dependency_providers_overview>`.

.. signature::
  cmake_language(SET_DEPENDENCY_PROVIDER <command>
                 SUPPORTED_METHODS <methods>...)

  When a call is made to ``find_package()`` or
  ``FetchContent_MakeAvailable()``, the call may be forwarded to a
  dependency provider which then has the opportunity to fulfill the request.
  If the request is for one of the ``<methods>`` specified when the provider
  was set, CMake calls the provider's ``<command>`` with a set of
  method-specific arguments.  If the provider does not fulfill the request,
  or if the provider doesn't support the request's method, or no provider
  is set, the built-in ``find_package()`` or
  ``FetchContent_MakeAvailable()`` implementation is used to fulfill
  the request in the usual way.

  One or more of the following values can be specified for the ``<methods>``
  when setting the provider:

  ``FIND_PACKAGE``
    The provider command accepts ``find_package()`` requests.

  ``FETCHCONTENT_MAKEAVAILABLE_SERIAL``
    The provider command accepts ``FetchContent_MakeAvailable()``
    requests.  It expects each dependency to be fed to the provider command
    one at a time, not the whole list in one go.

  Only one provider can be set at any point in time.  If a provider is already
  set when ``cmake_language(SET_DEPENDENCY_PROVIDER)`` is called, the new
  provider replaces the previously set one.  The specified ``<command>`` must
  already exist when ``cmake_language(SET_DEPENDENCY_PROVIDER)`` is called.
  As a special case, providing an empty string for the ``<command>`` and no
  ``<methods>`` will discard any previously set provider.

  The dependency provider can only be set while processing one of the files
  specified by the ``CMAKE_PROJECT_TOP_LEVEL_INCLUDES`` variable.
  Thus, dependency providers can only be set as part of the first call to
  ``project()``.  Calling ``cmake_language(SET_DEPENDENCY_PROVIDER)``
  outside of that context will result in an error.

  .. versionadded:: 3.30
    The ``PROPAGATE_TOP_LEVEL_INCLUDES_TO_TRY_COMPILE`` global
    property can be set if the dependency provider also wants to be enabled
    in whole-project calls to ``try_compile()``.

  .. note::
    The choice of dependency provider should always be under the user's control.
    As a convenience, a project may choose to provide a file that users can
    list in their ``CMAKE_PROJECT_TOP_LEVEL_INCLUDES`` variable, but
    the use of such a file should always be the user's choice.

Provider commands
"""""""""""""""""

Providers define a single ``<command>`` to accept requests.  The name of
the command should be specific to that provider, not something overly
generic that another provider might also use.  This enables users to compose
different providers in their own custom provider.  The recommended form is
``xxx_provide_dependency()``, where ``xxx`` is the provider-specific part
(e.g. ``vcpkg_provide_dependency()``, ``conan_provide_dependency()``,
``ourcompany_provide_dependency()``, and so on).

 xxx_provide_dependency(<method> [<method-specific-args>...])

Because some methods expect certain variables to be set in the calling scope,
the provider command should typically be implemented as a macro rather than a
function.  This ensures it does not introduce a new variable scope.

The arguments CMake passes to the dependency provider depend on the type of
request.  The first argument is always the method, and it will only ever
be one of the ``<methods>`` that was specified when setting the provider.

``FIND_PACKAGE``
  The ``<method-specific-args>`` will be everything passed to the
  ``find_package()`` call that requested the dependency.  The first of
  these ``<method-specific-args>`` will therefore always be the name of the
  dependency.  Dependency names are case-sensitive for this method because
  ``find_package()`` treats them case-sensitively too.

  If the provider command fulfills the request, it must set the same variable
  that ``find_package()`` expects to be set.  For a dependency named
  ``depName``, the provider must set ``depName_FOUND`` to true if it fulfilled
  the request.  If the provider returns without setting this variable, CMake
  will assume the request was not fulfilled and will fall back to the
  built-in implementation.

  If the provider needs to call the built-in ``find_package()``
  implementation as part of its processing, it can do so by including the
  ``BYPASS_PROVIDER`` keyword as one of the arguments.

``FETCHCONTENT_MAKEAVAILABLE_SERIAL``
  The ``<method-specific-args>`` will be everything passed to the
  ``FetchContent_Declare()`` call that corresponds to the requested
  dependency, with the following exceptions:

  * If ``SOURCE_DIR`` or ``BINARY_DIR`` were not part of the original
    declared arguments, they will be added with their default values.
  * If ``FETCHCONTENT_TRY_FIND_PACKAGE_MODE`` is set to ``NEVER``,
    any ``FIND_PACKAGE_ARGS`` will be omitted.
  * The ``OVERRIDE_FIND_PACKAGE`` keyword is always omitted.

  The first of the ``<method-specific-args>`` will always be the name of the
  dependency.  Dependency names are case-insensitive for this method because
  ``FetchContent`` also treats them case-insensitively.

  If the provider fulfills the request, it should call
  ``FetchContent_SetPopulated()``, passing the name of the dependency as
  the first argument.  The ``SOURCE_DIR`` and ``BINARY_DIR`` arguments to that
  command should only be given if the provider makes the dependency's source
  and build directories available in exactly the same way as the built-in
  ``FetchContent_MakeAvailable()`` command.

  If the provider returns without calling ``FetchContent_SetPopulated()``
  for the named dependency, CMake will assume the request was not fulfilled
  and will fall back to the built-in implementation.

  Note that empty arguments may be significant for this method (e.g. an empty
  string following a ``GIT_SUBMODULES`` keyword).  Therefore, if forwarding
  these arguments on to another command, extra care must be taken to avoid such
  arguments being silently dropped.

  If ``FETCHCONTENT_SOURCE_DIR_<uppercaseDepName>`` is set, then the
  dependency provider will never see requests for the ``<depName>`` dependency
  for this method. When the user sets such a variable, they are explicitly
  overriding where to get that dependency from and are taking on the
  responsibility that their overriding version meets any requirements for that
  dependency and is compatible with whatever else in the project uses it.
  Depending on the value of ``FETCHCONTENT_TRY_FIND_PACKAGE_MODE``
  and whether the ``OVERRIDE_FIND_PACKAGE`` option was given to
  ``FetchContent_Declare()``, having
  ``FETCHCONTENT_SOURCE_DIR_<uppercaseDepName>`` set may also prevent the
  dependency provider from seeing requests for a ``find_package(depName)``
  call too.

Provider Examples
"""""""""""""""""

This first example only intercepts ``find_package()`` calls.  The
provider command runs an external tool which copies the relevant artifacts
into a provider-specific directory, if that tool knows about the dependency.
It then relies on the built-in implementation to then find those artifacts.
``FetchContent_MakeAvailable()`` calls would not go through the provider.

 :caption: mycomp_provider.cmake

 # Always ensure we have the policy settings this provider expects
 cmake_minimum_required(VERSION 3.24)

 set(MYCOMP_PROVIDER_INSTALL_DIR ${CMAKE_BINARY_DIR}/mycomp_packages
   CACHE PATH "The directory this provider installs packages to"
 )
 # Tell the built-in implementation to look in our area first, unless
 # the find_package() call uses NO_..._PATH options to exclude it
 list(APPEND CMAKE_MODULE_PATH ${MYCOMP_PROVIDER_INSTALL_DIR}/cmake)
 list(APPEND CMAKE_PREFIX_PATH ${MYCOMP_PROVIDER_INSTALL_DIR})

 macro(mycomp_provide_dependency method package_name)
   execute_process(
     COMMAND some_tool ${package_name} --installdir ${MYCOMP_PROVIDER_INSTALL_DIR}
     COMMAND_ERROR_IS_FATAL ANY
   )
 endmacro()

 cmake_language(
   SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
   SUPPORTED_METHODS FIND_PACKAGE
 )

The user would then typically use the above file like so::

 cmake -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=/path/to/mycomp_provider.cmake ...

The next example demonstrates a provider that accepts both methods, but
only handles one specific dependency.  It enforces providing Google Test
using ``FetchContent``, but leaves all other dependencies to be
fulfilled by CMake's built-in implementation.  It accepts a few different
names, which demonstrates one way of working around projects that hard-code
an unusual or undesirable way of adding this particular dependency to the
build.  The example also demonstrates how to use the ``list()`` command
to preserve variables that may be overwritten by a call to
``FetchContent_MakeAvailable()``.

 :caption: mycomp_provider.cmake

 cmake_minimum_required(VERSION 3.24)

 # Because we declare this very early, it will take precedence over any
 # details the project might declare later for the same thing
 include(FetchContent)
 FetchContent_Declare(
   googletest
   GIT_REPOSITORY https://github.com/google/googletest.git
   GIT_TAG        e2239ee6043f73722e7aa812a459f54a28552929 # release-1.11.0
 )

 # Both FIND_PACKAGE and FETCHCONTENT_MAKEAVAILABLE_SERIAL methods provide
 # the package or dependency name as the first method-specific argument.
 macro(mycomp_provide_dependency method dep_name)
   if("${dep_name}" MATCHES "^(gtest|googletest)$")
     # Save our current command arguments in case we are called recursively
     list(APPEND mycomp_provider_args ${method} ${dep_name})

     # This will forward to the built-in FetchContent implementation,
     # which detects a recursive call for the same thing and avoids calling
     # the provider again if dep_name is the same as the current call.
     FetchContent_MakeAvailable(googletest)

     # Restore our command arguments
     list(POP_BACK mycomp_provider_args dep_name method)

     # Tell the caller we fulfilled the request
     if("${method}" STREQUAL "FIND_PACKAGE")
       # We need to set this if we got here from a find_package() call
       # since we used a different method to fulfill the request.
       # This example assumes projects only use the gtest targets,
       # not any of the variables the FindGTest module may define.
       set(${dep_name}_FOUND TRUE)
     elseif(NOT "${dep_name}" STREQUAL "googletest")
       # We used the same method, but were given a different name to the
       # one we populated with. Tell the caller about the name it used.
       FetchContent_SetPopulated(${dep_name}
         SOURCE_DIR "${googletest_SOURCE_DIR}"
         BINARY_DIR "${googletest_BINARY_DIR}"
       )
     endif()
   endif()
 endmacro()

 cmake_language(
   SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
   SUPPORTED_METHODS
     FIND_PACKAGE
     FETCHCONTENT_MAKEAVAILABLE_SERIAL
 )

The final example demonstrates how to modify arguments to a
``find_package()`` call.  It forces all such calls to have the
``QUIET`` keyword.  It uses the ``BYPASS_PROVIDER`` keyword to prevent
calling the provider command recursively for the same dependency.

 :caption: mycomp_provider.cmake

 cmake_minimum_required(VERSION 3.24)

 macro(mycomp_provide_dependency method)
   find_package(${ARGN} BYPASS_PROVIDER QUIET)
 endmacro()

 cmake_language(
   SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
   SUPPORTED_METHODS FIND_PACKAGE
 )

Getting current message log level
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.25

.. signature::
  cmake_language(GET_MESSAGE_LOG_LEVEL <output_variable>)

  Writes the current ``message()`` logging level
  into the given ``<output_variable>``.

  See ``message()`` for the possible logging levels.

  The current message logging level can be set either using the
  :option:`--log-level <cmake --log-level>`
  command line option of the ``cmake(1)`` program or using
  the ``CMAKE_MESSAGE_LOG_LEVEL`` variable.

  If both the command line option and the variable are set, the command line
  option takes precedence. If neither are set, the default logging level
  is returned.

Terminating Scripts
^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.29

.. signature::
  cmake_language(EXIT <exit-code>)

  Terminate the current :option:`cmake -P` script and exit with ``<exit-code>``.

  This command works only in :ref:`script mode <Script Processing Mode>`.
  If used outside of that context, it will cause a fatal error.

  The ``<exit-code>`` should be non-negative.
  If ``<exit-code>`` is negative, then the behavior
  is unspecified (e.g., on Windows the error code -1
  becomes ``0xffffffff``, and on Linux it becomes 255).
  Exit codes above 255 may not be supported by the underlying
  shell or platform, and some shells may interpret values
  above 125 specially.  Therefore, it is advisable to only
  specify an ``<exit-code>`` in the range 0 to 125.

cmake_minimum_required
----------------------

Require a minimum version of cmake.

 cmake_minimum_required(VERSION <min>[...<policy_max>] [FATAL_ERROR])

.. versionadded:: 3.12
  The optional ``<policy_max>`` version.

Sets the minimum required version of cmake for a project.
Also updates the policy settings as explained below.

``<min>`` and the optional ``<policy_max>`` are each CMake versions of the
form ``major.minor[.patch[.tweak]]``, and the ``...`` is literal.

If the running version of CMake is lower than the ``<min>`` required
version it will stop processing the project and report an error.
The optional ``<policy_max>`` version, if specified, must be at least the
``<min>`` version and affects policy settings as described in Policy Settings.
If the running version of CMake is older than 3.12, the extra ``...``
dots will be seen as version component separators, resulting in the
``...<max>`` part being ignored and preserving the pre-3.12 behavior
of basing policies on ``<min>``.

This command will set the value of the
``CMAKE_MINIMUM_REQUIRED_VERSION`` variable to ``<min>``.

The ``FATAL_ERROR`` option is accepted but ignored by CMake 2.6 and
higher.  It should be specified so CMake versions 2.4 and lower fail
with an error instead of just a warning.

.. note::
  Call the ``cmake_minimum_required()`` command at the beginning of
  the top-level ``CMakeLists.txt`` file even before calling the
  ``project()`` command.  It is important to establish version
  and policy settings before invoking other commands whose behavior
  they may affect.  See also policy ``CMP0000``.

  Calling ``cmake_minimum_required()`` inside a ``function()``
  limits some effects to the function scope when invoked.  For example,
  the ``CMAKE_MINIMUM_REQUIRED_VERSION`` variable won't be set
  in the calling scope.  Functions do not introduce their own policy
  scope though, so policy settings of the caller *will* be affected
  (see below).  Due to this mix of things that do and do not affect the
  calling scope, calling ``cmake_minimum_required()`` inside a function
  is generally discouraged.

Policy Settings
^^^^^^^^^^^^^^^

The ``cmake_minimum_required(VERSION)`` command implicitly invokes the
``cmake_policy(VERSION)`` command to specify that the current
project code is written for the given range of CMake versions.
All policies known to the running version of CMake and introduced
in the ``<min>`` (or ``<max>``, if specified) version or earlier will
be set to use ``NEW`` behavior.  All policies introduced in later
versions will be unset.  This effectively requests behavior preferred
as of a given CMake version and tells newer CMake versions to warn
about their new policies.

When a ``<min>`` version higher than 2.4 is specified the command
implicitly invokes

 cmake_policy(VERSION <min>[...<max>])

which sets CMake policies based on the range of versions specified.
When a ``<min>`` version 2.4 or lower is given the command implicitly
invokes

 cmake_policy(VERSION 2.4[...<max>])

which enables compatibility features for CMake 2.4 and lower.

.. versionchanged:: 3.27

  Compatibility with versions of CMake older than 3.5 is deprecated.
  Calls to ``cmake_minimum_required(VERSION)`` or
  ``cmake_policy(VERSION)`` that do not specify at least
  3.5 as their policy version (optionally via ``...<max>``)
  will produce a deprecation warning in CMake 3.27 and above.

.. versionchanged:: 3.19

  Compatibility with versions of CMake older than 2.8.12 is deprecated.
  Calls to ``cmake_minimum_required(VERSION)`` or
  ``cmake_policy(VERSION)`` that do not specify at least
  2.8.12 as their policy version (optionally via ``...<max>``)
  will produce a deprecation warning in CMake 3.19 and above.

See Also
^^^^^^^^

* ``cmake_policy()``

cmake_parse_arguments
---------------------

Parse function or macro arguments.

 cmake_parse_arguments(<prefix> <options> <one_value_keywords>
                       <multi_value_keywords> <args>...)

 cmake_parse_arguments(PARSE_ARGV <N> <prefix> <options>
                       <one_value_keywords> <multi_value_keywords>)

.. versionadded:: 3.5
  This command is implemented natively.  Previously, it has been defined in the
  module ``CMakeParseArguments``.

This command is for use in macros or functions.
It processes the arguments given to that macro or function,
and defines a set of variables which hold the values of the
respective options.

The first signature reads processes arguments passed in the ``<args>...``.
This may be used in either a ``macro()`` or a ``function()``.

.. versionadded:: 3.7
  The ``PARSE_ARGV`` signature is only for use in a ``function()``
  body.  In this case the arguments that are parsed come from the
  ``ARGV#`` variables of the calling function.  The parsing starts with
  the ``<N>``-th argument, where ``<N>`` is an unsigned integer.
  This allows for the values to have special characters like ``;`` in them.

The ``<options>`` argument contains all options for the respective macro,
i.e.  keywords which can be used when calling the macro without any value
following, like e.g.  the ``OPTIONAL`` keyword of the ``install()``
command.

The ``<one_value_keywords>`` argument contains all keywords for this macro
which are followed by one value, like e.g. ``DESTINATION`` keyword of the
``install()`` command.

The ``<multi_value_keywords>`` argument contains all keywords for this
macro which can be followed by more than one value, like e.g. the
``TARGETS`` or ``FILES`` keywords of the ``install()`` command.

.. versionchanged:: 3.5
  All keywords shall be unique. I.e. every keyword shall only be specified
  once in either ``<options>``, ``<one_value_keywords>`` or
  ``<multi_value_keywords>``. A warning will be emitted if uniqueness is
  violated.

When done, ``cmake_parse_arguments`` will consider for each of the
keywords listed in ``<options>``, ``<one_value_keywords>`` and
``<multi_value_keywords>`` a variable composed of the given ``<prefix>``
followed by ``"_"`` and the name of the respective keyword.  These
variables will then hold the respective value from the argument list
or be undefined if the associated option could not be found.
For the ``<options>`` keywords, these will always be defined,
to ``TRUE`` or ``FALSE``, whether the option is in the argument list or not.

All remaining arguments are collected in a variable
``<prefix>_UNPARSED_ARGUMENTS`` that will be undefined if all arguments
were recognized. This can be checked afterwards to see
whether your macro was called with unrecognized parameters.

.. versionadded:: 3.15
   ``<one_value_keywords>`` and ``<multi_value_keywords>`` that were given no
   values at all are collected in a variable
   ``<prefix>_KEYWORDS_MISSING_VALUES`` that will be undefined if all keywords
   received values. This can be checked to see if there were keywords without
   any values given.

Consider the following example macro, ``my_install()``, which takes similar
arguments to the real ``install()`` command:

 macro(my_install)
     set(options OPTIONAL FAST)
     set(oneValueArgs DESTINATION RENAME)
     set(multiValueArgs TARGETS CONFIGURATIONS)
     cmake_parse_arguments(MY_INSTALL "${options}" "${oneValueArgs}"
                           "${multiValueArgs}" ${ARGN} )

     # ...

Assume ``my_install()`` has been called like this:

 my_install(TARGETS foo bar DESTINATION bin OPTIONAL blub CONFIGURATIONS)

After the ``cmake_parse_arguments`` call the macro will have set or undefined
the following variables::

 MY_INSTALL_OPTIONAL = TRUE
 MY_INSTALL_FAST = FALSE # was not used in call to my_install
 MY_INSTALL_DESTINATION = "bin"
 MY_INSTALL_RENAME <UNDEFINED> # was not used
 MY_INSTALL_TARGETS = "foo;bar"
 MY_INSTALL_CONFIGURATIONS <UNDEFINED> # was not used
 MY_INSTALL_UNPARSED_ARGUMENTS = "blub" # nothing expected after "OPTIONAL"
 MY_INSTALL_KEYWORDS_MISSING_VALUES = "CONFIGURATIONS"
          # No value for "CONFIGURATIONS" given

You can then continue and process these variables.

Keywords terminate lists of values, e.g. if directly after a
``one_value_keyword`` another recognized keyword follows, this is
interpreted as the beginning of the new option.  E.g.
``my_install(TARGETS foo DESTINATION OPTIONAL)`` would result in
``MY_INSTALL_DESTINATION`` set to ``"OPTIONAL"``, but as ``OPTIONAL``
is a keyword itself ``MY_INSTALL_DESTINATION`` will be empty (but added
to ``MY_INSTALL_KEYWORDS_MISSING_VALUES``) and ``MY_INSTALL_OPTIONAL`` will
therefore be set to ``TRUE``.

See Also
^^^^^^^^

* ``function()``
* ``macro()``

cmake_path
----------

.. versionadded:: 3.20

This command is for the manipulation of paths.  Only syntactic aspects of
paths are handled, there is no interaction of any kind with any underlying
file system.  The path may represent a non-existing path or even one that
is not allowed to exist on the current file system or platform.
For operations that do interact with the filesystem, see the ``file()``
command.

.. note::

  The ``cmake_path`` command handles paths in the format of the build system
  (i.e. the host platform), not the target system.  When cross-compiling,
  if the path contains elements that are not representable on the host
  platform (e.g. a drive letter when the host is not Windows), the results
  will be unpredictable.

Synopsis
^^^^^^^^

 Conventions

 Path Structure And Terminology

 Normalization

 Decomposition
   cmake_path(GET <path-var> :ref:`ROOT_NAME <GET_ROOT_NAME>` <out-var>)
   cmake_path(GET <path-var> :ref:`ROOT_DIRECTORY <GET_ROOT_DIRECTORY>` <out-var>)
   cmake_path(GET <path-var> :ref:`ROOT_PATH <GET_ROOT_PATH>` <out-var>)
   cmake_path(GET <path-var> :ref:`FILENAME <GET_FILENAME>` <out-var>)
   cmake_path(GET <path-var> :ref:`EXTENSION <GET_EXTENSION>` [LAST_ONLY] <out-var>)
   cmake_path(GET <path-var> :ref:`STEM <GET_STEM>` [LAST_ONLY] <out-var>)
   cmake_path(GET <path-var> :ref:`RELATIVE_PART <GET_RELATIVE_PART>` <out-var>)
   cmake_path(GET <path-var> :ref:`PARENT_PATH <GET_PARENT_PATH>` <out-var>)

 Query
   cmake_path(HAS_ROOT_NAME <path-var> <out-var>)
   cmake_path(HAS_ROOT_DIRECTORY <path-var> <out-var>)
   cmake_path(HAS_ROOT_PATH <path-var> <out-var>)
   cmake_path(HAS_FILENAME <path-var> <out-var>)
   cmake_path(HAS_EXTENSION <path-var> <out-var>)
   cmake_path(HAS_STEM <path-var> <out-var>)
   cmake_path(HAS_RELATIVE_PART <path-var> <out-var>)
   cmake_path(HAS_PARENT_PATH <path-var> <out-var>)
   cmake_path(IS_ABSOLUTE <path-var> <out-var>)
   cmake_path(IS_RELATIVE <path-var> <out-var>)
   cmake_path(IS_PREFIX <path-var> <input> [NORMALIZE] <out-var>)
   cmake_path(COMPARE <input1> <OP> <input2> <out-var>)

 Modification
   cmake_path(:ref:`SET <cmake_path-SET>` <path-var> [NORMALIZE] <input>)
   cmake_path(APPEND <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])
   cmake_path(APPEND_STRING <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])
   cmake_path(REMOVE_FILENAME <path-var> [OUTPUT_VARIABLE <out-var>])
   cmake_path(REPLACE_FILENAME <path-var> <input> [OUTPUT_VARIABLE <out-var>])
   cmake_path(REMOVE_EXTENSION <path-var> [LAST_ONLY] [OUTPUT_VARIABLE <out-var>])
   cmake_path(REPLACE_EXTENSION <path-var> [LAST_ONLY] <input> [OUTPUT_VARIABLE <out-var>])

 Generation
   cmake_path(NORMAL_PATH <path-var> [OUTPUT_VARIABLE <out-var>])
   cmake_path(RELATIVE_PATH <path-var> [BASE_DIRECTORY <input>] [OUTPUT_VARIABLE <out-var>])
   cmake_path(ABSOLUTE_PATH <path-var> [BASE_DIRECTORY <input>] [NORMALIZE] [OUTPUT_VARIABLE <out-var>])

 Native Conversion
   cmake_path(NATIVE_PATH <path-var> [NORMALIZE] <out-var>)
   cmake_path(CONVERT <input> TO_CMAKE_PATH_LIST <out-var> [NORMALIZE])
   cmake_path(CONVERT <input> TO_NATIVE_PATH_LIST <out-var> [NORMALIZE])

 Hashing
   cmake_path(HASH <path-var> <out-var>)

Conventions
^^^^^^^^^^^

The following conventions are used in this command's documentation:

``<path-var>``
  Always the name of a variable.  For commands that expect a ``<path-var>``
  as input, the variable must exist and it is expected to hold a single path.

``<input>``
  A string literal which may contain a path, path fragment, or multiple paths
  with a special separator depending on the command.  See the description of
  each command to see how this is interpreted.

``<input>...``
  Zero or more string literal arguments.

``<out-var>``
  The name of a variable into which the result of a command will be written.


Path Structure And Terminology
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

A path has the following structure (all components are optional, with some
constraints):

::

 root-name root-directory-separator (item-name directory-separator)* filename

``root-name``
  Identifies the root on a filesystem with multiple roots (such as ``"C:"``
  or ``"//myserver"``). It is optional.

``root-directory-separator``
  A directory separator that, if present, indicates that this path is
  absolute.  If it is missing and the first element other than the
  ``root-name`` is an ``item-name``, then the path is relative.

``item-name``
  A sequence of characters that aren't directory separators.  This name may
  identify a file, a hard link, a symbolic link, or a directory.  Two special
  cases are recognized:

    * The item name consisting of a single dot character ``.`` is a
      directory name that refers to the current directory.

    * The item name consisting of two dot characters ``..`` is a
      directory name that refers to the parent directory.

  The ``(...)*`` pattern shown above is to indicate that there can be zero
  or more item names, with multiple items separated by a
  ``directory-separator``.  The ``()*`` characters are not part of the path.

``directory-separator``
  The only recognized directory separator is a forward slash character ``/``.
  If this character is repeated, it is treated as a single directory
  separator.  In other words, ``/usr///////lib`` is the same as ``/usr/lib``.

``filename``
  A path has a ``filename`` if it does not end with a ``directory-separator``.
  The ``filename`` is effectively the last ``item-name`` of the path, so it
  can also be a hard link, symbolic link or a directory.

  A ``filename`` can have an *extension*.  By default, the extension is
  defined as the sub-string beginning at the left-most period (including
  the period) and until the end of the ``filename``.  In commands that
  accept a ``LAST_ONLY`` keyword, ``LAST_ONLY`` changes the interpretation
  to the sub-string beginning at the right-most period.

  The following exceptions apply to the above interpretation:

    * If the first character in the ``filename`` is a period, that period is
      ignored (i.e. a ``filename`` like ``".profile"`` is treated as having
      no extension).

    * If the ``filename`` is either ``.`` or ``..``, it has no extension.

  The *stem* is the part of the ``filename`` before the extension.

Some commands refer to a ``root-path``.  This is the concatenation of
``root-name`` and ``root-directory-separator``, either or both of which can
be empty.  A ``relative-part`` refers to the full path with any ``root-path``
removed.


Creating A Path Variable
^^^^^^^^^^^^^^^^^^^^^^^^

While a path can be created with care using an ordinary ``set()``
command, it is recommended to use :ref:`cmake_path(SET) <cmake_path-SET>`
instead, as it automatically converts the path to the required form where
required.  The :ref:`cmake_path(APPEND) <APPEND>` subcommand may
be another suitable alternative where a path needs to be constructed by
joining fragments.  The following example compares the three methods for
constructing the same path:

 set(path1 "${CMAKE_CURRENT_SOURCE_DIR}/data")

 cmake_path(SET path2 "${CMAKE_CURRENT_SOURCE_DIR}/data")

 cmake_path(APPEND path3 "${CMAKE_CURRENT_SOURCE_DIR}" "data")

Modification and Generation sub-commands can either store the result
in-place, or in a separate variable named after an ``OUTPUT_VARIABLE``
keyword.  All other sub-commands store the result in a mandatory ``<out-var>``
variable.

Normalization
^^^^^^^^^^^^^

Some sub-commands support *normalizing* a path.  The algorithm used to
normalize a path is as follows:

1. If the path is empty, stop (the normalized form of an empty path is
   also an empty path).
2. Replace each ``directory-separator``, which may consist of multiple
   separators, with a single ``/`` (``/a///b  --> /a/b``).
3. Remove each solitary period (``.``) and any immediately following
   ``directory-separator`` (``/a/./b/. --> /a/b``).
4. Remove each ``item-name`` (other than ``..``) that is immediately
   followed by a ``directory-separator`` and a ``..``, along with any
   immediately following ``directory-separator`` (``/a/b/../c --> a/c``).
5. If there is a ``root-directory``, remove any ``..`` and any
   ``directory-separators`` immediately following them.  The parent of the
   root directory is treated as still the root directory (``/../a --> /a``).
6. If the last ``item-name`` is ``..``, remove any trailing
   ``directory-separator`` (``../ --> ..``).
7. If the path is empty by this stage, add a ``dot`` (normal form of ``./``
   is ``.``).


Decomposition
^^^^^^^^^^^^^

The following forms of the ``GET`` subcommand each retrieve a different
component or group of components from a path.  See
Path Structure And Terminology for the meaning of each path component.

 cmake_path(GET <path-var> ROOT_NAME <out-var>)
 cmake_path(GET <path-var> ROOT_DIRECTORY <out-var>)
 cmake_path(GET <path-var> ROOT_PATH <out-var>)
 cmake_path(GET <path-var> FILENAME <out-var>)
 cmake_path(GET <path-var> EXTENSION [LAST_ONLY] <out-var>)
 cmake_path(GET <path-var> STEM [LAST_ONLY] <out-var>)
 cmake_path(GET <path-var> RELATIVE_PART <out-var>)
 cmake_path(GET <path-var> PARENT_PATH <out-var>)

If a requested component is not present in the path, an empty string will be
stored in ``<out-var>``.  For example, only Windows systems have the concept
of a ``root-name``, so when the host machine is non-Windows, the ``ROOT_NAME``
subcommand will always return an empty string.

For ``PARENT_PATH``, if the HAS_RELATIVE_PART subcommand returns false,
the result is a copy of ``<path-var>``.  Note that this implies that a root
directory is considered to have a parent, with that parent being itself.
Where HAS_RELATIVE_PART returns true, the result will essentially be
``<path-var>`` with one less element.

Root examples
"""""""""""""

 set(path "c:/a")

 cmake_path(GET path ROOT_NAME rootName)
 cmake_path(GET path ROOT_DIRECTORY rootDir)
 cmake_path(GET path ROOT_PATH rootPath)

 message("Root name is \"${rootName}\"")
 message("Root directory is \"${rootDir}\"")
 message("Root path is \"${rootPath}\"")

::

 Root name is "c:"
 Root directory is "/"
 Root path is "c:/"

Filename examples
"""""""""""""""""

 set(path "/a/b")
 cmake_path(GET path FILENAME filename)
 message("First filename is \"${filename}\"")

 # Trailing slash means filename is empty
 set(path "/a/b/")
 cmake_path(GET path FILENAME filename)
 message("Second filename is \"${filename}\"")

::

 First filename is "b"
 Second filename is ""

Extension and stem examples
"""""""""""""""""""""""""""

 set(path "name.ext1.ext2")

 cmake_path(GET path EXTENSION fullExt)
 cmake_path(GET path STEM fullStem)
 message("Full extension is \"${fullExt}\"")
 message("Full stem is \"${fullStem}\"")

 # Effect of LAST_ONLY
 cmake_path(GET path EXTENSION LAST_ONLY lastExt)
 cmake_path(GET path STEM LAST_ONLY lastStem)
 message("Last extension is \"${lastExt}\"")
 message("Last stem is \"${lastStem}\"")

 # Special cases
 set(dotPath "/a/.")
 set(dotDotPath "/a/..")
 set(someMorePath "/a/.some.more")
 cmake_path(GET dotPath EXTENSION dotExt)
 cmake_path(GET dotPath STEM dotStem)
 cmake_path(GET dotDotPath EXTENSION dotDotExt)
 cmake_path(GET dotDotPath STEM dotDotStem)
 cmake_path(GET dotMorePath EXTENSION someMoreExt)
 cmake_path(GET dotMorePath STEM someMoreStem)
 message("Dot extension is \"${dotExt}\"")
 message("Dot stem is \"${dotStem}\"")
 message("Dot-dot extension is \"${dotDotExt}\"")
 message("Dot-dot stem is \"${dotDotStem}\"")
 message(".some.more extension is \"${someMoreExt}\"")
 message(".some.more stem is \"${someMoreStem}\"")

::

 Full extension is ".ext1.ext2"
 Full stem is "name"
 Last extension is ".ext2"
 Last stem is "name.ext1"
 Dot extension is ""
 Dot stem is "."
 Dot-dot extension is ""
 Dot-dot stem is ".."
 .some.more extension is ".more"
 .some.more stem is ".some"

Relative part examples
""""""""""""""""""""""

 set(path "c:/a/b")
 cmake_path(GET path RELATIVE_PART result)
 message("Relative part is \"${result}\"")

 set(path "c/d")
 cmake_path(GET path RELATIVE_PART result)
 message("Relative part is \"${result}\"")

 set(path "/")
 cmake_path(GET path RELATIVE_PART result)
 message("Relative part is \"${result}\"")

::

 Relative part is "a/b"
 Relative part is "c/d"
 Relative part is ""

Path traversal examples
"""""""""""""""""""""""

 set(path "c:/a/b")
 cmake_path(GET path PARENT_PATH result)
 message("Parent path is \"${result}\"")

 set(path "c:/")
 cmake_path(GET path PARENT_PATH result)
 message("Parent path is \"${result}\"")

::

 Parent path is "c:/a"
 Parent path is "c:/"

Query
^^^^^

Each of the ``GET`` subcommands has a corresponding ``HAS_...``
subcommand which can be used to discover whether a particular path
component is present.  See Path Structure And Terminology for the
meaning of each path component.

 cmake_path(HAS_ROOT_NAME <path-var> <out-var>)
 cmake_path(HAS_ROOT_DIRECTORY <path-var> <out-var>)
 cmake_path(HAS_ROOT_PATH <path-var> <out-var>)
 cmake_path(HAS_FILENAME <path-var> <out-var>)
 cmake_path(HAS_EXTENSION <path-var> <out-var>)
 cmake_path(HAS_STEM <path-var> <out-var>)
 cmake_path(HAS_RELATIVE_PART <path-var> <out-var>)
 cmake_path(HAS_PARENT_PATH <path-var> <out-var>)

Each of the above follows the predictable pattern of setting ``<out-var>``
to true if the path has the associated component, or false otherwise.
Note the following special cases:

* For ``HAS_ROOT_PATH``, a true result will only be returned if at least one
  of ``root-name`` or ``root-directory`` is non-empty.

* For ``HAS_PARENT_PATH``, the root directory is also considered to have a
  parent, which will be itself.  The result is true except if the path
  consists of just a :ref:`filename <FILENAME_DEF>`.

 cmake_path(IS_ABSOLUTE <path-var> <out-var>)

Sets ``<out-var>`` to true if ``<path-var>`` is absolute.  An absolute path
is a path that unambiguously identifies the location of a file without
reference to an additional starting location.  On Windows, this means the
path must have both a ``root-name`` and a ``root-directory-separator`` to be
considered absolute.  On other platforms, just a ``root-directory-separator``
is sufficient.  Note that this means on Windows, ``IS_ABSOLUTE`` can be
false while ``HAS_ROOT_DIRECTORY`` can be true.

 cmake_path(IS_RELATIVE <path-var> <out-var>)

This will store the opposite of ``IS_ABSOLUTE`` in ``<out-var>``.

 cmake_path(IS_PREFIX <path-var> <input> [NORMALIZE] <out-var>)

Checks if ``<path-var>`` is the prefix of ``<input>``.

When the ``NORMALIZE`` option is specified, ``<path-var>`` and ``<input>``
are :ref:`normalized <Normalization>` before the check.

 set(path "/a/b/c")
 cmake_path(IS_PREFIX path "/a/b/c/d" result) # result = true
 cmake_path(IS_PREFIX path "/a/b" result)     # result = false
 cmake_path(IS_PREFIX path "/x/y/z" result)   # result = false

 set(path "/a/b")
 cmake_path(IS_PREFIX path "/a/c/../b" NORMALIZE result)   # result = true

 cmake_path(COMPARE <input1> EQUAL <input2> <out-var>)
 cmake_path(COMPARE <input1> NOT_EQUAL <input2> <out-var>)

Compares the lexical representations of two paths provided as string literals.
No normalization is performed on either path, except multiple consecutive
directory separators are effectively collapsed into a single separator.
Equality is determined according to the following pseudo-code logic:

::

 if(NOT <input1>.root_name() STREQUAL <input2>.root_name())
   return FALSE

 if(<input1>.has_root_directory() XOR <input2>.has_root_directory())
   return FALSE

 Return FALSE if a relative portion of <input1> is not lexicographically
 equal to the relative portion of <input2>. This comparison is performed path
 component-wise. If all of the components compare equal, then return TRUE.

.. note::
  Unlike most other ``cmake_path()`` subcommands, the ``COMPARE`` subcommand
  takes literal strings as input, not the names of variables.


Modification
^^^^^^^^^^^^

 cmake_path(SET <path-var> [NORMALIZE] <input>)

Assign the ``<input>`` path to ``<path-var>``.  If ``<input>`` is a native
path, it is converted into a cmake-style path with forward-slashes
(``/``). On Windows, the long filename marker is taken into account.

When the ``NORMALIZE`` option is specified, the path is :ref:`normalized
<Normalization>` after the conversion.

For example:

 set(native_path "c:\\a\\b/..\\c")
 cmake_path(SET path "${native_path}")
 message("CMake path is \"${path}\"")

 cmake_path(SET path NORMALIZE "${native_path}")
 message("Normalized CMake path is \"${path}\"")

Output::

 CMake path is "c:/a/b/../c"
 Normalized CMake path is "c:/a/c"

 cmake_path(APPEND <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])

Append all the ``<input>`` arguments to the ``<path-var>`` using ``/`` as
the ``directory-separator``.  Depending on the ``<input>``, the previous
contents of ``<path-var>`` may be discarded.  For each ``<input>`` argument,
the following algorithm (pseudo-code) applies:

::

 # <path> is the contents of <path-var>

 if(<input>.is_absolute() OR
    (<input>.has_root_name() AND
     NOT <input>.root_name() STREQUAL <path>.root_name()))
   replace <path> with <input>
   return()
 endif()

 if(<input>.has_root_directory())
   remove any root-directory and the entire relative path from <path>
 elseif(<path>.has_filename() OR
        (NOT <path-var>.has_root_directory() OR <path>.is_absolute()))
   append directory-separator to <path>
 endif()

 append <input> omitting any root-name to <path>

 cmake_path(APPEND_STRING <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])

Append all the ``<input>`` arguments to the ``<path-var>`` without adding any
``directory-separator``.

 cmake_path(REMOVE_FILENAME <path-var> [OUTPUT_VARIABLE <out-var>])

Removes the :ref:`filename <FILENAME_DEF>` component (as returned by
:ref:`GET ... FILENAME <GET_FILENAME>`) from ``<path-var>``.  After removal,
any trailing ``directory-separator`` is left alone, if present.

If ``OUTPUT_VARIABLE`` is not given, then after this function returns,
HAS_FILENAME returns false for ``<path-var>``.

For example:

 set(path "/a/b")
 cmake_path(REMOVE_FILENAME path)
 message("First path is \"${path}\"")

 # filename is now already empty, the following removes nothing
 cmake_path(REMOVE_FILENAME path)
 message("Second path is \"${path}\"")

Output::

 First path is "/a/"
 Second path is "/a/"

 cmake_path(REPLACE_FILENAME <path-var> <input> [OUTPUT_VARIABLE <out-var>])

Replaces the :ref:`filename <FILENAME_DEF>` component from ``<path-var>``
with ``<input>``.  If ``<path-var>`` has no filename component (i.e.
HAS_FILENAME returns false), the path is unchanged.  The operation is
equivalent to the following:

 cmake_path(HAS_FILENAME path has_filename)
 if(has_filename)
   cmake_path(REMOVE_FILENAME path)
   cmake_path(APPEND path input);
 endif()

 cmake_path(REMOVE_EXTENSION <path-var> [LAST_ONLY]
                                        [OUTPUT_VARIABLE <out-var>])

Removes the :ref:`extension <EXTENSION_DEF>`, if any, from ``<path-var>``.

 cmake_path(REPLACE_EXTENSION <path-var> [LAST_ONLY] <input>
                              [OUTPUT_VARIABLE <out-var>])

Replaces the :ref:`extension <EXTENSION_DEF>` with ``<input>``.  Its effect
is equivalent to the following:

 cmake_path(REMOVE_EXTENSION path)
 if(NOT "input" MATCHES "^\\.")
   cmake_path(APPEND_STRING path ".")
 endif()
 cmake_path(APPEND_STRING path "input")

Generation
^^^^^^^^^^

 cmake_path(NORMAL_PATH <path-var> [OUTPUT_VARIABLE <out-var>])

Normalize ``<path-var>`` according the steps described in :ref:`Normalization`.

 cmake_path(RELATIVE_PATH <path-var> [BASE_DIRECTORY <input>]
                                     [OUTPUT_VARIABLE <out-var>])

Modifies ``<path-var>`` to make it relative to the ``BASE_DIRECTORY`` argument.
If ``BASE_DIRECTORY`` is not specified, the default base directory will be
``CMAKE_CURRENT_SOURCE_DIR``.

For reference, the algorithm used to compute the relative path is the same
as that used by C++
`std::filesystem::path::lexically_relative
<https://en.cppreference.com/w/cpp/filesystem/path/lexically_normal>`_.

 cmake_path(ABSOLUTE_PATH <path-var> [BASE_DIRECTORY <input>] [NORMALIZE]
                                     [OUTPUT_VARIABLE <out-var>])

If ``<path-var>`` is a relative path (IS_RELATIVE is true), it is evaluated
relative to the given base directory specified by ``BASE_DIRECTORY`` option.
If ``BASE_DIRECTORY`` is not specified, the default base directory will be
``CMAKE_CURRENT_SOURCE_DIR``.

When the ``NORMALIZE`` option is specified, the path is :ref:`normalized
<Normalization>` after the path computation.

Because ``cmake_path()`` does not access the filesystem, symbolic links are
not resolved and any leading tilde is not expanded.  To compute a real path
with symbolic links resolved and leading tildes expanded, use the
``file(REAL_PATH)`` command instead.

Native Conversion
^^^^^^^^^^^^^^^^^

For commands in this section, *native* refers to the host platform, not the
target platform when cross-compiling.

 cmake_path(NATIVE_PATH <path-var> [NORMALIZE] <out-var>)

Converts a cmake-style ``<path-var>`` into a native path with
platform-specific slashes (``\`` on Windows hosts and ``/`` elsewhere).

When the ``NORMALIZE`` option is specified, the path is :ref:`normalized
<Normalization>` before the conversion.

 cmake_path(CONVERT <input> TO_CMAKE_PATH_LIST <out-var> [NORMALIZE])

Converts a native ``<input>`` path into a cmake-style path with forward
slashes (``/``).  On Windows hosts, the long filename marker is taken into
account.  The input can be a single path or a system search path like
``$ENV{PATH}``.  A search path will be converted to a cmake-style list
separated by ``;`` characters (on non-Windows platforms, this essentially
means ``:`` separators are replaced with ``;``).  The result of the
conversion is stored in the ``<out-var>`` variable.

When the ``NORMALIZE`` option is specified, the path is :ref:`normalized
<Normalization>` before the conversion.

.. note::
  Unlike most other ``cmake_path()`` subcommands, the ``CONVERT`` subcommand
  takes a literal string as input, not the name of a variable.

 cmake_path(CONVERT <input> TO_NATIVE_PATH_LIST <out-var> [NORMALIZE])

Converts a cmake-style ``<input>`` path into a native path with
platform-specific slashes (``\`` on Windows hosts and ``/`` elsewhere).
The input can be a single path or a cmake-style list.  A list will be
converted into a native search path (``;``-separated on Windows,
``:``-separated on other platforms).  The result of the conversion is
stored in the ``<out-var>`` variable.

When the ``NORMALIZE`` option is specified, the path is :ref:`normalized
<Normalization>` before the conversion.

.. note::
  Unlike most other ``cmake_path()`` subcommands, the ``CONVERT`` subcommand
  takes a literal string as input, not the name of a variable.

For example:

 set(paths "/a/b/c" "/x/y/z")
 cmake_path(CONVERT "${paths}" TO_NATIVE_PATH_LIST native_paths)
 message("Native path list is \"${native_paths}\"")

Output on Windows::

 Native path list is "\a\b\c;\x\y\z"

Output on all other platforms::

 Native path list is "/a/b/c:/x/y/z"

Hashing
^^^^^^^

 cmake_path(HASH <path-var> <out-var>)

Compute a hash value of ``<path-var>`` such that for two paths ``p1`` and
``p2`` that compare equal (:ref:`COMPARE ... EQUAL <COMPARE>`), the hash
value of ``p1`` is equal to the hash value of ``p2``.  The path is always
:ref:`normalized <Normalization>` before the hash is computed.

cmake_policy
------------

Manage CMake Policy settings.  See the ``cmake-policies(7)``
manual for defined policies.

As CMake evolves it is sometimes necessary to change existing behavior
in order to fix bugs or improve implementations of existing features.
The CMake Policy mechanism is designed to help keep existing projects
building as new versions of CMake introduce changes in behavior.  Each
new policy (behavioral change) is given an identifier of the form
``CMP<NNNN>`` where ``<NNNN>`` is an integer index.  Documentation
associated with each policy describes the ``OLD`` and ``NEW`` behavior
and the reason the policy was introduced.  Projects may set each policy
to select the desired behavior.  When CMake needs to know which behavior
to use it checks for a setting specified by the project.  If no
setting is available the ``OLD`` behavior is assumed and a warning is
produced requesting that the policy be set.

Setting Policies by CMake Version
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``cmake_policy`` command is used to set policies to ``OLD`` or ``NEW``
behavior.  While setting policies individually is supported, we
encourage projects to set policies based on CMake versions:

.. signature:: cmake_policy(VERSION <min>[...<max>])
  :target: VERSION

.. versionadded:: 3.12
  The optional ``<max>`` version.

``<min>`` and the optional ``<max>`` are each CMake versions of the form
``major.minor[.patch[.tweak]]``, and the ``...`` is literal.  The ``<min>``
version must be at least ``2.4`` and at most the running version of CMake.
The ``<max>`` version, if specified, must be at least the ``<min>`` version
but may exceed the running version of CMake.  If the running version of
CMake is older than 3.12, the extra ``...`` dots will be seen as version
component separators, resulting in the ``...<max>`` part being ignored and
preserving the pre-3.12 behavior of basing policies on ``<min>``.

This specifies that the current CMake code is written for the given
range of CMake versions.  All policies known to the running version of CMake
and introduced in the ``<min>`` (or ``<max>``, if specified) version
or earlier will be set to use ``NEW`` behavior.  All policies
introduced in later versions will be unset (unless the
``CMAKE_POLICY_DEFAULT_CMP<NNNN>`` variable sets a default).
This effectively requests behavior preferred as of a given CMake
version and tells newer CMake versions to warn about their new policies.

Note that the ``cmake_minimum_required(VERSION)``
command implicitly calls ``cmake_policy(VERSION)`` too.

.. versionchanged:: 3.27

  Compatibility with versions of CMake older than 3.5 is deprecated.
  Calls to ``cmake_minimum_required(VERSION)`` or
  ``cmake_policy(VERSION)`` that do not specify at least
  3.5 as their policy version (optionally via ``...<max>``)
  will produce a deprecation warning in CMake 3.27 and above.

.. versionchanged:: 3.19

  Compatibility with versions of CMake older than 2.8.12 is deprecated.
  Calls to ``cmake_minimum_required(VERSION)`` or
  ``cmake_policy(VERSION)`` that do not specify at least
  2.8.12 as their policy version (optionally via ``...<max>``)
  will produce a deprecation warning in CMake 3.19 and above.

Setting Policies Explicitly
^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. signature:: cmake_policy(SET CMP<NNNN> NEW|OLD)
  :target: SET

Tell CMake to use the ``OLD`` or ``NEW`` behavior for a given policy.
Projects depending on the old behavior of a given policy may silence a
policy warning by setting the policy state to ``OLD``.  Alternatively
one may fix the project to work with the new behavior and set the
policy state to ``NEW``.

.. note::
  The ``OLD`` behavior of a policy is
  ``deprecated by definition``
  and may be removed in a future version of CMake.

Checking Policy Settings
^^^^^^^^^^^^^^^^^^^^^^^^

.. signature:: cmake_policy(GET CMP<NNNN> <variable>)
  :target: GET

Check whether a given policy is set to ``OLD`` or ``NEW`` behavior.
The output ``<variable>`` value will be ``OLD`` or ``NEW`` if the
policy is set, and empty otherwise.

CMake Policy Stack
^^^^^^^^^^^^^^^^^^

CMake keeps policy settings on a stack, so changes made by the
``cmake_policy`` command affect only the top of the stack.  A new entry on
the policy stack is managed automatically for each subdirectory to
protect its parents and siblings.  CMake also manages a new entry for
scripts loaded by ``include()`` and ``find_package()`` commands
except when invoked with the ``NO_POLICY_SCOPE`` option
(see also policy ``CMP0011``).
The ``cmake_policy`` command provides an interface to manage custom
entries on the policy stack:

.. signature:: cmake_policy(PUSH)
  :target: PUSH

  Create a new entry on the policy stack.

.. signature:: cmake_policy(POP)
  :target: POP

  Remove the last policy stack entry created with ``cmake_policy(PUSH)``.

Each ``PUSH`` must have a matching ``POP`` to erase any changes.
This is useful to make temporary changes to policy settings.
Calls to the ``cmake_minimum_required(VERSION)``,
``cmake_policy(VERSION)``, or ``cmake_policy(SET)`` commands
influence only the current top of the policy stack.

.. versionadded:: 3.25
  The ``block(SCOPE_FOR POLICIES)`` command offers a more flexible
  and more secure way to manage the policy stack. The pop action is done
  automatically when leaving the block scope, so there is no need to
  precede each ``return()`` with a call to ``cmake_policy(POP)``.

  .. code-block:: cmake

    # stack management with cmake_policy()
    function(my_func)
      cmake_policy(PUSH)
      cmake_policy(SET ...)
      if (<cond1>)
        ...
        cmake_policy(POP)
        return()
      elseif(<cond2>)
        ...
        cmake_policy(POP)
        return()
      endif()
      ...
      cmake_policy(POP)
    endfunction()

    # stack management with block()/endblock()
    function(my_func)
      block(SCOPE_FOR POLICIES)
        cmake_policy(SET ...)
        if (<cond1>)
          ...
          return()
        elseif(<cond2>)
          ...
          return()
        endif()
        ...
      endblock()
    endfunction()

Commands created by the ``function()`` and ``macro()``
commands record policy settings when they are created and
use the pre-record policies when they are invoked.  If the function or
macro implementation sets policies, the changes automatically
propagate up through callers until they reach the closest nested
policy stack entry.

See Also
^^^^^^^^

* ``cmake_minimum_required()``

configure_file
--------------

Copy a file to another location and modify its contents.

 configure_file(<input> <output>
                [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS |
                 FILE_PERMISSIONS <permissions>...]
                [COPYONLY] [ESCAPE_QUOTES] [@ONLY]
                [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

Copies an ``<input>`` file to an ``<output>`` file while performing
transformations of the input file content.

If the input file is modified the build system will re-run CMake to
re-configure the file and generate the build system again.
The generated file is modified and its timestamp updated on subsequent
cmake runs only if its content is changed.

Options
^^^^^^^

The options are:

``<input>``
  Path to the input file.  A relative path is treated with respect to
  the value of ``CMAKE_CURRENT_SOURCE_DIR``.  The input path
  must be a file, not a directory.

``<output>``
  Path to the output file or directory.  A relative path is treated
  with respect to the value of ``CMAKE_CURRENT_BINARY_DIR``.
  If the path names an existing directory the output file is placed
  in that directory with the same file name as the input file.
  If the path contains non-existent directories, they are created.

``NO_SOURCE_PERMISSIONS``
  .. versionadded:: 3.19

  Do not transfer the permissions of the input file to the output file.
  The copied file permissions default to the standard 644 value
  (-rw-r--r--).

``USE_SOURCE_PERMISSIONS``
  .. versionadded:: 3.20

  Transfer the permissions of the input file to the output file.
  This is already the default behavior if none of the three permissions-related
  keywords are given (``NO_SOURCE_PERMISSIONS``, ``USE_SOURCE_PERMISSIONS``
  or ``FILE_PERMISSIONS``).  The ``USE_SOURCE_PERMISSIONS`` keyword mostly
  serves as a way of making the intended behavior clearer at the call site.

``FILE_PERMISSIONS <permissions>...``
  .. versionadded:: 3.20

  Ignore the input file's permissions and use the specified ``<permissions>``
  for the output file instead.

``COPYONLY``
  Copy the file without replacing any variable references or other
  content.  This option may not be used with ``NEWLINE_STYLE``.

``ESCAPE_QUOTES``
  Escape any substituted quotes with backslashes (C-style).

``@ONLY``
  Restrict variable replacement to references of the form ``@VAR@``.
  This is useful for configuring scripts that use ``${VAR}`` syntax.

``NEWLINE_STYLE <style>``
  Specify the newline style for the output file.  Specify
  ``UNIX`` or ``LF`` for ``\n`` newlines, or specify
  ``DOS``, ``WIN32``, or ``CRLF`` for ``\r\n`` newlines.
  This option may not be used with ``COPYONLY``.

Transformations
^^^^^^^^^^^^^^^

:ref:`Variables <CMake Language Variables>` referenced in the input
file content as ``@VAR@``, ``${VAR}``, ``$CACHE{VAR}``, and
:ref:`environment variables <CMake Language Environment Variables>`
referenced as ``$ENV{VAR}``, will each be replaced with the current value
of the variable, or the empty string if the variable is not defined.
Furthermore, input lines of the form

 #cmakedefine VAR ...

will be replaced with either

 #define VAR ...

or

 /* #undef VAR */

depending on whether ``VAR`` is set in CMake to any value not considered
a false constant by the ``if()`` command.  The "..." content on the
line after the variable name, if any, is processed as above.

Unlike lines of the form ``#cmakedefine VAR ...``, in lines of the form
``#cmakedefine01 VAR``, ``VAR`` itself will expand to ``VAR 0`` or ``VAR 1``
rather than being assigned the value ``...``. Therefore, input lines of the form

 #cmakedefine01 VAR

will be replaced with either

 #define VAR 0

or

 #define VAR 1

Input lines of the form ``#cmakedefine01 VAR ...`` will expand
as ``#cmakedefine01 VAR ... 0`` or ``#cmakedefine01 VAR ... 1``,
which may lead to undefined behavior.

.. versionadded:: 3.10
  The result lines (with the exception of the ``#undef`` comments) can be
  indented using spaces and/or tabs between the ``#`` character
  and the ``cmakedefine`` or ``cmakedefine01`` words. This whitespace
  indentation will be preserved in the output lines:

  .. code-block:: c

    #  cmakedefine VAR
    #  cmakedefine01 VAR

  will be replaced, if ``VAR`` is defined, with

  .. code-block:: c

    #  define VAR
    #  define VAR 1

Example
^^^^^^^

Consider a source tree containing a ``foo.h.in`` file:

 #cmakedefine FOO_ENABLE
 #cmakedefine FOO_STRING "@FOO_STRING@"

An adjacent ``CMakeLists.txt`` may use ``configure_file`` to
configure the header:

 option(FOO_ENABLE "Enable Foo" ON)
 if(FOO_ENABLE)
   set(FOO_STRING "foo")
 endif()
 configure_file(foo.h.in foo.h @ONLY)

This creates a ``foo.h`` in the build directory corresponding to
this source directory.  If the ``FOO_ENABLE`` option is on, the
configured file will contain:

 #define FOO_ENABLE
 #define FOO_STRING "foo"

Otherwise it will contain:

 /* #undef FOO_ENABLE */
 /* #undef FOO_STRING */

One may then use the ``target_include_directories()`` command to
specify the output directory as an include directory:

 target_include_directories(<target> [SYSTEM] <INTERFACE|PUBLIC|PRIVATE> "${CMAKE_CURRENT_BINARY_DIR}")

so that sources may include the header as ``#include <foo.h>``.

See Also
^^^^^^^^

* ``file(GENERATE)``

continue
--------

.. versionadded:: 3.2

Continue to the top of enclosing foreach or while loop.

 continue()

The ``continue()`` command allows a cmake script to abort the rest of the
current iteration of a ``foreach()`` or ``while()`` loop, and start
at the top of the next iteration.

See also the ``break()`` command.

else
----

Starts the else portion of an if block.

 else([<condition>])

See the ``if()`` command.

elseif
------

Starts an elseif portion of an if block.

 elseif(<condition>)

See the ``if()`` command, especially for the syntax and logic
of the ``<condition>``.

endblock
--------

.. versionadded:: 3.25

Ends a list of commands in a ``block()`` and removes the scopes
created by the ``block()`` command.

 endblock()

endforeach
----------

Ends a list of commands in a foreach block.

 endforeach([<loop_var>])

See the ``foreach()`` command.

The optional ``<loop_var>`` argument is supported for backward compatibility
only. If used it must be a verbatim repeat of the ``<loop_var>`` argument of
the opening ``foreach`` clause.

endfunction
-----------

Ends a list of commands in a function block.

 endfunction([<name>])

See the ``function()`` command.

The optional ``<name>`` argument is supported for backward compatibility
only. If used it must be a verbatim repeat of the ``<name>`` argument
of the opening ``function`` command.

endif
-----

Ends a list of commands in an if block.

 endif([<condition>])

See the ``if()`` command.

The optional ``<condition>`` argument is supported for backward compatibility
only. If used it must be a verbatim repeat of the argument of the opening
``if`` clause.

endmacro
--------

Ends a list of commands in a macro block.

 endmacro([<name>])

See the ``macro()`` command.

The optional ``<name>`` argument is supported for backward compatibility
only. If used it must be a verbatim repeat of the ``<name>`` argument
of the opening ``macro`` command.

endwhile
--------

Ends a list of commands in a while block.

 endwhile([<condition>])

See the ``while()`` command.

The optional ``<condition>`` argument is supported for backward compatibility
only. If used it must be a verbatim repeat of the argument of the opening
``while`` clause.

execute_process
---------------

Execute one or more child processes.

 execute_process(COMMAND <cmd1> [<arguments>]
                 [COMMAND <cmd2> [<arguments>]]...
                 [WORKING_DIRECTORY <directory>]
                 [TIMEOUT <seconds>]
                 [RESULT_VARIABLE <variable>]
                 [RESULTS_VARIABLE <variable>]
                 [OUTPUT_VARIABLE <variable>]
                 [ERROR_VARIABLE <variable>]
                 [INPUT_FILE <file>]
                 [OUTPUT_FILE <file>]
                 [ERROR_FILE <file>]
                 [OUTPUT_QUIET]
                 [ERROR_QUIET]
                 [COMMAND_ECHO <where>]
                 [OUTPUT_STRIP_TRAILING_WHITESPACE]
                 [ERROR_STRIP_TRAILING_WHITESPACE]
                 [ENCODING <name>]
                 [ECHO_OUTPUT_VARIABLE]
                 [ECHO_ERROR_VARIABLE]
                 [COMMAND_ERROR_IS_FATAL <ANY|LAST>])

Runs the given sequence of one or more commands.

Commands are executed concurrently as a pipeline, with the standard
output of each process piped to the standard input of the next.
A single standard error pipe is used for all processes.

``execute_process`` runs commands while CMake is configuring the project,
prior to build system generation.  Use the ``add_custom_target()`` and
``add_custom_command()`` commands to create custom commands that run
at build time.

Options:

``COMMAND``
 A child process command line.

 CMake executes the child process using operating system APIs directly:

 * On POSIX platforms, the command line is passed to the
   child process in an ``argv[]`` style array.

 * On Windows platforms, the command line is encoded as a string such
   that child processes using ``CommandLineToArgvW`` will decode the
   original arguments.

 No intermediate shell is used, so shell operators such as ``>``
 are treated as normal arguments.
 (Use the ``INPUT_*``, ``OUTPUT_*``, and ``ERROR_*`` options to
 redirect stdin, stdout, and stderr.)

 For **sequential execution** of multiple commands use multiple
 ``execute_process`` calls each with a single ``COMMAND`` argument.

``WORKING_DIRECTORY``
 The named directory will be set as the current working directory of
 the child processes.

``TIMEOUT``
 After the specified number of seconds (fractions allowed), all unfinished
 child processes will be terminated, and the ``RESULT_VARIABLE`` will be
 set to a string mentioning the "timeout".

``RESULT_VARIABLE``
 The variable will be set to contain the result of last child process.
 This will be an integer return code from the last child or a string
 describing an error condition.

``RESULTS_VARIABLE <variable>``
 .. versionadded:: 3.10

 The variable will be set to contain the result of all processes as a
 :ref:`semicolon-separated list <CMake Language Lists>`, in order of the
 given ``COMMAND`` arguments.  Each entry will be an integer return code
 from the corresponding child or a string describing an error condition.

``INPUT_FILE <file>``
 ``<file>`` is attached to the standard input pipe of the *first* ``COMMAND``
 process.

``OUTPUT_FILE <file>``
 ``<file>`` is attached to the standard output pipe of the *last* ``COMMAND``
 process.

``ERROR_FILE <file>``
 ``<file>`` is attached to the standard error pipe of *all* ``COMMAND``
 processes.

.. versionadded:: 3.3
  If the same ``<file>`` is named for both ``OUTPUT_FILE`` and ``ERROR_FILE``
  then it will be used for both standard output and standard error pipes.

``OUTPUT_QUIET``, ``ERROR_QUIET``
 The standard output on ``OUTPUT_VARIABLE`` or standard error on
 ``ERROR_VARIABLE`` are not connected (no variable content).
 The  ``*_FILE`` and ``ECHO_*_VARIABLE`` options are not affected.

``OUTPUT_VARIABLE``, ``ERROR_VARIABLE``
 The variable named will be set with the contents of the standard output
 and standard error pipes, respectively.  If the same variable is named
 for both pipes their output will be merged in the order produced.

``ECHO_OUTPUT_VARIABLE``, ``ECHO_ERROR_VARIABLE``
  .. versionadded:: 3.18

  The standard output or standard error will not be exclusively redirected to
  the specified variables.

  The output will be duplicated into the specified variables and also onto
  standard output or standard error analogous to the ``tee`` Unix command.

.. note::
  If more than one ``OUTPUT_*`` or ``ERROR_*`` option is given for the
  same pipe the precedence is *not specified*.
  If no ``OUTPUT_*`` or ``ERROR_*`` options are given the output will
  be shared with the corresponding pipes of the CMake process itself.

``COMMAND_ECHO <where>``
 .. versionadded:: 3.15

 The command being run will be echo'ed to ``<where>`` with ``<where>``
 being set to one of ``STDERR``, ``STDOUT`` or ``NONE``.
 See the ``CMAKE_EXECUTE_PROCESS_COMMAND_ECHO`` variable for a way
 to control the default behavior when this option is not present.

``ENCODING <name>``
 .. versionadded:: 3.8

 On Windows, the encoding that is used to decode output from the process.
 Ignored on other platforms.
 Valid encoding names are:

 ``NONE``
   Perform no decoding.  This assumes that the process output is encoded
   in the same way as CMake's internal encoding (UTF-8).
   This is the default.
 ``AUTO``
   Use the current active console's codepage or if that isn't
   available then use ANSI.
 ``ANSI``
   Use the ANSI codepage.
 ``OEM``
   Use the original equipment manufacturer (OEM) code page.
 ``UTF8`` or ``UTF-8``
   Use the UTF-8 codepage.

   .. versionadded:: 3.11
     Accept ``UTF-8`` spelling for consistency with the
     UTF-8 RFC naming convention.

``COMMAND_ERROR_IS_FATAL <ANY|LAST>``
  .. versionadded:: 3.19

  The option following ``COMMAND_ERROR_IS_FATAL`` determines the behavior when
  an error is encountered:

    ``ANY``
    If any of the commands in the list of commands fail, the
    ``execute_process()`` command halts with an error.

    ``LAST``
    If the last command in the list of commands fails, the
    ``execute_process()`` command halts with an error.  Commands earlier in the
    list will not cause a fatal error.

file
----

File manipulation command.

This command is dedicated to file and path manipulation requiring access to the
filesystem.

For other path manipulation, handling only syntactic aspects, have a look at
``cmake_path()`` command.

.. note::

  The sub-commands RELATIVE_PATH, TO_CMAKE_PATH and TO_NATIVE_PATH has
  been superseded, respectively, by sub-commands
  :ref:`RELATIVE_PATH <cmake_path-RELATIVE_PATH>`,
  :ref:`CONVERT ... TO_CMAKE_PATH_LIST <cmake_path-TO_CMAKE_PATH_LIST>` and
  :ref:`CONVERT ... TO_NATIVE_PATH_LIST <cmake_path-TO_NATIVE_PATH_LIST>` of
  ``cmake_path()`` command.

Synopsis
^^^^^^^^

 Reading
   file(READ <filename> <out-var> [...])
   file(STRINGS <filename> <out-var> [...])
   file(<HASH> <filename> <out-var>)
   file(TIMESTAMP <filename> <out-var> [...])

 Writing
   file({WRITE | APPEND} <filename> <content>...)
   file({TOUCH | TOUCH_NOCREATE} <file>...)
   file(GENERATE OUTPUT <output-file> [...])
   file(CONFIGURE OUTPUT <output-file> CONTENT <content> [...])

 Filesystem
   file({GLOB | GLOB_RECURSE} <out-var> [...] <globbing-expr>...)
   file(MAKE_DIRECTORY <directories>...)
   file({REMOVE | REMOVE_RECURSE } <files>...)
   file(RENAME <oldname> <newname> [...])
   file(COPY_FILE <oldname> <newname> [...])
   file({COPY | INSTALL} <file>... DESTINATION <dir> [...])
   file(SIZE <filename> <out-var>)
   file(READ_SYMLINK <linkname> <out-var>)
   file(CREATE_LINK <original> <linkname> [...])
   file(CHMOD <files>... <directories>... PERMISSIONS <permissions>... [...])
   file(CHMOD_RECURSE <files>... <directories>... PERMISSIONS <permissions>... [...])

 Path Conversion
   file(REAL_PATH <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])
   file(RELATIVE_PATH <out-var> <directory> <file>)
   file({TO_CMAKE_PATH | TO_NATIVE_PATH} <path> <out-var>)

 Transfer
   file(DOWNLOAD <url> [<file>] [...])
   file(UPLOAD <file> <url> [...])

 Locking
   file(LOCK <path> [...])

 Archiving
   file(ARCHIVE_CREATE OUTPUT <archive> PATHS <paths>... [...])
   file(ARCHIVE_EXTRACT INPUT <archive> [...])

 Handling Runtime Binaries
   file(GET_RUNTIME_DEPENDENCIES [...])

Reading
^^^^^^^

.. signature::
  file(READ <filename> <variable>
       [OFFSET <offset>] [LIMIT <max-in>] [HEX])

  Read content from a file called ``<filename>`` and store it in a
  ``<variable>``.  Optionally start from the given ``<offset>`` and
  read at most ``<max-in>`` bytes.  The ``HEX`` option causes data to
  be converted to a hexadecimal representation (useful for binary data).
  If the ``HEX`` option is specified, letters in the output
  (``a`` through ``f``) are in lowercase.

.. signature::
  file(STRINGS <filename> <variable> <options>...)

  Parse a list of ASCII strings from ``<filename>`` and store it in
  ``<variable>``.  Binary data in the file are ignored.  Carriage return
  (``\r``, CR) characters are ignored.  The options are:

    ``LENGTH_MAXIMUM <max-len>``
      Consider only strings of at most a given length.

    ``LENGTH_MINIMUM <min-len>``
      Consider only strings of at least a given length.

    ``LIMIT_COUNT <max-num>``
      Limit the number of distinct strings to be extracted.

    ``LIMIT_INPUT <max-in>``
      Limit the number of input bytes to read from the file.

    ``LIMIT_OUTPUT <max-out>``
      Limit the number of total bytes to store in the ``<variable>``.

    ``NEWLINE_CONSUME``
      Treat newline characters (``\n``, LF) as part of string content
      instead of terminating at them.

    ``NO_HEX_CONVERSION``
      Intel Hex and Motorola S-record files are automatically converted to
      binary while reading unless this option is given.

    ``REGEX <regex>``
      Consider only strings that match the given regular expression,
      as described under :ref:`string(REGEX) <Regex Specification>`.

      .. versionchanged:: 3.29
        Capture groups from the last match in the file are stored in
        ``CMAKE_MATCH_<n>``, similar to
        ``string(REGEX MATCHALL)``.  See policy ``CMP0159``.

    ``ENCODING <encoding-type>``
      .. versionadded:: 3.1

      Consider strings of a given encoding.  Currently supported encodings are:
      ``UTF-8``, ``UTF-16LE``, ``UTF-16BE``, ``UTF-32LE``, ``UTF-32BE``.
      If the ``ENCODING`` option is not provided and the file
      has a Byte Order Mark, the ``ENCODING`` option will be defaulted
      to respect the Byte Order Mark.

  .. versionadded:: 3.2
    Added the ``UTF-16LE``, ``UTF-16BE``, ``UTF-32LE``, ``UTF-32BE`` encodings.

  For example, the code

  .. code-block:: cmake

    file(STRINGS myfile.txt myfile)

  stores a list in the variable ``myfile`` in which each item is a line
  from the input file.

.. signature::
  file(<HASH> <filename> <variable>)
  :target: <HASH>

  Compute a cryptographic hash of the content of ``<filename>`` and
  store it in a ``<variable>``.  The supported ``<HASH>`` algorithm names
  are those listed by the ``string(<HASH>)`` command.

.. signature::
  file(TIMESTAMP <filename> <variable> [<format>] [UTC])

  Compute a string representation of the modification time of ``<filename>``
  and store it in ``<variable>``.  Should the command be unable to obtain a
  timestamp variable will be set to the empty string ("").

  See the ``string(TIMESTAMP)`` command for documentation of
  the ``<format>`` and ``UTC`` options.

Writing
^^^^^^^

.. signature::
  file(WRITE <filename> <content>...)
  file(APPEND <filename> <content>...)

  Write ``<content>`` into a file called ``<filename>``.  If the file does
  not exist, it will be created.  If the file already exists, ``WRITE``
  mode will overwrite it and ``APPEND`` mode will append to the end.
  Any directories in the path specified by ``<filename>`` that do not
  exist will be created.

  If the file is a build input, use the ``configure_file()`` command
  to update the file only when its content changes.

.. signature::
  file(TOUCH <files>...)
  file(TOUCH_NOCREATE <files>...)

  .. versionadded:: 3.12

  Create a file with no content if it does not yet exist. If the file already
  exists, its access and/or modification will be updated to the time when the
  function call is executed.

  Use ``TOUCH_NOCREATE`` to touch a file if it exists but not create it.
  If a file does not exist it will be silently ignored.

  With ``TOUCH`` and ``TOUCH_NOCREATE``, the contents of an existing file
  will not be modified.

  .. versionchanged:: 3.30
    ``<files>`` can be an empty list. CMake 3.29 and earlier required
    at least one file to be given.

.. signature::
  file(GENERATE [...])

  Generate an output file for each build configuration supported by the current
  ``CMake Generator``.  Evaluate
  ``generator expressions``
  from the input content to produce the output content.

  .. code-block:: cmake

    file(GENERATE OUTPUT <output-file>
         <INPUT <input-file>|CONTENT <content>>
         [CONDITION <expression>] [TARGET <target>]
         [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS |
          FILE_PERMISSIONS <permissions>...]
         [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

  The options are:

    ``CONDITION <condition>``
      Generate the output file for a particular configuration only if
      the condition is true.  The condition must be either ``0`` or ``1``
      after evaluating generator expressions.

    ``CONTENT <content>``
      Use the content given explicitly as input.

    ``INPUT <input-file>``
      Use the content from a given file as input.

      .. versionchanged:: 3.10
        A relative path is treated with respect to the value of
        ``CMAKE_CURRENT_SOURCE_DIR``.  See policy ``CMP0070``.

    ``OUTPUT <output-file>``
      Specify the output file name to generate.  Use generator expressions
      such as ``$<CONFIG>`` to specify a configuration-specific
      output file name.  Multiple configurations may generate the same output
      file only if the generated content is identical.  Otherwise, the
      ``<output-file>`` must evaluate to an unique name for each configuration.

      .. versionchanged:: 3.10
        A relative path (after evaluating generator expressions) is treated
        with respect to the value of ``CMAKE_CURRENT_BINARY_DIR``.
        See policy ``CMP0070``.

    ``TARGET <target>``
      .. versionadded:: 3.19

      Specify which target to use when evaluating generator expressions that
      require a target for evaluation (e.g.
      ``$<COMPILE_FEATURES:...>``,
      ``$<TARGET_PROPERTY:prop>``).

    ``NO_SOURCE_PERMISSIONS``
      .. versionadded:: 3.20

      The generated file permissions default to the standard 644 value
      (-rw-r--r--).

    ``USE_SOURCE_PERMISSIONS``
      .. versionadded:: 3.20

      Transfer the file permissions of the ``INPUT`` file to the generated
      file. This is already the default behavior if none of the three
      permissions-related keywords are given (``NO_SOURCE_PERMISSIONS``,
      ``USE_SOURCE_PERMISSIONS`` or ``FILE_PERMISSIONS``).  The
      ``USE_SOURCE_PERMISSIONS`` keyword mostly serves as a way of making
      the intended behavior clearer at the call site. It is an error to
      specify this option without ``INPUT``.

    ``FILE_PERMISSIONS <permissions>...``
      .. versionadded:: 3.20

      Use the specified permissions for the generated file.

    ``NEWLINE_STYLE <style>``
      .. versionadded:: 3.20

      Specify the newline style for the generated file.  Specify
      ``UNIX`` or ``LF`` for ``\n`` newlines, or specify
      ``DOS``, ``WIN32``, or ``CRLF`` for ``\r\n`` newlines.

  Exactly one ``CONTENT`` or ``INPUT`` option must be given.  A specific
  ``OUTPUT`` file may be named by at most one invocation of ``file(GENERATE)``.
  Generated files are modified and their timestamp updated on subsequent cmake
  runs only if their content is changed.

  Note also that ``file(GENERATE)`` does not create the output file until the
  generation phase. The output file will not yet have been written when the
  ``file(GENERATE)`` command returns, it is written only after processing all
  of a project's ``CMakeLists.txt`` files.

.. signature::
  file(CONFIGURE OUTPUT <output-file>
       CONTENT <content>
       [ESCAPE_QUOTES] [@ONLY]
       [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])
  :target: CONFIGURE

  .. versionadded:: 3.18

  Generate an output file using the input given by ``CONTENT`` and substitute
  variable values referenced as ``@VAR@`` or ``${VAR}`` contained therein. The
  substitution rules behave the same as the ``configure_file()`` command.
  In order to match ``configure_file()``'s behavior, generator expressions
  are not supported for both ``OUTPUT`` and ``CONTENT``.

  The arguments are:

    ``OUTPUT <output-file>``
      Specify the output file name to generate. A relative path is treated with
      respect to the value of ``CMAKE_CURRENT_BINARY_DIR``.
      ``<output-file>`` does not support generator expressions.

    ``CONTENT <content>``
      Use the content given explicitly as input.
      ``<content>`` does not support generator expressions.

    ``ESCAPE_QUOTES``
      Escape any substituted quotes with backslashes (C-style).

    ``@ONLY``
      Restrict variable replacement to references of the form ``@VAR@``.
      This is useful for configuring scripts that use ``${VAR}`` syntax.

    ``NEWLINE_STYLE <style>``
      Specify the newline style for the output file.  Specify
      ``UNIX`` or ``LF`` for ``\n`` newlines, or specify
      ``DOS``, ``WIN32``, or ``CRLF`` for ``\r\n`` newlines.

Filesystem
^^^^^^^^^^

.. signature::
  file(GLOB <variable>
       [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS]
       <globbing-expressions>...)
  file(GLOB_RECURSE <variable> [FOLLOW_SYMLINKS]
       [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS]
       <globbing-expressions>...)

  Generate a list of files that match the ``<globbing-expressions>`` and
  store it into the ``<variable>``.  Globbing expressions are similar to
  regular expressions, but much simpler.  If ``RELATIVE`` flag is
  specified, the results will be returned as relative paths to the given
  path.

  .. versionchanged:: 3.6
    The results will be ordered lexicographically.

  On Windows and macOS, globbing is case-insensitive even if the underlying
  filesystem is case-sensitive (both filenames and globbing expressions are
  converted to lowercase before matching).  On other platforms, globbing is
  case-sensitive.

  .. versionadded:: 3.3
    By default ``GLOB`` lists directories. Directories are omitted in the
    result if ``LIST_DIRECTORIES`` is set to false.

  .. versionadded:: 3.12
    If the ``CONFIGURE_DEPENDS`` flag is specified, CMake will add logic
    to the main build system check target to rerun the flagged ``GLOB``
    commands at build time. If any of the outputs change, CMake will regenerate
    the build system.

  .. note::
    We do not recommend using GLOB to collect a list of source files from
    your source tree.  If no CMakeLists.txt file changes when a source is
    added or removed then the generated build system cannot know when to
    ask CMake to regenerate.
    The ``CONFIGURE_DEPENDS`` flag may not work reliably on all generators, or
    if a new generator is added in the future that cannot support it, projects
    using it will be stuck. Even if ``CONFIGURE_DEPENDS`` works reliably, there
    is still a cost to perform the check on every rebuild.

  Examples of globbing expressions include:

  ============== ======================================================
  ``*.cxx``      match all files with extension ``cxx``
  ``*.vt?``      match all files with extension ``vta``, ..., ``vtz``
  ``f[3-5].txt`` match files ``f3.txt``, ``f4.txt``, ``f5.txt``
  ============== ======================================================

  The ``GLOB_RECURSE`` mode will traverse all the subdirectories of the
  matched directory and match the files.  Subdirectories that are symlinks
  are only traversed if ``FOLLOW_SYMLINKS`` is given or policy
  ``CMP0009`` is not set to ``NEW``.

  .. versionadded:: 3.3
    By default ``GLOB_RECURSE`` omits directories from result list. Setting
    ``LIST_DIRECTORIES`` to true adds directories to result list.
    If ``FOLLOW_SYMLINKS`` is given or policy ``CMP0009`` is not set to
    ``NEW`` then ``LIST_DIRECTORIES`` treats symlinks as directories.

  Examples of recursive globbing include:

  ============== ======================================================
  ``/dir/*.py``  match all python files in ``/dir`` and subdirectories
  ============== ======================================================

.. signature::
  file(MAKE_DIRECTORY <directories>...)

  Create the given directories and their parents as needed.

  .. versionchanged:: 3.30
    ``<directories>`` can be an empty list. CMake 3.29 and earlier required
    at least one directory to be given.

.. signature::
  file(REMOVE <files>...)
  file(REMOVE_RECURSE <files>...)

  Remove the given files.  The ``REMOVE_RECURSE`` mode will remove the given
  files and directories, including non-empty directories. No error is emitted
  if a given file does not exist.  Relative input paths are evaluated with
  respect to the current source directory.

  .. versionchanged:: 3.15
    Empty input paths are ignored with a warning.  Previous versions of CMake
    interpreted empty strings as a relative path with respect to the current
    directory and removed its contents.

.. signature::
  file(RENAME <oldname> <newname> [RESULT <result>] [NO_REPLACE])

  Move a file or directory within a filesystem from ``<oldname>`` to
  ``<newname>``, replacing the destination atomically.

  The options are:

    ``RESULT <result>``
      .. versionadded:: 3.21

      Set ``<result>`` variable to ``0`` on success or an error message
      otherwise. If ``RESULT`` is not specified and the operation fails,
      an error is emitted.

    ``NO_REPLACE``
      .. versionadded:: 3.21

      If the ``<newname>`` path already exists, do not replace it.
      If ``RESULT <result>`` is used, the result variable will be
      set to ``NO_REPLACE``.  Otherwise, an error is emitted.

.. signature::
  file(COPY_FILE <oldname> <newname>
       [RESULT <result>]
       [ONLY_IF_DIFFERENT]
       [INPUT_MAY_BE_RECENT])

  .. versionadded:: 3.21

  Copy a file from ``<oldname>`` to ``<newname>``. Directories are not
  supported. Symlinks are ignored and ``<oldfile>``'s content is read and
  written to ``<newname>`` as a new file.

  The options are:

    ``RESULT <result>``
      Set ``<result>`` variable to ``0`` on success or an error message
      otherwise.  If ``RESULT`` is not specified and the operation fails,
      an error is emitted.

    ``ONLY_IF_DIFFERENT``
      If the ``<newname>`` path already exists, do not replace it if the file's
      contents are already the same as ``<oldname>`` (this avoids updating
      ``<newname>``'s timestamp).

    ``INPUT_MAY_BE_RECENT``
      .. versionadded:: 3.26

      Tell CMake that the input file may have been recently created.  This is
      meaningful only on Windows, where files may be inaccessible for a short
      time after they are created.  With this option, if permission is denied,
      CMake will retry reading the input a few times.

  This sub-command has some similarities to ``configure_file()``
  with the ``COPYONLY`` option.  An important difference is that
  ``configure_file()`` creates a dependency on the source file,
  so CMake will be re-run if it changes. The ``file(COPY_FILE)``
  sub-command does not create such a dependency.

  See also the ``file(COPY)`` sub-command just below which provides
  further file-copying capabilities.

.. signature::
  file(COPY [...])
  file(INSTALL [...])

  The ``COPY`` signature copies files, directories, and symlinks to a
  destination folder.  Relative input paths are evaluated with respect
  to the current source directory, and a relative destination is
  evaluated with respect to the current build directory.  Copying
  preserves input file timestamps, and optimizes out a file if it exists
  at the destination with the same timestamp.  Copying preserves input
  permissions unless explicit permissions or ``NO_SOURCE_PERMISSIONS``
  are given (default is ``USE_SOURCE_PERMISSIONS``).

  .. code-block:: cmake

    file(<COPY|INSTALL> <files>... DESTINATION <dir>
         [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS]
         [FILE_PERMISSIONS <permissions>...]
         [DIRECTORY_PERMISSIONS <permissions>...]
         [FOLLOW_SYMLINK_CHAIN]
         [FILES_MATCHING]
         [[PATTERN <pattern> | REGEX <regex>]
          [EXCLUDE] [PERMISSIONS <permissions>...]] [...])

  .. note::

   For a simple file copying operation, the :command:`file(COPY_FILE)`
   sub-command just above may be easier to use.

 .. versionadded:: 3.15
   If ``FOLLOW_SYMLINK_CHAIN`` is specified, ``COPY`` will recursively resolve
   the symlinks at the paths given until a real file is found, and install
   a corresponding symlink in the destination for each symlink encountered.
   For each symlink that is installed, the resolution is stripped of the
   directory, leaving only the filename, meaning that the new symlink points
   to a file in the same directory as the symlink. This feature is useful on
   some Unix systems, where libraries are installed as a chain of symlinks
   with version numbers, with less specific versions pointing to more specific
   versions. ``FOLLOW_SYMLINK_CHAIN`` will install all of these symlinks and
   the library itself into the destination directory. For example, if you have
   the following directory structure:

     * ``/opt/foo/lib/libfoo.so.1.2.3``
     * ``/opt/foo/lib/libfoo.so.1.2 -> libfoo.so.1.2.3``
     * ``/opt/foo/lib/libfoo.so.1 -> libfoo.so.1.2``
     * ``/opt/foo/lib/libfoo.so -> libfoo.so.1``

   and you do:

   .. code-block:: cmake

     file(COPY /opt/foo/lib/libfoo.so DESTINATION lib FOLLOW_SYMLINK_CHAIN)

   This will install all of the symlinks and ``libfoo.so.1.2.3`` itself into
   ``lib``.

 See the :command:`install(DIRECTORY)` command for documentation of
 permissions, ``FILES_MATCHING``, ``PATTERN``, ``REGEX``, and
 ``EXCLUDE`` options.  Copying directories preserves the structure
 of their content even if options are used to select a subset of
 files.

 The ``INSTALL`` signature differs slightly from ``COPY``: it prints
 status messages, and ``NO_SOURCE_PERMISSIONS`` is default. Installation
 scripts generated by the :command:`install` command use this signature
 (with some undocumented options for internal use).

 .. versionchanged:: 3.22

   The environment variable :envvar:`CMAKE_INSTALL_MODE` can override the
   default copying behavior of :command:`file(INSTALL)`.

.. signature::
  file(SIZE <filename> <variable>)

  .. versionadded:: 3.14

  Determine the file size of the ``<filename>`` and put the result in
  ``<variable>`` variable. Requires that ``<filename>`` is a valid path
  pointing to a file and is readable.

.. signature::
  file(READ_SYMLINK <linkname> <variable>)

  .. versionadded:: 3.14

  Query the symlink ``<linkname>`` and stores the path it points to
  in the result ``<variable>``.  If ``<linkname>`` does not exist
  or is not a symlink, CMake issues a fatal error.

  Note that this command returns the raw symlink path and does not resolve
  a relative path.  The following is an example of how to ensure that an
  absolute path is obtained:

  .. code-block:: cmake

    set(linkname "/path/to/foo.sym")
    file(READ_SYMLINK "${linkname}" result)
    if(NOT IS_ABSOLUTE "${result}")
      get_filename_component(dir "${linkname}" DIRECTORY)
      set(result "${dir}/${result}")
    endif()

.. signature::
  file(CREATE_LINK <original> <linkname>
       [RESULT <result>] [COPY_ON_ERROR] [SYMBOLIC])

  .. versionadded:: 3.14

  Create a link ``<linkname>`` that points to ``<original>``.
  It will be a hard link by default, but providing the ``SYMBOLIC`` option
  results in a symbolic link instead.  Hard links require that ``original``
  exists and is a file, not a directory.  If ``<linkname>`` already exists,
  it will be overwritten.

  The ``<result>`` variable, if specified, receives the status of the
  operation.  It is set to ``0`` upon success or an error message otherwise.
  If ``RESULT`` is not specified and the operation fails, a fatal error is
  emitted.

  Specifying ``COPY_ON_ERROR`` enables copying the file as a fallback if
  creating the link fails.  It can be useful for handling situations such as
  ``<original>`` and ``<linkname>`` being on different drives or mount points,
  which would make them unable to support a hard link.

.. signature::
  file(CHMOD <files>... <directories>...
       [PERMISSIONS <permissions>...]
       [FILE_PERMISSIONS <permissions>...]
       [DIRECTORY_PERMISSIONS <permissions>...])

  .. versionadded:: 3.19

  Set the permissions for the ``<files>...`` and ``<directories>...``
  specified. Valid permissions are  ``OWNER_READ``, ``OWNER_WRITE``,
  ``OWNER_EXECUTE``, ``GROUP_READ``, ``GROUP_WRITE``, ``GROUP_EXECUTE``,
  ``WORLD_READ``, ``WORLD_WRITE``, ``WORLD_EXECUTE``, ``SETUID``, ``SETGID``.

  Valid combination of keywords are:

    ``PERMISSIONS``
      All items are changed.

    ``FILE_PERMISSIONS``
      Only files are changed.

    ``DIRECTORY_PERMISSIONS``
      Only directories are changed.

    ``PERMISSIONS`` and ``FILE_PERMISSIONS``
      ``FILE_PERMISSIONS`` overrides ``PERMISSIONS`` for files.

    ``PERMISSIONS`` and ``DIRECTORY_PERMISSIONS``
      ``DIRECTORY_PERMISSIONS`` overrides ``PERMISSIONS`` for directories.

    ``FILE_PERMISSIONS`` and ``DIRECTORY_PERMISSIONS``
      Use ``FILE_PERMISSIONS`` for files and ``DIRECTORY_PERMISSIONS`` for
      directories.

.. signature::
  file(CHMOD_RECURSE <files>... <directories>...
       [PERMISSIONS <permissions>...]
       [FILE_PERMISSIONS <permissions>...]
       [DIRECTORY_PERMISSIONS <permissions>...])

  .. versionadded:: 3.19

  Same as ``CHMOD``, but change the permissions of files and directories
  present in the ``<directories>...`` recursively.


Path Conversion
^^^^^^^^^^^^^^^

.. signature::
  file(REAL_PATH <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])

  .. versionadded:: 3.19

  Compute the absolute path to an existing file or directory with symlinks
  resolved.  The options are:

    ``BASE_DIRECTORY <dir>``
      If the provided ``<path>`` is a relative path, it is evaluated relative
      to the given base directory ``<dir>``. If no base directory is provided,
      the default base directory will be ``CMAKE_CURRENT_SOURCE_DIR``.

    ``EXPAND_TILDE``
      .. versionadded:: 3.21

      If the ``<path>`` is ``~`` or starts with ``~/``, the ``~`` is replaced
      by the user's home directory.  The path to the home directory is obtained
      from environment variables.  On Windows, the ``USERPROFILE`` environment
      variable is used, falling back to the ``HOME`` environment variable
      if ``USERPROFILE`` is not defined.  On all other platforms, only ``HOME``
      is used.

  .. versionchanged:: 3.28

    All symlinks are resolved before collapsing ``../`` components.
    See policy ``CMP0152``.

.. signature::
  file(RELATIVE_PATH <variable> <directory> <file>)

  Compute the relative path from a ``<directory>`` to a ``<file>`` and
  store it in the ``<variable>``.

.. signature::
  file(TO_CMAKE_PATH "<path>" <variable>)
  file(TO_NATIVE_PATH "<path>" <variable>)

  The ``TO_CMAKE_PATH`` mode converts a native ``<path>`` into a cmake-style
  path with forward-slashes (``/``).  The input can be a single path or a
  system search path like ``$ENV{PATH}``.  A search path will be converted
  to a cmake-style list separated by ``;`` characters.

  The ``TO_NATIVE_PATH`` mode converts a cmake-style ``<path>`` into a native
  path with platform-specific slashes (``\`` on Windows hosts and ``/``
  elsewhere).

  Always use double quotes around the ``<path>`` to be sure it is treated
  as a single argument to this command.

Transfer
^^^^^^^^

.. signature::
  file(DOWNLOAD <url> [<file>] <options>...)
  file(UPLOAD <file> <url> <options>...)

  The ``DOWNLOAD`` subcommand downloads the given ``<url>`` to a local
  ``<file>``.  The ``UPLOAD`` mode uploads a local ``<file>`` to a given
  ``<url>``.

  .. versionadded:: 3.19
    If ``<file>`` is not specified for ``file(DOWNLOAD)``, the file is not
    saved. This can be useful if you want to know if a file can be downloaded
    (for example, to check that it exists) without actually saving it anywhere.

  Options to both ``DOWNLOAD`` and ``UPLOAD`` are:

    ``INACTIVITY_TIMEOUT <seconds>``
      Terminate the operation after a period of inactivity.

    ``LOG <variable>``
      Store a human-readable log of the operation in a variable.

    ``SHOW_PROGRESS``
      Print progress information as status messages until the operation is
      complete.

    ``STATUS <variable>``
      Store the resulting status of the operation in a variable.
      The status is a ``;`` separated list of length 2.
      The first element is the numeric return value for the operation,
      and the second element is a string value for the error.
      A ``0`` numeric error means no error in the operation.

    ``TIMEOUT <seconds>``
      Terminate the operation after a given total time has elapsed.

    ``USERPWD <username>:<password>``
      .. versionadded:: 3.7

      Set username and password for operation.

    ``HTTPHEADER <HTTP-header>``
      .. versionadded:: 3.7

      HTTP header for ``DOWNLOAD`` and ``UPLOAD`` operations. ``HTTPHEADER``
      can be repeated for multiple options:

      .. code-block:: cmake

        file(DOWNLOAD <url>
             HTTPHEADER "Authorization: Bearer <auth-token>"
             HTTPHEADER "UserAgent: Mozilla/5.0")

    ``NETRC <level>``
      .. versionadded:: 3.11

      Specify whether the .netrc file is to be used for operation.  If this
      option is not specified, the value of the ``CMAKE_NETRC``
      variable will be used instead.

      Valid levels are:

        ``IGNORED``
          The .netrc file is ignored.
          This is the default.

        ``OPTIONAL``
          The .netrc file is optional, and information in the URL is preferred.
          The file will be scanned to find which ever information is not
          specified in the URL.

        ``REQUIRED``
          The .netrc file is required, and information in the URL is ignored.

    ``NETRC_FILE <file>``
      .. versionadded:: 3.11

      Specify an alternative .netrc file to the one in your home directory,
      if the ``NETRC`` level is ``OPTIONAL`` or ``REQUIRED``. If this option
      is not specified, the value of the ``CMAKE_NETRC_FILE`` variable
      will be used instead.

    ``TLS_VERSION <min>``
      .. versionadded:: 3.30

      Specify minimum TLS version for ``https://`` URLs.
      If this option is not specified, the value of the
      ``CMAKE_TLS_VERSION`` variable or ``CMAKE_TLS_VERSION``
      environment variable will be used instead.
      See ``CMAKE_TLS_VERSION`` for allowed values.

    ``TLS_VERIFY <ON|OFF>``
      Specify whether to verify the server certificate for ``https://`` URLs.
      The default is to *not* verify. If this option is not specified, the
      value of the ``CMAKE_TLS_VERIFY`` variable will be used instead.

      .. versionadded:: 3.18
        Added support to ``file(UPLOAD)``.

    ``TLS_CAINFO <file>``
      Specify a custom Certificate Authority file for ``https://`` URLs.
      If this option is not specified, the value of the
      ``CMAKE_TLS_CAINFO`` variable will be used instead.

      .. versionadded:: 3.18
        Added support to ``file(UPLOAD)``.

  For ``https://`` URLs CMake must be built with OpenSSL support.  ``TLS/SSL``
  certificates are not checked by default.  Set ``TLS_VERIFY`` to ``ON`` to
  check certificates.

  Additional options to ``DOWNLOAD`` are:

    ``EXPECTED_HASH <algorithm>=<value>``
      Verify that the downloaded content hash matches the expected value, where
      ``<algorithm>`` is one of the algorithms supported by ``<HASH>``.
      If the file already exists and matches the hash, the download is skipped.
      If the file already exists and does not match the hash, the file is
      downloaded again. If after download the file does not match the hash, the
      operation fails with an error. It is an error to specify this option if
      ``DOWNLOAD`` is not given a ``<file>``.

    ``EXPECTED_MD5 <value>``
      Historical short-hand for ``EXPECTED_HASH MD5=<value>``. It is an error
      to specify this if ``DOWNLOAD`` is not given a ``<file>``.

    ``RANGE_START <value>``
      .. versionadded:: 3.24

      Offset of the start of the range in file in bytes. Could be omitted to
      download up to the specified ``RANGE_END``.

    ``RANGE_END <value>``
      .. versionadded:: 3.24

      Offset of the end of the range in file in bytes. Could be omitted to
      download everything from the specified ``RANGE_START`` to the end of
      file.

Locking
^^^^^^^

.. signature::
  file(LOCK <path> [DIRECTORY] [RELEASE]
       [GUARD <FUNCTION|FILE|PROCESS>]
       [RESULT_VARIABLE <variable>]
       [TIMEOUT <seconds>])

  .. versionadded:: 3.2

  Lock a file specified by ``<path>`` if no ``DIRECTORY`` option present and
  file ``<path>/cmake.lock`` otherwise.  The file will be locked for the scope
  defined by the ``GUARD`` option (default value is ``PROCESS``).  The
  ``RELEASE`` option can be used to unlock the file explicitly.  If the
  ``TIMEOUT`` option is not specified, CMake will wait until the lock succeeds
  or until a fatal error occurs.  If ``TIMEOUT`` is set to ``0``, locking will
  be tried once and the result will be reported immediately.  If ``TIMEOUT``
  is not ``0``, CMake will try to lock the file for the period specified by
  the ``TIMEOUT <seconds>`` value.  Any errors will be interpreted as fatal if
  there is no ``RESULT_VARIABLE`` option.  Otherwise, the result will be stored
  in ``<variable>`` and will be ``0`` on success or an error message on
  failure.

  Note that lock is advisory; there is no guarantee that other processes will
  respect this lock, i.e. lock synchronize two or more CMake instances sharing
  some modifiable resources. Similar logic applies to the ``DIRECTORY`` option;
  locking a parent directory doesn't prevent other ``LOCK`` commands from
  locking any child directory or file.

  Trying to lock the same file twice is not allowed.  Any intermediate
  directories and the file itself will be created if they not exist.  The
  ``GUARD`` and ``TIMEOUT`` options are ignored on the ``RELEASE`` operation.

Archiving
^^^^^^^^^

.. signature::
  file(ARCHIVE_CREATE OUTPUT <archive>
    PATHS <paths>...
    [FORMAT <format>]
    [COMPRESSION <compression>
     [COMPRESSION_LEVEL <compression-level>]]
    [MTIME <mtime>]
    [VERBOSE])
  :target: ARCHIVE_CREATE
  :break: verbatim

  .. versionadded:: 3.18

  Creates the specified ``<archive>`` file with the files and directories
  listed in ``<paths>``.  Note that ``<paths>`` must list actual files or
  directories; wildcards are not supported.

  Use the ``FORMAT`` option to specify the archive format.  Supported values
  for ``<format>`` are ``7zip``, ``gnutar``, ``pax``, ``paxr``, ``raw`` and
  ``zip``.  If ``FORMAT`` is not given, the default format is ``paxr``.

  Some archive formats allow the type of compression to be specified.
  The ``7zip`` and ``zip`` archive formats already imply a specific type of
  compression.  The other formats use no compression by default, but can be
  directed to do so with the ``COMPRESSION`` option.  Valid values for
  ``<compression>`` are ``None``, ``BZip2``, ``GZip``, ``XZ``, and ``Zstd``.

  .. versionadded:: 3.19
    The compression level can be specified with the ``COMPRESSION_LEVEL``
    option.  The ``<compression-level>`` should be between 0-9, with the
    default being 0.  The ``COMPRESSION`` option must be present when
    ``COMPRESSION_LEVEL`` is given.

  .. versionadded:: 3.26
    The ``<compression-level>`` of the ``Zstd`` algorithm can be set
    between 0-19.

  .. note::
    With ``FORMAT`` set to ``raw``, only one file will be compressed with the
    compression type specified by ``COMPRESSION``.

  The ``VERBOSE`` option enables verbose output for the archive operation.

  To specify the modification time recorded in tarball entries, use
  the ``MTIME`` option.

.. signature::
  file(ARCHIVE_EXTRACT
    INPUT <archive>
    [DESTINATION <dir>]
    [PATTERNS <patterns>...]
    [LIST_ONLY]
    [VERBOSE]
    [TOUCH])
  :target: ARCHIVE_EXTRACT

  .. versionadded:: 3.18

  Extracts or lists the content of the specified ``<archive>``.

  The directory where the content of the archive will be extracted to can
  be specified using the ``DESTINATION`` option.  If the directory does not
  exist, it will be created.  If ``DESTINATION`` is not given, the current
  binary directory will be used.

  If required, you may select which files and directories to list or extract
  from the archive using the specified ``<patterns>``.  Wildcards are
  supported.  If the ``PATTERNS`` option is not given, the entire archive will
  be listed or extracted.

  ``LIST_ONLY`` will list the files in the archive rather than extract them.

  .. note::
    The working directory for this subcommand is the ``DESTINATION`` directory
    (provided or computed) except when ``LIST_ONLY`` is specified. Therefore,
    outside of script mode, it may be best to provide absolute paths to
    ``INPUT`` archives as they are unlikely to be extracted where a relative
    path works.

  .. versionadded:: 3.24
    The ``TOUCH`` option gives extracted files a current local
    timestamp instead of extracting file timestamps from the archive.

  With ``VERBOSE``, the command will produce verbose output.

Handling Runtime Binaries
^^^^^^^^^^^^^^^^^^^^^^^^^

.. signature::
  file(GET_RUNTIME_DEPENDENCIES [...])

  .. versionadded:: 3.16

  Recursively get the list of libraries depended on by the given files:

  .. code-block:: cmake

    file(GET_RUNTIME_DEPENDENCIES
      [RESOLVED_DEPENDENCIES_VAR <deps_var>]
      [UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>]
      [CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>]
      [EXECUTABLES <executable_files>...]
      [LIBRARIES <library_files>...]
      [MODULES <module_files>...]
      [DIRECTORIES <directories>...]
      [BUNDLE_EXECUTABLE <bundle_executable_file>]
      [PRE_INCLUDE_REGEXES <regexes>...]
      [PRE_EXCLUDE_REGEXES <regexes>...]
      [POST_INCLUDE_REGEXES <regexes>...]
      [POST_EXCLUDE_REGEXES <regexes>...]
      [POST_INCLUDE_FILES <files>...]
      [POST_EXCLUDE_FILES <files>...]
      )

  Please note that this sub-command is not intended to be used in project mode.
  It is intended for use at install time, either from code generated by the
  ``install(RUNTIME_DEPENDENCY_SET)`` command, or from code provided by
  the project via ``install(CODE)`` or ``install(SCRIPT)``.
  For example:

  .. code-block:: cmake

    install(CODE [[
      file(GET_RUNTIME_DEPENDENCIES
        # ...
        )
      ]])

  The arguments are as follows:

    ``RESOLVED_DEPENDENCIES_VAR <deps_var>``
      Name of the variable in which to store the list of resolved dependencies.

    ``UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>``
      Name of the variable in which to store the list of unresolved
      dependencies. If this variable is not specified, and there are any
      unresolved dependencies, an error is issued.

    ``CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>``
      Variable prefix in which to store conflicting dependency information.
      Dependencies are conflicting if two files with the same name are found in
      two different directories. The list of filenames that conflict are stored
      in ``<conflicting_deps_prefix>_FILENAMES``. For each filename, the list
      of paths that were found for that filename are stored in
      ``<conflicting_deps_prefix>_<filename>``.

    ``EXECUTABLES <executable_files>...``
      List of executable files to read for dependencies. These are executables
      that are typically created with ``add_executable()``, but they do
      not have to be created by CMake. On Apple platforms, the paths to these
      files determine the value of ``@executable_path`` when recursively
      resolving the libraries. Specifying any kind of library (``STATIC``,
      ``MODULE``, or ``SHARED``) here will result in undefined behavior.

    ``LIBRARIES <library_files>...``
      List of library files to read for dependencies. These are libraries that
      are typically created with ``add_library(SHARED)``, but they do
      not have to be created by CMake. Specifying ``STATIC`` libraries,
      ``MODULE`` libraries, or executables here will result in undefined
      behavior.

    ``MODULES <module_files>...``
      List of loadable module files to read for dependencies. These are modules
      that are typically created with ``add_library(MODULE)``, but they
      do not have to be created by CMake. They are typically used by calling
      ``dlopen()`` at runtime rather than linked at link time with ``ld -l``.
      Specifying ``STATIC`` libraries, ``SHARED`` libraries, or executables
      here will result in undefined behavior.

    ``DIRECTORIES <directories>...``
      List of additional directories to search for dependencies. On Linux
      platforms, these directories are searched if the dependency is not found
      in any of the other usual paths. If it is found in such a directory, a
      warning is issued, because it means that the file is incomplete (it does
      not list all of the directories that contain its dependencies).
      On Windows platforms, these directories are searched if the dependency
      is not found in any of the other search paths, but no warning is issued,
      because searching other paths is a normal part of Windows dependency
      resolution. On Apple platforms, this argument has no effect.

    ``BUNDLE_EXECUTABLE <bundle_executable_file>``
      Executable to treat as the "bundle executable" when resolving libraries.
      On Apple platforms, this argument determines the value of
      ``@executable_path`` when recursively resolving libraries for
      ``LIBRARIES`` and ``MODULES`` files. It has no effect on ``EXECUTABLES``
      files. On other platforms, it has no effect. This is typically (but not
      always) one of the executables in the ``EXECUTABLES`` argument which
      designates the "main" executable of the package.

  The following arguments specify filters for including or excluding libraries
  to be resolved. See below for a full description of how they work.

    ``PRE_INCLUDE_REGEXES <regexes>...``
      List of pre-include regexes through which to filter the names of
      not-yet-resolved dependencies.

    ``PRE_EXCLUDE_REGEXES <regexes>...``
      List of pre-exclude regexes through which to filter the names of
      not-yet-resolved dependencies.

    ``POST_INCLUDE_REGEXES <regexes>...``
      List of post-include regexes through which to filter the names of
      resolved dependencies.

    ``POST_EXCLUDE_REGEXES <regexes>...``
      List of post-exclude regexes through which to filter the names of
      resolved dependencies.

    ``POST_INCLUDE_FILES <files>...``
      .. versionadded:: 3.21

      List of post-include filenames through which to filter the names of
      resolved dependencies. Symlinks are resolved when attempting to match
      these filenames.

    ``POST_EXCLUDE_FILES <files>...``
      .. versionadded:: 3.21

      List of post-exclude filenames through which to filter the names of
      resolved dependencies. Symlinks are resolved when attempting to match
      these filenames.

  These arguments can be used to exclude unwanted system libraries when
  resolving the dependencies, or to include libraries from a specific
  directory. The filtering works as follows:

  1. If the not-yet-resolved dependency matches any of the
     ``PRE_INCLUDE_REGEXES``, steps 2 and 3 are skipped, and the dependency
     resolution proceeds to step 4.

  2. If the not-yet-resolved dependency matches any of the
     ``PRE_EXCLUDE_REGEXES``, dependency resolution stops for that dependency.

  3. Otherwise, dependency resolution proceeds.

  4. ``file(GET_RUNTIME_DEPENDENCIES)`` searches for the dependency according
     to the linking rules of the platform (see below).

  5. If the dependency is found, and its full path matches one of the
     ``POST_INCLUDE_REGEXES`` or ``POST_INCLUDE_FILES``, the full path is added
     to the resolved dependencies, and ``file(GET_RUNTIME_DEPENDENCIES)``
     recursively resolves that library's own dependencies. Otherwise, resolution
     proceeds to step 6.

  6. If the dependency is found, but its full path matches one of the
     ``POST_EXCLUDE_REGEXES`` or ``POST_EXCLUDE_FILES``, it is not added to the
     resolved dependencies, and dependency resolution stops for that dependency.

  7. If the dependency is found, and its full path does not match either
     ``POST_INCLUDE_REGEXES``, ``POST_INCLUDE_FILES``, ``POST_EXCLUDE_REGEXES``,
     or ``POST_EXCLUDE_FILES``, the full path is added to the resolved
     dependencies, and ``file(GET_RUNTIME_DEPENDENCIES)``  recursively resolves
     that library's own dependencies.

  Different platforms have different rules for how dependencies are resolved.
  These specifics are described here.

  On Linux platforms, library resolution works as follows:

  1. If the depending file does not have any ``RUNPATH`` entries, and the
     library exists in one of the depending file's ``RPATH`` entries, or its
     parents', in that order, the dependency is resolved to that file.
  2. Otherwise, if the depending file has any ``RUNPATH`` entries, and the
     library exists in one of those entries, the dependency is resolved to that
     file.
  3. Otherwise, if the library exists in one of the directories listed by
     ``ldconfig``, the dependency is resolved to that file.
  4. Otherwise, if the library exists in one of the ``DIRECTORIES`` entries,
     the dependency is resolved to that file. In this case, a warning is
     issued, because finding a file in one of the ``DIRECTORIES`` means that
     the depending file is not complete (it does not list all the directories
     from which it pulls dependencies).

  5. Otherwise, the dependency is unresolved.

  On Windows platforms, library resolution works as follows:

  1. DLL dependency names are converted to lowercase for matching filters.
     Windows DLL names are case-insensitive, and some linkers mangle the
     case of the DLL dependency names.  However, this makes it more difficult
     for ``PRE_INCLUDE_REGEXES``, ``PRE_EXCLUDE_REGEXES``,
     ``POST_INCLUDE_REGEXES``, and ``POST_EXCLUDE_REGEXES`` to properly
     filter DLL names - every regex would have to check for both uppercase
     and lowercase letters.  For example:

     .. code-block:: cmake

       file(GET_RUNTIME_DEPENDENCIES
         # ...
         PRE_INCLUDE_REGEXES "^[Mm][Yy][Ll][Ii][Bb][Rr][Aa][Rr][Yy]\\.[Dd][Ll][Ll]$"
         )

     Converting the DLL name to lowercase allows the regexes to only match
     lowercase names, thus simplifying the regex. For example:

     .. code-block:: cmake

       file(GET_RUNTIME_DEPENDENCIES
         # ...
         PRE_INCLUDE_REGEXES "^mylibrary\\.dll$"
         )

     This regex will match ``mylibrary.dll`` regardless of how it is cased,
     either on disk or in the depending file. (For example, it will match
     ``mylibrary.dll``, ``MyLibrary.dll``, and ``MYLIBRARY.DLL``.)

     .. versionchanged:: 3.27

       The conversion to lowercase only applies while matching filters.
       Results reported after filtering case-preserve each DLL name as it is
       found on disk, if resolved, and otherwise as it is referenced by the
       dependent binary.

       Prior to CMake 3.27, the results were reported with lowercase DLL
       file names, but the directory portion retained its casing.

  2. (**Not yet implemented**) If the depending file is a Windows Store app,
     and the dependency is listed as a dependency in the application's package
     manifest, the dependency is resolved to that file.

  3. Otherwise, if the library exists in the same directory as the depending
     file, the dependency is resolved to that file.

  4. Otherwise, if the library exists in either the operating system's
     ``system32`` directory or the ``Windows`` directory, in that order, the
     dependency is resolved to that file.

  5. Otherwise, if the library exists in one of the directories specified by
     ``DIRECTORIES``, in the order they are listed, the dependency is resolved
     to that file. In this case, a warning is not issued, because searching
     other directories is a normal part of Windows library resolution.

  6. Otherwise, the dependency is unresolved.

  On Apple platforms, library resolution works as follows:

  1. If the dependency starts with ``@executable_path/``, and an
     ``EXECUTABLES`` argument is in the process of being resolved, and
     replacing ``@executable_path/`` with the directory of the executable
     yields an existing file, the dependency is resolved to that file.

  2. Otherwise, if the dependency starts with ``@executable_path/``, and there
     is a ``BUNDLE_EXECUTABLE`` argument, and replacing ``@executable_path/``
     with the directory of the bundle executable yields an existing file, the
     dependency is resolved to that file.

  3. Otherwise, if the dependency starts with ``@loader_path/``, and replacing
     ``@loader_path/`` with the directory of the depending file yields an
     existing file, the dependency is resolved to that file.

  4. Otherwise, if the dependency starts with ``@rpath/``, and replacing
     ``@rpath/`` with one of the ``RPATH`` entries of the depending file
     yields an existing file, the dependency is resolved to that file.
     Note that ``RPATH`` entries that start with ``@executable_path/`` or
     ``@loader_path/`` also have these items replaced with the appropriate
     path.

  5. Otherwise, if the dependency is an absolute file that exists,
     the dependency is resolved to that file.

  6. Otherwise, the dependency is unresolved.

  This function accepts several variables that determine which tool is used for
  dependency resolution:

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM

    Determines which operating system and executable format the files are built
    for. This could be one of several values:

    * ``linux+elf``
    * ``windows+pe``
    * ``macos+macho``

    If this variable is not specified, it is determined automatically by system
    introspection.

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL

    Determines the tool to use for dependency resolution. It could be one of
    several values, depending on the value of
    ``CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM``:

    ================================================= =============================================
       ``CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM``       ``CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL``
    ================================================= =============================================
    ``linux+elf``                                     ``objdump``
    ``windows+pe``                                    ``objdump`` or ``dumpbin``
    ``macos+macho``                                   ``otool``
    ================================================= =============================================

    If this variable is not specified, it is determined automatically by system
    introspection.

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_COMMAND

    Determines the path to the tool to use for dependency resolution. This is
    the actual path to ``objdump``, ``dumpbin``, or ``otool``.

    If this variable is not specified, it is determined by the value of
    ``CMAKE_OBJDUMP`` if set, else by system introspection.

    .. versionadded:: 3.18
      Use ``CMAKE_OBJDUMP`` if set.

find_file
---------

A short-hand signature is:

 find_file (<VAR> name1 [path1 path2 ...])

The general signature is:

 find_file (
           <VAR>
           name | NAMES name1 [name2 ...]
           [HINTS [path | ENV var]... ]
           [PATHS [path | ENV var]... ]
           [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
           [PATH_SUFFIXES suffix1 [suffix2 ...]]
           [VALIDATOR function]
           [DOC "cache documentation string"]
           [NO_CACHE]
           [REQUIRED]
           [NO_DEFAULT_PATH]
           [NO_PACKAGE_ROOT_PATH]
           [NO_CMAKE_PATH]
           [NO_CMAKE_ENVIRONMENT_PATH]
           [NO_SYSTEM_ENVIRONMENT_PATH]
           [NO_CMAKE_SYSTEM_PATH]
           [NO_CMAKE_INSTALL_PREFIX]
           [CMAKE_FIND_ROOT_PATH_BOTH |
            ONLY_CMAKE_FIND_ROOT_PATH |
            NO_CMAKE_FIND_ROOT_PATH]
          )

This command is used to find a full path to named file.
A cache entry, or a normal variable if ``NO_CACHE`` is specified,
named by ``<VAR>`` is created to store the result of this command.
If the full path to a file is found the result is stored in the variable
and the search will not be repeated unless the variable is cleared.
If nothing is found, the result will be ``<VAR>-NOTFOUND``.

Options include:

``NAMES``
  Specify one or more possible names for the full path to a file.

  When using this to specify names with and without a version
  suffix, we recommend specifying the unversioned name first
  so that locally-built packages can be found before those
  provided by distributions.

``HINTS``, ``PATHS``
  Specify directories to search in addition to the default locations.
  The ``ENV var`` sub-option reads paths from a system environment
  variable.

  .. versionchanged:: 3.24
    On ``Windows`` platform, it is possible to include registry queries as part
    of the directories, using a :ref:`dedicated syntax <Find Using Windows Registry>`.
    Such specifications will be ignored on all other platforms.

``REGISTRY_VIEW``
  .. versionadded:: 3.24

  .. include:: FIND_XXX_REGISTRY_VIEW.txt

``PATH_SUFFIXES``
  Specify additional subdirectories to check below each directory
  location otherwise considered.

``VALIDATOR``
  .. versionadded:: 3.25

  Specify a ``function()`` to be called for each candidate item found
  (a ``macro()`` cannot be provided, that will result in an error).
  Two arguments will be passed to the validator function: the name of a
  result variable, and the absolute path to the candidate item.  The item
  will be accepted and the search will end unless the function sets the
  value in the result variable to false in the calling scope.  The result
  variable will hold a true value when the validator function is entered.

  .. parsed-literal::

    function(my_check validator_result_var item)
      if(NOT item MATCHES ...)
        set(${validator_result_var} FALSE PARENT_SCOPE)
      endif()
    endfunction()

    |FIND_XXX| (result NAMES ... VALIDATOR my_check)

 Note that if a cached result is used, the search is skipped and any
 ``VALIDATOR`` is ignored.  The cached result is not required to pass the
 validation function.

``DOC``
  Specify the documentation string for the ``<VAR>`` cache entry.

``NO_CACHE``
  .. versionadded:: 3.21

  The result of the search will be stored in a normal variable rather than
  a cache entry.

  .. note::

   If the variable is already set before the call (as a normal or cache
   variable) then the search will not occur.

 .. warning::

   This option should be used with caution because it can greatly increase
   the cost of repeated configure steps.

``REQUIRED``
  .. versionadded:: 3.18

  Stop processing with an error message if nothing is found, otherwise
  the search will be attempted again the next time find_file is invoked
  with the same variable.

If ``NO_DEFAULT_PATH`` is specified, then no additional paths are
added to the search.
If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to
   ``find_package(<PackageName>)``, search prefixes unique to the
   current package being found.  See policy ``CMP0074``.

   .. versionadded:: 3.12

   Specifically, search paths specified by the following variables, in order:

   a. ``<PackageName>_ROOT`` CMake variable,
      where ``<PackageName>`` is the case-preserved package name.

   b. ``<PACKAGENAME>_ROOT`` CMake variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   c. ``<PackageName>_ROOT`` environment variable,
      where ``<PackageName>`` is the case-preserved package name.

   d. ``<PACKAGENAME>_ROOT`` environment variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   The package root variables are maintained as a stack, so if called from
   nested find modules or config packages, root paths from the parent's find
   module or config package will be searched after paths from the current
   module or package.  In other words, the search order would be
   ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
   ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_PACKAGE_ROOT_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in the ``<PackageName>_ROOT`` CMake variable and the ``<PackageName>_ROOT`` environment variable if called from within a find module loaded by ``find_package(<PackageName>)``

2. Search paths specified in cmake-specific cache variables.
   These are intended to be used on the command line with a ``-DVAR=value``.
   The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
   This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_INCLUDE_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

3. Search paths specified in cmake-specific environment variables.
   These are intended to be set in the user's shell configuration,
   and therefore use the host's native path separator
   (``;`` on Windows and ``:`` on UNIX).
   This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or
   by setting the ``CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_INCLUDE_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

4. Search the paths specified by the ``HINTS`` option.
   These should be paths computed by system introspection, such as a
   hint provided by the location of another item already found.
   Hard-coded guesses should be specified with the ``PATHS`` option.

5. Search the standard system environment variables.
   This can be skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed or by
   setting the ``CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH`` to ``FALSE``.

   * The directories in ``INCLUDE`` and ``PATH``.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>/[s]bin`` in ``PATH``, and ``<entry>/include`` for other entries in ``PATH``. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files
   for the current system.  The searching of ``CMAKE_INSTALL_PREFIX`` and
   ``CMAKE_STAGING_PREFIX`` can be
   skipped if ``NO_CMAKE_INSTALL_PREFIX`` is passed or by setting the
   ``CMAKE_FIND_USE_INSTALL_PREFIX`` to ``FALSE``. All these locations
   can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_SYSTEM_PREFIX_PATH``
   * ``CMAKE_SYSTEM_INCLUDE_PATH``
   * ``CMAKE_SYSTEM_FRAMEWORK_PATH``

   The platform paths that these variables contain are locations that
   typically include installed software. An example being ``/usr/local`` for
   UNIX based platforms.

7. Search the paths specified by the PATHS option
   or in the short-hand version of the command.
   These are typically hard-coded guesses.

The ``CMAKE_IGNORE_PATH``, ``CMAKE_IGNORE_PREFIX_PATH``,
``CMAKE_SYSTEM_IGNORE_PATH`` and
``CMAKE_SYSTEM_IGNORE_PREFIX_PATH`` variables can also cause some
of the above locations to be ignored.

.. versionadded:: 3.16
  Added ``CMAKE_FIND_USE_<CATEGORY>_PATH`` variables to globally disable
  various search locations.

On macOS the ``CMAKE_FIND_FRAMEWORK`` and
``CMAKE_FIND_APPBUNDLE`` variables determine the order of
preference between Apple-style and unix-style package components.

The CMake variable ``CMAKE_FIND_ROOT_PATH`` specifies one or more
directories to be prepended to all other search directories.  This
effectively "re-roots" the entire search under given locations.
Paths which are descendants of the ``CMAKE_STAGING_PREFIX`` are excluded
from this re-rooting, because that variable is always a path on the host system.
By default the ``CMAKE_FIND_ROOT_PATH`` is empty.

The ``CMAKE_SYSROOT`` variable can also be used to specify exactly one
directory to use as a prefix.  Setting ``CMAKE_SYSROOT`` also has other
effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to
point to the root directory of the target environment and CMake will
search there too.  By default at first the directories listed in
``CMAKE_FIND_ROOT_PATH`` are searched, then the ``CMAKE_SYSROOT``
directory is searched, and then the non-rooted directories will be
searched.  The default behavior can be adjusted by setting
``CMAKE_FIND_ROOT_PATH_MODE_INCLUDE``.  This behavior can be manually
overridden on a per-call basis using options:

``CMAKE_FIND_ROOT_PATH_BOTH``
  Search in the order described above.

``NO_CMAKE_FIND_ROOT_PATH``
  Do not use the ``CMAKE_FIND_ROOT_PATH`` variable.

``ONLY_CMAKE_FIND_ROOT_PATH``
  Search only the re-rooted directories and directories below
  ``CMAKE_STAGING_PREFIX``.

The default search order is designed to be most-specific to
least-specific for common use cases.
Projects may override the order by simply calling the command
multiple times and using the ``NO_*`` options:

 find_file (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
 find_file (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set
and stored in the cache so that no call will search again.

find_library
------------

A short-hand signature is:

 find_library (<VAR> name1 [path1 path2 ...])

The general signature is:

 find_library (
           <VAR>
           name | NAMES name1 [name2 ...] [NAMES_PER_DIR]
           [HINTS [path | ENV var]... ]
           [PATHS [path | ENV var]... ]
           [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
           [PATH_SUFFIXES suffix1 [suffix2 ...]]
           [VALIDATOR function]
           [DOC "cache documentation string"]
           [NO_CACHE]
           [REQUIRED]
           [NO_DEFAULT_PATH]
           [NO_PACKAGE_ROOT_PATH]
           [NO_CMAKE_PATH]
           [NO_CMAKE_ENVIRONMENT_PATH]
           [NO_SYSTEM_ENVIRONMENT_PATH]
           [NO_CMAKE_SYSTEM_PATH]
           [NO_CMAKE_INSTALL_PREFIX]
           [CMAKE_FIND_ROOT_PATH_BOTH |
            ONLY_CMAKE_FIND_ROOT_PATH |
            NO_CMAKE_FIND_ROOT_PATH]
          )

This command is used to find a library.
A cache entry, or a normal variable if ``NO_CACHE`` is specified,
named by ``<VAR>`` is created to store the result of this command.
If the library is found the result is stored in the variable
and the search will not be repeated unless the variable is cleared.
If nothing is found, the result will be ``<VAR>-NOTFOUND``.

Options include:

``NAMES``
  Specify one or more possible names for the library.

  When using this to specify names with and without a version
  suffix, we recommend specifying the unversioned name first
  so that locally-built packages can be found before those
  provided by distributions.

``HINTS``, ``PATHS``
  Specify directories to search in addition to the default locations.
  The ``ENV var`` sub-option reads paths from a system environment
  variable.

  .. versionchanged:: 3.24
    On ``Windows`` platform, it is possible to include registry queries as part
    of the directories, using a :ref:`dedicated syntax <Find Using Windows Registry>`.
    Such specifications will be ignored on all other platforms.

``REGISTRY_VIEW``
  .. versionadded:: 3.24

  .. include:: FIND_XXX_REGISTRY_VIEW.txt

``PATH_SUFFIXES``
  Specify additional subdirectories to check below each directory
  location otherwise considered.

``VALIDATOR``
  .. versionadded:: 3.25

  Specify a ``function()`` to be called for each candidate item found
  (a ``macro()`` cannot be provided, that will result in an error).
  Two arguments will be passed to the validator function: the name of a
  result variable, and the absolute path to the candidate item.  The item
  will be accepted and the search will end unless the function sets the
  value in the result variable to false in the calling scope.  The result
  variable will hold a true value when the validator function is entered.

  .. parsed-literal::

    function(my_check validator_result_var item)
      if(NOT item MATCHES ...)
        set(${validator_result_var} FALSE PARENT_SCOPE)
      endif()
    endfunction()

    |FIND_XXX| (result NAMES ... VALIDATOR my_check)

 Note that if a cached result is used, the search is skipped and any
 ``VALIDATOR`` is ignored.  The cached result is not required to pass the
 validation function.

``DOC``
  Specify the documentation string for the ``<VAR>`` cache entry.

``NO_CACHE``
  .. versionadded:: 3.21

  The result of the search will be stored in a normal variable rather than
  a cache entry.

  .. note::

   If the variable is already set before the call (as a normal or cache
   variable) then the search will not occur.

 .. warning::

   This option should be used with caution because it can greatly increase
   the cost of repeated configure steps.

``REQUIRED``
  .. versionadded:: 3.18

  Stop processing with an error message if nothing is found, otherwise
  the search will be attempted again the next time find_library is invoked
  with the same variable.

If ``NO_DEFAULT_PATH`` is specified, then no additional paths are
added to the search.
If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to
   ``find_package(<PackageName>)``, search prefixes unique to the
   current package being found.  See policy ``CMP0074``.

   .. versionadded:: 3.12

   Specifically, search paths specified by the following variables, in order:

   a. ``<PackageName>_ROOT`` CMake variable,
      where ``<PackageName>`` is the case-preserved package name.

   b. ``<PACKAGENAME>_ROOT`` CMake variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   c. ``<PackageName>_ROOT`` environment variable,
      where ``<PackageName>`` is the case-preserved package name.

   d. ``<PACKAGENAME>_ROOT`` environment variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   The package root variables are maintained as a stack, so if called from
   nested find modules or config packages, root paths from the parent's find
   module or config package will be searched after paths from the current
   module or package.  In other words, the search order would be
   ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
   ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_PACKAGE_ROOT_PATH`` to ``FALSE``.

   * ``<prefix>/lib/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/lib`` for each ``<prefix>`` in the ``<PackageName>_ROOT`` CMake variable and the ``<PackageName>_ROOT`` environment variable if called from within a find module loaded by ``find_package(<PackageName>)``

2. Search paths specified in cmake-specific cache variables.
   These are intended to be used on the command line with a ``-DVAR=value``.
   The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
   This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_PATH`` to ``FALSE``.

   * ``<prefix>/lib/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/lib`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_LIBRARY_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

3. Search paths specified in cmake-specific environment variables.
   These are intended to be set in the user's shell configuration,
   and therefore use the host's native path separator
   (``;`` on Windows and ``:`` on UNIX).
   This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or
   by setting the ``CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH`` to ``FALSE``.

   * ``<prefix>/lib/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/lib`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_LIBRARY_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

4. Search the paths specified by the ``HINTS`` option.
   These should be paths computed by system introspection, such as a
   hint provided by the location of another item already found.
   Hard-coded guesses should be specified with the ``PATHS`` option.

5. Search the standard system environment variables.
   This can be skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed or by
   setting the ``CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH`` to ``FALSE``.

   * The directories in ``LIB`` and ``PATH``.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: ``<prefix>/lib/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/lib`` for each ``<prefix>/[s]bin`` in ``PATH``, and ``<entry>/lib`` for other entries in ``PATH``. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files
   for the current system.  The searching of ``CMAKE_INSTALL_PREFIX`` and
   ``CMAKE_STAGING_PREFIX`` can be
   skipped if ``NO_CMAKE_INSTALL_PREFIX`` is passed or by setting the
   ``CMAKE_FIND_USE_INSTALL_PREFIX`` to ``FALSE``. All these locations
   can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`` to ``FALSE``.

   * ``<prefix>/lib/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/lib`` for each ``<prefix>`` in ``CMAKE_SYSTEM_PREFIX_PATH``
   * ``CMAKE_SYSTEM_LIBRARY_PATH``
   * ``CMAKE_SYSTEM_FRAMEWORK_PATH``

   The platform paths that these variables contain are locations that
   typically include installed software. An example being ``/usr/local`` for
   UNIX based platforms.

7. Search the paths specified by the PATHS option
   or in the short-hand version of the command.
   These are typically hard-coded guesses.

The ``CMAKE_IGNORE_PATH``, ``CMAKE_IGNORE_PREFIX_PATH``,
``CMAKE_SYSTEM_IGNORE_PATH`` and
``CMAKE_SYSTEM_IGNORE_PREFIX_PATH`` variables can also cause some
of the above locations to be ignored.

.. versionadded:: 3.16
  Added ``CMAKE_FIND_USE_<CATEGORY>_PATH`` variables to globally disable
  various search locations.

On macOS the ``CMAKE_FIND_FRAMEWORK`` and
``CMAKE_FIND_APPBUNDLE`` variables determine the order of
preference between Apple-style and unix-style package components.

The CMake variable ``CMAKE_FIND_ROOT_PATH`` specifies one or more
directories to be prepended to all other search directories.  This
effectively "re-roots" the entire search under given locations.
Paths which are descendants of the ``CMAKE_STAGING_PREFIX`` are excluded
from this re-rooting, because that variable is always a path on the host system.
By default the ``CMAKE_FIND_ROOT_PATH`` is empty.

The ``CMAKE_SYSROOT`` variable can also be used to specify exactly one
directory to use as a prefix.  Setting ``CMAKE_SYSROOT`` also has other
effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to
point to the root directory of the target environment and CMake will
search there too.  By default at first the directories listed in
``CMAKE_FIND_ROOT_PATH`` are searched, then the ``CMAKE_SYSROOT``
directory is searched, and then the non-rooted directories will be
searched.  The default behavior can be adjusted by setting
``CMAKE_FIND_ROOT_PATH_MODE_LIBRARY``.  This behavior can be manually
overridden on a per-call basis using options:

``CMAKE_FIND_ROOT_PATH_BOTH``
  Search in the order described above.

``NO_CMAKE_FIND_ROOT_PATH``
  Do not use the ``CMAKE_FIND_ROOT_PATH`` variable.

``ONLY_CMAKE_FIND_ROOT_PATH``
  Search only the re-rooted directories and directories below
  ``CMAKE_STAGING_PREFIX``.

The default search order is designed to be most-specific to
least-specific for common use cases.
Projects may override the order by simply calling the command
multiple times and using the ``NO_*`` options:

 find_library (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
 find_library (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set
and stored in the cache so that no call will search again.

When more than one value is given to the ``NAMES`` option this command by
default will consider one name at a time and search every directory
for it.  The ``NAMES_PER_DIR`` option tells this command to consider one
directory at a time and search for all names in it.

Each library name given to the ``NAMES`` option is first considered
as a library file name and then considered with platform-specific
prefixes (e.g. ``lib``) and suffixes (e.g. ``.so``).  Therefore one
may specify library file names such as ``libfoo.a`` directly.
This can be used to locate static libraries on UNIX-like systems.

If the library found is a framework, then ``<VAR>`` will be set to the full
path to the framework ``<fullPath>/A.framework``.  When a full path to a
framework is used as a library, CMake will use a ``-framework A``, and a
``-F<fullPath>`` to link the framework to the target.

.. versionadded:: 3.28

  The library found can now be a ``.xcframework`` folder.

If the ``CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX`` variable is set all
search paths will be tested as normal, with the suffix appended, and with
all matches of ``lib/`` replaced with
``lib${CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX}/``.  This variable overrides
the ``FIND_LIBRARY_USE_LIB32_PATHS``,
``FIND_LIBRARY_USE_LIBX32_PATHS``,
and ``FIND_LIBRARY_USE_LIB64_PATHS`` global properties.

If the ``FIND_LIBRARY_USE_LIB32_PATHS`` global property is set
all search paths will be tested as normal, with ``32/`` appended, and
with all matches of ``lib/`` replaced with ``lib32/``.  This property is
automatically set for the platforms that are known to need it if at
least one of the languages supported by the ``project()`` command
is enabled.

If the ``FIND_LIBRARY_USE_LIBX32_PATHS`` global property is set
all search paths will be tested as normal, with ``x32/`` appended, and
with all matches of ``lib/`` replaced with ``libx32/``.  This property is
automatically set for the platforms that are known to need it if at
least one of the languages supported by the ``project()`` command
is enabled.

If the ``FIND_LIBRARY_USE_LIB64_PATHS`` global property is set
all search paths will be tested as normal, with ``64/`` appended, and
with all matches of ``lib/`` replaced with ``lib64/``.  This property is
automatically set for the platforms that are known to need it if at
least one of the languages supported by the ``project()`` command
is enabled.

find_package
------------

.. note:: The :guide:`Using Dependencies Guide` provides a high-level
  introduction to this general topic. It provides a broader overview of
  where the ``find_package()`` command fits into the bigger picture,
  including its relationship to the ``FetchContent`` module.
  The guide is recommended pre-reading before moving on to the details below.

Find a package (usually provided by something external to the project),
and load its package-specific details.  Calls to this command can also
be intercepted by :ref:`dependency providers <dependency_providers>`.

Typical Usage
^^^^^^^^^^^^^

Most calls to ``find_package()`` typically have the following form:

 find_package(<PackageName> [<version>] [REQUIRED] [COMPONENTS <components>...])

The ``<PackageName>`` is the only mandatory argument.  The ``<version>`` is
often omitted, and ``REQUIRED`` should be given if the project cannot be
configured successfully without the package.  Some more complicated packages
support components which can be selected with the ``COMPONENTS`` keyword, but
most packages don't have that level of complexity.

The above is a reduced form of the basic signature.  Where possible,
projects should find packages using this form.  This reduces complexity and
maximizes the ways in which the package can be found or provided.

Understanding the basic signature should be enough for general usage of
``find_package()``.  Project maintainers who intend to provide a config
package should understand the bigger picture, as explained in
:ref:`Full Signature` and all subsequent sections on this page.

Search Modes
^^^^^^^^^^^^

The command has a few modes by which it searches for packages:

**Module mode**
  In this mode, CMake searches for a file called ``Find<PackageName>.cmake``,
  looking first in the locations listed in the ``CMAKE_MODULE_PATH``,
  then among the :ref:`Find Modules` provided by the CMake installation.
  If the file is found, it is read and processed by CMake.  It is responsible
  for finding the package, checking the version, and producing any needed
  messages.  Some Find modules provide limited or no support for versioning;
  check the Find module's documentation.

  The ``Find<PackageName>.cmake`` file is not typically provided by the
  package itself.  Rather, it is normally provided by something external to
  the package, such as the operating system, CMake itself, or even the project
  from which the ``find_package()`` command was called.  Being externally
  provided, :ref:`Find Modules` tend to be heuristic in nature and are
  susceptible to becoming out-of-date.  They typically search for certain
  libraries, files and other package artifacts.

  Module mode is only supported by the
  :ref:`basic command signature <Basic Signature>`.

**Config mode**
  In this mode, CMake searches for a file called
  ``<lowercasePackageName>-config.cmake`` or ``<PackageName>Config.cmake``.
  It will also look for ``<lowercasePackageName>-config-version.cmake`` or
  ``<PackageName>ConfigVersion.cmake`` if version details were specified
  (see :ref:`version selection` for an explanation of how these separate
  version files are used).

  In config mode, the command can be given a list of names to search for
  as package names.  The locations where CMake searches for the config and
  version files is considerably more complicated than for Module mode
  (see :ref:`search procedure`).

  The config and version files are typically installed as part of the
  package, so they tend to be more reliable than Find modules.  They usually
  contain direct knowledge of the package contents, so no searching or
  heuristics are needed within the config or version files themselves.

  Config mode is supported by both the :ref:`basic <Basic Signature>` and
  :ref:`full <Full Signature>` command signatures.

**FetchContent redirection mode**
  .. versionadded:: 3.24
    A call to ``find_package()`` can be redirected internally to a package
    provided by the ``FetchContent`` module.  To the caller, the behavior
    will appear similar to Config mode, except that the search logic is
    by-passed and the component information is not used.  See
    ``FetchContent_Declare()`` and ``FetchContent_MakeAvailable()``
    for further details.

When not redirected to a package provided by ``FetchContent``, the
command arguments determine whether Module or Config mode is used.  When the
basic signature is used, the command searches in Module mode first.
If the package is not found, the search falls back to Config mode.
A user may set the ``CMAKE_FIND_PACKAGE_PREFER_CONFIG`` variable
to true to reverse the priority and direct CMake to search using Config mode
first before falling back to Module mode.  The basic signature can also be
forced to use only Module mode with a ``MODULE`` keyword.  If the
full signature is used, the command only searches in Config mode.

Basic Signature
^^^^^^^^^^^^^^^

 find_package(<PackageName> [version] [EXACT] [QUIET] [MODULE]
              [REQUIRED] [[COMPONENTS] [components...]]
              [OPTIONAL_COMPONENTS components...]
              [REGISTRY_VIEW  (64|32|64_32|32_64|HOST|TARGET|BOTH)]
              [GLOBAL]
              [NO_POLICY_SCOPE]
              [BYPASS_PROVIDER])

The basic signature is supported by both Module and Config modes.
The ``MODULE`` keyword implies that only Module mode can be used to find
the package, with no fallback to Config mode.

Regardless of the mode used, a ``<PackageName>_FOUND`` variable will be
set to indicate whether the package was found.  When the package is found,
package-specific information may be provided through other variables and
:ref:`Imported Targets` documented by the package itself.  The
``QUIET`` option disables informational messages, including those indicating
that the package cannot be found if it is not ``REQUIRED``.  The ``REQUIRED``
option stops processing with an error message if the package cannot be found.

A package-specific list of required components may be listed after the
``COMPONENTS`` keyword.  If any of these components are not able to be
satisfied, the package overall is considered to be not found.  If the
``REQUIRED`` option is also present, this is treated as a fatal error,
otherwise execution still continues.  As a form of shorthand, if the
``REQUIRED`` option is present, the ``COMPONENTS`` keyword can be omitted
and the required components can be listed directly after ``REQUIRED``.

Additional optional components may be listed after
``OPTIONAL_COMPONENTS``.  If these cannot be satisfied, the package overall
can still be considered found, as long as all required components are
satisfied.

The set of available components and their meaning are defined by the
target package.  Formally, it is up to the target package how to
interpret the component information given to it, but it should follow
the expectations stated above.  For calls where no components are specified,
there is no single expected behavior and target packages should clearly
define what occurs in such cases.  Common arrangements include assuming it
should find all components, no components or some well-defined subset of the
available components.

.. versionadded:: 3.24
  The ``REGISTRY_VIEW`` keyword specifies which registry views should be
  queried. This keyword is only meaningful on ``Windows`` platforms and will
  be ignored on all others. Formally, it is up to the target package how to
  interpret the registry view information given to it.

.. versionadded:: 3.24
  Specifying the ``GLOBAL`` keyword will promote all imported targets to
  a global scope in the importing project. Alternatively, this functionality
  can be enabled by setting the ``CMAKE_FIND_PACKAGE_TARGETS_GLOBAL``
  variable.

The ``[version]`` argument requests a version with which the package found
should be compatible. There are two possible forms in which it may be
specified:

  * A single version with the format ``major[.minor[.patch[.tweak]]]``, where
    each component is a numeric value.
  * A version range with the format ``versionMin...[<]versionMax`` where
    ``versionMin`` and ``versionMax`` have the same format and constraints
    on components being integers as the single version.  By default, both end
    points are included.  By specifying ``<``, the upper end point will be
    excluded. Version ranges are only supported with CMake 3.19 or later.

The ``EXACT`` option requests that the version be matched exactly. This option
is incompatible with the specification of a version range.

If no ``[version]`` and/or component list is given to a recursive invocation
inside a find-module, the corresponding arguments are forwarded
automatically from the outer call (including the ``EXACT`` flag for
``[version]``).  Version support is currently provided only on a
package-by-package basis (see the Version Selection section below).
When a version range is specified but the package is only designed to expect
a single version, the package will ignore the upper end point of the range and
only take the single version at the lower end of the range into account.

See the ``cmake_policy()`` command documentation for discussion
of the ``NO_POLICY_SCOPE`` option.

.. versionadded:: 3.24
  The ``BYPASS_PROVIDER`` keyword is only allowed when ``find_package()`` is
  being called by a :ref:`dependency provider <dependency_providers>`.
  It can be used by providers to call the built-in ``find_package()``
  implementation directly and prevent that call from being re-routed back to
  itself.  Future versions of CMake may detect attempts to use this keyword
  from places other than a dependency provider and halt with a fatal error.

Full Signature
^^^^^^^^^^^^^^

 find_package(<PackageName> [version] [EXACT] [QUIET]
              [REQUIRED] [[COMPONENTS] [components...]]
              [OPTIONAL_COMPONENTS components...]
              [CONFIG|NO_MODULE]
              [GLOBAL]
              [NO_POLICY_SCOPE]
              [BYPASS_PROVIDER]
              [NAMES name1 [name2 ...]]
              [CONFIGS config1 [config2 ...]]
              [HINTS path1 [path2 ... ]]
              [PATHS path1 [path2 ... ]]
              [REGISTRY_VIEW  (64|32|64_32|32_64|HOST|TARGET|BOTH)]
              [PATH_SUFFIXES suffix1 [suffix2 ...]]
              [NO_DEFAULT_PATH]
              [NO_PACKAGE_ROOT_PATH]
              [NO_CMAKE_PATH]
              [NO_CMAKE_ENVIRONMENT_PATH]
              [NO_SYSTEM_ENVIRONMENT_PATH]
              [NO_CMAKE_PACKAGE_REGISTRY]
              [NO_CMAKE_BUILDS_PATH] # Deprecated; does nothing.
              [NO_CMAKE_SYSTEM_PATH]
              [NO_CMAKE_INSTALL_PREFIX]
              [NO_CMAKE_SYSTEM_PACKAGE_REGISTRY]
              [CMAKE_FIND_ROOT_PATH_BOTH |
               ONLY_CMAKE_FIND_ROOT_PATH |
               NO_CMAKE_FIND_ROOT_PATH])

The ``CONFIG`` option, the synonymous ``NO_MODULE`` option, or the use
of options not specified in the basic signature all enforce pure Config
mode.  In pure Config mode, the command skips Module mode search and
proceeds at once with Config mode search.

Config mode search attempts to locate a configuration file provided by the
package to be found.  A cache entry called ``<PackageName>_DIR`` is created to
hold the directory containing the file.  By default, the command searches for
a package with the name ``<PackageName>``.  If the ``NAMES`` option is given,
the names following it are used instead of ``<PackageName>``.  The names are
also considered when determining whether to redirect the call to a package
provided by ``FetchContent``.

The command searches for a file called ``<PackageName>Config.cmake`` or
``<lowercasePackageName>-config.cmake`` for each name specified.
A replacement set of possible configuration file names may be given
using the ``CONFIGS`` option.  The :ref:`search procedure` is specified below.
Once found, any :ref:`version constraint <version selection>` is checked,
and if satisfied, the configuration file is read and processed by CMake.
Since the file is provided by the package it already knows the
location of package contents.  The full path to the configuration file
is stored in the cmake variable ``<PackageName>_CONFIG``.

All configuration files which have been considered by CMake while
searching for the package with an appropriate version are stored in the
``<PackageName>_CONSIDERED_CONFIGS`` variable, and the associated versions
in the ``<PackageName>_CONSIDERED_VERSIONS`` variable.

If the package configuration file cannot be found CMake will generate
an error describing the problem unless the ``QUIET`` argument is
specified.  If ``REQUIRED`` is specified and the package is not found a
fatal error is generated and the configure step stops executing.  If
``<PackageName>_DIR`` has been set to a directory not containing a
configuration file CMake will ignore it and search from scratch.

Package maintainers providing CMake package configuration files are
encouraged to name and install them such that the :ref:`search procedure`
outlined below will find them without requiring use of additional options.

Config Mode Search Procedure
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. note::
  When Config mode is used, this search procedure is applied regardless of
  whether the :ref:`full <full signature>` or :ref:`basic <basic signature>`
  signature was given.

.. versionadded:: 3.24
  All calls to ``find_package()`` (even in Module mode) first look for a config
  package file in the ``CMAKE_FIND_PACKAGE_REDIRECTS_DIR`` directory.
  The ``FetchContent`` module, or even the project itself, may write files
  to that location to redirect ``find_package()`` calls to content already
  provided by the project.  If no config package file is found in that location,
  the search proceeds with the logic described below.

CMake constructs a set of possible installation prefixes for the
package.  Under each prefix several directories are searched for a
configuration file.  The tables below show the directories searched.
Each entry is meant for installation trees following Windows (``W``), UNIX
(``U``), or Apple (``A``) conventions:

==================================================================== ==========
 Entry                                                               Convention
==================================================================== ==========
 ``<prefix>/``                                                          W
 ``<prefix>/(cmake|CMake)/``                                            W
 ``<prefix>/<name>*/``                                                  W
 ``<prefix>/<name>*/(cmake|CMake)/``                                    W
 ``<prefix>/<name>*/(cmake|CMake)/<name>*/`` [#]_                       W
 ``<prefix>/(lib/<arch>|lib*|share)/cmake/<name>*/``                    U
 ``<prefix>/(lib/<arch>|lib*|share)/<name>*/``                          U
 ``<prefix>/(lib/<arch>|lib*|share)/<name>*/(cmake|CMake)/``            U
 ``<prefix>/<name>*/(lib/<arch>|lib*|share)/cmake/<name>*/``            W/U
 ``<prefix>/<name>*/(lib/<arch>|lib*|share)/<name>*/``                  W/U
 ``<prefix>/<name>*/(lib/<arch>|lib*|share)/<name>*/(cmake|CMake)/``    W/U
==================================================================== ==========

On systems supporting macOS ``FRAMEWORK`` and ``BUNDLE``, the
following directories are searched for Frameworks or Application Bundles
containing a configuration file:

=========================================================== ==========
 Entry                                                      Convention
=========================================================== ==========
 ``<prefix>/<name>.framework/Resources/``                      A
 ``<prefix>/<name>.framework/Resources/CMake/``                A
 ``<prefix>/<name>.framework/Versions/*/Resources/``           A
 ``<prefix>/<name>.framework/Versions/*/Resources/CMake/``     A
 ``<prefix>/<name>.app/Contents/Resources/``                   A
 ``<prefix>/<name>.app/Contents/Resources/CMake/``             A
=========================================================== ==========

In all cases the ``<name>`` is treated as case-insensitive and corresponds
to any of the names specified (``<PackageName>`` or names given by ``NAMES``).

If at least one compiled language has been enabled, the architecture-specific
``lib/<arch>`` and ``lib*`` directories may be searched based on the compiler's
target architecture, in the following order:

``lib/<arch>``
  Searched if the ``CMAKE_LIBRARY_ARCHITECTURE`` variable is set.

``lib64``
  Searched on 64 bit platforms (``CMAKE_SIZEOF_VOID_P`` is 8) and the
  ``FIND_LIBRARY_USE_LIB64_PATHS`` property is set to ``TRUE``.

``lib32``
  Searched on 32 bit platforms (``CMAKE_SIZEOF_VOID_P`` is 4) and the
  ``FIND_LIBRARY_USE_LIB32_PATHS`` property is set to ``TRUE``.

``libx32``
  Searched on platforms using the x32 ABI
  if the ``FIND_LIBRARY_USE_LIBX32_PATHS`` property is set to ``TRUE``.

``lib``
  Always searched.

.. versionchanged:: 3.24
  On ``Windows`` platform, it is possible to include registry queries as part
  of the directories specified through ``HINTS`` and ``PATHS`` keywords, using
  a :ref:`dedicated syntax <Find Using Windows Registry>`. Such specifications
  will be ignored on all other platforms.

.. versionadded:: 3.24
  ``REGISTRY_VIEW`` can be specified to manage ``Windows`` registry queries
  specified as part of ``PATHS`` and ``HINTS``.

  .. include:: FIND_XXX_REGISTRY_VIEW.txt

If ``PATH_SUFFIXES`` is specified, the suffixes are appended to each
(``W``) or (``U``) directory entry one-by-one.

This set of directories is intended to work in cooperation with
projects that provide configuration files in their installation trees.
Directories above marked with (``W``) are intended for installations on
Windows where the prefix may point at the top of an application's
installation directory.  Those marked with (``U``) are intended for
installations on UNIX platforms where the prefix is shared by multiple
packages.  This is merely a convention, so all (``W``) and (``U``) directories
are still searched on all platforms.  Directories marked with (``A``) are
intended for installations on Apple platforms.  The
``CMAKE_FIND_FRAMEWORK`` and ``CMAKE_FIND_APPBUNDLE``
variables determine the order of preference.

The set of installation prefixes is constructed using the following
steps.  If ``NO_DEFAULT_PATH`` is specified all ``NO_*`` options are
enabled.

1. Search prefixes unique to the current ``<PackageName>`` being found.
   See policy ``CMP0074``.

   .. versionadded:: 3.12

   Specifically, search prefixes specified by the following variables,
   in order:

   a. ``<PackageName>_ROOT`` CMake variable,
      where ``<PackageName>`` is the case-preserved package name.

   b. ``<PACKAGENAME>_ROOT`` CMake variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   c. ``<PackageName>_ROOT`` environment variable,
      where ``<PackageName>`` is the case-preserved package name.

   d. ``<PACKAGENAME>_ROOT`` environment variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   The package root variables are maintained as a stack so if
   called from within a find module, root paths from the parent's find
   module will also be searched after paths for the current package.
   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_PACKAGE_ROOT_PATH`` to ``FALSE``.

2. Search paths specified in cmake-specific cache variables.  These
   are intended to be used on the command line with a :option:`-DVAR=VALUE <cmake -D>`.
   The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
   This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_PATH`` to ``FALSE``:

   * ``CMAKE_PREFIX_PATH``
   * ``CMAKE_FRAMEWORK_PATH``
   * ``CMAKE_APPBUNDLE_PATH``

3. Search paths specified in cmake-specific environment variables.
   These are intended to be set in the user's shell configuration,
   and therefore use the host's native path separator
   (``;`` on Windows and ``:`` on UNIX).
   This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH`` to ``FALSE``:

   * ``<PackageName>_DIR``
   * ``CMAKE_PREFIX_PATH``
   * ``CMAKE_FRAMEWORK_PATH``
   * ``CMAKE_APPBUNDLE_PATH``

4. Search paths specified by the ``HINTS`` option.  These should be paths
   computed by system introspection, such as a hint provided by the
   location of another item already found.  Hard-coded guesses should
   be specified with the ``PATHS`` option.

5. Search the standard system environment variables.  This can be
   skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed  or by setting the
   ``CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH`` to ``FALSE``. Path entries
   ending in ``/bin`` or ``/sbin`` are automatically converted to their
   parent directories:

   * ``PATH``

6. Search paths stored in the CMake :ref:`User Package Registry`.
   This can be skipped if ``NO_CMAKE_PACKAGE_REGISTRY`` is passed or by
   setting the variable ``CMAKE_FIND_USE_PACKAGE_REGISTRY``
   to ``FALSE`` or the deprecated variable
   ``CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY`` to ``TRUE``.

   See the ``cmake-packages(7)`` manual for details on the user
   package registry.

7. Search cmake variables defined in the Platform files for the
   current system. The searching of ``CMAKE_INSTALL_PREFIX`` and
   ``CMAKE_STAGING_PREFIX`` can be
   skipped if ``NO_CMAKE_INSTALL_PREFIX`` is passed or by setting the
   ``CMAKE_FIND_USE_INSTALL_PREFIX`` to ``FALSE``. All these locations
   can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`` to ``FALSE``:

   * ``CMAKE_SYSTEM_PREFIX_PATH``
   * ``CMAKE_SYSTEM_FRAMEWORK_PATH``
   * ``CMAKE_SYSTEM_APPBUNDLE_PATH``

   The platform paths that these variables contain are locations that
   typically include installed software. An example being ``/usr/local`` for
   UNIX based platforms.

8. Search paths stored in the CMake :ref:`System Package Registry`.
   This can be skipped if ``NO_CMAKE_SYSTEM_PACKAGE_REGISTRY`` is passed
   or by setting the ``CMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY``
   variable to ``FALSE`` or the deprecated variable
   ``CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY`` to ``TRUE``.

   See the ``cmake-packages(7)`` manual for details on the system
   package registry.

9. Search paths specified by the ``PATHS`` option.  These are typically
   hard-coded guesses.

The ``CMAKE_IGNORE_PATH``, ``CMAKE_IGNORE_PREFIX_PATH``,
``CMAKE_SYSTEM_IGNORE_PATH`` and
``CMAKE_SYSTEM_IGNORE_PREFIX_PATH`` variables can also cause some
of the above locations to be ignored.

.. versionadded:: 3.16
   Added the ``CMAKE_FIND_USE_<CATEGORY>`` variables to globally disable
   various search locations.

The CMake variable ``CMAKE_FIND_ROOT_PATH`` specifies one or more
directories to be prepended to all other search directories.  This
effectively "re-roots" the entire search under given locations.
Paths which are descendants of the ``CMAKE_STAGING_PREFIX`` are excluded
from this re-rooting, because that variable is always a path on the host system.
By default the ``CMAKE_FIND_ROOT_PATH`` is empty.

The ``CMAKE_SYSROOT`` variable can also be used to specify exactly one
directory to use as a prefix.  Setting ``CMAKE_SYSROOT`` also has other
effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to
point to the root directory of the target environment and CMake will
search there too.  By default at first the directories listed in
``CMAKE_FIND_ROOT_PATH`` are searched, then the ``CMAKE_SYSROOT``
directory is searched, and then the non-rooted directories will be
searched.  The default behavior can be adjusted by setting
``CMAKE_FIND_ROOT_PATH_MODE_PACKAGE``.  This behavior can be manually
overridden on a per-call basis using options:

``CMAKE_FIND_ROOT_PATH_BOTH``
  Search in the order described above.

``NO_CMAKE_FIND_ROOT_PATH``
  Do not use the ``CMAKE_FIND_ROOT_PATH`` variable.

``ONLY_CMAKE_FIND_ROOT_PATH``
  Search only the re-rooted directories and directories below
  ``CMAKE_STAGING_PREFIX``.

The default search order is designed to be most-specific to
least-specific for common use cases.
Projects may override the order by simply calling the command
multiple times and using the ``NO_*`` options:

 find_package (<PackageName> PATHS paths... NO_DEFAULT_PATH)
 find_package (<PackageName>)

Once one of the calls succeeds the result variable will be set
and stored in the cache so that no call will search again.

By default the value stored in the result variable will be the path at
which the file is found.  The ``CMAKE_FIND_PACKAGE_RESOLVE_SYMLINKS``
variable may be set to ``TRUE`` before calling ``find_package`` in order
to resolve symbolic links and store the real path to the file.

Every non-REQUIRED ``find_package`` call can be disabled or made REQUIRED:

* Setting the ``CMAKE_DISABLE_FIND_PACKAGE_<PackageName>`` variable
  to ``TRUE`` disables the package.  This also disables redirection to a
  package provided by ``FetchContent``.

* Setting the ``CMAKE_REQUIRE_FIND_PACKAGE_<PackageName>`` variable
  to ``TRUE`` makes the package REQUIRED.

Setting both variables to ``TRUE`` simultaneously is an error.

Config Mode Version Selection
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. note::
  When Config mode is used, this version selection process is applied
  regardless of whether the :ref:`full <full signature>` or
  :ref:`basic <basic signature>` signature was given.

When the ``[version]`` argument is given, Config mode will only find a
version of the package that claims compatibility with the requested
version (see :ref:`format specification <FIND_PACKAGE_VERSION_FORMAT>`). If the
``EXACT`` option is given, only a version of the package claiming an exact match
of the requested version may be found.  CMake does not establish any
convention for the meaning of version numbers.  Package version
numbers are checked by "version" files provided by the packages themselves
or by ``FetchContent``.  For a candidate package configuration file
``<config-file>.cmake`` the corresponding version file is located next
to it and named either ``<config-file>-version.cmake`` or
``<config-file>Version.cmake``.  If no such version file is available
then the configuration file is assumed to not be compatible with any
requested version.  A basic version file containing generic version
matching code can be created using the
``CMakePackageConfigHelpers`` module.  When a version file
is found it is loaded to check the requested version number.  The
version file is loaded in a nested scope in which the following
variables have been defined:

``PACKAGE_FIND_NAME``
  The ``<PackageName>``
``PACKAGE_FIND_VERSION``
  Full requested version string
``PACKAGE_FIND_VERSION_MAJOR``
  Major version if requested, else 0
``PACKAGE_FIND_VERSION_MINOR``
  Minor version if requested, else 0
``PACKAGE_FIND_VERSION_PATCH``
  Patch version if requested, else 0
``PACKAGE_FIND_VERSION_TWEAK``
  Tweak version if requested, else 0
``PACKAGE_FIND_VERSION_COUNT``
  Number of version components, 0 to 4

When a version range is specified, the above version variables will hold
values based on the lower end of the version range.  This is to preserve
compatibility with packages that have not been implemented to expect version
ranges.  In addition, the version range will be described by the following
variables:

``PACKAGE_FIND_VERSION_RANGE``
  Full requested version range string
``PACKAGE_FIND_VERSION_RANGE_MIN``
  This specifies whether the lower end point of the version range should be
  included or excluded.  Currently, the only supported value for this variable
  is ``INCLUDE``.
``PACKAGE_FIND_VERSION_RANGE_MAX``
  This specifies whether the upper end point of the version range should be
  included or excluded.  The supported values for this variable are
  ``INCLUDE`` and ``EXCLUDE``.

``PACKAGE_FIND_VERSION_MIN``
  Full requested version string of the lower end point of the range
``PACKAGE_FIND_VERSION_MIN_MAJOR``
  Major version of the lower end point if requested, else 0
``PACKAGE_FIND_VERSION_MIN_MINOR``
  Minor version of the lower end point if requested, else 0
``PACKAGE_FIND_VERSION_MIN_PATCH``
  Patch version of the lower end point if requested, else 0
``PACKAGE_FIND_VERSION_MIN_TWEAK``
  Tweak version of the lower end point if requested, else 0
``PACKAGE_FIND_VERSION_MIN_COUNT``
  Number of version components of the lower end point, 0 to 4

``PACKAGE_FIND_VERSION_MAX``
  Full requested version string of the upper end point of the range
``PACKAGE_FIND_VERSION_MAX_MAJOR``
  Major version of the upper end point if requested, else 0
``PACKAGE_FIND_VERSION_MAX_MINOR``
  Minor version of the upper end point if requested, else 0
``PACKAGE_FIND_VERSION_MAX_PATCH``
  Patch version of the upper end point if requested, else 0
``PACKAGE_FIND_VERSION_MAX_TWEAK``
  Tweak version of the upper end point if requested, else 0
``PACKAGE_FIND_VERSION_MAX_COUNT``
  Number of version components of the upper end point, 0 to 4

Regardless of whether a single version or a version range is specified, the
variable ``PACKAGE_FIND_VERSION_COMPLETE`` will be defined and will hold
the full requested version string as specified.

The version file checks whether it satisfies the requested version and
sets these variables:

``PACKAGE_VERSION``
  Full provided version string
``PACKAGE_VERSION_EXACT``
  True if version is exact match
``PACKAGE_VERSION_COMPATIBLE``
  True if version is compatible
``PACKAGE_VERSION_UNSUITABLE``
  True if unsuitable as any version

These variables are checked by the ``find_package`` command to determine
whether the configuration file provides an acceptable version.  They
are not available after the ``find_package`` call returns.  If the version
is acceptable the following variables are set:

``<PackageName>_VERSION``
  Full provided version string
``<PackageName>_VERSION_MAJOR``
  Major version if provided, else 0
``<PackageName>_VERSION_MINOR``
  Minor version if provided, else 0
``<PackageName>_VERSION_PATCH``
  Patch version if provided, else 0
``<PackageName>_VERSION_TWEAK``
  Tweak version if provided, else 0
``<PackageName>_VERSION_COUNT``
  Number of version components, 0 to 4

and the corresponding package configuration file is loaded.
When multiple package configuration files are available whose version files
claim compatibility with the version requested it is unspecified which
one is chosen: unless the variable ``CMAKE_FIND_PACKAGE_SORT_ORDER``
is set no attempt is made to choose a highest or closest version number.

To control the order in which ``find_package`` checks for compatibility use
the two variables ``CMAKE_FIND_PACKAGE_SORT_ORDER`` and
``CMAKE_FIND_PACKAGE_SORT_DIRECTION``.
For instance in order to select the highest version one can set

 SET(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
 SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)

before calling ``find_package``.

Package File Interface Variables
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When loading a find module or package configuration file ``find_package``
defines variables to provide information about the call arguments (and
restores their original state before returning):

``CMAKE_FIND_PACKAGE_NAME``
  The ``<PackageName>`` which is searched for
``<PackageName>_FIND_REQUIRED``
  True if ``REQUIRED`` option was given
``<PackageName>_FIND_QUIETLY``
  True if ``QUIET`` option was given
``<PackageName>_FIND_REGISTRY_VIEW``
  The requested view if ``REGISTRY_VIEW`` option was given
``<PackageName>_FIND_VERSION``
  Full requested version string
``<PackageName>_FIND_VERSION_MAJOR``
  Major version if requested, else 0
``<PackageName>_FIND_VERSION_MINOR``
  Minor version if requested, else 0
``<PackageName>_FIND_VERSION_PATCH``
  Patch version if requested, else 0
``<PackageName>_FIND_VERSION_TWEAK``
  Tweak version if requested, else 0
``<PackageName>_FIND_VERSION_COUNT``
  Number of version components, 0 to 4
``<PackageName>_FIND_VERSION_EXACT``
  True if ``EXACT`` option was given
``<PackageName>_FIND_COMPONENTS``
  List of specified components (required and optional)
``<PackageName>_FIND_REQUIRED_<c>``
  True if component ``<c>`` is required,
  false if component ``<c>`` is optional

When a version range is specified, the above version variables will hold
values based on the lower end of the version range.  This is to preserve
compatibility with packages that have not been implemented to expect version
ranges.  In addition, the version range will be described by the following
variables:

``<PackageName>_FIND_VERSION_RANGE``
  Full requested version range string
``<PackageName>_FIND_VERSION_RANGE_MIN``
  This specifies whether the lower end point of the version range is
  included or excluded.  Currently, ``INCLUDE`` is the only supported value.
``<PackageName>_FIND_VERSION_RANGE_MAX``
  This specifies whether the upper end point of the version range is
  included or excluded.  The possible values for this variable are
  ``INCLUDE`` or ``EXCLUDE``.

``<PackageName>_FIND_VERSION_MIN``
  Full requested version string of the lower end point of the range
``<PackageName>_FIND_VERSION_MIN_MAJOR``
  Major version of the lower end point if requested, else 0
``<PackageName>_FIND_VERSION_MIN_MINOR``
  Minor version of the lower end point if requested, else 0
``<PackageName>_FIND_VERSION_MIN_PATCH``
  Patch version of the lower end point if requested, else 0
``<PackageName>_FIND_VERSION_MIN_TWEAK``
  Tweak version of the lower end point if requested, else 0
``<PackageName>_FIND_VERSION_MIN_COUNT``
  Number of version components of the lower end point, 0 to 4

``<PackageName>_FIND_VERSION_MAX``
  Full requested version string of the upper end point of the range
``<PackageName>_FIND_VERSION_MAX_MAJOR``
  Major version of the upper end point if requested, else 0
``<PackageName>_FIND_VERSION_MAX_MINOR``
  Minor version of the upper end point if requested, else 0
``<PackageName>_FIND_VERSION_MAX_PATCH``
  Patch version of the upper end point if requested, else 0
``<PackageName>_FIND_VERSION_MAX_TWEAK``
  Tweak version of the upper end point if requested, else 0
``<PackageName>_FIND_VERSION_MAX_COUNT``
  Number of version components of the upper end point, 0 to 4

Regardless of whether a single version or a version range is specified, the
variable ``<PackageName>_FIND_VERSION_COMPLETE`` will be defined and will hold
the full requested version string as specified.

In Module mode the loaded find module is responsible to honor the
request detailed by these variables; see the find module for details.
In Config mode ``find_package`` handles ``REQUIRED``, ``QUIET``, and
``[version]`` options automatically but leaves it to the package
configuration file to handle components in a way that makes sense
for the package.  The package configuration file may set
``<PackageName>_FOUND`` to false to tell ``find_package`` that component
requirements are not satisfied.

find_path
---------

A short-hand signature is:

 find_path (<VAR> name1 [path1 path2 ...])

The general signature is:

 find_path (
           <VAR>
           name | NAMES name1 [name2 ...]
           [HINTS [path | ENV var]... ]
           [PATHS [path | ENV var]... ]
           [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
           [PATH_SUFFIXES suffix1 [suffix2 ...]]
           [VALIDATOR function]
           [DOC "cache documentation string"]
           [NO_CACHE]
           [REQUIRED]
           [NO_DEFAULT_PATH]
           [NO_PACKAGE_ROOT_PATH]
           [NO_CMAKE_PATH]
           [NO_CMAKE_ENVIRONMENT_PATH]
           [NO_SYSTEM_ENVIRONMENT_PATH]
           [NO_CMAKE_SYSTEM_PATH]
           [NO_CMAKE_INSTALL_PREFIX]
           [CMAKE_FIND_ROOT_PATH_BOTH |
            ONLY_CMAKE_FIND_ROOT_PATH |
            NO_CMAKE_FIND_ROOT_PATH]
          )

This command is used to find a directory containing the named file.
A cache entry, or a normal variable if ``NO_CACHE`` is specified,
named by ``<VAR>`` is created to store the result of this command.
If the file in a directory is found the result is stored in the variable
and the search will not be repeated unless the variable is cleared.
If nothing is found, the result will be ``<VAR>-NOTFOUND``.

Options include:

``NAMES``
  Specify one or more possible names for the file in a directory.

  When using this to specify names with and without a version
  suffix, we recommend specifying the unversioned name first
  so that locally-built packages can be found before those
  provided by distributions.

``HINTS``, ``PATHS``
  Specify directories to search in addition to the default locations.
  The ``ENV var`` sub-option reads paths from a system environment
  variable.

  .. versionchanged:: 3.24
    On ``Windows`` platform, it is possible to include registry queries as part
    of the directories, using a :ref:`dedicated syntax <Find Using Windows Registry>`.
    Such specifications will be ignored on all other platforms.

``REGISTRY_VIEW``
  .. versionadded:: 3.24

  .. include:: FIND_XXX_REGISTRY_VIEW.txt

``PATH_SUFFIXES``
  Specify additional subdirectories to check below each directory
  location otherwise considered.

``VALIDATOR``
  .. versionadded:: 3.25

  Specify a ``function()`` to be called for each candidate item found
  (a ``macro()`` cannot be provided, that will result in an error).
  Two arguments will be passed to the validator function: the name of a
  result variable, and the absolute path to the candidate item.  The item
  will be accepted and the search will end unless the function sets the
  value in the result variable to false in the calling scope.  The result
  variable will hold a true value when the validator function is entered.

  .. parsed-literal::

    function(my_check validator_result_var item)
      if(NOT item MATCHES ...)
        set(${validator_result_var} FALSE PARENT_SCOPE)
      endif()
    endfunction()

    |FIND_XXX| (result NAMES ... VALIDATOR my_check)

 Note that if a cached result is used, the search is skipped and any
 ``VALIDATOR`` is ignored.  The cached result is not required to pass the
 validation function.

``DOC``
  Specify the documentation string for the ``<VAR>`` cache entry.

``NO_CACHE``
  .. versionadded:: 3.21

  The result of the search will be stored in a normal variable rather than
  a cache entry.

  .. note::

   If the variable is already set before the call (as a normal or cache
   variable) then the search will not occur.

 .. warning::

   This option should be used with caution because it can greatly increase
   the cost of repeated configure steps.

``REQUIRED``
  .. versionadded:: 3.18

  Stop processing with an error message if nothing is found, otherwise
  the search will be attempted again the next time find_path is invoked
  with the same variable.

If ``NO_DEFAULT_PATH`` is specified, then no additional paths are
added to the search.
If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to
   ``find_package(<PackageName>)``, search prefixes unique to the
   current package being found.  See policy ``CMP0074``.

   .. versionadded:: 3.12

   Specifically, search paths specified by the following variables, in order:

   a. ``<PackageName>_ROOT`` CMake variable,
      where ``<PackageName>`` is the case-preserved package name.

   b. ``<PACKAGENAME>_ROOT`` CMake variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   c. ``<PackageName>_ROOT`` environment variable,
      where ``<PackageName>`` is the case-preserved package name.

   d. ``<PACKAGENAME>_ROOT`` environment variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   The package root variables are maintained as a stack, so if called from
   nested find modules or config packages, root paths from the parent's find
   module or config package will be searched after paths from the current
   module or package.  In other words, the search order would be
   ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
   ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_PACKAGE_ROOT_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in the ``<PackageName>_ROOT`` CMake variable and the ``<PackageName>_ROOT`` environment variable if called from within a find module loaded by ``find_package(<PackageName>)``

2. Search paths specified in cmake-specific cache variables.
   These are intended to be used on the command line with a ``-DVAR=value``.
   The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
   This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_INCLUDE_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

3. Search paths specified in cmake-specific environment variables.
   These are intended to be set in the user's shell configuration,
   and therefore use the host's native path separator
   (``;`` on Windows and ``:`` on UNIX).
   This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or
   by setting the ``CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_INCLUDE_PATH``
   * ``CMAKE_FRAMEWORK_PATH``

4. Search the paths specified by the ``HINTS`` option.
   These should be paths computed by system introspection, such as a
   hint provided by the location of another item already found.
   Hard-coded guesses should be specified with the ``PATHS`` option.

5. Search the standard system environment variables.
   This can be skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed or by
   setting the ``CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH`` to ``FALSE``.

   * The directories in ``INCLUDE`` and ``PATH``.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>/[s]bin`` in ``PATH``, and ``<entry>/include`` for other entries in ``PATH``. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files
   for the current system.  The searching of ``CMAKE_INSTALL_PREFIX`` and
   ``CMAKE_STAGING_PREFIX`` can be
   skipped if ``NO_CMAKE_INSTALL_PREFIX`` is passed or by setting the
   ``CMAKE_FIND_USE_INSTALL_PREFIX`` to ``FALSE``. All these locations
   can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`` to ``FALSE``.

   * ``<prefix>/include/<arch>`` if ``CMAKE_LIBRARY_ARCHITECTURE`` is set, and ``<prefix>/include`` for each ``<prefix>`` in ``CMAKE_SYSTEM_PREFIX_PATH``
   * ``CMAKE_SYSTEM_INCLUDE_PATH``
   * ``CMAKE_SYSTEM_FRAMEWORK_PATH``

   The platform paths that these variables contain are locations that
   typically include installed software. An example being ``/usr/local`` for
   UNIX based platforms.

7. Search the paths specified by the PATHS option
   or in the short-hand version of the command.
   These are typically hard-coded guesses.

The ``CMAKE_IGNORE_PATH``, ``CMAKE_IGNORE_PREFIX_PATH``,
``CMAKE_SYSTEM_IGNORE_PATH`` and
``CMAKE_SYSTEM_IGNORE_PREFIX_PATH`` variables can also cause some
of the above locations to be ignored.

.. versionadded:: 3.16
  Added ``CMAKE_FIND_USE_<CATEGORY>_PATH`` variables to globally disable
  various search locations.

On macOS the ``CMAKE_FIND_FRAMEWORK`` and
``CMAKE_FIND_APPBUNDLE`` variables determine the order of
preference between Apple-style and unix-style package components.

The CMake variable ``CMAKE_FIND_ROOT_PATH`` specifies one or more
directories to be prepended to all other search directories.  This
effectively "re-roots" the entire search under given locations.
Paths which are descendants of the ``CMAKE_STAGING_PREFIX`` are excluded
from this re-rooting, because that variable is always a path on the host system.
By default the ``CMAKE_FIND_ROOT_PATH`` is empty.

The ``CMAKE_SYSROOT`` variable can also be used to specify exactly one
directory to use as a prefix.  Setting ``CMAKE_SYSROOT`` also has other
effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to
point to the root directory of the target environment and CMake will
search there too.  By default at first the directories listed in
``CMAKE_FIND_ROOT_PATH`` are searched, then the ``CMAKE_SYSROOT``
directory is searched, and then the non-rooted directories will be
searched.  The default behavior can be adjusted by setting
``CMAKE_FIND_ROOT_PATH_MODE_INCLUDE``.  This behavior can be manually
overridden on a per-call basis using options:

``CMAKE_FIND_ROOT_PATH_BOTH``
  Search in the order described above.

``NO_CMAKE_FIND_ROOT_PATH``
  Do not use the ``CMAKE_FIND_ROOT_PATH`` variable.

``ONLY_CMAKE_FIND_ROOT_PATH``
  Search only the re-rooted directories and directories below
  ``CMAKE_STAGING_PREFIX``.

The default search order is designed to be most-specific to
least-specific for common use cases.
Projects may override the order by simply calling the command
multiple times and using the ``NO_*`` options:

 find_path (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
 find_path (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set
and stored in the cache so that no call will search again.

When searching for frameworks, if the file is specified as ``A/b.h``, then
the framework search will look for ``A.framework/Headers/b.h``.  If that
is found the path will be set to the path to the framework.  CMake
will convert this to the correct ``-F`` option to include the file.

find_program
------------

A short-hand signature is:

 find_program (<VAR> name1 [path1 path2 ...])

The general signature is:

 find_program (
           <VAR>
           name | NAMES name1 [name2 ...] [NAMES_PER_DIR]
           [HINTS [path | ENV var]... ]
           [PATHS [path | ENV var]... ]
           [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
           [PATH_SUFFIXES suffix1 [suffix2 ...]]
           [VALIDATOR function]
           [DOC "cache documentation string"]
           [NO_CACHE]
           [REQUIRED]
           [NO_DEFAULT_PATH]
           [NO_PACKAGE_ROOT_PATH]
           [NO_CMAKE_PATH]
           [NO_CMAKE_ENVIRONMENT_PATH]
           [NO_SYSTEM_ENVIRONMENT_PATH]
           [NO_CMAKE_SYSTEM_PATH]
           [NO_CMAKE_INSTALL_PREFIX]
           [CMAKE_FIND_ROOT_PATH_BOTH |
            ONLY_CMAKE_FIND_ROOT_PATH |
            NO_CMAKE_FIND_ROOT_PATH]
          )

This command is used to find a program.
A cache entry, or a normal variable if ``NO_CACHE`` is specified,
named by ``<VAR>`` is created to store the result of this command.
If the program is found the result is stored in the variable
and the search will not be repeated unless the variable is cleared.
If nothing is found, the result will be ``<VAR>-NOTFOUND``.

Options include:

``NAMES``
  Specify one or more possible names for the program.

  When using this to specify names with and without a version
  suffix, we recommend specifying the unversioned name first
  so that locally-built packages can be found before those
  provided by distributions.

``HINTS``, ``PATHS``
  Specify directories to search in addition to the default locations.
  The ``ENV var`` sub-option reads paths from a system environment
  variable.

  .. versionchanged:: 3.24
    On ``Windows`` platform, it is possible to include registry queries as part
    of the directories, using a :ref:`dedicated syntax <Find Using Windows Registry>`.
    Such specifications will be ignored on all other platforms.

``REGISTRY_VIEW``
  .. versionadded:: 3.24

  .. include:: FIND_XXX_REGISTRY_VIEW.txt

``PATH_SUFFIXES``
  Specify additional subdirectories to check below each directory
  location otherwise considered.

``VALIDATOR``
  .. versionadded:: 3.25

  Specify a ``function()`` to be called for each candidate item found
  (a ``macro()`` cannot be provided, that will result in an error).
  Two arguments will be passed to the validator function: the name of a
  result variable, and the absolute path to the candidate item.  The item
  will be accepted and the search will end unless the function sets the
  value in the result variable to false in the calling scope.  The result
  variable will hold a true value when the validator function is entered.

  .. parsed-literal::

    function(my_check validator_result_var item)
      if(NOT item MATCHES ...)
        set(${validator_result_var} FALSE PARENT_SCOPE)
      endif()
    endfunction()

    |FIND_XXX| (result NAMES ... VALIDATOR my_check)

 Note that if a cached result is used, the search is skipped and any
 ``VALIDATOR`` is ignored.  The cached result is not required to pass the
 validation function.

``DOC``
  Specify the documentation string for the ``<VAR>`` cache entry.

``NO_CACHE``
  .. versionadded:: 3.21

  The result of the search will be stored in a normal variable rather than
  a cache entry.

  .. note::

   If the variable is already set before the call (as a normal or cache
   variable) then the search will not occur.

 .. warning::

   This option should be used with caution because it can greatly increase
   the cost of repeated configure steps.

``REQUIRED``
  .. versionadded:: 3.18

  Stop processing with an error message if nothing is found, otherwise
  the search will be attempted again the next time find_program is invoked
  with the same variable.

If ``NO_DEFAULT_PATH`` is specified, then no additional paths are
added to the search.
If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to
   ``find_package(<PackageName>)``, search prefixes unique to the
   current package being found.  See policy ``CMP0074``.

   .. versionadded:: 3.12

   Specifically, search paths specified by the following variables, in order:

   a. ``<PackageName>_ROOT`` CMake variable,
      where ``<PackageName>`` is the case-preserved package name.

   b. ``<PACKAGENAME>_ROOT`` CMake variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   c. ``<PackageName>_ROOT`` environment variable,
      where ``<PackageName>`` is the case-preserved package name.

   d. ``<PACKAGENAME>_ROOT`` environment variable,
      where ``<PACKAGENAME>`` is the upper-cased package name.
      See policy ``CMP0144``.

      .. versionadded:: 3.27

   The package root variables are maintained as a stack, so if called from
   nested find modules or config packages, root paths from the parent's find
   module or config package will be searched after paths from the current
   module or package.  In other words, the search order would be
   ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
   ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
   the ``CMAKE_FIND_USE_PACKAGE_ROOT_PATH`` to ``FALSE``.

   * ``<prefix>/[s]bin`` for each ``<prefix>`` in the ``<PackageName>_ROOT`` CMake variable and the ``<PackageName>_ROOT`` environment variable if called from within a find module loaded by ``find_package(<PackageName>)``

2. Search paths specified in cmake-specific cache variables.
   These are intended to be used on the command line with a ``-DVAR=value``.
   The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
   This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_PATH`` to ``FALSE``.

   * ``<prefix>/[s]bin`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_PROGRAM_PATH``
   * ``CMAKE_APPBUNDLE_PATH``

3. Search paths specified in cmake-specific environment variables.
   These are intended to be set in the user's shell configuration,
   and therefore use the host's native path separator
   (``;`` on Windows and ``:`` on UNIX).
   This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or
   by setting the ``CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH`` to ``FALSE``.

   * ``<prefix>/[s]bin`` for each ``<prefix>`` in ``CMAKE_PREFIX_PATH``
   * ``CMAKE_PROGRAM_PATH``
   * ``CMAKE_APPBUNDLE_PATH``

4. Search the paths specified by the ``HINTS`` option.
   These should be paths computed by system introspection, such as a
   hint provided by the location of another item already found.
   Hard-coded guesses should be specified with the ``PATHS`` option.

5. Search the standard system environment variables.
   This can be skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed or by
   setting the ``CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH`` to ``FALSE``.

   * The directories in ``PATH`` itself.

   \

6. Search cmake variables defined in the Platform files
   for the current system.  The searching of ``CMAKE_INSTALL_PREFIX`` and
   ``CMAKE_STAGING_PREFIX`` can be
   skipped if ``NO_CMAKE_INSTALL_PREFIX`` is passed or by setting the
   ``CMAKE_FIND_USE_INSTALL_PREFIX`` to ``FALSE``. All these locations
   can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is passed or by setting the
   ``CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`` to ``FALSE``.

   * ``<prefix>/[s]bin`` for each ``<prefix>`` in ``CMAKE_SYSTEM_PREFIX_PATH``
   * ``CMAKE_SYSTEM_PROGRAM_PATH``
   * ``CMAKE_SYSTEM_APPBUNDLE_PATH``

   The platform paths that these variables contain are locations that
   typically include installed software. An example being ``/usr/local`` for
   UNIX based platforms.

7. Search the paths specified by the PATHS option
   or in the short-hand version of the command.
   These are typically hard-coded guesses.

The ``CMAKE_IGNORE_PATH``, ``CMAKE_IGNORE_PREFIX_PATH``,
``CMAKE_SYSTEM_IGNORE_PATH`` and
``CMAKE_SYSTEM_IGNORE_PREFIX_PATH`` variables can also cause some
of the above locations to be ignored.

.. versionadded:: 3.16
  Added ``CMAKE_FIND_USE_<CATEGORY>_PATH`` variables to globally disable
  various search locations.

On macOS the ``CMAKE_FIND_FRAMEWORK`` and
``CMAKE_FIND_APPBUNDLE`` variables determine the order of
preference between Apple-style and unix-style package components.

The CMake variable ``CMAKE_FIND_ROOT_PATH`` specifies one or more
directories to be prepended to all other search directories.  This
effectively "re-roots" the entire search under given locations.
Paths which are descendants of the ``CMAKE_STAGING_PREFIX`` are excluded
from this re-rooting, because that variable is always a path on the host system.
By default the ``CMAKE_FIND_ROOT_PATH`` is empty.

The ``CMAKE_SYSROOT`` variable can also be used to specify exactly one
directory to use as a prefix.  Setting ``CMAKE_SYSROOT`` also has other
effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to
point to the root directory of the target environment and CMake will
search there too.  By default at first the directories listed in
``CMAKE_FIND_ROOT_PATH`` are searched, then the ``CMAKE_SYSROOT``
directory is searched, and then the non-rooted directories will be
searched.  The default behavior can be adjusted by setting
``CMAKE_FIND_ROOT_PATH_MODE_PROGRAM``.  This behavior can be manually
overridden on a per-call basis using options:

``CMAKE_FIND_ROOT_PATH_BOTH``
  Search in the order described above.

``NO_CMAKE_FIND_ROOT_PATH``
  Do not use the ``CMAKE_FIND_ROOT_PATH`` variable.

``ONLY_CMAKE_FIND_ROOT_PATH``
  Search only the re-rooted directories and directories below
  ``CMAKE_STAGING_PREFIX``.

The default search order is designed to be most-specific to
least-specific for common use cases.
Projects may override the order by simply calling the command
multiple times and using the ``NO_*`` options:

 find_program (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
 find_program (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set
and stored in the cache so that no call will search again.

When more than one value is given to the ``NAMES`` option this command by
default will consider one name at a time and search every directory
for it.  The ``NAMES_PER_DIR`` option tells this command to consider one
directory at a time and search for all names in it.

foreach
-------

Evaluate a group of commands for each value in a list.

 foreach(<loop_var> <items>)
   <commands>
 endforeach()

where ``<items>`` is a list of items that are separated by
semicolon or whitespace.
All commands between ``foreach`` and the matching ``endforeach`` are recorded
without being invoked.  Once the ``endforeach`` is evaluated, the recorded
list of commands is invoked once for each item in ``<items>``.
At the beginning of each iteration the variable ``<loop_var>`` will be set
to the value of the current item.

The scope of ``<loop_var>`` is restricted to the loop scope. See policy
``CMP0124`` for details.

The commands ``break()`` and ``continue()`` provide means to
escape from the normal control flow.

Per legacy, the ``endforeach()`` command admits
an optional ``<loop_var>`` argument.
If used, it must be a verbatim
repeat of the argument of the opening
``foreach`` command.

 foreach(<loop_var> RANGE <stop>)

In this variant, ``foreach`` iterates over the numbers
0, 1, ... up to (and including) the nonnegative integer ``<stop>``.

 foreach(<loop_var> RANGE <start> <stop> [<step>])

In this variant, ``foreach`` iterates over the numbers from
``<start>`` up to at most ``<stop>`` in steps of ``<step>``.
If ``<step>`` is not specified, then the step size is 1.
The three arguments ``<start>`` ``<stop>`` ``<step>`` must
all be nonnegative integers, and ``<stop>`` must not be
smaller than ``<start>``; otherwise you enter the danger zone
of undocumented behavior that may change in future releases.

 foreach(<loop_var> IN [LISTS [<lists>]] [ITEMS [<items>]])

In this variant, ``<lists>`` is a whitespace or semicolon
separated list of list-valued variables. The ``foreach``
command iterates over each item in each given list.
The ``<items>`` following the ``ITEMS`` keyword are processed
as in the first variant of the ``foreach`` command.
The forms ``LISTS A`` and ``ITEMS ${A}`` are
equivalent.

The following example shows how the ``LISTS`` option is
processed:

 set(A 0;1)
 set(B 2 3)
 set(C "4 5")
 set(D 6;7 8)
 set(E "")
 foreach(X IN LISTS A B C D E)
     message(STATUS "X=${X}")
 endforeach()

yields::

 -- X=0
 -- X=1
 -- X=2
 -- X=3
 -- X=4 5
 -- X=6
 -- X=7
 -- X=8

 foreach(<loop_var>... IN ZIP_LISTS <lists>)

.. versionadded:: 3.17

In this variant, ``<lists>`` is a whitespace or semicolon
separated list of list-valued variables. The ``foreach``
command iterates over each list simultaneously setting the
iteration variables as follows:

- if the only ``loop_var`` given, then it sets a series of
  ``loop_var_N`` variables to the current item from the
  corresponding list;
- if multiple variable names passed, their count should match
  the lists variables count;
- if any of the lists are shorter, the corresponding iteration
  variable is not defined for the current iteration.

 list(APPEND English one two three four)
 list(APPEND Bahasa satu dua tiga)

 foreach(num IN ZIP_LISTS English Bahasa)
     message(STATUS "num_0=${num_0}, num_1=${num_1}")
 endforeach()

 foreach(en ba IN ZIP_LISTS English Bahasa)
     message(STATUS "en=${en}, ba=${ba}")
 endforeach()

yields::

 -- num_0=one, num_1=satu
 -- num_0=two, num_1=dua
 -- num_0=three, num_1=tiga
 -- num_0=four, num_1=
 -- en=one, ba=satu
 -- en=two, ba=dua
 -- en=three, ba=tiga
 -- en=four, ba=

See Also
^^^^^^^^

* ``break()``
* ``continue()``
* ``endforeach()``
* ``while()``

function
--------

Start recording a function for later invocation as a command.

 function(<name> [<arg1> ...])
   <commands>
 endfunction()

Defines a function named ``<name>`` that takes arguments named
``<arg1>``, ...  The ``<commands>`` in the function definition
are recorded; they are not executed until the function is invoked.

Per legacy, the ``endfunction()`` command admits an optional
``<name>`` argument. If used, it must be a verbatim repeat of the
argument of the opening ``function`` command.

A function opens a new scope: see ``set(var PARENT_SCOPE)`` for
details.

See the ``cmake_policy()`` command documentation for the behavior
of policies inside functions.

See the ``macro()`` command documentation for differences
between CMake functions and macros.

Invocation
^^^^^^^^^^

The function invocation is case-insensitive. A function defined as

 function(foo)
   <commands>
 endfunction()

can be invoked through any of

 foo()
 Foo()
 FOO()
 cmake_language(CALL foo)

and so on. However, it is strongly recommended to stay with the
case chosen in the function definition. Typically functions use
all-lowercase names.

.. versionadded:: 3.18
  The ``cmake_language(CALL ...)`` command can also be used to
  invoke the function.

Arguments
^^^^^^^^^

When the function is invoked, the recorded ``<commands>`` are first
modified by replacing formal parameters (``${arg1}``, ...) with the
arguments passed, and then invoked as normal commands.

In addition to referencing the formal parameters you can reference the
``ARGC`` variable which will be set to the number of arguments passed
into the function as well as ``ARGV0``, ``ARGV1``, ``ARGV2``, ...  which
will have the actual values of the arguments passed in.  This facilitates
creating functions with optional arguments.

Furthermore, ``ARGV`` holds the list of all arguments given to the
function and ``ARGN`` holds the list of arguments past the last expected
argument.  Referencing to ``ARGV#`` arguments beyond ``ARGC`` have
undefined behavior.  Checking that ``ARGC`` is greater than ``#`` is
the only way to ensure that ``ARGV#`` was passed to the function as an
extra argument.

See Also
^^^^^^^^

* ``cmake_parse_arguments()``
* ``endfunction()``
* ``return()``

get_cmake_property
------------------

Get a global property of the CMake instance.

 get_cmake_property(<variable> <property>)

Gets a global property from the CMake instance.  The value of
the ``<property>`` is stored in the specified ``<variable>``.
If the property is not found, ``<variable>`` will be set to ``NOTFOUND``.
See the ``cmake-properties(7)`` manual for available properties.

In addition to global properties, this command (for historical reasons)
also supports the ``VARIABLES`` and ``MACROS`` directory
properties.  It also supports a special ``COMPONENTS`` global property that
lists the components given to the ``install()`` command.

See Also
^^^^^^^^

* the ``get_property()`` command ``GLOBAL`` option

get_directory_property
----------------------

Get a property of ``DIRECTORY`` scope.

 get_directory_property(<variable> [DIRECTORY <dir>] <prop-name>)

Stores a property of directory scope in the named ``<variable>``.

The ``DIRECTORY`` argument specifies another directory from which
to retrieve the property value instead of the current directory.
Relative paths are treated as relative to the
current source directory.  CMake must already know about the directory,
either by having added it through a call to ``add_subdirectory()``
or being the top level directory.

.. versionadded:: 3.19
  ``<dir>`` may reference a binary directory.

If the property is not defined for the nominated directory scope,
an empty string is returned.  In the case of ``INHERITED`` properties,
if the property is not found for the nominated directory scope,
the search will chain to a parent scope as described for the
``define_property()`` command.

 get_directory_property(<variable> [DIRECTORY <dir>]
                        DEFINITION <var-name>)

Get a variable definition from a directory.  This form is useful to
get a variable definition from another directory.


See Also
^^^^^^^^

* ``define_property()``
* the more general ``get_property()`` command

get_filename_component
----------------------

Get a specific component of a full filename.

.. versionchanged:: 3.20
  This command has been superseded by the ``cmake_path()`` command, except
  for ``REALPATH``, which is now offered by ``file(REAL_PATH)``, and
  ``PROGRAM``, now available in ``separate_arguments(PROGRAM)``.

.. versionchanged:: 3.24
  The undocumented feature offering the capability to query the ``Windows``
  registry is superseded by
  :ref:`cmake_host_system_information(QUERY WINDOWS_REGISTRY)<Query Windows registry>`
  command.

 get_filename_component(<var> <FileName> <mode> [CACHE])

Sets ``<var>`` to a component of ``<FileName>``, where ``<mode>`` is one of:

::

 DIRECTORY = Directory without file name
 NAME      = File name without directory
 EXT       = File name longest extension (.b.c from d/a.b.c)
 NAME_WE   = File name with neither the directory nor the longest extension
 LAST_EXT  = File name last extension (.c from d/a.b.c)
 NAME_WLE  = File name with neither the directory nor the last extension
 PATH      = Legacy alias for DIRECTORY (use for CMake <= 2.8.11)

.. versionadded:: 3.14
  Added the ``LAST_EXT`` and ``NAME_WLE`` modes.

Paths are returned with forward slashes and have no trailing slashes.
If the optional ``CACHE`` argument is specified, the result variable is
added to the cache.

 get_filename_component(<var> <FileName> <mode> [BASE_DIR <dir>] [CACHE])

.. versionadded:: 3.4

Sets ``<var>`` to the absolute path of ``<FileName>``, where ``<mode>`` is one
of:

::

 ABSOLUTE  = Full path to file
 REALPATH  = Full path to existing file with symlinks resolved

If the provided ``<FileName>`` is a relative path, it is evaluated relative
to the given base directory ``<dir>``.  If no base directory is
provided, the default base directory will be
``CMAKE_CURRENT_SOURCE_DIR``.

Paths are returned with forward slashes and have no trailing slashes.  If the
optional ``CACHE`` argument is specified, the result variable is added to the
cache.

 get_filename_component(<var> <FileName> PROGRAM [PROGRAM_ARGS <arg_var>] [CACHE])

The program in ``<FileName>`` will be found in the system search path or
left as a full path.  If ``PROGRAM_ARGS`` is present with ``PROGRAM``, then
any command-line arguments present in the ``<FileName>`` string are split
from the program name and stored in ``<arg_var>``.  This is used to
separate a program name from its arguments in a command line string.

See Also
^^^^^^^^

* ``cmake_path()``

get_property
------------

Get a property.

 get_property(<variable>
              <GLOBAL             |
               DIRECTORY [<dir>]  |
               TARGET    <target> |
               SOURCE    <source>
                         [DIRECTORY <dir> | TARGET_DIRECTORY <target>] |
               INSTALL   <file>   |
               TEST      <test>
                         [DIRECTORY <dir>] |
               CACHE     <entry>  |
               VARIABLE           >
              PROPERTY <name>
              [SET | DEFINED | BRIEF_DOCS | FULL_DOCS])

Gets one property from one object in a scope.

The first argument specifies the variable in which to store the result.
The second argument determines the scope from which to get the property.
It must be one of the following:

``GLOBAL``
  Scope is unique and does not accept a name.

``DIRECTORY``
  Scope defaults to the current directory but another
  directory (already processed by CMake) may be named by the
  full or relative path ``<dir>``.
  Relative paths are treated as relative to the current source directory.
  See also the ``get_directory_property()`` command.

  .. versionadded:: 3.19
    ``<dir>`` may reference a binary directory.

``TARGET``
  Scope must name one existing target.
  See also the ``get_target_property()`` command.

``SOURCE``
  Scope must name one source file.  By default, the source file's property
  will be read from the current source directory's scope.

  .. versionadded:: 3.18
    Directory scope can be overridden with one of the following sub-options:

    ``DIRECTORY <dir>``
      The source file property will be read from the ``<dir>`` directory's
      scope.  CMake must already know about
      the directory, either by having added it through a call
      to ``add_subdirectory()`` or ``<dir>`` being the top level directory.
      Relative paths are treated as relative to the current source directory.

      .. versionadded:: 3.19
        ``<dir>`` may reference a binary directory.

    ``TARGET_DIRECTORY <target>``
      The source file property will be read from the directory scope in which
      ``<target>`` was created (``<target>`` must therefore already exist).

  See also the ``get_source_file_property()`` command.

``INSTALL``
  .. versionadded:: 3.1

  Scope must name one installed file path.

``TEST``
  Scope must name one existing test.
  See also the ``get_test_property()`` command.

  .. versionadded:: 3.28
    Directory scope can be overridden with the following sub-option:

    ``DIRECTORY <dir>``
      The test property will be read from the ``<dir>`` directory's
      scope.  CMake must already know about the directory, either by having added
      it through a call to ``add_subdirectory()`` or ``<dir>`` being the top
      level directory. Relative paths are treated as relative to the current
      source directory. ``<dir>`` may reference a binary directory.

``CACHE``
  Scope must name one cache entry.

``VARIABLE``
  Scope is unique and does not accept a name.

The required ``PROPERTY`` option is immediately followed by the name of
the property to get.  If the property is not set an empty value is
returned, although some properties support inheriting from a parent scope
if defined to behave that way (see ``define_property()``).

If the ``SET`` option is given the variable is set to a boolean
value indicating whether the property has been set.  If the ``DEFINED``
option is given the variable is set to a boolean value indicating
whether the property has been defined such as with the
``define_property()`` command.

If ``BRIEF_DOCS`` or ``FULL_DOCS`` is given then the variable is set to a
string containing documentation for the requested property.  If
documentation is requested for a property that has not been defined
``NOTFOUND`` is returned.

.. note::

  The ``GENERATED`` source file property may be globally visible.
  See its documentation for details.

See Also
^^^^^^^^

* ``define_property()``
* ``set_property()``

if
--

Conditionally execute a group of commands.

Synopsis
^^^^^^^^

 if(<condition>)
   <commands>
 elseif(<condition>) # optional block, can be repeated
   <commands>
 else()              # optional block
   <commands>
 endif()

Evaluates the ``condition`` argument of the ``if`` clause according to the
Condition syntax described below. If the result is true, then the
``commands`` in the ``if`` block are executed.
Otherwise, optional ``elseif`` blocks are processed in the same way.
Finally, if no ``condition`` is true, ``commands`` in the optional ``else``
block are executed.

Per legacy, the ``else()`` and ``endif()`` commands admit
an optional ``<condition>`` argument.
If used, it must be a verbatim
repeat of the argument of the opening
``if`` command.

Condition Syntax
^^^^^^^^^^^^^^^^

The following syntax applies to the ``condition`` argument of
the ``if``, ``elseif`` and ``while()`` clauses.

Compound conditions are evaluated in the following order of precedence:

1. Parentheses.

2. Unary tests such as EXISTS, COMMAND, and DEFINED.

3. Binary tests such as EQUAL, LESS, LESS_EQUAL, GREATER,
   GREATER_EQUAL, STREQUAL, STRLESS, STRLESS_EQUAL,
   STRGREATER, STRGREATER_EQUAL, VERSION_EQUAL, VERSION_LESS,
   VERSION_LESS_EQUAL, VERSION_GREATER, VERSION_GREATER_EQUAL,
   PATH_EQUAL, and MATCHES.

4. Unary logical operator NOT.

5. Binary logical operators AND and OR, from left to right,
   without any short-circuit.

Basic Expressions
"""""""""""""""""

.. signature:: if(<constant>)
  :target: constant

  True if the constant is ``1``, ``ON``, ``YES``, ``TRUE``, ``Y``,
  or a non-zero number (including floating point numbers).
  False if the constant is ``0``, ``OFF``,
  ``NO``, ``FALSE``, ``N``, ``IGNORE``, ``NOTFOUND``, the empty string,
  or ends in the suffix ``-NOTFOUND``.  Named boolean constants are
  case-insensitive.  If the argument is not one of these specific
  constants, it is treated as a variable or string (see Variable Expansion
  further below) and one of the following two forms applies.

.. signature:: if(<variable>)
  :target: variable

  True if given a variable that is defined to a value that is not a false
  constant.  False otherwise, including if the variable is undefined.
  Note that macro arguments are not variables.
  :ref:`Environment Variables <CMake Language Environment Variables>` also
  cannot be tested this way, e.g. ``if(ENV{some_var})`` will always evaluate
  to false.

.. signature:: if(<string>)
  :target: string

  A quoted string always evaluates to false unless:

  * The string's value is one of the true constants, or
  * Policy ``CMP0054`` is not set to ``NEW`` and the string's value
    happens to be a variable name that is affected by ``CMP0054``'s
    behavior.

Logic Operators
"""""""""""""""

.. signature:: if(NOT <condition>)

  True if the condition is not true.

.. signature:: if(<cond1> AND <cond2>)
  :target: AND

  True if both conditions would be considered true individually.

.. signature:: if(<cond1> OR <cond2>)
  :target: OR

  True if either condition would be considered true individually.

.. signature:: if((condition) AND (condition OR (condition)))
  :target: parentheses

  The conditions inside the parenthesis are evaluated first and then
  the remaining condition is evaluated as in the other examples.
  Where there are nested parenthesis the innermost are evaluated as part
  of evaluating the condition that contains them.

Existence Checks
""""""""""""""""

.. signature:: if(COMMAND <command-name>)

  True if the given name is a command, macro or function that can be
  invoked.

.. signature:: if(POLICY <policy-id>)

  True if the given name is an existing policy (of the form ``CMP<NNNN>``).

.. signature:: if(TARGET <target-name>)

  True if the given name is an existing logical target name created
  by a call to the ``add_executable()``, ``add_library()``,
  or ``add_custom_target()`` command that has already been invoked
  (in any directory).

.. signature:: if(TEST <test-name>)

  .. versionadded:: 3.3

  True if the given name is an existing test name created by the
  ``add_test()`` command.

.. signature:: if(DEFINED <name>|CACHE{<name>}|ENV{<name>})

  True if a variable, cache variable or environment variable
  with given ``<name>`` is defined. The value of the variable
  does not matter. Note the following caveats:

  * Macro arguments are not variables.
  * It is not possible to test directly whether a `<name>` is a non-cache
    variable.  The expression ``if(DEFINED someName)`` will evaluate to true
    if either a cache or non-cache variable ``someName`` exists.  In
    comparison, the expression ``if(DEFINED CACHE{someName})`` will only
    evaluate to true if a cache variable ``someName`` exists.  Both expressions
    need to be tested if you need to know whether a non-cache variable exists:
    ``if(DEFINED someName AND NOT DEFINED CACHE{someName})``.

 .. versionadded:: 3.14
  Added support for ``CACHE{<name>}`` variables.

.. signature:: if(<variable|string> IN_LIST <variable>)
  :target: IN_LIST

  .. versionadded:: 3.3

  True if the given element is contained in the named list variable.

File Operations
"""""""""""""""

.. signature:: if(EXISTS <path-to-file-or-directory>)

  True if the named file or directory exists and is readable.  Behavior
  is well-defined only for explicit full paths (a leading ``~/`` is not
  expanded as a home directory and is considered a relative path).
  Resolves symbolic links, i.e. if the named file or directory is a
  symbolic link, returns true if the target of the symbolic link exists.

  False if the given path is an empty string.

  .. note::
    Prefer ``if(IS_READABLE)`` to check file readability.  ``if(EXISTS)``
    may be changed in the future to only check file existence.

.. signature:: if(IS_READABLE <path-to-file-or-directory>)

  .. versionadded:: 3.29

  True if the named file or directory is readable.  Behavior
  is well-defined only for explicit full paths (a leading ``~/`` is not
  expanded as a home directory and is considered a relative path).
  Resolves symbolic links, i.e. if the named file or directory is a
  symbolic link, returns true if the target of the symbolic link is readable.

  False if the given path is an empty string.

.. signature:: if(IS_WRITABLE <path-to-file-or-directory>)

  .. versionadded:: 3.29

  True if the named file or directory is writable.  Behavior
  is well-defined only for explicit full paths (a leading ``~/`` is not
  expanded as a home directory and is considered a relative path).
  Resolves symbolic links, i.e. if the named file or directory is a
  symbolic link, returns true if the target of the symbolic link is writable.

  False if the given path is an empty string.

.. signature:: if(IS_EXECUTABLE <path-to-file-or-directory>)

  .. versionadded:: 3.29

  True if the named file or directory is executable.  Behavior
  is well-defined only for explicit full paths (a leading ``~/`` is not
  expanded as a home directory and is considered a relative path).
  Resolves symbolic links, i.e. if the named file or directory is a
  symbolic link, returns true if the target of the symbolic link is executable.

  False if the given path is an empty string.

.. signature:: if(<file1> IS_NEWER_THAN <file2>)
  :target: IS_NEWER_THAN

  True if ``file1`` is newer than ``file2`` or if one of the two files doesn't
  exist.  Behavior is well-defined only for full paths.  If the file
  time stamps are exactly the same, an ``IS_NEWER_THAN`` comparison returns
  true, so that any dependent build operations will occur in the event
  of a tie.  This includes the case of passing the same file name for
  both file1 and file2.

.. signature:: if(IS_DIRECTORY <path>)

  True if ``path`` is a directory.  Behavior is well-defined only
  for full paths.

  False if the given path is an empty string.

.. signature:: if(IS_SYMLINK <path>)

  True if the given path is a symbolic link.  Behavior is well-defined
  only for full paths.

.. signature:: if(IS_ABSOLUTE <path>)

  True if the given path is an absolute path.  Note the following special
  cases:

  * An empty ``path`` evaluates to false.
  * On Windows hosts, any ``path`` that begins with a drive letter and colon
    (e.g. ``C:``), a forward slash or a backslash will evaluate to true.
    This means a path like ``C:no\base\dir`` will evaluate to true, even
    though the non-drive part of the path is relative.
  * On non-Windows hosts, any ``path`` that begins with a tilde (``~``)
    evaluates to true.

Comparisons
"""""""""""

.. signature:: if(<variable|string> MATCHES <regex>)
  :target: MATCHES

  True if the given string or variable's value matches the given regular
  expression.  See :ref:`Regex Specification` for regex format.

  .. versionadded:: 3.9
   ``()`` groups are captured in ``CMAKE_MATCH_<n>`` variables.

.. signature:: if(<variable|string> LESS <variable|string>)
  :target: LESS

  True if the given string or variable's value parses as a real number
  (like a C ``double``) and less than that on the right.

.. signature:: if(<variable|string> GREATER <variable|string>)
  :target: GREATER

  True if the given string or variable's value parses as a real number
  (like a C ``double``) and greater than that on the right.

.. signature:: if(<variable|string> EQUAL <variable|string>)
  :target: EQUAL

  True if the given string or variable's value parses as a real number
  (like a C ``double``) and equal to that on the right.

.. signature:: if(<variable|string> LESS_EQUAL <variable|string>)
  :target: LESS_EQUAL

  .. versionadded:: 3.7

  True if the given string or variable's value parses as a real number
  (like a C ``double``) and less than or equal to that on the right.

.. signature:: if(<variable|string> GREATER_EQUAL <variable|string>)
  :target: GREATER_EQUAL

  .. versionadded:: 3.7

  True if the given string or variable's value parses as a real number
  (like a C ``double``) and greater than or equal to that on the right.

.. signature:: if(<variable|string> STRLESS <variable|string>)
  :target: STRLESS

  True if the given string or variable's value is lexicographically less
  than the string or variable on the right.

.. signature:: if(<variable|string> STRGREATER <variable|string>)
  :target: STRGREATER

  True if the given string or variable's value is lexicographically greater
  than the string or variable on the right.

.. signature:: if(<variable|string> STREQUAL <variable|string>)
  :target: STREQUAL

  True if the given string or variable's value is lexicographically equal
  to the string or variable on the right.

.. signature:: if(<variable|string> STRLESS_EQUAL <variable|string>)
  :target: STRLESS_EQUAL

  .. versionadded:: 3.7

  True if the given string or variable's value is lexicographically less
  than or equal to the string or variable on the right.

.. signature:: if(<variable|string> STRGREATER_EQUAL <variable|string>)
  :target: STRGREATER_EQUAL

  .. versionadded:: 3.7

  True if the given string or variable's value is lexicographically greater
  than or equal to the string or variable on the right.

Version Comparisons
"""""""""""""""""""

.. signature:: if(<variable|string> VERSION_LESS <variable|string>)
  :target: VERSION_LESS

  Component-wise integer version number comparison (version format is
  ``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
  Any non-integer version component or non-integer trailing part of a version
  component effectively truncates the string at that point.

.. signature:: if(<variable|string> VERSION_GREATER <variable|string>)
  :target: VERSION_GREATER

  Component-wise integer version number comparison (version format is
  ``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
  Any non-integer version component or non-integer trailing part of a version
  component effectively truncates the string at that point.

.. signature:: if(<variable|string> VERSION_EQUAL <variable|string>)
  :target: VERSION_EQUAL

  Component-wise integer version number comparison (version format is
  ``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
  Any non-integer version component or non-integer trailing part of a version
  component effectively truncates the string at that point.

.. signature:: if(<variable|string> VERSION_LESS_EQUAL <variable|string>)
  :target: VERSION_LESS_EQUAL

  .. versionadded:: 3.7

  Component-wise integer version number comparison (version format is
  ``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
  Any non-integer version component or non-integer trailing part of a version
  component effectively truncates the string at that point.

.. signature:: if(<variable|string> VERSION_GREATER_EQUAL <variable|string>)
  :target: VERSION_GREATER_EQUAL

  .. versionadded:: 3.7

  Component-wise integer version number comparison (version format is
  ``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
  Any non-integer version component or non-integer trailing part of a version
  component effectively truncates the string at that point.

Path Comparisons
""""""""""""""""

.. signature:: if(<variable|string> PATH_EQUAL <variable|string>)
  :target: PATH_EQUAL

  .. versionadded:: 3.24

  Compares the two paths component-by-component.  Only if every component of
  both paths match will the two paths compare equal.  Multiple path separators
  are effectively collapsed into a single separator, but note that backslashes
  are not converted to forward slashes.  No other
  :ref:`path normalization <Normalization>` is performed.

  Component-wise comparison is superior to string-based comparison due to the
  handling of multiple path separators.  In the following example, the
  expression evaluates to true using ``PATH_EQUAL``, but false with
  ``STREQUAL``:

  .. code-block:: cmake

    # comparison is TRUE
    if ("/a//b/c" PATH_EQUAL "/a/b/c")
       ...
    endif()

    # comparison is FALSE
    if ("/a//b/c" STREQUAL "/a/b/c")
       ...
    endif()

  See :ref:`cmake_path(COMPARE) <Path COMPARE>` for more details.

Variable Expansion
^^^^^^^^^^^^^^^^^^

The if command was written very early in CMake's history, predating
the ``${}`` variable evaluation syntax, and for convenience evaluates
variables named by its arguments as shown in the above signatures.
Note that normal variable evaluation with ``${}`` applies before the if
command even receives the arguments.  Therefore code like

 set(var1 OFF)
 set(var2 "var1")
 if(${var2})

appears to the if command as

 if(var1)

and is evaluated according to the ``if(<variable>)`` case documented
above.  The result is ``OFF`` which is false.  However, if we remove the
``${}`` from the example then the command sees

 if(var2)

which is true because ``var2`` is defined to ``var1`` which is not a false
constant.

Automatic evaluation applies in the other cases whenever the
above-documented condition syntax accepts ``<variable|string>``:

* The left hand argument to MATCHES is first checked to see if it is
  a defined variable.  If so, the variable's value is used, otherwise the
  original value is used.

* If the left hand argument to MATCHES is missing it returns false
  without error

* Both left and right hand arguments to LESS, GREATER, EQUAL,
  LESS_EQUAL, and GREATER_EQUAL, are independently tested to see if
  they are defined variables.  If so, their defined values are used otherwise
  the original value is used.

* Both left and right hand arguments to STRLESS, STRGREATER,
  STREQUAL, STRLESS_EQUAL, and STRGREATER_EQUAL are independently
  tested to see if they are defined variables.  If so, their defined values are
  used otherwise the original value is used.

* Both left and right hand arguments to VERSION_LESS,
  VERSION_GREATER, VERSION_EQUAL, VERSION_LESS_EQUAL, and
  VERSION_GREATER_EQUAL are independently tested to see if they are defined
  variables.  If so, their defined values are used otherwise the original value
  is used.

* The right hand argument to NOT is tested to see if it is a boolean
  constant.  If so, the value is used, otherwise it is assumed to be a
  variable and it is dereferenced.

* The left and right hand arguments to AND and OR are independently
  tested to see if they are boolean constants.  If so, they are used as
  such, otherwise they are assumed to be variables and are dereferenced.

.. versionchanged:: 3.1
  To prevent ambiguity, potential variable or keyword names can be
  specified in a :ref:`Quoted Argument` or a :ref:`Bracket Argument`.
  A quoted or bracketed variable or keyword will be interpreted as a
  string and not dereferenced or interpreted.
  See policy ``CMP0054``.

There is no automatic evaluation for environment or cache
:ref:`Variable References`.  Their values must be referenced as
``$ENV{<name>}`` or ``$CACHE{<name>}`` wherever the above-documented
condition syntax accepts ``<variable|string>``.

See also
^^^^^^^^

* ``else()``
* ``elseif()``
* ``endif()``

include
-------

Load and run CMake code from a file or module.

 include(<file|module> [OPTIONAL] [RESULT_VARIABLE <var>]
                       [NO_POLICY_SCOPE])

Loads and runs CMake code from the file given.  Variable reads and
writes access the scope of the caller (dynamic scoping).  If ``OPTIONAL``
is present, then no error is raised if the file does not exist.  If
``RESULT_VARIABLE`` is given the variable ``<var>`` will be set to the
full filename which has been included or ``NOTFOUND`` if it failed.

If a module is specified instead of a file, the file with name
``<modulename>.cmake`` is searched first in ``CMAKE_MODULE_PATH``,
then in the CMake module directory.  There is one exception to this: if
the file which calls ``include()`` is located itself in the CMake builtin
module directory, then first the CMake builtin module directory is searched and
``CMAKE_MODULE_PATH`` afterwards.  See also policy ``CMP0017``.

See the ``cmake_policy()`` command documentation for discussion of the
``NO_POLICY_SCOPE`` option.

include_guard
-------------

.. versionadded:: 3.10

Provides an include guard for the file currently being processed by CMake.

 include_guard([DIRECTORY|GLOBAL])

Sets up an include guard for the current CMake file (see the
``CMAKE_CURRENT_LIST_FILE`` variable documentation).

CMake will end its processing of the current file at the location of the
``include_guard`` command if the current file has already been
processed for the applicable scope (see below). This provides functionality
similar to the include guards commonly used in source headers or to the
``#pragma once`` directive. If the current file has been processed previously
for the applicable scope, the effect is as though ``return()`` had been
called. Do not call this command from inside a function being defined within
the current file.

An optional argument specifying the scope of the guard may be provided.
Possible values for the option are:

``DIRECTORY``
  The include guard applies within the current directory and below. The file
  will only be included once within this directory scope, but may be included
  again by other files outside of this directory (i.e. a parent directory or
  another directory not pulled in by ``add_subdirectory()`` or
  ``include()`` from the current file or its children).

``GLOBAL``
  The include guard applies globally to the whole build. The current file
  will only be included once regardless of the scope.

If no arguments given, ``include_guard`` has the same scope as a variable,
meaning that the include guard effect is isolated by the most recent
function scope or current directory if no inner function scopes exist.
In this case the command behavior is the same as:

 if(__CURRENT_FILE_VAR__)
   return()
 endif()
 set(__CURRENT_FILE_VAR__ TRUE)

list
----

Operations on :ref:`semicolon-separated lists <CMake Language Lists>`.

Synopsis
^^^^^^^^

 Reading
   list(LENGTH <list> <out-var>)
   list(GET <list> <element index> [<index> ...] <out-var>)
   list(JOIN <list> <glue> <out-var>)
   list(SUBLIST <list> <begin> <length> <out-var>)

 Search
   list(FIND <list> <value> <out-var>)

 Modification
   list(APPEND <list> [<element>...])
   list(FILTER <list> {INCLUDE | EXCLUDE} REGEX <regex>)
   list(INSERT <list> <index> [<element>...])
   list(POP_BACK <list> [<out-var>...])
   list(POP_FRONT <list> [<out-var>...])
   list(PREPEND <list> [<element>...])
   list(REMOVE_ITEM <list> <value>...)
   list(REMOVE_AT <list> <index>...)
   list(REMOVE_DUPLICATES <list>)
   list(TRANSFORM <list> <ACTION> [...])

 Ordering
   list(REVERSE <list>)
   list(SORT <list> [...])

Introduction
^^^^^^^^^^^^

The list subcommands ``APPEND``, ``INSERT``, ``FILTER``,
``PREPEND``, ``POP_BACK``, ``POP_FRONT``, ``REMOVE_AT``,
``REMOVE_ITEM``, ``REMOVE_DUPLICATES``, ``REVERSE`` and
``SORT`` may create new values for the list within the current CMake
variable scope.  Similar to the ``set()`` command, the ``list`` command
creates new variable values in the current scope, even if the list itself is
actually defined in a parent scope.  To propagate the results of these
operations upwards, use ``set()`` with ``PARENT_SCOPE``,
``set()`` with ``CACHE INTERNAL``, or some other means of value
propagation.

.. note::

  A list in cmake is a ``;`` separated group of strings.  To create a
  list, the ``set()`` command can be used.  For example,
  ``set(var a b c d e)`` creates a list with ``a;b;c;d;e``, and
  ``set(var "a b c d e")`` creates a string or a list with one item in it.
  (Note that macro arguments are not variables, and therefore cannot be used
  in ``LIST`` commands.)

  Individual elements may not contain an unequal number of ``[`` and ``]``
  characters, and may not end in a backslash (``\``).
  See :ref:`semicolon-separated lists <CMake Language Lists>` for details.

.. note::

  When specifying index values, if ``<element index>`` is 0 or greater, it
  is indexed from the beginning of the list, with 0 representing the
  first list element.  If ``<element index>`` is -1 or lesser, it is indexed
  from the end of the list, with -1 representing the last list element.
  Be careful when counting with negative indices: they do not start from
  0.  -0 is equivalent to 0, the first list element.

Reading
^^^^^^^

.. signature::
  list(LENGTH <list> <output variable>)

  Returns the list's length.

.. signature::
  list(GET <list> <element index> [<element index> ...] <output variable>)

  Returns the list of elements specified by indices from the list.

.. signature:: list(JOIN <list> <glue> <output variable>)

  .. versionadded:: 3.12

  Returns a string joining all list's elements using the glue string.
  To join multiple strings, which are not part of a list,
  use ``string(JOIN)``.

.. signature::
  list(SUBLIST <list> <begin> <length> <output variable>)

  .. versionadded:: 3.12

  Returns a sublist of the given list.
  If ``<length>`` is 0, an empty list will be returned.
  If ``<length>`` is -1 or the list is smaller than ``<begin>+<length>`` then
  the remaining elements of the list starting at ``<begin>`` will be returned.

Search
^^^^^^

.. signature::
  list(FIND <list> <value> <output variable>)

  Returns the index of the element specified in the list
  or ``-1`` if it wasn't found.

Modification
^^^^^^^^^^^^

.. signature::
  list(APPEND <list> [<element> ...])

  Appends elements to the list. If no variable named ``<list>`` exists in the
  current scope its value is treated as empty and the elements are appended to
  that empty list.

.. signature::
  list(FILTER <list> <INCLUDE|EXCLUDE> REGEX <regular_expression>)

.. versionadded:: 3.6

Includes or removes items from the list that match the mode's pattern.
In ``REGEX`` mode, items will be matched against the given regular expression.

For more information on regular expressions look under
:ref:`string(REGEX) <Regex Specification>`.

.. signature::
  list(INSERT <list> <element_index> <element> [<element> ...])

  Inserts elements to the list to the specified index. It is an
  error to specify an out-of-range index. Valid indexes are 0 to `N`
  where `N` is the length of the list, inclusive. An empty list
  has length 0. If no variable named ``<list>`` exists in the
  current scope its value is treated as empty and the elements are
  inserted in that empty list.

.. signature::
  list(POP_BACK <list> [<out-var>...])

  .. versionadded:: 3.15

  If no variable name is given, removes exactly one element. Otherwise,
  with `N` variable names provided, assign the last `N` elements' values
  to the given variables and then remove the last `N` values from
  ``<list>``.

.. signature::
  list(POP_FRONT <list> [<out-var>...])

  .. versionadded:: 3.15

  If no variable name is given, removes exactly one element. Otherwise,
  with `N` variable names provided, assign the first `N` elements' values
  to the given variables and then remove the first `N` values from
  ``<list>``.

.. signature::
  list(PREPEND <list> [<element> ...])

  .. versionadded:: 3.15

  Insert elements to the 0th position in the list. If no variable named
  ``<list>`` exists in the current scope its value is treated as empty and
  the elements are prepended to that empty list.

.. signature::
  list(REMOVE_ITEM <list> <value> [<value> ...])

  Removes all instances of the given items from the list.

.. signature::
  list(REMOVE_AT <list> <index> [<index> ...])

  Removes items at given indices from the list.

.. signature::
  list(REMOVE_DUPLICATES <list>)

  Removes duplicated items in the list. The relative order of items
  is preserved, but if duplicates are encountered,
  only the first instance is preserved.

.. signature::
  list(TRANSFORM <list> <ACTION> [<SELECTOR>]
       [OUTPUT_VARIABLE <output variable>])

  .. versionadded:: 3.12

  Transforms the list by applying an ``<ACTION>`` to all or, by specifying a
  ``<SELECTOR>``, to the selected elements of the list, storing the result
  in-place or in the specified output variable.

  .. note::

   The ``TRANSFORM`` sub-command does not change the number of elements in the
   list. If a ``<SELECTOR>`` is specified, only some elements will be changed,
   the other ones will remain the same as before the transformation.

 ``<ACTION>`` specifies the action to apply to the elements of the list.
 The actions have exactly the same semantics as sub-commands of the
 :command:`string` command.  ``<ACTION>`` must be one of the following:

   :command:`APPEND <string(APPEND)>`, :command:`PREPEND <string(PREPEND)>`
     Append, prepend specified value to each element of the list.

     .. signature::
       list(TRANSFORM <list> (APPEND|PREPEND) <value> ...)
       :target: TRANSFORM_APPEND

   :command:`TOLOWER <string(TOLOWER)>`, :command:`TOUPPER <string(TOUPPER)>`
     Convert each element of the list to lower, upper characters.

     .. signature::
       list(TRANSFORM <list> (TOLOWER|TOUPPER) ...)
       :target: TRANSFORM_TOLOWER

   :command:`STRIP <string(STRIP)>`
     Remove leading and trailing spaces from each element of the list.

     .. signature::
       list(TRANSFORM <list> STRIP ...)
       :target: TRANSFORM_STRIP

   :command:`GENEX_STRIP <string(GENEX_STRIP)>`
     Strip any
     :manual:`generator expressions <cmake-generator-expressions(7)>`
     from each element of the list.

     .. signature::
       list(TRANSFORM <list> GENEX_STRIP ...)
       :target: TRANSFORM_GENEX_STRIP

   :command:`REPLACE <string(REGEX REPLACE)>`:
     Match the regular expression as many times as possible and substitute
     the replacement expression for the match for each element of the list
     (same semantic as :command:`string(REGEX REPLACE)`).

     .. signature::
       list(TRANSFORM <list> REPLACE <regular_expression>
                                     <replace_expression> ...)
       :target: TRANSFORM_REPLACE

 ``<SELECTOR>`` determines which elements of the list will be transformed.
 Only one type of selector can be specified at a time.
 When given, ``<SELECTOR>`` must be one of the following:

   ``AT``
     Specify a list of indexes.

     .. code-block:: cmake

       list(TRANSFORM <list> <ACTION> AT <index> [<index> ...] ...)

   ``FOR``
     Specify a range with, optionally,
     an increment used to iterate over the range.

     .. code-block:: cmake

       list(TRANSFORM <list> <ACTION> FOR <start> <stop> [<step>] ...)

   ``REGEX``
     Specify a regular expression.
     Only elements matching the regular expression will be transformed.

     .. code-block:: cmake

       list(TRANSFORM <list> <ACTION> REGEX <regular_expression> ...)

Ordering
^^^^^^^^

.. signature::
  list(REVERSE <list>)

  Reverses the contents of the list in-place.

.. signature::
  list(SORT <list> [COMPARE <compare>] [CASE <case>] [ORDER <order>])

  Sorts the list in-place alphabetically.

  .. versionadded:: 3.13
    Added the ``COMPARE``, ``CASE``, and ``ORDER`` options.

  .. versionadded:: 3.18
    Added the ``COMPARE NATURAL`` option.

  Use the ``COMPARE`` keyword to select the comparison method for sorting.
  The ``<compare>`` option should be one of:

    ``STRING``
      Sorts a list of strings alphabetically.
      This is the default behavior if the ``COMPARE`` option is not given.

    ``FILE_BASENAME``
      Sorts a list of pathnames of files by their basenames.

    ``NATURAL``
      Sorts a list of strings using natural order
      (see ``strverscmp(3)`` manual), i.e. such that contiguous digits
      are compared as whole numbers.
      For example: the following list `10.0 1.1 2.1 8.0 2.0 3.1`
      will be sorted as `1.1 2.0 2.1 3.1 8.0 10.0` if the ``NATURAL``
      comparison is selected where it will be sorted as
      `1.1 10.0 2.0 2.1 3.1 8.0` with the ``STRING`` comparison.

  Use the ``CASE`` keyword to select a case sensitive or case insensitive
  sort mode.  The ``<case>`` option should be one of:

    ``SENSITIVE``
      List items are sorted in a case-sensitive manner.
      This is the default behavior if the ``CASE`` option is not given.

    ``INSENSITIVE``
      List items are sorted case insensitively.  The order of
      items which differ only by upper/lowercase is not specified.

  To control the sort order, the ``ORDER`` keyword can be given.
  The ``<order>`` option should be one of:

    ``ASCENDING``
      Sorts the list in ascending order.
      This is the default behavior when the ``ORDER`` option is not given.

    ``DESCENDING``
      Sorts the list in descending order.

macro
-----

Start recording a macro for later invocation as a command

 macro(<name> [<arg1> ...])
   <commands>
 endmacro()

Defines a macro named ``<name>`` that takes arguments named
``<arg1>``, ... Commands listed after macro, but before the
matching ``endmacro()``, are not executed until the macro
is invoked.

Per legacy, the ``endmacro()`` command admits an optional
``<name>`` argument. If used, it must be a verbatim repeat of the
argument of the opening ``macro`` command.

See the ``cmake_policy()`` command documentation for the behavior
of policies inside macros.

See the :ref:`Macro vs Function` section below for differences
between CMake macros and ``functions``.

Invocation
^^^^^^^^^^

The macro invocation is case-insensitive. A macro defined as

 macro(foo)
   <commands>
 endmacro()

can be invoked through any of

 foo()
 Foo()
 FOO()
 cmake_language(CALL foo)

and so on. However, it is strongly recommended to stay with the
case chosen in the macro definition.  Typically macros use
all-lowercase names.

.. versionadded:: 3.18
  The ``cmake_language(CALL ...)`` command can also be used to
  invoke the macro.

Arguments
^^^^^^^^^

When a macro is invoked, the commands recorded in the macro are
first modified by replacing formal parameters (``${arg1}``, ...)
with the arguments passed, and then invoked as normal commands.

In addition to referencing the formal parameters you can reference the
values ``${ARGC}`` which will be set to the number of arguments passed
into the macro as well as ``${ARGV0}``, ``${ARGV1}``, ``${ARGV2}``,
...  which will have the actual values of the arguments passed in.
This facilitates creating macros with optional arguments.

Furthermore, ``${ARGV}`` holds the list of all arguments given to the
macro and ``${ARGN}`` holds the list of arguments past the last expected
argument.
Referencing to ``${ARGV#}`` arguments beyond ``${ARGC}`` have undefined
behavior. Checking that ``${ARGC}`` is greater than ``#`` is the only
way to ensure that ``${ARGV#}`` was passed to the function as an extra
argument.

Macro vs Function
^^^^^^^^^^^^^^^^^

The ``macro`` command is very similar to the ``function()`` command.
Nonetheless, there are a few important differences.

In a function, ``ARGN``, ``ARGC``, ``ARGV`` and ``ARGV0``, ``ARGV1``, ...
are true variables in the usual CMake sense.  In a macro, they are not,
they are string replacements much like the C preprocessor would do
with a macro.  This has a number of consequences, as explained in
the :ref:`Argument Caveats` section below.

Another difference between macros and functions is the control flow.
A function is executed by transferring control from the calling
statement to the function body.  A macro is executed as if the macro
body were pasted in place of the calling statement.  This has the
consequence that a ``return()`` in a macro body does not
just terminate execution of the macro; rather, control is returned
from the scope of the macro call.  To avoid confusion, it is recommended
to avoid ``return()`` in macros altogether.

Unlike a function, the ``CMAKE_CURRENT_FUNCTION``,
``CMAKE_CURRENT_FUNCTION_LIST_DIR``,
``CMAKE_CURRENT_FUNCTION_LIST_FILE``,
``CMAKE_CURRENT_FUNCTION_LIST_LINE`` variables are not
set for a macro.

Argument Caveats
^^^^^^^^^^^^^^^^

Since ``ARGN``, ``ARGC``, ``ARGV``, ``ARGV0`` etc. are not variables,
you will NOT be able to use commands like

 if(ARGV1) # ARGV1 is not a variable
 if(DEFINED ARGV2) # ARGV2 is not a variable
 if(ARGC GREATER 2) # ARGC is not a variable
 foreach(loop_var IN LISTS ARGN) # ARGN is not a variable

In the first case, you can use ``if(${ARGV1})``.  In the second and
third case, the proper way to check if an optional variable was
passed to the macro is to use ``if(${ARGC} GREATER 2)``.  In the
last case, you can use ``foreach(loop_var ${ARGN})`` but this will
skip empty arguments.  If you need to include them, you can use

 set(list_var "${ARGN}")
 foreach(loop_var IN LISTS list_var)

Note that if you have a variable with the same name in the scope from
which the macro is called, using unreferenced names will use the
existing variable instead of the arguments. For example:

 macro(bar)
   foreach(arg IN LISTS ARGN)
     <commands>
   endforeach()
 endmacro()

 function(foo)
   bar(x y z)
 endfunction()

 foo(a b c)

Will loop over ``a;b;c`` and not over ``x;y;z`` as one might have expected.
If you want true CMake variables and/or better CMake scope control you
should look at the function command.

See Also
^^^^^^^^

* ``cmake_parse_arguments()``
* ``endmacro()``

mark_as_advanced
----------------

Mark cmake cached variables as advanced.

 mark_as_advanced([CLEAR|FORCE] <var1> ...)

Sets the advanced/non-advanced state of the named
cached variables.

An advanced variable will not be displayed in any
of the cmake GUIs unless the ``show advanced`` option is on.
In script mode, the advanced/non-advanced state has no effect.

If the keyword ``CLEAR`` is given
then advanced variables are changed back to unadvanced.
If the keyword ``FORCE`` is given
then the variables are made advanced.
If neither ``FORCE`` nor ``CLEAR`` is specified,
new values will be marked as advanced, but if a
variable already has an advanced/non-advanced state,
it will not be changed.

.. versionchanged:: 3.17
  Variables passed to this command which are not already in the cache
  are ignored. See policy ``CMP0102``.

math
----

Evaluate a mathematical expression.

 math(EXPR <variable> "<expression>" [OUTPUT_FORMAT <format>])

Evaluates a mathematical ``<expression>`` and sets ``<variable>`` to the
resulting value.  The result of the expression must be representable as a
64-bit signed integer. Floating point inputs are invalid e.g. ``1.1 * 10``.
Non-integer results e.g. ``3 / 2`` are truncated.

The mathematical expression must be given as a string (i.e. enclosed in
double quotation marks). An example is ``"5 * (10 + 13)"``.
Supported operators are ``+``, ``-``, ``*``, ``/``, ``%``, ``|``, ``&``,
``^``, ``~``, ``<<``, ``>>``, and ``(...)``; they have the same meaning
as in C code.

.. versionadded:: 3.13
  Hexadecimal numbers are recognized when prefixed with ``0x``, as in C code.

.. versionadded:: 3.13
  The result is formatted according to the option ``OUTPUT_FORMAT``,
  where ``<format>`` is one of

  ``HEXADECIMAL``
    Hexadecimal notation as in C code, i. e. starting with "0x".
  ``DECIMAL``
    Decimal notation. Which is also used if no ``OUTPUT_FORMAT`` option
    is specified.

For example

 math(EXPR value "100 * 0xA" OUTPUT_FORMAT DECIMAL)      # value is set to "1000"
 math(EXPR value "100 * 0xA" OUTPUT_FORMAT HEXADECIMAL)  # value is set to "0x3e8"

message
-------

Log a message.

Synopsis
^^^^^^^^

 General messages
   message([<mode>] "message text" ...)

 Reporting checks
   message(<checkState> "message text" ...)

 Configure Log
   message(CONFIGURE_LOG <text>...)

General messages
^^^^^^^^^^^^^^^^

 message([<mode>] "message text" ...)

Record the specified message text in the log.  If more than one message
string is given, they are concatenated into a single message with no
separator between the strings.

The optional ``<mode>`` keyword determines the type of message, which
influences the way the message is handled:

``FATAL_ERROR``
  CMake Error, stop processing and generation.

  The ``cmake(1)`` executable will return a non-zero
  :ref:`exit code <CMake Exit Code>`.

``SEND_ERROR``
  CMake Error, continue processing, but skip generation.

``WARNING``
  CMake Warning, continue processing.

``AUTHOR_WARNING``
  CMake Warning (dev), continue processing.

``DEPRECATION``
  CMake Deprecation Error or Warning if variable
  ``CMAKE_ERROR_DEPRECATED`` or ``CMAKE_WARN_DEPRECATED``
  is enabled, respectively, else no message.

(none) or ``NOTICE``
  Important message printed to stderr to attract user's attention.

``STATUS``
  The main interesting messages that project users might be interested in.
  Ideally these should be concise, no more than a single line, but still
  informative.

``VERBOSE``
  Detailed informational messages intended for project users.  These messages
  should provide additional details that won't be of interest in most cases,
  but which may be useful to those building the project when they want deeper
  insight into what's happening.

``DEBUG``
  Detailed informational messages intended for developers working on the
  project itself as opposed to users who just want to build it.  These messages
  will not typically be of interest to other users building the project and
  will often be closely related to internal implementation details.

``TRACE``
  Fine-grained messages with very low-level implementation details.  Messages
  using this log level would normally only be temporary and would expect to be
  removed before releasing the project, packaging up the files, etc.

.. versionadded:: 3.15
  Added the ``NOTICE``, ``VERBOSE``, ``DEBUG``, and ``TRACE`` levels.

The CMake command-line tool displays ``STATUS`` to ``TRACE`` messages on stdout
with the message preceded by two hyphens and a space.  All other message types
are sent to stderr and are not prefixed with hyphens.  The
``CMake GUI`` displays all messages in its log area.
The ``curses interface`` shows ``STATUS`` to ``TRACE``
messages one at a time on a status line and other messages in an
interactive pop-up box.  The :option:`--log-level <cmake --log-level>`
command-line option to each of these tools can be used to control which
messages will be shown.

.. versionadded:: 3.17
  To make a log level persist between CMake runs, the
  ``CMAKE_MESSAGE_LOG_LEVEL`` variable can be set instead.
  Note that the command line option takes precedence over the cache variable.

.. versionadded:: 3.16
  Messages of log levels ``NOTICE`` and below will have each line preceded
  by the content of the ``CMAKE_MESSAGE_INDENT`` variable (converted to
  a single string by concatenating its list items).  For ``STATUS`` to ``TRACE``
  messages, this indenting content will be inserted after the hyphens.

.. versionadded:: 3.17
  Messages of log levels ``NOTICE`` and below can also have each line preceded
  with context of the form ``[some.context.example]``.  The content between the
  square brackets is obtained by converting the ``CMAKE_MESSAGE_CONTEXT``
  list variable to a dot-separated string.  The message context will always
  appear before any indenting content but after any automatically added leading
  hyphens. By default, message context is not shown, it has to be explicitly
  enabled by giving the :option:`cmake --log-context`
  command-line option or by setting the ``CMAKE_MESSAGE_CONTEXT_SHOW``
  variable to true.  See the ``CMAKE_MESSAGE_CONTEXT`` documentation for
  usage examples.

CMake Warning and Error message text displays using a simple markup
language.  Non-indented text is formatted in line-wrapped paragraphs
delimited by newlines.  Indented text is considered pre-formatted.


Reporting checks
^^^^^^^^^^^^^^^^

.. versionadded:: 3.17

A common pattern in CMake output is a message indicating the start of some
sort of check, followed by another message reporting the result of that check.
For example:

 message(STATUS "Looking for someheader.h")
 #... do the checks, set checkSuccess with the result
 if(checkSuccess)
   message(STATUS "Looking for someheader.h - found")
 else()
   message(STATUS "Looking for someheader.h - not found")
 endif()

This can be more robustly and conveniently expressed using the ``CHECK_...``
keyword form of the ``message()`` command:

 message(<checkState> "message" ...)

where ``<checkState>`` must be one of the following:

  ``CHECK_START``
    Record a concise message about the check about to be performed.

  ``CHECK_PASS``
    Record a successful result for a check.

  ``CHECK_FAIL``
    Record an unsuccessful result for a check.

When recording a check result, the command repeats the message from the most
recently started check for which no result has yet been reported, then some
separator characters and then the message text provided after the
``CHECK_PASS`` or ``CHECK_FAIL`` keyword.  Check messages are always reported
at ``STATUS`` log level.

Checks may be nested and every ``CHECK_START`` should have exactly one
matching ``CHECK_PASS`` or ``CHECK_FAIL``.
The ``CMAKE_MESSAGE_INDENT`` variable can also be used to add
indenting to nested checks if desired.  For example:

 message(CHECK_START "Finding my things")
 list(APPEND CMAKE_MESSAGE_INDENT "  ")
 unset(missingComponents)

 message(CHECK_START "Finding partA")
 # ... do check, assume we find A
 message(CHECK_PASS "found")

 message(CHECK_START "Finding partB")
 # ... do check, assume we don't find B
 list(APPEND missingComponents B)
 message(CHECK_FAIL "not found")

 list(POP_BACK CMAKE_MESSAGE_INDENT)
 if(missingComponents)
   message(CHECK_FAIL "missing components: ${missingComponents}")
 else()
   message(CHECK_PASS "all components found")
 endif()

Output from the above would appear something like the following::

 -- Finding my things
 --   Finding partA
 --   Finding partA - found
 --   Finding partB
 --   Finding partB - not found
 -- Finding my things - missing components: B

Configure Log
^^^^^^^^^^^^^

.. versionadded:: 3.26

 message(CONFIGURE_LOG <text>...)

Record a :ref:`configure-log message event <message configure-log event>`
with the specified ``<text>``.  By convention, if the text contains more
than one line, the first line should be a summary of the event.

This mode is intended to record the details of a system inspection check
or other one-time operation guarded by a cache entry, but that is not
performed using ``try_compile()`` or ``try_run()``, which
automatically log their details.  Projects should avoid calling it every
time CMake runs.  For example:

 if (NOT DEFINED MY_CHECK_RESULT)
   # Print check summary in configure output.
   message(CHECK_START "My Check")

   # ... perform system inspection, e.g., with execute_process ...

   # Cache the result so we do not run the check again.
   set(MY_CHECK_RESULT "${MY_CHECK_RESULT}" CACHE INTERNAL "My Check")

   # Record the check details in the cmake-configure-log.
   message(CONFIGURE_LOG
     "My Check Result: ${MY_CHECK_RESULT}\n"
     "${details}"
   )

   # Print check result in configure output.
   if(MY_CHECK_RESULT)
     message(CHECK_PASS "passed")
   else()
     message(CHECK_FAIL "failed")
   endif()
 endif()

If no project is currently being configured, such as in
:ref:`cmake -P <Script Processing Mode>` script mode,
this command does nothing.

See Also
^^^^^^^^

* ``cmake_language(GET_MESSAGE_LOG_LEVEL)``

option
------

Provide a boolean option that the user can optionally select.

 option(<variable> "<help_text>" [value])

If no initial ``<value>`` is provided, boolean ``OFF`` is the default value.
If ``<variable>`` is already set as a normal or cache variable,
then the command does nothing (see policy ``CMP0077``).

For options that depend on the values of other options, see
the module help for ``CMakeDependentOption``.

In CMake project mode, a boolean cache variable is created with the option
value. In CMake script mode, a boolean variable is set with the option value.

return
------

Return from a file, directory or function.

 return([PROPAGATE <var-name>...])

When this command is encountered in an included file (via ``include()`` or
``find_package()``), it causes processing of the current file to stop
and control is returned to the including file.  If it is encountered in a
file which is not included by another file, e.g. a ``CMakeLists.txt``,
deferred calls scheduled by ``cmake_language(DEFER)`` are invoked and
control is returned to the parent directory if there is one.

If ``return()`` is called in a function, control is returned to the caller
of that function.  Note that a ``macro()``, unlike a ``function()``,
is expanded in place and therefore cannot handle ``return()``.

Policy ``CMP0140`` controls the behavior regarding the arguments of the
command.  All arguments are ignored unless that policy is set to ``NEW``.

``PROPAGATE``
  .. versionadded:: 3.25

  This option sets or unsets the specified variables in the parent directory or
  function caller scope. This is equivalent to ``set(PARENT_SCOPE)`` or
  ``unset(PARENT_SCOPE)`` commands, except for the way it interacts
  with the ``block()`` command, as described below.

  The ``PROPAGATE`` option can be very useful in conjunction with the
  ``block()`` command.  A ``return`` will propagate the
  specified variables through any enclosing block scopes created by the
  ``block()`` commands.  Inside a function, this ensures the variables
  are propagated to the function's caller, regardless of any blocks within
  the function.  If not inside a function, it ensures the variables are
  propagated to the parent file or directory scope. For example:

  .. code-block:: cmake
    :caption: CMakeLists.txt

    cmake_minimum_required(VERSION 3.25)
    project(example)

    set(var1 "top-value")

    block(SCOPE_FOR VARIABLES)
      add_subdirectory(subDir)
      # var1 has the value "block-nested"
    endblock()

    # var1 has the value "top-value"

  .. code-block:: cmake
    :caption: subDir/CMakeLists.txt

    function(multi_scopes result_var1 result_var2)
      block(SCOPE_FOR VARIABLES)
        # This would only propagate out of the immediate block, not to
        # the caller of the function.
        #set(${result_var1} "new-value" PARENT_SCOPE)
        #unset(${result_var2} PARENT_SCOPE)

        # This propagates the variables through the enclosing block and
        # out to the caller of the function.
        set(${result_var1} "new-value")
        unset(${result_var2})
        return(PROPAGATE ${result_var1} ${result_var2})
      endblock()
    endfunction()

    set(var1 "some-value")
    set(var2 "another-value")

    multi_scopes(var1 var2)
    # Now var1 will hold "new-value" and var2 will be unset

    block(SCOPE_FOR VARIABLES)
      # This return() will set var1 in the directory scope that included us
      # via add_subdirectory(). The surrounding block() here does not limit
      # propagation to the current file, but the block() in the parent
      # directory scope does prevent propagation going any further.
      set(var1 "block-nested")
      return(PROPAGATE var1)
    endblock()

See Also
^^^^^^^^

* ``block()``
* ``function()``

separate_arguments
------------------

Parse command-line arguments into a semicolon-separated list.

 separate_arguments(<variable> <mode> [PROGRAM [SEPARATE_ARGS]] <args>)

Parses a space-separated string ``<args>`` into a list of items,
and stores this list in semicolon-separated standard form in ``<variable>``.

This function is intended for parsing command-line arguments.
The entire command line must be passed as one string in the
argument ``<args>``.

The exact parsing rules depend on the operating system.
They are specified by the ``<mode>`` argument which must
be one of the following keywords:

``UNIX_COMMAND``
  Arguments are separated by unquoted whitespace.
  Both single-quote and double-quote pairs are respected.
  A backslash escapes the next literal character (``\"`` is ``"``);
  there are no special escapes (``\n`` is just ``n``).

``WINDOWS_COMMAND``
  A Windows command-line is parsed using the same
  syntax the runtime library uses to construct argv at startup.  It
  separates arguments by whitespace that is not double-quoted.
  Backslashes are literal unless they precede double-quotes.  See the
  MSDN article Parsing C Command-Line Arguments for details.

``NATIVE_COMMAND``
  .. versionadded:: 3.9

  Proceeds as in ``WINDOWS_COMMAND`` mode if the host system is Windows.
  Otherwise proceeds as in ``UNIX_COMMAND`` mode.

``PROGRAM``
  .. versionadded:: 3.19

  The first item in ``<args>`` is assumed to be an executable and will be
  searched in the system search path or left as a full path. If not found,
  ``<variable>`` will be empty. Otherwise, ``<variable>`` is a list of 2
  elements:

    0. Absolute path of the program
    1. Any command-line arguments present in ``<args>`` as a string

  For example:

  .. code-block:: cmake

    separate_arguments (out UNIX_COMMAND PROGRAM "cc -c main.c")

  * First element of the list: ``/path/to/cc``
  * Second element of the list: ``" -c main.c"``

``SEPARATE_ARGS``
  When this sub-option of ``PROGRAM`` option is specified, command-line
  arguments will be split as well and stored in ``<variable>``.

  For example:

  .. code-block:: cmake

    separate_arguments (out UNIX_COMMAND PROGRAM SEPARATE_ARGS "cc -c main.c")

  The contents of ``out`` will be: ``/path/to/cc;-c;main.c``

 separate_arguments(<var>)

Convert the value of ``<var>`` to a semi-colon separated list.  All
spaces are replaced with ';'.  This helps with generating command
lines.

set
---

Set a normal, cache, or environment variable to a given value.
See the :ref:`cmake-language(7) variables <CMake Language Variables>`
documentation for the scopes and interaction of normal variables
and cache entries.

Signatures of this command that specify a ``<value>...`` placeholder
expect zero or more arguments.  Multiple arguments will be joined as
a :ref:`semicolon-separated list <CMake Language Lists>` to form the
actual variable value to be set.

Set Normal Variable
^^^^^^^^^^^^^^^^^^^

.. signature::
  set(<variable> <value>... [PARENT_SCOPE])
  :target: normal

  Set or unset ``<variable>`` in the current function or directory scope:

  * If at least one ``<value>...`` is given, set the variable to that value.
  * If no value is given, unset the variable.  This is equivalent to
    ``unset(<variable>)``.

  If the ``PARENT_SCOPE`` option is given the variable will be set in
  the scope above the current scope.  Each new directory or ``function()``
  command creates a new scope.  A scope can also be created with the
  ``block()`` command. ``set(PARENT_SCOPE)`` will set the value
  of a variable into the parent directory, calling function, or
  encompassing scope (whichever is applicable to the case at hand).
  The previous state of the variable's value stays the same in the
  current scope (e.g., if it was undefined before, it is still undefined
  and if it had a value, it is still that value).

  The ``block(PROPAGATE)`` and ``return(PROPAGATE)`` commands
  can be used as an alternate method to the ``set(PARENT_SCOPE)``
  and ``unset(PARENT_SCOPE)`` commands to update the parent scope.

.. note::

  When evaluating :ref:`Variable References` of the form ``${VAR}``, CMake
  first searches for a normal variable with that name.  If no such normal
  variable exists, CMake will then search for a cache entry with that name.
  Because of this, **unsetting a normal variable can expose a cache variable
  that was previously hidden**.  To force a variable reference of the form
  ``${VAR}`` to return an empty string, use ``set(<variable> "")``, which
  clears the normal variable but leaves it defined.

Set Cache Entry
^^^^^^^^^^^^^^^

.. signature::
  set(<variable> <value>... CACHE <type> <docstring> [FORCE])
  :target: CACHE

  Sets the given cache ``<variable>`` (cache entry).  Since cache entries
  are meant to provide user-settable values this does not overwrite
  existing cache entries by default.  Use the ``FORCE`` option to
  overwrite existing entries.

  The ``<type>`` must be specified as one of:

    ``BOOL``
      Boolean ``ON/OFF`` value.
      ``cmake-gui(1)`` offers a checkbox.

    ``FILEPATH``
      Path to a file on disk.
      ``cmake-gui(1)`` offers a file dialog.

    ``PATH``
      Path to a directory on disk.
      ``cmake-gui(1)`` offers a file dialog.

    ``STRING``
      A line of text.
      ``cmake-gui(1)`` offers a text field or a drop-down selection
      if the ``STRINGS`` cache entry property is set.

    ``INTERNAL``
      A line of text.
      ``cmake-gui(1)`` does not show internal entries.
      They may be used to store variables persistently across runs.
      Use of this type implies ``FORCE``.

  The ``<docstring>`` must be specified as a line of text
  providing a quick summary of the option
  for presentation to ``cmake-gui(1)`` users.

  If the cache entry does not exist prior to the call or the ``FORCE``
  option is given then the cache entry will be set to the given value.

  .. note::

   The content of the cache variable will not be directly accessible
   if a normal variable of the same name already exists
   (see :ref:`rules of variable evaluation <CMake Language Variables>`).
   If policy :policy:`CMP0126` is set to ``OLD``, any normal variable
   binding in the current scope will be removed.

 It is possible for the cache entry to exist prior to the call but
 have no type set if it was created on the :manual:`cmake(1)` command
 line by a user through the :option:`-D\<var\>=\<value\> <cmake -D>` option
 without specifying a type.  In this case the ``set`` command will add the
 type.  Furthermore, if the ``<type>`` is ``PATH`` or ``FILEPATH``
 and the ``<value>`` provided on the command line is a relative path,
 then the ``set`` command will treat the path as relative to the
 current working directory and convert it to an absolute path.

Set Environment Variable
^^^^^^^^^^^^^^^^^^^^^^^^

.. signature::
  set(ENV{<variable>} [<value>])
  :target: ENV

  Sets an ``Environment Variable``
  to the given value.
  Subsequent calls of ``$ENV{<variable>}`` will return this new value.

  This command affects only the current CMake process, not the process
  from which CMake was called, nor the system environment at large,
  nor the environment of subsequent build or test processes.

  If no argument is given after ``ENV{<variable>}`` or if ``<value>`` is
  an empty string, then this command will clear any existing value of the
  environment variable.

  Arguments after ``<value>`` are ignored. If extra arguments are found,
  then an author warning is issued.

See Also
^^^^^^^^

* ``unset()``

set_directory_properties
------------------------

Set properties of the current directory and subdirectories.

 set_directory_properties(PROPERTIES <prop1> <value1> [<prop2> <value2>] ...)

Sets properties of the current directory and its subdirectories in key-value
pairs.

See also the ``set_property(DIRECTORY)`` command.

See :ref:`Directory Properties` for the list of properties known to CMake
and their individual documentation for the behavior of each property.

See Also
^^^^^^^^

* ``define_property()``
* ``get_directory_property()``
* the more general ``set_property()`` command

set_property
------------

Set a named property in a given scope.

 set_property(<GLOBAL                      |
               DIRECTORY [<dir>]           |
               TARGET    [<target1> ...]   |
               SOURCE    [<src1> ...]
                         [DIRECTORY <dirs> ...]
                         [TARGET_DIRECTORY <targets> ...] |
               INSTALL   [<file1> ...]     |
               TEST      [<test1> ...]
                         [DIRECTORY <dir>] |
               CACHE     [<entry1> ...]    >
              [APPEND] [APPEND_STRING]
              PROPERTY <name> [<value1> ...])

Sets one property on zero or more objects of a scope.

The first argument determines the scope in which the property is set.
It must be one of the following:

``GLOBAL``
  Scope is unique and does not accept a name.

``DIRECTORY``
  Scope defaults to the current directory but other directories
  (already processed by CMake) may be named by full or relative path.
  Relative paths are treated as relative to the current source directory.
  See also the ``set_directory_properties()`` command.

  .. versionadded:: 3.19
    ``<dir>`` may reference a binary directory.

``TARGET``
  Scope may name zero or more existing targets.
  See also the ``set_target_properties()`` command.

  :ref:`Alias Targets` do not support setting target properties.

``SOURCE``
  Scope may name zero or more source files.  By default, source file properties
  are only visible to targets added in the same directory (``CMakeLists.txt``).

  .. versionadded:: 3.18
    Visibility can be set in other directory scopes using one or both of the
    following sub-options:

    ``DIRECTORY <dirs>...``
      The source file property will be set in each of the ``<dirs>``
      directories' scopes.  CMake must already know about
      each of these directories, either by having added them through a call to
      ``add_subdirectory()`` or it being the top level source directory.
      Relative paths are treated as relative to the current source directory.

      .. versionadded:: 3.19
        ``<dirs>`` may reference a binary directory.

    ``TARGET_DIRECTORY <targets>...``
      The source file property will be set in each of the directory scopes
      where any of the specified ``<targets>`` were created (the ``<targets>``
      must therefore already exist).

  See also the ``set_source_files_properties()`` command.

``INSTALL``
  .. versionadded:: 3.1

  Scope may name zero or more installed file paths.
  These are made available to CPack to influence deployment.

  Both the property key and value may use generator expressions.
  Specific properties may apply to installed files and/or directories.

  Path components have to be separated by forward slashes,
  must be normalized and are case sensitive.

  To reference the installation prefix itself with a relative path use ``.``.

  Currently installed file properties are only defined for
  the WIX generator where the given paths are relative
  to the installation prefix.

``TEST``
  Scope is limited to the directory the command is called in. It may name zero
  or more existing tests. See also command ``set_tests_properties()``.

  Test property values may be specified using
  ``generator expressions``
  for tests created by the ``add_test(NAME)`` signature.

  .. versionadded:: 3.28

    Visibility can be set in other directory scopes using the following sub-option:

    ``DIRECTORY <dir>``
      The test property will be set in the ``<dir>`` directory's scope. CMake must
      already know about this directory, either by having added it through a call
      to ``add_subdirectory()`` or it being the top level source directory.
      Relative paths are treated as relative to the current source directory.
      ``<dir>`` may reference a binary directory.

``CACHE``
  Scope must name zero or more existing cache entries.

The required ``PROPERTY`` option is immediately followed by the name of
the property to set.  Remaining arguments are used to compose the
property value in the form of a semicolon-separated list.

If the ``APPEND`` option is given the list is appended to any existing
property value (except that empty values are ignored and not appended).
If the ``APPEND_STRING`` option is given the string is
appended to any existing property value as string, i.e. it results in a
longer string and not a list of strings.  When using ``APPEND`` or
``APPEND_STRING`` with a property defined to support ``INHERITED``
behavior (see ``define_property()``), no inheriting occurs when
finding the initial value to append to.  If the property is not already
directly set in the nominated scope, the command will behave as though
``APPEND`` or ``APPEND_STRING`` had not been given.

.. note::

  The ``GENERATED`` source file property may be globally visible.
  See its documentation for details.

See Also
^^^^^^^^

* ``define_property()``
* ``get_property()``
* The ``cmake-properties(7)`` manual for a list of properties
  in each scope.

site_name
---------

Set the given variable to the name of the computer.

 site_name(variable)

On UNIX-like platforms, if the variable ``HOSTNAME`` is set, its value
will be executed as a command expected to print out the host name,
much like the ``hostname`` command-line tool.

string
------

String operations.

Synopsis
^^^^^^^^

 Search and Replace
   string(FIND <string> <substring> <out-var> [...])
   string(REPLACE <match-string> <replace-string> <out-var> <input>...)
   string(REGEX MATCH <match-regex> <out-var> <input>...)
   string(REGEX MATCHALL <match-regex> <out-var> <input>...)
   string(REGEX REPLACE <match-regex> <replace-expr> <out-var> <input>...)

 Manipulation
   string(APPEND <string-var> [<input>...])
   string(PREPEND <string-var> [<input>...])
   string(CONCAT <out-var> [<input>...])
   string(JOIN <glue> <out-var> [<input>...])
   string(TOLOWER <string> <out-var>)
   string(TOUPPER <string> <out-var>)
   string(LENGTH <string> <out-var>)
   string(SUBSTRING <string> <begin> <length> <out-var>)
   string(STRIP <string> <out-var>)
   string(GENEX_STRIP <string> <out-var>)
   string(REPEAT <string> <count> <out-var>)

 Comparison
   string(COMPARE <op> <string1> <string2> <out-var>)

 Hashing
   string(<HASH> <out-var> <input>)

 Generation
   string(ASCII <number>... <out-var>)
   string(HEX <string> <out-var>)
   string(CONFIGURE <string> <out-var> [...])
   string(MAKE_C_IDENTIFIER <string> <out-var>)
   string(RANDOM [<option>...] <out-var>)
   string(TIMESTAMP <out-var> [<format string>] [UTC])
   string(UUID <out-var> ...)

 JSON
   string(JSON <out-var> [ERROR_VARIABLE <error-var>]
          {GET | TYPE | LENGTH | REMOVE}
          <json-string> <member|index> [<member|index> ...])
   string(JSON <out-var> [ERROR_VARIABLE <error-var>]
          MEMBER <json-string>
          [<member|index> ...] <index>)
   string(JSON <out-var> [ERROR_VARIABLE <error-var>]
          SET <json-string>
          <member|index> [<member|index> ...] <value>)
   string(JSON <out-var> [ERROR_VARIABLE <error-var>]
          EQUAL <json-string1> <json-string2>)

Search and Replace
^^^^^^^^^^^^^^^^^^

Search and Replace With Plain Strings
"""""""""""""""""""""""""""""""""""""

.. signature::
  string(FIND <string> <substring> <output_variable> [REVERSE])

  Return the position where the given ``<substring>`` was found in
  the supplied ``<string>``.  If the ``REVERSE`` flag was used, the command
  will search for the position of the last occurrence of the specified
  ``<substring>``.  If the ``<substring>`` is not found, a position of -1 is
  returned.

  The ``string(FIND)`` subcommand treats all strings as ASCII-only characters.
  The index stored in ``<output_variable>`` will also be counted in bytes,
  so strings containing multi-byte characters may lead to unexpected results.

.. signature::
  string(REPLACE <match_string>
         <replace_string> <output_variable>
         <input> [<input>...])

  Replace all occurrences of ``<match_string>`` in the ``<input>``
  with ``<replace_string>`` and store the result in the ``<output_variable>``.

Search and Replace With Regular Expressions
"""""""""""""""""""""""""""""""""""""""""""

.. signature::
  string(REGEX MATCH <regular_expression>
         <output_variable> <input> [<input>...])

  Match the ``<regular_expression>`` once and store the match in the
  ``<output_variable>``.
  All ``<input>`` arguments are concatenated before matching.
  Regular expressions are specified in the subsection just below.

.. signature::
  string(REGEX MATCHALL <regular_expression>
         <output_variable> <input> [<input>...])

  Match the ``<regular_expression>`` as many times as possible and store the
  matches in the ``<output_variable>`` as a list.
  All ``<input>`` arguments are concatenated before matching.

.. signature::
  string(REGEX REPLACE <regular_expression>
         <replacement_expression> <output_variable>
         <input> [<input>...])

  Match the ``<regular_expression>`` as many times as possible and substitute
  the ``<replacement_expression>`` for the match in the output.
  All ``<input>`` arguments are concatenated before matching.

  The ``<replacement_expression>`` may refer to parenthesis-delimited
  subexpressions of the match using ``\1``, ``\2``, ..., ``\9``.  Note that
  two backslashes (``\\1``) are required in CMake code to get a backslash
  through argument parsing.

Regex Specification
"""""""""""""""""""

The following characters have special meaning in regular expressions:

``^``
  Matches at beginning of input
``$``
  Matches at end of input
``.``
  Matches any single character
``\<char>``
  Matches the single character specified by ``<char>``.  Use this to
  match special regex characters, e.g. ``\.`` for a literal ``.``
  or ``\\`` for a literal backslash ``\``.  Escaping a non-special
  character is unnecessary but allowed, e.g. ``\a`` matches ``a``.
``[ ]``
  Matches any character(s) inside the brackets.
  To match a literal ``]``, make it the first character, e.g., ``[]ab]``.
``[^ ]``
  Matches any character(s) not inside the brackets.
  To not match a literal ``]``, make it the first character, e.g., ``[^]ab]``.
``-``
  Inside brackets, specifies an inclusive range between characters on
  either side, e.g., ``[a-f]`` is ``[abcdef]``.
  To match a literal ``-`` using brackets, make it the first or the last
  character, e.g., ``[+*/-]`` matches basic mathematical operators.
``*``
  Matches preceding pattern zero or more times
``+``
  Matches preceding pattern one or more times
``?``
  Matches preceding pattern zero or once only
``|``
  Matches a pattern on either side of the ``|``
``()``
  Saves a matched subexpression, which can be referenced
  in the ``REGEX REPLACE`` operation.

  .. versionadded:: 3.9
    All regular expression-related commands, including e.g.
    ``if(MATCHES)``, save subgroup matches in the variables
    ``CMAKE_MATCH_<n>`` for ``<n>`` 0..9.

``*``, ``+`` and ``?`` have higher precedence than concatenation.  ``|``
has lower precedence than concatenation.  This means that the regular
expression ``^ab+d$`` matches ``abbd`` but not ``ababd``, and the regular
expression ``^(ab|cd)$`` matches ``ab`` but not ``abd``.

CMake language :ref:`Escape Sequences` such as ``\t``, ``\r``, ``\n``,
and ``\\`` may be used to construct literal tabs, carriage returns,
newlines, and backslashes (respectively) to pass in a regex.  For example:

* The quoted argument ``"[ \t\r\n]"`` specifies a regex that matches
  any single whitespace character.
* The quoted argument ``"[/\\]"`` specifies a regex that matches
  a single forward slash ``/`` or backslash ``\``.
* The quoted argument ``"[A-Za-z0-9_]"`` specifies a regex that matches
  any single "word" character in the C locale.
* The quoted argument ``"\\(\\a\\+b\\)"`` specifies a regex that matches
  the exact string ``(a+b)``.  Each ``\\`` is parsed in a quoted argument
  as just ``\``, so the regex itself is actually ``\(\a\+\b\)``.  This
  can alternatively be specified in a :ref:`bracket argument` without
  having to escape the backslashes, e.g. ``[[\(\a\+\b\)]]``.

Manipulation
^^^^^^^^^^^^

.. signature::
  string(APPEND <string_variable> [<input>...])

  .. versionadded:: 3.4

  Append all the ``<input>`` arguments to the string.

.. signature::
  string(PREPEND <string_variable> [<input>...])

  .. versionadded:: 3.10

  Prepend all the ``<input>`` arguments to the string.

.. signature::
  string(CONCAT <output_variable> [<input>...])

  Concatenate all the ``<input>`` arguments together and store
  the result in the named ``<output_variable>``.

.. signature::
  string(JOIN <glue> <output_variable> [<input>...])

  .. versionadded:: 3.12

  Join all the ``<input>`` arguments together using the ``<glue>``
  string and store the result in the named ``<output_variable>``.

  To join a list's elements, prefer to use the ``JOIN`` operator
  from the ``list()`` command.  This allows for the elements to have
  special characters like ``;`` in them.

.. signature::
  string(TOLOWER <string> <output_variable>)

  Convert ``<string>`` to lower characters.

.. signature::
  string(TOUPPER <string> <output_variable>)

  Convert ``<string>`` to upper characters.

.. signature::
  string(LENGTH <string> <output_variable>)

  Store in an ``<output_variable>`` a given string's length in bytes.
  Note that this means if ``<string>`` contains multi-byte characters,
  the result stored in ``<output_variable>`` will *not* be
  the number of characters.

.. signature::
  string(SUBSTRING <string> <begin> <length> <output_variable>)

  Store in an ``<output_variable>`` a substring of a given ``<string>``.  If
  ``<length>`` is ``-1`` the remainder of the string starting at ``<begin>``
  will be returned.

  .. versionchanged:: 3.2
    If ``<string>`` is shorter than ``<length>``
    then the end of the string is used instead.
    Previous versions of CMake reported an error in this case.

  Both ``<begin>`` and ``<length>`` are counted in bytes, so care must
  be exercised if ``<string>`` could contain multi-byte characters.

.. signature::
  string(STRIP <string> <output_variable>)

  Store in an ``<output_variable>`` a substring of a given ``<string>``
  with leading and trailing spaces removed.

.. signature::
  string(GENEX_STRIP <string> <output_variable>)

  .. versionadded:: 3.1

  Strip any ``generator expressions``
  from the input ``<string>`` and store the result
  in the ``<output_variable>``.

.. signature::
  string(REPEAT <string> <count> <output_variable>)

  .. versionadded:: 3.15

  Produce the output string as the input ``<string>``
  repeated ``<count>`` times.

Comparison
^^^^^^^^^^

.. signature::
  string(COMPARE LESS <string1> <string2> <output_variable>)
  string(COMPARE GREATER <string1> <string2> <output_variable>)
  string(COMPARE EQUAL <string1> <string2> <output_variable>)
  string(COMPARE NOTEQUAL <string1> <string2> <output_variable>)
  string(COMPARE LESS_EQUAL <string1> <string2> <output_variable>)
  string(COMPARE GREATER_EQUAL <string1> <string2> <output_variable>)

  Compare the strings and store true or false in the ``<output_variable>``.

  .. versionadded:: 3.7
    Added the ``LESS_EQUAL`` and ``GREATER_EQUAL`` options.

Hashing
^^^^^^^

.. signature::
  string(<HASH> <output_variable> <input>)
  :target: <HASH>

  Compute a cryptographic hash of the ``<input>`` string.
  The supported ``<HASH>`` algorithm names are:

  ``MD5``
    Message-Digest Algorithm 5, RFC 1321.
  ``SHA1``
    US Secure Hash Algorithm 1, RFC 3174.
  ``SHA224``
    US Secure Hash Algorithms, RFC 4634.
  ``SHA256``
    US Secure Hash Algorithms, RFC 4634.
  ``SHA384``
    US Secure Hash Algorithms, RFC 4634.
  ``SHA512``
    US Secure Hash Algorithms, RFC 4634.
  ``SHA3_224``
    Keccak SHA-3.
  ``SHA3_256``
    Keccak SHA-3.
  ``SHA3_384``
    Keccak SHA-3.
  ``SHA3_512``
    Keccak SHA-3.

  .. versionadded:: 3.8
    Added the ``SHA3_*`` hash algorithms.

Generation
^^^^^^^^^^

.. signature::
  string(ASCII <number> [<number> ...] <output_variable>)

  Convert all numbers into corresponding ASCII characters.

.. signature::
  string(HEX <string> <output_variable>)

  .. versionadded:: 3.18

  Convert each byte in the input ``<string>`` to its hexadecimal representation
  and store the concatenated hex digits in the ``<output_variable>``.
  Letters in the output (``a`` through ``f``) are in lowercase.

.. signature::
  string(CONFIGURE <string> <output_variable>
         [@ONLY] [ESCAPE_QUOTES])

  Transform a ``<string>`` like ``configure_file()`` transforms a file.

.. signature::
  string(MAKE_C_IDENTIFIER <string> <output_variable>)

  Convert each non-alphanumeric character in the input ``<string>`` to an
  underscore and store the result in the ``<output_variable>``.  If the first
  character of the ``<string>`` is a digit, an underscore will also be
  prepended to the result.

.. signature::
  string(RANDOM [LENGTH <length>] [ALPHABET <alphabet>]
         [RANDOM_SEED <seed>] <output_variable>)

  Return a random string of given ``<length>`` consisting of
  characters from the given ``<alphabet>``.  Default length is 5 characters
  and default alphabet is all numbers and upper and lower case letters.
  If an integer ``RANDOM_SEED`` is given, its value will be used to seed the
  random number generator.

.. signature::
  string(TIMESTAMP <output_variable> [<format_string>] [UTC])

  Write a string representation of the current date
  and/or time to the ``<output_variable>``.

  If the command is unable to obtain a timestamp, the ``<output_variable>``
  will be set to the empty string ``""``.

  The optional ``UTC`` flag requests the current date/time representation to
  be in Coordinated Universal Time (UTC) rather than local time.

  The optional ``<format_string>`` may contain the following format
  specifiers:

  ``%%``
    .. versionadded:: 3.8

    A literal percent sign (%).

  ``%d``
    The day of the current month (01-31).

  ``%H``
    The hour on a 24-hour clock (00-23).

  ``%I``
    The hour on a 12-hour clock (01-12).

  ``%j``
    The day of the current year (001-366).

  ``%m``
    The month of the current year (01-12).

  ``%b``
    .. versionadded:: 3.7

    Abbreviated month name (e.g. Oct).

  ``%B``
    .. versionadded:: 3.10

    Full month name (e.g. October).

  ``%M``
    The minute of the current hour (00-59).

  ``%s``
    .. versionadded:: 3.6

    Seconds since midnight (UTC) 1-Jan-1970 (UNIX time).

  ``%S``
    The second of the current minute.  60 represents a leap second. (00-60)

  ``%f``
    .. versionadded:: 3.23

    The microsecond of the current second (000000-999999).

  ``%U``
    The week number of the current year (00-53).

  ``%V``
    .. versionadded:: 3.22

    The ISO 8601 week number of the current year (01-53).

  ``%w``
    The day of the current week. 0 is Sunday. (0-6)

  ``%a``
    .. versionadded:: 3.7

    Abbreviated weekday name (e.g. Fri).

  ``%A``
    .. versionadded:: 3.10

    Full weekday name (e.g. Friday).

  ``%y``
    The last two digits of the current year (00-99).

  ``%Y``
    The current year.

  ``%z``
    .. versionadded:: 3.26

    The offset of the time zone from UTC, in hours and minutes,
    with format ``+hhmm`` or ``-hhmm``.

  ``%Z``
    .. versionadded:: 3.26

    The time zone name.

  Unknown format specifiers will be ignored and copied to the output
  as-is.

  If no explicit ``<format_string>`` is given, it will default to:

  ::

   %Y-%m-%dT%H:%M:%S    for local time.
   %Y-%m-%dT%H:%M:%SZ   for UTC.

 .. versionadded:: 3.8
   If the ``SOURCE_DATE_EPOCH`` environment variable is set,
   its value will be used instead of the current time.
   See https://reproducible-builds.org/specs/source-date-epoch/ for details.

.. signature::
  string(UUID <output_variable> NAMESPACE <namespace> NAME <name>
         TYPE <MD5|SHA1> [UPPER])

  .. versionadded:: 3.1

  Create a universally unique identifier (aka GUID) as per RFC4122
  based on the hash of the combined values of ``<namespace>``
  (which itself has to be a valid UUID) and ``<name>``.
  The hash algorithm can be either ``MD5`` (Version 3 UUID) or
  ``SHA1`` (Version 5 UUID).
  A UUID has the format ``xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx``
  where each ``x`` represents a lower case hexadecimal character.
  Where required, an uppercase representation can be requested
  with the optional ``UPPER`` flag.

JSON
^^^^

.. versionadded:: 3.19

Functionality for querying a JSON string.

.. note::
  In each of the following JSON-related subcommands, if the optional
  ``ERROR_VARIABLE`` argument is given, errors will be reported in
  ``<error-variable>`` and the ``<out-var>`` will be set to
  ``<member|index>-[<member|index>...]-NOTFOUND`` with the path elements
  up to the point where the error occurred, or just ``NOTFOUND`` if there
  is no relevant path.  If an error occurs but the ``ERROR_VARIABLE``
  option is not present, a fatal error message is generated.  If no error
  occurs, the ``<error-variable>`` will be set to ``NOTFOUND``.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-variable>]
         GET <json-string> <member|index> [<member|index> ...])
  :target: JSON GET

  Get an element from ``<json-string>`` at the location given
  by the list of ``<member|index>`` arguments.
  Array and object elements will be returned as a JSON string.
  Boolean elements will be returned as ``ON`` or ``OFF``.
  Null elements will be returned as an empty string.
  Number and string types will be returned as strings.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-variable>]
         TYPE <json-string> <member|index> [<member|index> ...])
  :target: JSON TYPE

  Get the type of an element in ``<json-string>`` at the location
  given by the list of ``<member|index>`` arguments. The ``<out-var>``
  will be set to one of ``NULL``, ``NUMBER``, ``STRING``, ``BOOLEAN``,
  ``ARRAY``, or ``OBJECT``.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         MEMBER <json-string>
         [<member|index> ...] <index>)
  :target: JSON MEMBER

  Get the name of the ``<index>``-th member in ``<json-string>``
  at the location given by the list of ``<member|index>`` arguments.
  Requires an element of object type.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-variable>]
         LENGTH <json-string> [<member|index> ...])
  :target: JSON LENGTH

  Get the length of an element in ``<json-string>`` at the location
  given by the list of ``<member|index>`` arguments.
  Requires an element of array or object type.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-variable>]
         REMOVE <json-string> <member|index> [<member|index> ...])
  :target: JSON REMOVE

  Remove an element from ``<json-string>`` at the location
  given by the list of ``<member|index>`` arguments. The JSON string
  without the removed element will be stored in ``<out-var>``.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-variable>]
         SET <json-string> <member|index> [<member|index> ...] <value>)
  :target: JSON SET

  Set an element in ``<json-string>`` at the location
  given by the list of ``<member|index>`` arguments to ``<value>``.
  The contents of ``<value>`` should be valid JSON.
  If ``<json-string>`` is an array, ``<value>`` can be appended to the end of
  the array by using a number greater or equal to the array length as the
  ``<member|index>`` argument.

.. signature::
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         EQUAL <json-string1> <json-string2>)
  :target: JSON EQUAL

  Compare the two JSON objects given by ``<json-string1>``
  and ``<json-string2>`` for equality.  The contents of ``<json-string1>``
  and ``<json-string2>`` should be valid JSON.  The ``<out-var>``
  will be set to a true value if the JSON objects are considered equal,
  or a false value otherwise.

unset
-----

Unset a variable, cache variable, or environment variable.

Unset Normal Variable or Cache Entry
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 unset(<variable> [CACHE | PARENT_SCOPE])

Removes a normal variable from the current scope, causing it
to become undefined.  If ``CACHE`` is present, then a cache variable
is removed instead of a normal variable.

If ``PARENT_SCOPE`` is present then the variable is removed from the scope
above the current scope.  See the same option in the ``set()`` command
for further details.

.. note::

  When evaluating :ref:`Variable References` of the form ``${VAR}``, CMake
  first searches for a normal variable with that name.  If no such normal
  variable exists, CMake will then search for a cache entry with that name.
  Because of this, **unsetting a normal variable can expose a cache variable
  that was previously hidden**.  To force a variable reference of the form
  ``${VAR}`` to return an empty string, use ``set(<variable> "")``, which
  clears the normal variable but leaves it defined.

Unset Environment Variable
^^^^^^^^^^^^^^^^^^^^^^^^^^

 unset(ENV{<variable>})

Removes ``<variable>`` from the currently available
``Environment Variables``.
Subsequent calls of ``$ENV{<variable>}`` will return the empty string.

This command affects only the current CMake process, not the process
from which CMake was called, nor the system environment at large,
nor the environment of subsequent build or test processes.

See Also
^^^^^^^^

* ``set()``

variable_watch
--------------

Watch the CMake variable for change.

 variable_watch(<variable> [<command>])

If the specified ``<variable>`` changes and no ``<command>`` is given,
a message will be printed to inform about the change.

If ``<command>`` is given, this command will be executed instead.
The command will receive the following arguments:
``COMMAND(<variable> <access> <value> <current_list_file> <stack>)``

``<variable>``
 Name of the variable being accessed.

``<access>``
 One of ``READ_ACCESS``, ``UNKNOWN_READ_ACCESS``, ``MODIFIED_ACCESS``,
 ``UNKNOWN_MODIFIED_ACCESS``, or ``REMOVED_ACCESS``.  The ``UNKNOWN_``
 values are only used when the variable has never been set.  Once set,
 they are never used again during the same CMake run, even if the
 variable is later unset.

``<value>``
 The value of the variable.  On a modification, this is the new
 (modified) value of the variable.  On removal, the value is empty.

``<current_list_file>``
 Full path to the file doing the access.

``<stack>``
 List of absolute paths of all files currently on the stack of file
 inclusion, with the bottom-most file first and the currently
 processed file (that is, ``current_list_file``) last.

Note that for some accesses such as ``list(APPEND)``, the watcher
is executed twice, first with a read access and then with a write one.
Also note that an ``if(DEFINED)`` query on the variable does not
register as an access and the watcher is not executed.

Only non-cache variables can be watched using this command.  Access to
cache variables is never watched.  However, the existence of a cache
variable ``var`` causes accesses to the non-cache variable ``var`` to
not use the ``UNKNOWN_`` prefix, even if a non-cache variable ``var``
has never existed.

while
-----

Evaluate a group of commands while a condition is true

 while(<condition>)
   <commands>
 endwhile()

All commands between while and the matching ``endwhile()`` are recorded
without being invoked.  Once the ``endwhile()`` is evaluated, the
recorded list of commands is invoked as long as the ``<condition>`` is true.

The ``<condition>`` has the same syntax and is evaluated using the same logic
as described at length for the ``if()`` command.

The commands ``break()`` and ``continue()`` provide means to
escape from the normal control flow.

Per legacy, the ``endwhile()`` command admits
an optional ``<condition>`` argument.
If used, it must be a verbatim repeat of the argument of the opening
``while`` command.

See Also
^^^^^^^^

* ``break()``
* ``continue()``
* ``foreach()``
* ``endwhile()``

Project Commands
================

These commands are available only in CMake projects.

add_compile_definitions
-----------------------

.. versionadded:: 3.12

Add preprocessor definitions to the compilation of source files.

 add_compile_definitions(<definition> ...)

Adds preprocessor definitions to the compiler command line.

The preprocessor definitions are added to the ``COMPILE_DEFINITIONS``
directory property for the current ``CMakeLists`` file. They are also added to
the ``COMPILE_DEFINITIONS`` target property for each target in the
current ``CMakeLists`` file.

Definitions are specified using the syntax ``VAR`` or ``VAR=value``.
Function-style definitions are not supported. CMake will automatically
escape the value correctly for the native build system (note that CMake
language syntax may require escapes to specify some values).

.. versionadded:: 3.26
  Any leading ``-D`` on an item will be removed.

Arguments to ``add_compile_definitions`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

See Also
^^^^^^^^

* The command ``target_compile_definitions()`` adds target-specific definitions.

add_compile_options
-------------------

Add options to the compilation of source files.

 add_compile_options(<option> ...)

Adds options to the ``COMPILE_OPTIONS`` directory property.
These options are used when compiling targets from the current
directory and below.

.. note::

  These options are not used when linking.
  See the ``add_link_options()`` command for that.

Arguments
^^^^^^^^^

Arguments to ``add_compile_options`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Option De-duplication
^^^^^^^^^^^^^^^^^^^^^

The final set of options used for a target is constructed by
accumulating options from the current target and the usage requirements of
its dependencies.  The set of options is de-duplicated to avoid repetition.

.. versionadded:: 3.12
  While beneficial for individual options, the de-duplication step can break
  up option groups.  For example, ``-option A -option B`` becomes
  ``-option A B``.  One may specify a group of options using shell-like
  quoting along with a ``SHELL:`` prefix.  The ``SHELL:`` prefix is dropped,
  and the rest of the option string is parsed using the
  ``separate_arguments()`` ``UNIX_COMMAND`` mode. For example,
  ``"SHELL:-option A" "SHELL:-option B"`` becomes ``-option A -option B``.

Example
^^^^^^^

Since different compilers support different options, a typical use of
this command is in a compiler-specific conditional clause:

 if (MSVC)
     # warning level 4
     add_compile_options(/W4)
 else()
     # additional warnings
     add_compile_options(-Wall -Wextra -Wpedantic)
 endif()

To set per-language options, use the ``$<COMPILE_LANGUAGE>``
or ``$<COMPILE_LANGUAGE:languages>`` generator expressions.

See Also
^^^^^^^^

* This command can be used to add any options. However, for
  adding preprocessor definitions and include directories it is recommended
  to use the more specific commands ``add_compile_definitions()``
  and ``include_directories()``.

* The command ``target_compile_options()`` adds target-specific options.

* This command adds compile options for all languages.
  Use the ``COMPILE_LANGUAGE`` generator expression to specify
  per-language compile options.

* The source file property ``COMPILE_OPTIONS`` adds options to one
  source file.

* ``add_link_options()`` adds options for linking.

* ``CMAKE_<LANG>_FLAGS`` and ``CMAKE_<LANG>_FLAGS_<CONFIG>``
  add language-wide flags passed to all invocations of the compiler.
  This includes invocations that drive compiling and those that drive linking.

add_custom_command
------------------

Add a custom build rule to the generated build system.

There are two main signatures for ``add_custom_command``.

Generating Files
^^^^^^^^^^^^^^^^

The first signature is for adding a custom command to produce an output:

 add_custom_command(OUTPUT output1 [output2 ...]
                    COMMAND command1 [ARGS] [args1...]
                    [COMMAND command2 [ARGS] [args2...] ...]
                    [MAIN_DEPENDENCY depend]
                    [DEPENDS [depends...]]
                    [BYPRODUCTS [files...]]
                    [IMPLICIT_DEPENDS <lang1> depend1
                                     [<lang2> depend2] ...]
                    [WORKING_DIRECTORY dir]
                    [COMMENT comment]
                    [DEPFILE depfile]
                    [JOB_POOL job_pool]
                    [JOB_SERVER_AWARE <bool>]
                    [VERBATIM] [APPEND] [USES_TERMINAL]
                    [COMMAND_EXPAND_LISTS]
                    [DEPENDS_EXPLICIT_ONLY])

This defines a command to generate specified ``OUTPUT`` file(s).
A target created in the same directory (``CMakeLists.txt`` file)
that specifies any output of the custom command as a source file
is given a rule to generate the file using the command at build time.

Do not list the output in more than one independent target that
may build in parallel or the instances of the rule may conflict.
Instead, use the ``add_custom_target()`` command to drive the
command and make the other targets depend on that one.  See the
Example: Generating Files for Multiple Targets below.

The options are:

``APPEND``
  Append the ``COMMAND`` and ``DEPENDS`` option values to the custom
  command for the first output specified.  There must have already
  been a previous call to this command with the same output.

  If the previous call specified the output via a generator expression,
  the output specified by the current call must match in at least one
  configuration after evaluating generator expressions.  In this case,
  the appended commands and dependencies apply to all configurations.

  The ``COMMENT``, ``MAIN_DEPENDENCY``, and ``WORKING_DIRECTORY``
  options are currently ignored when APPEND is given, but may be
  used in the future.

``BYPRODUCTS``
  .. versionadded:: 3.2

  Specify the files the command is expected to produce but whose
  modification time may or may not be newer than the dependencies.
  If a byproduct name is a relative path it will be interpreted
  relative to the build tree directory corresponding to the
  current source directory.
  Each byproduct file will be marked with the ``GENERATED``
  source file property automatically.

  *See policy* ``CMP0058`` *for the motivation behind this feature.*

  Explicit specification of byproducts is supported by the
  ``Ninja`` generator to tell the ``ninja`` build tool
  how to regenerate byproducts when they are missing.  It is
  also useful when other build rules (e.g. custom commands)
  depend on the byproducts.  Ninja requires a build rule for any
  generated file on which another rule depends even if there are
  order-only dependencies to ensure the byproducts will be
  available before their dependents build.

  The :ref:`Makefile Generators` will remove ``BYPRODUCTS`` and other
  ``GENERATED`` files during ``make clean``.

  .. versionadded:: 3.20
    Arguments to ``BYPRODUCTS`` may use a restricted set of
    ``generator expressions``.
    :ref:`Target-dependent expressions <Target-Dependent Expressions>`
    are not permitted.

  .. versionchanged:: 3.28
    In targets using :ref:`file sets`, custom command byproducts are now
    considered private unless they are listed in a non-private file set.
    See policy ``CMP0154``.

``COMMAND``
  Specify the command-line(s) to execute at build time.
  If more than one ``COMMAND`` is specified they will be executed in order,
  but *not* necessarily composed into a stateful shell or batch script.
  (To run a full script, use the ``configure_file()`` command or the
  ``file(GENERATE)`` command to create it, and then specify
  a ``COMMAND`` to launch it.)
  The optional ``ARGS`` argument is for backward compatibility and
  will be ignored.

  If ``COMMAND`` specifies an executable target name (created by the
  ``add_executable()`` command), it will automatically be replaced
  by the location of the executable created at build time if either of
  the following is true:

  * The target is not being cross-compiled (i.e. the
    ``CMAKE_CROSSCOMPILING`` variable is not set to true).
  * .. versionadded:: 3.6
      The target is being cross-compiled and an emulator is provided (i.e.
      its ``CROSSCOMPILING_EMULATOR`` target property is set).
      In this case, the contents of ``CROSSCOMPILING_EMULATOR`` will be
      prepended to the command before the location of the target executable.

  If neither of the above conditions are met, it is assumed that the
  command name is a program to be found on the ``PATH`` at build time.

  Arguments to ``COMMAND`` may use
  ``generator expressions``.
  Use the ``TARGET_FILE`` generator expression to refer to the location
  of a target later in the command line (i.e. as a command argument rather
  than as the command to execute).

  Whenever one of the following target based generator expressions are used as
  a command to execute or is mentioned in a command argument, a target-level
  dependency will be added automatically so that the mentioned target will be
  built before any target using this custom command
  (see policy ``CMP0112``).

    * ``TARGET_FILE``
    * ``TARGET_LINKER_FILE``
    * ``TARGET_SONAME_FILE``
    * ``TARGET_PDB_FILE``

  This target-level dependency does NOT add a file-level dependency that would
  cause the custom command to re-run whenever the executable is recompiled.
  List target names with the ``DEPENDS`` option to add such file-level
  dependencies.


``COMMENT``
  Display the given message before the commands are executed at
  build time.

  .. versionadded:: 3.26
    Arguments to ``COMMENT`` may use
    ``generator expressions``.

``DEPENDS``
  Specify files on which the command depends.  Each argument is converted
  to a dependency as follows:

  1. If the argument is the name of a target (created by the
     ``add_custom_target()``, ``add_executable()``, or
     ``add_library()`` command) a target-level dependency is
     created to make sure the target is built before any target
     using this custom command.  Additionally, if the target is an
     executable or library, a file-level dependency is created to
     cause the custom command to re-run whenever the target is
     recompiled.

  2. If the argument is an absolute path, a file-level dependency
     is created on that path.

  3. If the argument is the name of a source file that has been
     added to a target or on which a source file property has been set,
     a file-level dependency is created on that source file.

  4. If the argument is a relative path and it exists in the current
     source directory, a file-level dependency is created on that
     file in the current source directory.

  5. Otherwise, a file-level dependency is created on that path relative
     to the current binary directory.

  If any dependency is an ``OUTPUT`` of another custom command in the same
  directory (``CMakeLists.txt`` file), CMake automatically brings the other
  custom command into the target in which this command is built.

  .. versionadded:: 3.16
    A target-level dependency is added if any dependency is listed as
    ``BYPRODUCTS`` of a target or any of its build events in the same
    directory to ensure the byproducts will be available.

  If ``DEPENDS`` is not specified, the command will run whenever
  the ``OUTPUT`` is missing; if the command does not actually
  create the ``OUTPUT``, the rule will always run.

  .. versionadded:: 3.1
    Arguments to ``DEPENDS`` may use
    ``generator expressions``.

``COMMAND_EXPAND_LISTS``
  .. versionadded:: 3.8

  Lists in ``COMMAND`` arguments will be expanded, including those
  created with
  ``generator expressions``,
  allowing ``COMMAND`` arguments such as
  ``${CC} "-I$<JOIN:$<TARGET_PROPERTY:foo,INCLUDE_DIRECTORIES>,;-I>" foo.cc``
  to be properly expanded.

``IMPLICIT_DEPENDS``
  Request scanning of implicit dependencies of an input file.
  The language given specifies the programming language whose
  corresponding dependency scanner should be used.
  Currently only ``C`` and ``CXX`` language scanners are supported.
  The language has to be specified for every file in the
  ``IMPLICIT_DEPENDS`` list.  Dependencies discovered from the
  scanning are added to those of the custom command at build time.
  Note that the ``IMPLICIT_DEPENDS`` option is currently supported
  only for Makefile generators and will be ignored by other generators.

  .. note::

 This option cannot be specified at the same time as ``DEPFILE`` option.

``JOB_POOL``
  .. versionadded:: 3.15

  Specify a ``pool`` for the ``Ninja``
  generator. Incompatible with ``USES_TERMINAL``, which implies
  the ``console`` pool.
  Using a pool that is not defined by ``JOB_POOLS`` causes
  an error by ninja at build time.

``JOB_SERVER_AWARE``
  .. versionadded:: 3.28

  Specify that the command is GNU Make job server aware.

  For the ``Unix Makefiles``, ``MSYS Makefiles``, and
  ``MinGW Makefiles`` generators this will add the ``+`` prefix to the
  recipe line. See the GNU Make Documentation for more information.

  This option is silently ignored by other generators.

``MAIN_DEPENDENCY``
  Specify the primary input source file to the command.  This is
  treated just like any value given to the ``DEPENDS`` option
  but also suggests to Visual Studio generators where to hang
  the custom command. Each source file may have at most one command
  specifying it as its main dependency. A compile command (i.e. for a
  library or an executable) counts as an implicit main dependency which
  gets silently overwritten by a custom command specification.

``OUTPUT``
  Specify the output files the command is expected to produce.
  Each output file will be marked with the ``GENERATED``
  source file property automatically.
  If the output of the custom command is not actually created
  as a file on disk it should be marked with the ``SYMBOLIC``
  source file property.

  If an output file name is a relative path, its absolute path is
  determined by interpreting it relative to:

  1. the build directory corresponding to the current source directory
     (``CMAKE_CURRENT_BINARY_DIR``), or

  2. the current source directory (``CMAKE_CURRENT_SOURCE_DIR``).

  The path in the build directory is preferred unless the path in the
  source tree is mentioned as an absolute source file path elsewhere
  in the current directory.

  The output file path may not contain ``<`` or ``>`` characters.

  .. versionadded:: 3.20
    Arguments to ``OUTPUT`` may use a restricted set of
    ``generator expressions``.
    :ref:`Target-dependent expressions <Target-Dependent Expressions>`
    are not permitted.

  .. versionchanged:: 3.28
    In targets using :ref:`file sets`, custom command outputs are now
    considered private unless they are listed in a non-private file set.
    See policy ``CMP0154``.

  .. versionchanged:: 3.30
    The output file path may now use ``#`` characters, except
    when using the ``Borland Makefiles`` generator.

``USES_TERMINAL``
  .. versionadded:: 3.2

  The command will be given direct access to the terminal if possible.
  With the ``Ninja`` generator, this places the command in
  the ``console`` ``pool``.

``VERBATIM``
  All arguments to the commands will be escaped properly for the
  build tool so that the invoked command receives each argument
  unchanged.  Note that one level of escapes is still used by the
  CMake language processor before add_custom_command even sees the
  arguments.  Use of ``VERBATIM`` is recommended as it enables
  correct behavior.  When ``VERBATIM`` is not given the behavior
  is platform specific because there is no protection of
  tool-specific special characters.

``WORKING_DIRECTORY``
  Execute the command with the given current working directory.
  If it is a relative path it will be interpreted relative to the
  build tree directory corresponding to the current source directory.

  .. versionadded:: 3.13
    Arguments to ``WORKING_DIRECTORY`` may use
    ``generator expressions``.

``DEPFILE``
  .. versionadded:: 3.7

  Specify a depfile which holds dependencies for the custom command. It is
  usually emitted by the custom command itself.  This keyword may only be used
  if the generator supports it, as detailed below.

  The expected format, compatible with what is generated by ``gcc`` with the
  option ``-M``, is independent of the generator or platform.

  The formal syntax, as specified using
  BNF notation with
  the regular extensions, is the following:

  .. raw:: latex

    \begin{small}

  .. productionlist:: depfile
    depfile: `rule`*
    rule: `targets` (':' (`separator` `dependencies`?)?)? `eol`
    targets: `target` (`separator` `target`)* `separator`*
    target: `pathname`
    dependencies: `dependency` (`separator` `dependency`)* `separator`*
    dependency: `pathname`
    separator: (`space` | `line_continue`)+
    line_continue: '\' `eol`
    space: ' ' | '\t'
    pathname: `character`+
    character: `std_character` | `dollar` | `hash` | `whitespace`
    std_character: <any character except '$', '#' or ' '>
    dollar: '$$'
    hash: '\#'
    whitespace: '\ '
    eol: '\r'? '\n'

  .. raw:: latex

    \end{small}

  .. note::

   As part of ``pathname``, any slash and backslash is interpreted as
   a directory separator.

 .. versionadded:: 3.7
   The :generator:`Ninja` generator supports ``DEPFILE`` since the keyword
   was first added.

 .. versionadded:: 3.17
   Added the :generator:`Ninja Multi-Config` generator, which included
   support for the ``DEPFILE`` keyword.

 .. versionadded:: 3.20
   Added support for :ref:`Makefile Generators`.

   .. note::

     ``DEPFILE`` cannot be specified at the same time as the
     ``IMPLICIT_DEPENDS`` option for :ref:`Makefile Generators`.

 .. versionadded:: 3.21
   Added support for :ref:`Visual Studio Generators` with VS 2012 and above,
   and for the :generator:`Xcode` generator.  Support for
   :manual:`generator expressions <cmake-generator-expressions(7)>` was also
   added.

 .. versionadded:: 3.29
   The :ref:`Ninja Generators` will now incorporate the dependencies into its
   "deps log" database if the file is not listed in ``OUTPUTS`` or
   ``BYPRODUCTS``.

 Using ``DEPFILE`` with generators other than those listed above is an error.

 If the ``DEPFILE`` argument is relative, it should be relative to
 :variable:`CMAKE_CURRENT_BINARY_DIR`, and any relative paths inside the
 ``DEPFILE`` should also be relative to :variable:`CMAKE_CURRENT_BINARY_DIR`.
 See policy :policy:`CMP0116`, which is always ``NEW`` for
 :ref:`Makefile Generators`, :ref:`Visual Studio Generators`,
 and the :generator:`Xcode` generator.

``DEPENDS_EXPLICIT_ONLY``

  .. versionadded:: 3.27

  Indicates that the command's ``DEPENDS`` argument represents all files
  required by the command and implicit dependencies are not required.

  Without this option, if any target uses the output of the custom command,
  CMake will consider that target's dependencies as implicit dependencies for
  the custom command in case this custom command requires files implicitly
  created by those targets.

  This option can be enabled on all custom commands by setting
  ``CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY`` to ``ON``.

  Only the :ref:`Ninja Generators` actually use this information to remove
  unnecessary implicit dependencies.

  See also the ``OPTIMIZE_DEPENDENCIES`` target property, which may
  provide another way for reducing the impact of target dependencies in some
  scenarios.

Examples: Generating Files
^^^^^^^^^^^^^^^^^^^^^^^^^^

Custom commands may be used to generate source files.
For example, the code:

 add_custom_command(
   OUTPUT out.c
   COMMAND someTool -i ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
                    -o out.c
   DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
   VERBATIM)
 add_library(myLib out.c)

adds a custom command to run ``someTool`` to generate ``out.c`` and then
compile the generated source as part of a library.  The generation rule
will re-run whenever ``in.txt`` changes.

.. versionadded:: 3.20
  One may use generator expressions to specify per-configuration outputs.
  For example, the code:

  .. code-block:: cmake

    add_custom_command(
      OUTPUT "out-$<CONFIG>.c"
      COMMAND someTool -i ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
                       -o "out-$<CONFIG>.c"
                       -c "$<CONFIG>"
      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
      VERBATIM)
    add_library(myLib "out-$<CONFIG>.c")

  adds a custom command to run ``someTool`` to generate ``out-<config>.c``,
  where ``<config>`` is the build configuration, and then compile the generated
  source as part of a library.

Example: Generating Files for Multiple Targets
""""""""""""""""""""""""""""""""""""""""""""""

If multiple independent targets need the same custom command output,
it must be attached to a single custom target on which they all depend.
Consider the following example:

 add_custom_command(
   OUTPUT table.csv
   COMMAND makeTable -i ${CMAKE_CURRENT_SOURCE_DIR}/input.dat
                     -o table.csv
   DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/input.dat
   VERBATIM)
 add_custom_target(generate_table_csv DEPENDS table.csv)

 add_custom_command(
   OUTPUT foo.cxx
   COMMAND genFromTable -i table.csv -case foo -o foo.cxx
   DEPENDS table.csv           # file-level dependency
           generate_table_csv  # target-level dependency
   VERBATIM)
 add_library(foo foo.cxx)

 add_custom_command(
   OUTPUT bar.cxx
   COMMAND genFromTable -i table.csv -case bar -o bar.cxx
   DEPENDS table.csv           # file-level dependency
           generate_table_csv  # target-level dependency
   VERBATIM)
 add_library(bar bar.cxx)

Output ``foo.cxx`` is needed only by target ``foo`` and output ``bar.cxx``
is needed only by target ``bar``, but *both* targets need ``table.csv``,
transitively.  Since ``foo`` and ``bar`` are independent targets that may
build concurrently, we prevent them from racing to generate ``table.csv``
by placing its custom command in a separate target, ``generate_table_csv``.
The custom commands generating ``foo.cxx`` and ``bar.cxx`` each specify a
target-level dependency on ``generate_table_csv``, so the targets using them,
``foo`` and ``bar``, will not build until after target ``generate_table_csv``
is built.

Build Events
^^^^^^^^^^^^

The second signature adds a custom command to a target such as a
library or executable.  This is useful for performing an operation
before or after building the target.  The command becomes part of the
target and will only execute when the target itself is built.  If the
target is already built, the command will not execute.

 add_custom_command(TARGET <target>
                    PRE_BUILD | PRE_LINK | POST_BUILD
                    COMMAND command1 [ARGS] [args1...]
                    [COMMAND command2 [ARGS] [args2...] ...]
                    [BYPRODUCTS [files...]]
                    [WORKING_DIRECTORY dir]
                    [COMMENT comment]
                    [VERBATIM]
                    [COMMAND_EXPAND_LISTS])

This defines a new command that will be associated with building the
specified ``<target>``.  The ``<target>`` must be defined in the current
directory; targets defined in other directories may not be specified.

When the command will happen is determined by which
of the following is specified:

``PRE_BUILD``
  This option has unique behavior for the :ref:`Visual Studio Generators`.
  When using one of the Visual Studio generators, the command will run before
  any other rules are executed within the target.  With all other generators,
  this option behaves the same as ``PRE_LINK`` instead.  Because of this,
  it is recommended to avoid using ``PRE_BUILD`` except when it is known that
  a Visual Studio generator is being used.
``PRE_LINK``
  Run after sources have been compiled but before linking the binary
  or running the librarian or archiver tool of a static library.
  This is not defined for targets created by the
  ``add_custom_target()`` command.
``POST_BUILD``
  Run after all other rules within the target have been executed.

Projects should always specify one of the above three keywords when using
the ``TARGET`` form.  For backward compatibility reasons, ``POST_BUILD`` is
assumed if no such keyword is given, but projects should explicitly provide
one of the keywords to make clear the behavior they expect.

.. note::
  Because generator expressions can be used in custom commands,
  it is possible to define ``COMMAND`` lines or whole custom commands
  which evaluate to empty strings for certain configurations.
  For **Visual Studio 12 2013 (and newer)** generators these command
  lines or custom commands will be omitted for the specific
  configuration and no "empty-string-command" will be added.

  This allows adding individual build events for every configuration.

.. versionadded:: 3.21
  Support for target-dependent generator expressions.

.. versionadded:: 3.29
  The ``<target>`` may be an :ref:`ALIAS target <Alias Targets>`.

Examples: Build Events
^^^^^^^^^^^^^^^^^^^^^^

A ``POST_BUILD`` event may be used to post-process a binary after linking.
For example, the code:

 add_executable(myExe myExe.c)
 add_custom_command(
   TARGET myExe POST_BUILD
   COMMAND someHasher -i "$<TARGET_FILE:myExe>"
                      -o "$<TARGET_FILE:myExe>.hash"
   VERBATIM)

will run ``someHasher`` to produce a ``.hash`` file next to the executable
after linking.

.. versionadded:: 3.20
  One may use generator expressions to specify per-configuration byproducts.
  For example, the code:

  .. code-block:: cmake

    add_library(myPlugin MODULE myPlugin.c)
    add_custom_command(
      TARGET myPlugin POST_BUILD
      COMMAND someHasher -i "$<TARGET_FILE:myPlugin>"
                         --as-code "myPlugin-hash-$<CONFIG>.c"
      BYPRODUCTS "myPlugin-hash-$<CONFIG>.c"
      VERBATIM)
    add_executable(myExe myExe.c "myPlugin-hash-$<CONFIG>.c")

  will run ``someHasher`` after linking ``myPlugin``, e.g. to produce a ``.c``
  file containing code to check the hash of ``myPlugin`` that the ``myExe``
  executable can use to verify it before loading.

Ninja Multi-Config
^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.20

  ``add_custom_command`` supports the ``Ninja Multi-Config``
  generator's cross-config capabilities. See the generator documentation
  for more information.

See Also
^^^^^^^^

* ``add_custom_target()``

add_custom_target
-----------------

Add a target with no output so it will always be built.

 add_custom_target(Name [ALL] [command1 [args1...]]
                   [COMMAND command2 [args2...] ...]
                   [DEPENDS depend depend depend ... ]
                   [BYPRODUCTS [files...]]
                   [WORKING_DIRECTORY dir]
                   [COMMENT comment]
                   [JOB_POOL job_pool]
                   [JOB_SERVER_AWARE <bool>]
                   [VERBATIM] [USES_TERMINAL]
                   [COMMAND_EXPAND_LISTS]
                   [SOURCES src1 [src2...]])

Adds a target with the given name that executes the given commands.
The target has no output file and is *always considered out of date*
even if the commands try to create a file with the name of the target.
Use the ``add_custom_command()`` command to generate a file with
dependencies.  By default nothing depends on the custom target.  Use
the ``add_dependencies()`` command to add dependencies to or
from other targets.

The options are:

``ALL``
  Indicate that this target should be added to the default build
  target so that it will be run every time (the command cannot be
  called ``ALL``).

``BYPRODUCTS``
  .. versionadded:: 3.2

  Specify the files the command is expected to produce but whose
  modification time may or may not be updated on subsequent builds.
  If a byproduct name is a relative path it will be interpreted
  relative to the build tree directory corresponding to the
  current source directory.
  Each byproduct file will be marked with the ``GENERATED``
  source file property automatically.

  *See policy* ``CMP0058`` *for the motivation behind this feature.*

  Explicit specification of byproducts is supported by the
  ``Ninja`` generator to tell the ``ninja`` build tool
  how to regenerate byproducts when they are missing.  It is
  also useful when other build rules (e.g. custom commands)
  depend on the byproducts.  Ninja requires a build rule for any
  generated file on which another rule depends even if there are
  order-only dependencies to ensure the byproducts will be
  available before their dependents build.

  The :ref:`Makefile Generators` will remove ``BYPRODUCTS`` and other
  ``GENERATED`` files during ``make clean``.

  .. versionadded:: 3.20
    Arguments to ``BYPRODUCTS`` may use a restricted set of
    ``generator expressions``.
    :ref:`Target-dependent expressions <Target-Dependent Expressions>`
    are not permitted.

  .. versionchanged:: 3.28
    In custom targets using :ref:`file sets`, byproducts are now
    considered private unless they are listed in a non-private file set.
    See policy ``CMP0154``.

``COMMAND``
  Specify the command-line(s) to execute at build time.
  If more than one ``COMMAND`` is specified they will be executed in order,
  but *not* necessarily composed into a stateful shell or batch script.
  (To run a full script, use the ``configure_file()`` command or the
  ``file(GENERATE)`` command to create it, and then specify
  a ``COMMAND`` to launch it.)

  If ``COMMAND`` specifies an executable target name (created by the
  ``add_executable()`` command), it will automatically be replaced
  by the location of the executable created at build time if either of
  the following is true:

  * The target is not being cross-compiled (i.e. the
    ``CMAKE_CROSSCOMPILING`` variable is not set to true).
  * .. versionadded:: 3.6
      The target is being cross-compiled and an emulator is provided (i.e.
      its ``CROSSCOMPILING_EMULATOR`` target property is set).
      In this case, the contents of ``CROSSCOMPILING_EMULATOR`` will be
      prepended to the command before the location of the target executable.

  If neither of the above conditions are met, it is assumed that the
  command name is a program to be found on the ``PATH`` at build time.

  Arguments to ``COMMAND`` may use
  ``generator expressions``.
  Use the ``TARGET_FILE`` generator expression to refer to the location
  of a target later in the command line (i.e. as a command argument rather
  than as the command to execute).

  Whenever one of the following target based generator expressions are used as
  a command to execute or is mentioned in a command argument, a target-level
  dependency will be added automatically so that the mentioned target will be
  built before this custom target (see policy ``CMP0112``).

    * ``TARGET_FILE``
    * ``TARGET_LINKER_FILE``
    * ``TARGET_SONAME_FILE``
    * ``TARGET_PDB_FILE``

  The command and arguments are optional and if not specified an empty
  target will be created.

``COMMENT``
  Display the given message before the commands are executed at
  build time.

  .. versionadded:: 3.26
    Arguments to ``COMMENT`` may use
    ``generator expressions``.

``DEPENDS``
  Reference files and outputs of custom commands created with
  ``add_custom_command()`` command calls in the same directory
  (``CMakeLists.txt`` file).  They will be brought up to date when
  the target is built.

  .. versionchanged:: 3.16
    A target-level dependency is added if any dependency is a byproduct
    of a target or any of its build events in the same directory to ensure
    the byproducts will be available before this target is built.

  Use the ``add_dependencies()`` command to add dependencies
  on other targets.

``COMMAND_EXPAND_LISTS``
  .. versionadded:: 3.8

  Lists in ``COMMAND`` arguments will be expanded, including those
  created with
  ``generator expressions``,
  allowing ``COMMAND`` arguments such as
  ``${CC} "-I$<JOIN:$<TARGET_PROPERTY:foo,INCLUDE_DIRECTORIES>,;-I>" foo.cc``
  to be properly expanded.

``JOB_POOL``
  .. versionadded:: 3.15

  Specify a ``pool`` for the ``Ninja``
  generator. Incompatible with ``USES_TERMINAL``, which implies
  the ``console`` pool.
  Using a pool that is not defined by ``JOB_POOLS`` causes
  an error by ninja at build time.

``JOB_SERVER_AWARE``
  .. versionadded:: 3.28

  Specify that the command is GNU Make job server aware.

  For the ``Unix Makefiles``, ``MSYS Makefiles``, and
  ``MinGW Makefiles`` generators this will add the ``+`` prefix to the
  recipe line. See the GNU Make Documentation for more information.

  This option is silently ignored by other generators.

``SOURCES``
  Specify additional source files to be included in the custom target.
  Specified source files will be added to IDE project files for
  convenience in editing even if they have no build rules.

``VERBATIM``
  All arguments to the commands will be escaped properly for the
  build tool so that the invoked command receives each argument
  unchanged.  Note that one level of escapes is still used by the
  CMake language processor before ``add_custom_target`` even sees
  the arguments.  Use of ``VERBATIM`` is recommended as it enables
  correct behavior.  When ``VERBATIM`` is not given the behavior
  is platform specific because there is no protection of
  tool-specific special characters.

``USES_TERMINAL``
  .. versionadded:: 3.2

  The command will be given direct access to the terminal if possible.
  With the ``Ninja`` generator, this places the command in
  the ``console`` ``pool``.

``WORKING_DIRECTORY``
  Execute the command with the given current working directory.
  If it is a relative path it will be interpreted relative to the
  build tree directory corresponding to the current source directory.

  .. versionadded:: 3.13
    Arguments to ``WORKING_DIRECTORY`` may use
    ``generator expressions``.

Ninja Multi-Config
^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.20

  ``add_custom_target`` supports the ``Ninja Multi-Config``
  generator's cross-config capabilities. See the generator documentation
  for more information.

See Also
^^^^^^^^

* ``add_custom_command()``

add_definitions
---------------

Add ``-D`` define flags to the compilation of source files.

 add_definitions(-DFOO -DBAR ...)

Adds definitions to the compiler command line for targets in the current
directory, whether added before or after this command is invoked, and for
the ones in sub-directories added after. This command can be used to add any
flags, but it is intended to add preprocessor definitions.

.. note::

  This command has been superseded by alternatives:

  * Use ``add_compile_definitions()`` to add preprocessor definitions.
  * Use ``include_directories()`` to add include directories.
  * Use ``add_compile_options()`` to add other options.

Flags beginning in ``-D`` or ``/D`` that look like preprocessor definitions are
automatically added to the ``COMPILE_DEFINITIONS`` directory
property for the current directory.  Definitions with non-trivial values
may be left in the set of flags instead of being converted for reasons of
backwards compatibility.  See documentation of the
``directory``,
``target``,
``source file`` ``COMPILE_DEFINITIONS``
properties for details on adding preprocessor definitions to specific
scopes and configurations.

See Also
^^^^^^^^

* The ``cmake-buildsystem(7)`` manual for more on defining
  buildsystem properties.

add_dependencies
----------------

Add a dependency between top-level targets.

 add_dependencies(<target> [<target-dependency>]...)

Makes a top-level ``<target>`` depend on other top-level targets to
ensure that they build before ``<target>`` does.  A top-level target
is one created by one of the ``add_executable()``,
``add_library()``, or ``add_custom_target()`` commands
(but not targets generated by CMake like ``install``).

Dependencies added to an :ref:`imported target <Imported Targets>`
or an :ref:`interface library <Interface Libraries>` are followed
transitively in its place since the target itself does not build.

.. versionadded:: 3.3
  Allow adding dependencies to interface libraries.

.. versionadded:: 3.8
  Dependencies will populate the ``MANUALLY_ADDED_DEPENDENCIES``
  property of ``<target>``.

.. versionchanged:: 3.9
  The :ref:`Ninja Generators` use weaker ordering than
  other generators in order to improve available concurrency.
  They only guarantee that the dependencies' custom commands are
  finished before sources in ``<target>`` start compiling; this
  ensures generated sources are available.

See Also
^^^^^^^^

* The ``DEPENDS`` option of ``add_custom_target()`` and
  ``add_custom_command()`` commands for adding file-level
  dependencies in custom rules.

* The ``OBJECT_DEPENDS`` source file property to add
  file-level dependencies to object files.

add_executable
--------------

Add an executable to the project using the specified source files.

Normal Executables
^^^^^^^^^^^^^^^^^^

.. signature::
  add_executable(<name> <options>... <sources>...)
  :target: normal

  Add an executable target called ``<name>`` to be built from the source
  files listed in the command invocation.

  The options are:

  ``WIN32``
    Set the ``WIN32_EXECUTABLE`` target property automatically.
    See documentation of that target property for details.

  ``MACOSX_BUNDLE``
    Set the ``MACOSX_BUNDLE`` target property automatically.
    See documentation of that target property for details.

  ``EXCLUDE_FROM_ALL``
    Set the ``EXCLUDE_FROM_ALL`` target property automatically.
    See documentation of that target property for details.

The ``<name>`` corresponds to the logical target name and must be globally
unique within a project.  The actual file name of the executable built is
constructed based on conventions of the native platform (such as
``<name>.exe`` or just ``<name>``).

.. versionadded:: 3.1
  Source arguments to ``add_executable`` may use "generator expressions" with
  the syntax ``$<...>``.  See the ``cmake-generator-expressions(7)``
  manual for available expressions.

.. versionadded:: 3.11
  The source files can be omitted if they are added later using
  ``target_sources()``.

By default the executable file will be created in the build tree
directory corresponding to the source tree directory in which the
command was invoked.  See documentation of the
``RUNTIME_OUTPUT_DIRECTORY`` target property to change this
location.  See documentation of the ``OUTPUT_NAME`` target property
to change the ``<name>`` part of the final file name.

See the ``cmake-buildsystem(7)`` manual for more on defining
buildsystem properties.

See also ``HEADER_FILE_ONLY`` on what to do if some sources are
pre-processed, and you want to have the original sources reachable from
within IDE.

Imported Executables
^^^^^^^^^^^^^^^^^^^^

.. signature::
  add_executable(<name> IMPORTED [GLOBAL])
  :target: IMPORTED

  Add an :ref:`IMPORTED executable target <Imported Targets>` to reference
  an executable file located outside the project.  The target name may be
  referenced like any target built within the project, except that by
  default it is visible only in the directory in which it is created,
  and below.

  The options are:

  ``GLOBAL``
    Make the target name globally visible.

No rules are generated to build imported targets, and the ``IMPORTED``
target property is ``True``.  Imported executables are useful for convenient
reference from commands like ``add_custom_command()``.

Details about the imported executable are specified by setting properties
whose names begin in ``IMPORTED_``.  The most important such property is
``IMPORTED_LOCATION`` (and its per-configuration version
``IMPORTED_LOCATION_<CONFIG>``) which specifies the location of
the main executable file on disk.  See documentation of the ``IMPORTED_*``
properties for more information.

Alias Executables
^^^^^^^^^^^^^^^^^

.. signature::
  add_executable(<name> ALIAS <target>)
  :target: ALIAS

  Creates an :ref:`Alias Target <Alias Targets>`, such that ``<name>`` can
  be used to refer to ``<target>`` in subsequent commands.  The ``<name>``
  does not appear in the generated buildsystem as a make target.  The
  ``<target>`` may not be an ``ALIAS``.

.. versionadded:: 3.11
  An ``ALIAS`` can target a ``GLOBAL`` :ref:`Imported Target <Imported Targets>`

.. versionadded:: 3.18
  An ``ALIAS`` can target a non-``GLOBAL`` Imported Target. Such alias is
  scoped to the directory in which it is created and subdirectories.
  The ``ALIAS_GLOBAL`` target property can be used to check if the
  alias is global or not.

``ALIAS`` targets can be used as targets to read properties
from, executables for custom commands and custom targets.  They can also be
tested for existence with the regular ``if(TARGET)`` subcommand.
The ``<name>`` may not be used to modify properties of ``<target>``, that
is, it may not be used as the operand of ``set_property()``,
``set_target_properties()``, ``target_link_libraries()`` etc.
An ``ALIAS`` target may not be installed or exported.

See Also
^^^^^^^^

* ``add_library()``

add_library
-----------

Add a library to the project using the specified source files.

Normal Libraries
^^^^^^^^^^^^^^^^

.. signature::
  add_library(<name> [<type>] [EXCLUDE_FROM_ALL] <sources>...)
  :target: normal

  Add a library target called ``<name>`` to be built from the source files
  listed in the command invocation.

  The optional ``<type>`` specifies the type of library to be created:

  ``STATIC``
    An archive of object files for use when linking other targets.

  ``SHARED``
    A dynamic library that may be linked by other targets and loaded
    at runtime.

  ``MODULE``
    A plugin that may not be linked by other targets, but may be
    dynamically loaded at runtime using dlopen-like functionality.

  If no ``<type>`` is given the default is ``STATIC`` or ``SHARED``
  based on the value of the ``BUILD_SHARED_LIBS`` variable.

  The options are:

  ``EXCLUDE_FROM_ALL``
    Set the ``EXCLUDE_FROM_ALL`` target property automatically.
    See documentation of that target property for details.

The ``<name>`` corresponds to the logical target name and must be globally
unique within a project.  The actual file name of the library built is
constructed based on conventions of the native platform (such as
``lib<name>.a`` or ``<name>.lib``).

.. versionadded:: 3.1
  Source arguments to ``add_library`` may use "generator expressions" with
  the syntax ``$<...>``.  See the ``cmake-generator-expressions(7)``
  manual for available expressions.

.. versionadded:: 3.11
  The source files can be omitted if they are added later using
  ``target_sources()``.

For ``SHARED`` and ``MODULE`` libraries the
``POSITION_INDEPENDENT_CODE`` target
property is set to ``ON`` automatically.
A ``SHARED`` library may be marked with the ``FRAMEWORK``
target property to create an macOS Framework.

.. versionadded:: 3.8
  A ``STATIC`` library may be marked with the ``FRAMEWORK``
  target property to create a static Framework.

If a library does not export any symbols, it must not be declared as a
``SHARED`` library.  For example, a Windows resource DLL or a managed C++/CLI
DLL that exports no unmanaged symbols would need to be a ``MODULE`` library.
This is because CMake expects a ``SHARED`` library to always have an
associated import library on Windows.

By default the library file will be created in the build tree directory
corresponding to the source tree directory in which the command was
invoked.  See documentation of the ``ARCHIVE_OUTPUT_DIRECTORY``,
``LIBRARY_OUTPUT_DIRECTORY``, and
``RUNTIME_OUTPUT_DIRECTORY`` target properties to change this
location.  See documentation of the ``OUTPUT_NAME`` target
property to change the ``<name>`` part of the final file name.

See the ``cmake-buildsystem(7)`` manual for more on defining
buildsystem properties.

See also ``HEADER_FILE_ONLY`` on what to do if some sources are
pre-processed, and you want to have the original sources reachable from
within IDE.

.. versionchanged:: 3.30

  On platforms that do not support shared libraries, ``add_library``
  now fails on calls creating ``SHARED`` libraries instead of
  automatically converting them to ``STATIC`` libraries as before.
  See policy ``CMP0164``.

Object Libraries
^^^^^^^^^^^^^^^^

.. signature::
  add_library(<name> OBJECT <sources>...)
  :target: OBJECT

  Add an :ref:`Object Library <Object Libraries>` to compile source files
  without archiving or linking their object files into a library.

Other targets created by ``add_library`` or ``add_executable()``
may reference the objects using an expression of the
form ``$\<TARGET_OBJECTS:objlib\>`` as a source, where
``objlib`` is the object library name.  For example:

 add_library(... $<TARGET_OBJECTS:objlib> ...)
 add_executable(... $<TARGET_OBJECTS:objlib> ...)

will include objlib's object files in a library and an executable
along with those compiled from their own sources.  Object libraries
may contain only sources that compile, header files, and other files
that would not affect linking of a normal library (e.g. ``.txt``).
They may contain custom commands generating such sources, but not
``PRE_BUILD``, ``PRE_LINK``, or ``POST_BUILD`` commands.  Some native build
systems (such as Xcode) may not like targets that have only object files, so
consider adding at least one real source file to any target that references
``$\<TARGET_OBJECTS:objlib\>``.

.. versionadded:: 3.12
  Object libraries can be linked to with ``target_link_libraries()``.

Interface Libraries
^^^^^^^^^^^^^^^^^^^

.. signature::
  add_library(<name> INTERFACE)
  :target: INTERFACE

  Add an :ref:`Interface Library <Interface Libraries>` target that may
  specify usage requirements for dependents but does not compile sources
  and does not produce a library artifact on disk.

  An interface library with no source files is not included as a target
  in the generated buildsystem.  However, it may have
  properties set on it and it may be installed and exported.
  Typically, ``INTERFACE_*`` properties are populated on an interface
  target using the commands:

  * ``set_property()``,
  * ``target_link_libraries(INTERFACE)``,
  * ``target_link_options(INTERFACE)``,
  * ``target_include_directories(INTERFACE)``,
  * ``target_compile_options(INTERFACE)``,
  * ``target_compile_definitions(INTERFACE)``, and
  * ``target_sources(INTERFACE)``,

  and then it is used as an argument to ``target_link_libraries()``
  like any other target.

  .. versionadded:: 3.15
    An interface library can have ``PUBLIC_HEADER`` and
    ``PRIVATE_HEADER`` properties.  The headers specified by those
    properties can be installed using the ``install(TARGETS)`` command.

.. signature::
  add_library(<name> INTERFACE [EXCLUDE_FROM_ALL] <sources>...)
  :target: INTERFACE-with-sources

  .. versionadded:: 3.19

  Add an :ref:`Interface Library <Interface Libraries>` target with
  source files (in addition to usage requirements and properties as
  documented by the ``above signature``).
  Source files may be listed directly in the ``add_library`` call
  or added later by calls to ``target_sources()`` with the
  ``PRIVATE`` or ``PUBLIC`` keywords.

  If an interface library has source files (i.e. the ``SOURCES``
  target property is set), or header sets (i.e. the ``HEADER_SETS``
  target property is set), it will appear in the generated buildsystem
  as a build target much like a target defined by the
  ``add_custom_target()`` command.  It does not compile any sources,
  but does contain build rules for custom commands created by the
  ``add_custom_command()`` command.

  The options are:

  ``EXCLUDE_FROM_ALL``
    Set the ``EXCLUDE_FROM_ALL`` target property automatically.
    See documentation of that target property for details.

  .. note::
    In most command signatures where the ``INTERFACE`` keyword appears,
    the items listed after it only become part of that target's usage
    requirements and are not part of the target's own settings.  However,
    in this signature of ``add_library``, the ``INTERFACE`` keyword refers
    to the library type only.  Sources listed after it in the ``add_library``
    call are ``PRIVATE`` to the interface library and do not appear in its
    ``INTERFACE_SOURCES`` target property.

Imported Libraries
^^^^^^^^^^^^^^^^^^

.. signature::
  add_library(<name> <type> IMPORTED [GLOBAL])
  :target: IMPORTED

  Add an :ref:`IMPORTED library target <Imported Targets>` called ``<name>``.
  The target name may be referenced like any target built within the project,
  except that by default it is visible only in the directory in which it is
  created, and below.

  The ``<type>`` must be one of:

  ``STATIC``, ``SHARED``, ``MODULE``, ``UNKNOWN``
    References a library file located outside the project.  The
    ``IMPORTED_LOCATION`` target property (or its per-configuration
    variant ``IMPORTED_LOCATION_<CONFIG>``) specifies the
    location of the main library file on disk:

    * For a ``SHARED`` library on most non-Windows platforms, the main library
      file is the ``.so`` or ``.dylib`` file used by both linkers and dynamic
      loaders.  If the referenced library file has a ``SONAME`` (or on macOS,
      has a ``LC_ID_DYLIB`` starting in ``@rpath/``), the value of that field
      should be set in the ``IMPORTED_SONAME`` target property.
      If the referenced library file does not have a ``SONAME``, but the
      platform supports it, then  the ``IMPORTED_NO_SONAME`` target
      property should be set.

    * For a ``SHARED`` library on Windows, the ``IMPORTED_IMPLIB``
      target property (or its per-configuration variant
      ``IMPORTED_IMPLIB_<CONFIG>``) specifies the location of the
      DLL import library file (``.lib`` or ``.dll.a``) on disk, and the
      ``IMPORTED_LOCATION`` is the location of the ``.dll`` runtime
      library (and is optional, but needed by the ``TARGET_RUNTIME_DLLS``
      generator expression).

    Additional usage requirements may be specified in ``INTERFACE_*``
    properties.

    An ``UNKNOWN`` library type is typically only used in the implementation
    of :ref:`Find Modules`.  It allows the path to an imported library
    (often found using the ``find_library()`` command) to be used
    without having to know what type of library it is.  This is especially
    useful on Windows where a static library and a DLL's import library
    both have the same file extension.

  ``OBJECT``
    References a set of object files located outside the project.
    The ``IMPORTED_OBJECTS`` target property (or its per-configuration
    variant ``IMPORTED_OBJECTS_<CONFIG>``) specifies the locations of
    object files on disk.
    Additional usage requirements may be specified in ``INTERFACE_*``
    properties.

  ``INTERFACE``
    Does not reference any library or object files on disk, but may
    specify usage requirements in ``INTERFACE_*`` properties.

  The options are:

  ``GLOBAL``
    Make the target name globally visible.

No rules are generated to build imported targets, and the ``IMPORTED``
target property is ``True``.  Imported libraries are useful for convenient
reference from commands like ``target_link_libraries()``.

Details about the imported library are specified by setting properties whose
names begin in ``IMPORTED_`` and ``INTERFACE_``.  See documentation of
such properties for more information.

Alias Libraries
^^^^^^^^^^^^^^^

.. signature::
  add_library(<name> ALIAS <target>)
  :target: ALIAS

  Creates an :ref:`Alias Target <Alias Targets>`, such that ``<name>`` can be
  used to refer to ``<target>`` in subsequent commands.  The ``<name>`` does
  not appear in the generated buildsystem as a make target.  The ``<target>``
  may not be an ``ALIAS``.

.. versionadded:: 3.11
  An ``ALIAS`` can target a ``GLOBAL`` :ref:`Imported Target <Imported Targets>`

.. versionadded:: 3.18
  An ``ALIAS`` can target a non-``GLOBAL`` Imported Target. Such alias is
  scoped to the directory in which it is created and below.
  The ``ALIAS_GLOBAL`` target property can be used to check if the
  alias is global or not.

``ALIAS`` targets can be used as linkable targets and as targets to
read properties from.  They can also be tested for existence with the
regular ``if(TARGET)`` subcommand.  The ``<name>`` may not be used
to modify properties of ``<target>``, that is, it may not be used as the
operand of ``set_property()``, ``set_target_properties()``,
``target_link_libraries()`` etc.  An ``ALIAS`` target may not be
installed or exported.

See Also
^^^^^^^^

* ``add_executable()``

add_link_options
----------------

.. versionadded:: 3.13

Add options to the link step for executable, shared library or module
library targets in the current directory and below that are added after
this command is invoked.

 add_link_options(<option> ...)

This command can be used to add any link options, but alternative commands
exist to add libraries (``target_link_libraries()`` or
``link_libraries()``).  See documentation of the
``directory`` and
``target`` ``LINK_OPTIONS`` properties.

.. note::

  This command cannot be used to add options for static library targets,
  since they do not use a linker.  To add archiver or MSVC librarian flags,
  see the ``STATIC_LIBRARY_OPTIONS`` target property.

Arguments to ``add_link_options`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Host And Device Specific Link Options
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.18
  When a device link step is involved, which is controlled by
  ``CUDA_SEPARABLE_COMPILATION`` and
  ``CUDA_RESOLVE_DEVICE_SYMBOLS`` properties and policy ``CMP0105``,
  the raw options will be delivered to the host and device link steps (wrapped in
  ``-Xcompiler`` or equivalent for device link). Options wrapped with
  ``$<DEVICE_LINK:...>`` generator expression will be used
  only for the device link step. Options wrapped with ``$<HOST_LINK:...>``
  generator expression will be used only for the host link step.

Option De-duplication
^^^^^^^^^^^^^^^^^^^^^

The final set of options used for a target is constructed by
accumulating options from the current target and the usage requirements of
its dependencies.  The set of options is de-duplicated to avoid repetition.

.. versionadded:: 3.12
  While beneficial for individual options, the de-duplication step can break
  up option groups.  For example, ``-option A -option B`` becomes
  ``-option A B``.  One may specify a group of options using shell-like
  quoting along with a ``SHELL:`` prefix.  The ``SHELL:`` prefix is dropped,
  and the rest of the option string is parsed using the
  ``separate_arguments()`` ``UNIX_COMMAND`` mode. For example,
  ``"SHELL:-option A" "SHELL:-option B"`` becomes ``-option A -option B``.

Handling Compiler Driver Differences
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To pass options to the linker tool, each compiler driver has its own syntax.
The ``LINKER:`` prefix and ``,`` separator can be used to specify, in a portable
way, options to pass to the linker tool. ``LINKER:`` is replaced by the
appropriate driver option and ``,`` by the appropriate driver separator.
The driver prefix and driver separator are given by the values of the
``CMAKE_<LANG>_LINKER_WRAPPER_FLAG`` and
``CMAKE_<LANG>_LINKER_WRAPPER_FLAG_SEP`` variables.

For example, ``"LINKER:-z,defs"`` becomes ``-Xlinker -z -Xlinker defs`` for
``Clang`` and ``-Wl,-z,defs`` for ``GNU GCC``.

The ``LINKER:`` prefix can be specified as part of a ``SHELL:`` prefix
expression.

The ``LINKER:`` prefix supports, as an alternative syntax, specification of
arguments using the ``SHELL:`` prefix and space as separator. The previous
example then becomes ``"LINKER:SHELL:-z defs"``.

.. note::

  Specifying the ``SHELL:`` prefix anywhere other than at the beginning of the
  ``LINKER:`` prefix is not supported.

See Also
^^^^^^^^

* ``link_libraries()``
* ``target_link_libraries()``
* ``target_link_options()``

* ``CMAKE_<LANG>_FLAGS`` and ``CMAKE_<LANG>_FLAGS_<CONFIG>``
  add language-wide flags passed to all invocations of the compiler.
  This includes invocations that drive compiling and those that drive linking.

add_subdirectory
----------------

Add a subdirectory to the build.

 add_subdirectory(source_dir [binary_dir] [EXCLUDE_FROM_ALL] [SYSTEM])

Adds a subdirectory to the build.  The ``source_dir`` specifies the
directory in which the source ``CMakeLists.txt`` and code files are
located.  If it is a relative path, it will be evaluated with respect
to the current directory (the typical usage), but it may also be an
absolute path.  The ``binary_dir`` specifies the directory in which to
place the output files.  If it is a relative path, it will be evaluated
with respect to the current output directory, but it may also be an
absolute path.  If ``binary_dir`` is not specified, the value of
``source_dir``, before expanding any relative path, will be used (the
typical usage).  The ``CMakeLists.txt`` file in the specified source
directory will be processed immediately by CMake before processing in
the current input file continues beyond this command.

If the ``EXCLUDE_FROM_ALL`` argument is provided then the
``EXCLUDE_FROM_ALL`` property will be set on the added directory.
This will exclude the directory from a default build. See the directory
property ``EXCLUDE_FROM_ALL`` for full details.

.. versionadded:: 3.25
  If the ``SYSTEM`` argument is provided, the ``SYSTEM`` directory
  property of the subdirectory will be set to true.  This property is
  used to initialize the ``SYSTEM`` property of each non-imported
  target created in that subdirectory.

add_test
--------

Add a test to the project to be run by ``ctest(1)``.

 add_test(NAME <name> COMMAND <command> [<arg>...]
          [CONFIGURATIONS <config>...]
          [WORKING_DIRECTORY <dir>]
          [COMMAND_EXPAND_LISTS])

Adds a test called ``<name>``.  The test name may contain arbitrary
characters, expressed as a :ref:`Quoted Argument` or :ref:`Bracket Argument`
if necessary.  See policy ``CMP0110``.

CMake only generates tests if the ``enable_testing()`` command has been
invoked.  The ``CTest`` module invokes ``enable_testing`` automatically
unless ``BUILD_TESTING`` is set to ``OFF``.

Tests added with the ``add_test(NAME)`` signature support using
``generator expressions``
in test properties set by ``set_property(TEST)`` or
``set_tests_properties()``. Test properties may only be set in the
directory the test is created in.

``add_test`` options are:

``COMMAND``
  Specify the test command-line.

  If ``<command>`` specifies an executable target created by
  ``add_executable()``:

  * It will automatically be replaced by the location of the executable
    created at build time.

  * .. versionadded:: 3.3

      The target's ``CROSSCOMPILING_EMULATOR``, if set, will be
      used to run the command on the host::

       <emulator> <command>

     .. versionchanged:: 3.29

       The emulator is used only when
       :variable:`cross-compiling <CMAKE_CROSSCOMPILING>`.
       See policy :policy:`CMP0158`.

 * .. versionadded:: 3.29

     The target's :prop_tgt:`TEST_LAUNCHER`, if set, will be
     used to launch the command::

       <launcher> <command>

     If the :prop_tgt:`CROSSCOMPILING_EMULATOR` is also set, both are used::

       <launcher> <emulator> <command>

 The command may be specified using
 :manual:`generator expressions <cmake-generator-expressions(7)>`.

``CONFIGURATIONS``
  Restrict execution of the test only to the named configurations.

``WORKING_DIRECTORY``
  Set the test property ``WORKING_DIRECTORY`` in which to execute the
  test. If not specified, the test will be run in
  ``CMAKE_CURRENT_BINARY_DIR``. The working directory may be specified
  using ``generator expressions``.

``COMMAND_EXPAND_LISTS``
  .. versionadded:: 3.16

  Lists in ``COMMAND`` arguments will be expanded, including those created with
  ``generator expressions``.

If the test command exits with code ``0`` the test passes. Non-zero exit code
is a "failed" test. The test property ``WILL_FAIL`` inverts this
logic. Note that system-level test failures such as segmentation faults or
heap errors will still fail the test even if ``WILL_FAIL`` is true. Output
written to stdout or stderr is captured by ``ctest(1)`` and only
affects the pass/fail status via the ``PASS_REGULAR_EXPRESSION``,
``FAIL_REGULAR_EXPRESSION``, or ``SKIP_REGULAR_EXPRESSION``
test properties.

.. versionadded:: 3.16
  Added ``SKIP_REGULAR_EXPRESSION`` property.

Example usage:

 add_test(NAME mytest
          COMMAND testDriver --config $<CONFIG>
                             --exe $<TARGET_FILE:myexe>)

This creates a test ``mytest`` whose command runs a ``testDriver`` tool
passing the configuration name and the full path to the executable
file produced by target ``myexe``.

---------------------------------------------------------------------

The command syntax above is recommended over the older, less flexible form:

 add_test(<name> <command> [<arg>...])

Add a test called ``<name>`` with the given command-line.

Unlike the above ``NAME`` signature, target names are not supported
in the command-line.  Furthermore, tests added with this signature do not
support ``generator expressions``
in the command-line or test properties.

aux_source_directory
--------------------

Find all source files in a directory.

 aux_source_directory(<dir> <variable>)

Collects the names of all the source files in the specified directory
and stores the list in the ``<variable>`` provided.  This command is
intended to be used by projects that use explicit template
instantiation.  Template instantiation files can be stored in a
``Templates`` subdirectory and collected automatically using this
command to avoid manually listing all instantiations.

It is tempting to use this command to avoid writing the list of source
files for a library or executable target.  While this seems to work,
there is no way for CMake to generate a build system that knows when a
new source file has been added.  Normally the generated build system
knows when it needs to rerun CMake because the ``CMakeLists.txt`` file is
modified to add a new source.  When the source is just added to the
directory without modifying this file, one would have to manually
rerun CMake to generate a build system incorporating the new file.

build_command
-------------

Get a command line to build the current project.
This is mainly intended for internal use by the ``CTest`` module.

 build_command(<variable>
               [CONFIGURATION <config>]
               [PARALLEL_LEVEL <parallel>]
               [TARGET <target>]
               [PROJECT_NAME <projname>] # legacy, causes warning
              )

Sets the given ``<variable>`` to a command-line string of the form::

 <cmake> --build . [--config <config>] [--parallel <parallel>] [--target <target>...] [-- -i]

where ``<cmake>`` is the location of the ``cmake(1)`` command-line
tool, and ``<config>``, ``<parallel>`` and ``<target>`` are the values
provided to the ``CONFIGURATION``, ``PARALLEL_LEVEL`` and ``TARGET``
options, if any.  The trailing ``-- -i`` option is added for
:ref:`Makefile Generators` if policy ``CMP0061`` is not set to
``NEW``.

When invoked, this :option:`cmake --build` command line will launch the
underlying build system tool.

.. versionadded:: 3.21
  The ``PARALLEL_LEVEL`` argument can be used to set the
  :option:`--parallel <cmake--build --parallel>` flag.

 build_command(<cachevariable> <makecommand>)

This second signature is deprecated, but still available for backwards
compatibility.  Use the first signature instead.

It sets the given ``<cachevariable>`` to a command-line string as
above but without the :option:`--target <cmake--build --target>` option.
The ``<makecommand>`` is ignored but should be the full path to
devenv, nmake, make or one of the end user build tools
for legacy invocations.

.. note::
 In CMake versions prior to 3.0 this command returned a command
 line that directly invokes the native build tool for the current
 generator.  Their implementation of the ``PROJECT_NAME`` option
 had no useful effects, so CMake now warns on use of the option.

cmake_file_api
--------------

.. versionadded:: 3.27

Enables interacting with the ``CMake file API``.

.. signature::
  cmake_file_api(QUERY ...)

  The ``QUERY`` subcommand adds a file API query for the current CMake
  invocation.

  .. code-block:: cmake

    cmake_file_api(
      QUERY
      API_VERSION <version>
      [CODEMODEL <versions>...]
      [CACHE <versions>...]
      [CMAKEFILES <versions>...]
      [TOOLCHAINS <versions>...]
    )

  The ``API_VERSION`` must always be given.  Currently, the only supported
  value for ``<version>`` is 1.  See :ref:`file-api v1` for details of the
  reply content and location.

  Each of the optional keywords ``CODEMODEL``, ``CACHE``, ``CMAKEFILES`` and
  ``TOOLCHAINS`` correspond to one of the object kinds that can be requested
  by the project.  The ``configureLog`` object kind cannot be set with this
  command, since it must be set before CMake starts reading the top level
  ``CMakeLists.txt`` file.

  For each of the optional keywords, the ``<versions>`` list must contain one
  or more version values of the form ``major`` or ``major.minor``, where
  ``major`` and ``minor`` are integers.  Projects should list the versions they
  accept in their preferred order, as only the first supported value from the
  list will be selected.  The command will ignore versions with a ``major``
  version higher than any major version it supports for that object kind.
  It will raise an error if it encounters an invalid version number, or if none
  of the requested versions is supported.

  For each type of object kind requested, a query equivalent to a shared,
  stateless query will be added internally.  No query file will be created in
  the file system.  The reply *will* be written to the file system at
  generation time.

  It is not an error to add a query for the same thing more than once, whether
  from query files or from multiple calls to ``cmake_file_api(QUERY)``.
  The final set of queries will be a merged combination of all queries
  specified on disk and queries submitted by the project.

Example
^^^^^^^

A project may want to use replies from the file API at build time to implement
some form of verification task.  Instead of relying on something outside of
CMake to create a query file, the project can use ``cmake_file_api(QUERY)``
to request the required information for the current run.  It can then create
a custom command to run at build time, knowing that the requested information
should always be available.

 cmake_file_api(
   QUERY
   API_VERSION 1
   CODEMODEL 2.3
   TOOLCHAINS 1
 )

 add_custom_target(verify_project
   COMMAND ${CMAKE_COMMAND}
     -D BUILD_DIR=${CMAKE_BINARY_DIR}
     -D CONFIG=$<CONFIG>
     -P ${CMAKE_CURRENT_SOURCE_DIR}/verify_project.cmake
 )

create_test_sourcelist
----------------------

Create a test driver program that links together many small tests into a
single executable.  This is useful when building static executables with
large libraries to shrink the total required size.

.. signature::
  create_test_sourcelist(<sourceListName> <driverName> <test>... <options>...)
  :target: original

  Generate a test driver source file from a list of individual test sources
  and provide a combined list of sources that can be built as an executable.

  The options are:

  ``<sourceListName>``
    The name of a variable in which to store the list of source files needed
    to build the test driver.  The list will contain the ``<test>...`` sources
    and the generated ``<driverName>`` source.

    .. versionchanged:: 3.29

      The test driver source is listed by absolute path in the build tree.
      Previously it was listed only as ``<driverName>``.

  ``<driverName>``
    Name of the test driver source file to be generated into the build tree.
    The source file will contain a ``main()`` program entry point that
    dispatches to whatever test is named on the command line.

  ``<test>...``
    Test source files to be added to the driver binary.  Each test source
    file must have a function in it that is the same name as the file with the
    extension removed.  For example, a ``foo.cxx`` test source might contain:

    .. code-block:: c++

      int foo(int argc, char** argv)

  ``EXTRA_INCLUDE <header>``
    Specify a header file to ``#include`` in the generated test driver source.

  ``FUNCTION <function>``
    Specify a function to be called with pointers to ``argc`` and ``argv``.
    The function may be provided in the ``EXTRA_INCLUDE`` header:

    .. code-block:: c++

      void function(int* pargc, char*** pargv)

    This can be used to add extra command line processing to each test.

Additionally, some CMake variables affect test driver generation:

.. variable:: CMAKE_TESTDRIVER_BEFORE_TESTMAIN

  Code to be placed directly before calling each test's function.

.. variable:: CMAKE_TESTDRIVER_AFTER_TESTMAIN

  Code to be placed directly after the call to each test's function.

define_property
---------------

Define and document custom properties.

 define_property(<GLOBAL | DIRECTORY | TARGET | SOURCE |
                  TEST | VARIABLE | CACHED_VARIABLE>
                  PROPERTY <name> [INHERITED]
                  [BRIEF_DOCS <brief-doc> [docs...]]
                  [FULL_DOCS <full-doc> [docs...]]
                  [INITIALIZE_FROM_VARIABLE <variable>])

Defines one property in a scope for use with the ``set_property()`` and
``get_property()`` commands. It is mainly useful for defining the way
a property is initialized or inherited. Historically, the command also
associated documentation with a property, but that is no longer considered a
primary use case.

The first argument determines the kind of scope in which the property should
be used.  It must be one of the following:

::

 GLOBAL    = associated with the global namespace
 DIRECTORY = associated with one directory
 TARGET    = associated with one target
 SOURCE    = associated with one source file
 TEST      = associated with a test named with add_test
 VARIABLE  = documents a CMake language variable
 CACHED_VARIABLE = documents a CMake cache variable

Note that unlike ``set_property()`` and ``get_property()`` no
actual scope needs to be given; only the kind of scope is important.

The required ``PROPERTY`` option is immediately followed by the name of
the property being defined.

If the ``INHERITED`` option is given, then the ``get_property()`` command
will chain up to the next higher scope when the requested property is not set
in the scope given to the command.

* ``DIRECTORY`` scope chains to its parent directory's scope, continuing the
  walk up parent directories until a directory has the property set or there
  are no more parents.  If still not found at the top level directory, it
  chains to the ``GLOBAL`` scope.
* ``TARGET``, ``SOURCE`` and ``TEST`` properties chain to ``DIRECTORY`` scope,
  including further chaining up the directories, etc. as needed.

Note that this scope chaining behavior only applies to calls to
``get_property()``, ``get_directory_property()``,
``get_target_property()``, ``get_source_file_property()`` and
``get_test_property()``.  There is no inheriting behavior when *setting*
properties, so using ``APPEND`` or ``APPEND_STRING`` with the
``set_property()`` command will not consider inherited values when working
out the contents to append to.

The ``BRIEF_DOCS`` and ``FULL_DOCS`` options are followed by strings to be
associated with the property as its brief and full documentation.
CMake does not use this documentation other than making it available to the
project via corresponding options to the ``get_property()`` command.

.. versionchanged:: 3.23

  The ``BRIEF_DOCS`` and ``FULL_DOCS`` options are optional.

.. versionadded:: 3.23

  The ``INITIALIZE_FROM_VARIABLE`` option specifies a variable from which the
  property should be initialized. It can only be used with target properties.
  The ``<variable>`` name must end with the property name and must not begin
  with ``CMAKE_`` or ``_CMAKE_``. The property name must contain at least one
  underscore. It is recommended that the property name have a prefix specific
  to the project.

Property Redefinition
^^^^^^^^^^^^^^^^^^^^^

Once a property is defined for a particular type of scope, it cannot be
redefined. Attempts to redefine an existing property by calling
``define_property()`` with the same scope type and property name
will be silently ignored. Defining the same property name for two different
kinds of scope is valid.

``get_property()`` can be used to determine whether a property is
already defined for a particular kind of scope, and if so, to examine its
definition. For example:

 # Initial definition
 define_property(TARGET PROPERTY MY_NEW_PROP
   BRIEF_DOCS "My new custom property"
 )

 # Later examination
 get_property(my_new_prop_exists
   TARGET NONE
   PROPERTY MY_NEW_PROP
   DEFINED
 )

 if(my_new_prop_exists)
   get_property(my_new_prop_docs
     TARGET NONE
     PROPERTY MY_NEW_PROP
     BRIEF_DOCS
   )
   # ${my_new_prop_docs} is now set to "My new custom property"
 endif()

See Also
^^^^^^^^

* ``get_property()``
* ``set_property()``

enable_language
---------------

Enable languages (CXX/C/OBJC/OBJCXX/Fortran/etc)

 enable_language(<lang>... [OPTIONAL])

Enables support for the named languages in CMake.  This is the same as
the ``project()`` command but does not create any of the extra
variables that are created by the ``project()`` command.


Supported languages are ``C``, ``CXX`` (i.e.  C++), ``CSharp`` (i.e.  C#), ``CUDA``,
``OBJC`` (i.e. Objective-C), ``OBJCXX`` (i.e. Objective-C++), ``Fortran``, ``HIP``,
``ISPC``, ``Swift``, ``ASM``, ``ASM_NASM``, ``ASM_MARMASM``, ``ASM_MASM``, and ``ASM-ATT``.

  .. versionadded:: 3.8
    Added ``CSharp`` and ``CUDA`` support.

  .. versionadded:: 3.15
    Added ``Swift`` support.

  .. versionadded:: 3.16
    Added ``OBJC`` and ``OBJCXX`` support.

  .. versionadded:: 3.18
    Added ``ISPC`` support.

  .. versionadded:: 3.21
    Added ``HIP`` support.

  .. versionadded:: 3.26
    Added ``ASM_MARMASM`` support.

If enabling ``ASM``, list it last so that CMake can check whether
compilers for other languages like ``C`` work for assembly too.

The following restrictions apply to where ``enable_language()`` may be called:

* It must be called in file scope, not in a function call.
* It must not be called before the first call to ``project()``.
  See policy ``CMP0165``.
* It must be called in the highest directory common to all targets
  using the named language directly for compiling sources or
  indirectly through link dependencies.  It is simplest to enable all
  needed languages in the top-level directory of a project.

The ``OPTIONAL`` keyword is a placeholder for future implementation and
does not currently work. Instead you can use the ``CheckLanguage``
module to verify support before enabling.

enable_testing
--------------

Enable testing for current directory and below.

 enable_testing()

Enables testing for this directory and below.

This command should be in the source directory root
because ctest expects to find a test file in the build
directory root.

This command is automatically invoked when the ``CTest``
module is included, except if the ``BUILD_TESTING`` option is
turned off.

See also the ``add_test()`` command.

export
------

Export targets or packages for outside projects to use them directly
from the current project's build tree, without installation.

See the ``install(EXPORT)`` command to export targets from an
install tree.

Synopsis
^^^^^^^^

 export(TARGETS <target>... [...])
 export(EXPORT <export-name> [...])
 export(PACKAGE <PackageName>)
 export(SETUP <export-name> [...])

Exporting Targets
^^^^^^^^^^^^^^^^^

.. signature::
  export(TARGETS <target>... [...])

 export(TARGETS <target>... [NAMESPACE <namespace>]
        [APPEND] FILE <filename> [EXPORT_LINK_INTERFACE_LIBRARIES]
        [CXX_MODULES_DIRECTORY <directory>])

Creates a file ``<filename>`` that may be included by outside projects to
import targets named by ``<target>...`` from the current project's build tree.
This is useful during cross-compiling to build utility executables that can
run on the host platform in one project and then import them into another
project being compiled for the target platform.

The file created by this command is specific to the build tree and
should never be installed.  See the ``install(EXPORT)`` command to
export targets from an install tree.

The options are:

``NAMESPACE <namespace>``
  Prepend the ``<namespace>`` string to all target names written to the file.

``APPEND``
  Append to the file instead of overwriting it.  This can be used to
  incrementally export multiple targets to the same file.

``EXPORT_LINK_INTERFACE_LIBRARIES``
  Include the contents of the properties named with the pattern
  ``(IMPORTED_)?LINK_INTERFACE_LIBRARIES(_<CONFIG>)?``
  in the export, even when policy ``CMP0022`` is NEW.  This is useful
  to support consumers using CMake versions older than 2.8.12.

``CXX_MODULES_DIRECTORY <directory>``
  .. versionadded:: 3.28

  Export C++ module properties to files under the given directory. Each file
  will be named according to the target's export name (without any namespace).
  These files will automatically be included from the export file.

This signature requires all targets to be listed explicitly.  If a library
target is included in the export, but a target to which it links is not
included, the behavior is unspecified.  See the ``export(EXPORT)`` signature
to automatically export the same targets from the build tree as
``install(EXPORT)`` would from an install tree.

.. note::

  :ref:`Object Libraries` under ``Xcode`` have special handling if
  multiple architectures are listed in ``CMAKE_OSX_ARCHITECTURES``.
  In this case they will be exported as :ref:`Interface Libraries` with
  no object files available to clients.  This is sufficient to satisfy
  transitive usage requirements of other targets that link to the
  object libraries in their implementation.

This command exports all :ref:`build configurations` from the build tree.
See the ``CMAKE_MAP_IMPORTED_CONFIG_<CONFIG>`` variable to map
configurations of dependent projects to the exported configurations.

Exporting Targets to Android.mk
"""""""""""""""""""""""""""""""

 export(TARGETS <target>... ANDROID_MK <filename>)

.. versionadded:: 3.7

This signature exports cmake built targets to the android ndk build system
by creating an ``Android.mk`` file that references the prebuilt targets. The
Android NDK supports the use of prebuilt libraries, both static and shared.
This allows cmake to build the libraries of a project and make them available
to an ndk build system complete with transitive dependencies, include flags
and defines required to use the libraries. The signature takes a list of
targets and puts them in the ``Android.mk`` file specified by the
``<filename>`` given. This signature can only be used if policy
``CMP0022`` is NEW for all targets given. A error will be issued if
that policy is set to OLD for one of the targets.

Exporting Targets matching install(EXPORT)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. signature::
  export(EXPORT <export-name> [...])

 export(EXPORT <export-name> [NAMESPACE <namespace>] [FILE <filename>]
        [CXX_MODULES_DIRECTORY <directory>] [EXPORT_PACKAGE_DEPENDENCIES])

Creates a file ``<filename>`` that may be included by outside projects to
import targets from the current project's build tree.  This is the same
as the ``export(TARGETS)`` signature, except that the targets are not
explicitly listed.  Instead, it exports the targets associated with
the installation export ``<export-name>``.  Target installations may be
associated with the export ``<export-name>`` using the ``EXPORT`` option
of the ``install(TARGETS)`` command.

``EXPORT_PACKAGE_DEPENDENCIES``
  .. note::

   Experimental. Gated by ``CMAKE_EXPERIMENTAL_EXPORT_PACKAGE_DEPENDENCIES``.

 Specify that :command:`find_dependency` calls should be exported. See
 :command:`install(EXPORT)` for details on how this works.

Exporting Packages
^^^^^^^^^^^^^^^^^^

.. signature::
  export(PACKAGE <PackageName>)

 export(PACKAGE <PackageName>)

Store the current build directory in the CMake user package registry
for package ``<PackageName>``.  The ``find_package()`` command may consider the
directory while searching for package ``<PackageName>``.  This helps dependent
projects find and use a package from the current project's build tree
without help from the user.  Note that the entry in the package
registry that this command creates works only in conjunction with a
package configuration file (``<PackageName>Config.cmake``) that works with the
build tree. In some cases, for example for packaging and for system
wide installations, it is not desirable to write the user package
registry.

.. versionchanged:: 3.1
  If the ``CMAKE_EXPORT_NO_PACKAGE_REGISTRY`` variable
  is enabled, the ``export(PACKAGE)`` command will do nothing.

.. versionchanged:: 3.15
  By default the ``export(PACKAGE)`` command does nothing (see policy
  ``CMP0090``) because populating the user package registry has effects
  outside the source and build trees.  Set the
  ``CMAKE_EXPORT_PACKAGE_REGISTRY`` variable to add build directories
  to the CMake user package registry.

Configuring Exports
^^^^^^^^^^^^^^^^^^^

.. signature::
  export(SETUP <export-name> [...])

 export(SETUP <export-name>
        [PACKAGE_DEPENDENCY <dep>
         [ENABLED (<bool-true>|<bool-false>|AUTO)]
         [EXTRA_ARGS <args>...]
        ] [...]
        [TARGET <target>
         [XCFRAMEWORK_LOCATION <location>]
        ] [...]
        )

.. versionadded:: 3.29

Configure the parameters of an export. The arguments are as follows:

``PACKAGE_DEPENDENCY <dep>``
  .. note::

   Experimental. Gated by ``CMAKE_EXPERIMENTAL_EXPORT_PACKAGE_DEPENDENCIES``.

 Specify a package dependency to configure. This changes how
 :command:`find_dependency` calls are written during
 :command:`export(EXPORT)` and :command:`install(EXPORT)`. ``<dep>`` is the
 name of a package to export. This argument accepts the following additional
 arguments:

 ``ENABLED``
   Manually control whether or not the dependency is exported. This accepts
   the following values:

   ``<bool-true>``
     Any value that CMake recognizes as "true". Always export the dependency,
     even if no exported targets depend on it. This can be used to manually
     add :command:`find_dependency` calls to the export.

   ``<bool-false>``
     Any value that CMake recognizes as "false". Never export the dependency,
     even if an exported target depends on it.

   ``AUTO``
     Only export the dependency if an exported target depends on it.

 ``EXTRA_ARGS <args>``
   Specify additional arguments to pass to :command:`find_dependency` after
   the ``REQUIRED`` argument.

``TARGET <target>``
  Specify a target to configure in this export. This argument accepts the
  following additional arguments:

  ``XCFRAMEWORK_LOCATION``
    Specify the location of an ``.xcframework`` which contains the library from
    this target. If specified, the generated code will check to see if the
    ``.xcframework`` exists, and if it does, it will use the ``.xcframework``
    as its imported location instead of the installed library.

fltk_wrap_ui
------------

Create FLTK user interfaces Wrappers.

 fltk_wrap_ui(resultingLibraryName source1
              source2 ... sourceN )

Produce .h and .cxx files for all the .fl and .fld files listed.  The
resulting .h and .cxx files will be added to a variable named
``resultingLibraryName_FLTK_UI_SRCS`` which should be added to your
library.

get_source_file_property
------------------------

Get a property for a source file.

 get_source_file_property(<variable> <file>
                          [DIRECTORY <dir> | TARGET_DIRECTORY <target>]
                          <property>)

Gets a property from a source file.  The value of the property is stored in
the specified ``<variable>``.  If the ``<file>`` is not a source file, or the
source property is not found, ``<variable>`` will be set to ``NOTFOUND``.
If the source property was defined to be an ``INHERITED`` property (see
``define_property()``), the search will include the relevant parent
scopes, as described for the ``define_property()`` command.

By default, the source file's property will be read from the current source
directory's scope.

.. versionadded:: 3.18
  Directory scope can be overridden with one of the following sub-options:

  ``DIRECTORY <dir>``
    The source file property will be read from the ``<dir>`` directory's
    scope.  CMake must already know about that source directory, either by
    having added it through a call to ``add_subdirectory()`` or ``<dir>``
    being the top level source directory.  Relative paths are treated as
    relative to the current source directory.

  ``TARGET_DIRECTORY <target>``
    The source file property will be read from the directory scope in which
    ``<target>`` was created (``<target>`` must therefore already exist).

Use ``set_source_files_properties()`` to set property values.  Source
file properties usually control how the file is built. One property that is
always there is ``LOCATION``.

.. note::

  The ``GENERATED`` source file property may be globally visible.
  See its documentation for details.

See Also
^^^^^^^^

* ``define_property()``
* the more general ``get_property()`` command
* ``set_source_files_properties()``

get_target_property
-------------------

Get a property from a target.

 get_target_property(<variable> <target> <property>)

Get a property from a target.  The value of the property is stored in the
specified ``<variable>``.  If the target property is not found, ``<variable>``
will be set to ``<variable>-NOTFOUND``.  If the target property was defined to
be an ``INHERITED`` property (see ``define_property()``), the search will
include the relevant parent scopes, as described for the
``define_property()`` command.

Use ``set_target_properties()`` to set target property values.
Properties are usually used to control how a target is built, but some
query the target instead.  This command can get properties for any
target so far created.  The targets do not need to be in the current
``CMakeLists.txt`` file.

See Also
^^^^^^^^

* ``define_property()``
* the more general ``get_property()`` command
* ``set_target_properties()``
* :ref:`Target Properties` for the list of properties known to CMake

get_test_property
-----------------

Get a property of the test.

 get_test_property(<test> <property> [DIRECTORY <dir>] <variable>)

Get a property from the test.  The value of the property is stored in
the specified ``<variable>``.  If the ``<test>`` is not defined, or the
test property is not found, ``<variable>`` will be set to ``NOTFOUND``.
If the test property was defined to be an ``INHERITED`` property (see
``define_property()``), the search will include the relevant parent
scopes, as described for the ``define_property()`` command.

For a list of standard properties you can type
:option:`cmake --help-property-list`.

.. versionadded:: 3.28
  Directory scope can be overridden with the following sub-option:

  ``DIRECTORY <dir>``
    The test property will be read from the ``<dir>`` directory's
    scope.  CMake must already know about that source directory, either by
    having added it through a call to ``add_subdirectory()`` or ``<dir>``
    being the top level source directory.  Relative paths are treated as
    relative to the current source directory. ``<dir>`` may reference a binary
    directory.

See Also
^^^^^^^^

* ``define_property()``
* the more general ``get_property()`` command

include_directories
-------------------

Add include directories to the build.

 include_directories([AFTER|BEFORE] [SYSTEM] dir1 [dir2 ...])

Add the given directories to those the compiler uses to search for
include files.  Relative paths are interpreted as relative to the
current source directory.

The include directories are added to the ``INCLUDE_DIRECTORIES``
directory property for the current ``CMakeLists`` file.  They are also
added to the ``INCLUDE_DIRECTORIES`` target property for each
target in the current ``CMakeLists`` file.  The target property values
are the ones used by the generators.

By default the directories specified are appended onto the current list of
directories.  This default behavior can be changed by setting
``CMAKE_INCLUDE_DIRECTORIES_BEFORE`` to ``ON``.  By using
``AFTER`` or ``BEFORE`` explicitly, you can select between appending and
prepending, independent of the default.

If the ``SYSTEM`` option is given, the compiler will be told the
directories are meant as system include directories on some platforms.
Signaling this setting might achieve effects such as the compiler
skipping warnings, or these fixed-install system files not being
considered in dependency calculations - see compiler docs.

Arguments to ``include_directories`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

.. note::

  Prefer the ``target_include_directories()`` command to add include
  directories to individual targets and optionally propagate/export them
  to dependents.

See Also
^^^^^^^^

* ``target_include_directories()``

include_external_msproject
--------------------------

Include an external Microsoft project file in a workspace.

 include_external_msproject(projectname location
                            [TYPE projectTypeGUID]
                            [GUID projectGUID]
                            [PLATFORM platformName]
                            dep1 dep2 ...)

Includes an external Microsoft project in the generated workspace
file.  Currently does nothing on UNIX.  This will create a target
named ``[projectname]``.  This can be used in the ``add_dependencies()``
command to make things depend on the external project.

``TYPE``, ``GUID`` and ``PLATFORM`` are optional parameters that allow one to
specify the type of project, id (``GUID``) of the project and the name of
the target platform.  This is useful for projects requiring values
other than the default (e.g.  WIX projects).

.. versionadded:: 3.9
  If the imported project has different configuration names than the
  current project, set the ``MAP_IMPORTED_CONFIG_<CONFIG>``
  target property to specify the mapping.

include_regular_expression
--------------------------

Set the regular expression used for dependency checking.

 include_regular_expression(regex_match [regex_complain])

Sets the regular expressions used in dependency checking.  Only files
matching ``regex_match`` will be traced as dependencies.  Only files
matching ``regex_complain`` will generate warnings if they cannot be found
(standard header paths are not searched).  The defaults are:

::

 regex_match    = "^.*$" (match everything)
 regex_complain = "^$" (match empty string only)

install
-------

Specify rules to run at install time.

Synopsis
^^^^^^^^

 install(TARGETS <target>... [...])
 install(IMPORTED_RUNTIME_ARTIFACTS <target>... [...])
 install({FILES | PROGRAMS} <file>... [...])
 install(DIRECTORY <dir>... [...])
 install(SCRIPT <file> [...])
 install(CODE <code> [...])
 install(EXPORT <export-name> [...])
 install(RUNTIME_DEPENDENCY_SET <set-name> [...])

Introduction
^^^^^^^^^^^^

This command generates installation rules for a project.  Install rules
specified by calls to the ``install()`` command within a source directory
are executed in order during installation.

.. versionchanged:: 3.14
  Install rules in subdirectories
  added by calls to the ``add_subdirectory()`` command are interleaved
  with those in the parent directory to run in the order declared (see
  policy ``CMP0082``).

.. versionchanged:: 3.22
  The environment variable ``CMAKE_INSTALL_MODE`` can override the
  default copying behavior of ``install()``.

There are multiple signatures for this command.  Some of them define
installation options for files and targets.  Options common to
multiple signatures are covered here but they are valid only for
signatures that specify them.  The common options are:

``DESTINATION <dir>``
  Specify the directory on disk to which a file will be installed.
  ``<dir>`` should be a relative path.  An absolute path is allowed,
  but not recommended.

  When a relative path is given it is interpreted relative to the value
  of the ``CMAKE_INSTALL_PREFIX`` variable.
  The prefix can be relocated at install time using the ``DESTDIR``
  mechanism explained in the ``CMAKE_INSTALL_PREFIX`` variable
  documentation.

  As absolute paths do not work with the ``cmake --install`` command's
  :option:`--prefix <cmake--install --prefix>` option, or with the
  ``cpack`` installer generators, it is strongly recommended
  to use relative paths throughout for best support by package maintainers.
  In particular, there is no need to make paths absolute by prepending
  ``CMAKE_INSTALL_PREFIX``; this prefix is used by default if
  the DESTINATION is a relative path.

  If an absolute path (with a leading slash or drive letter) is given
  it is used verbatim.

``PERMISSIONS <permission>...``
  Specify permissions for installed files.  Valid permissions are
  ``OWNER_READ``, ``OWNER_WRITE``, ``OWNER_EXECUTE``, ``GROUP_READ``,
  ``GROUP_WRITE``, ``GROUP_EXECUTE``, ``WORLD_READ``, ``WORLD_WRITE``,
  ``WORLD_EXECUTE``, ``SETUID``, and ``SETGID``.  Permissions that do
  not make sense on certain platforms are ignored on those platforms.

  If this option is used multiple times in a single call, its list
  of permissions accumulates.  If an ``install(TARGETS)`` call
  uses <artifact-kind> arguments, a separate list of permissions
  is accumulated for each kind of artifact.

``CONFIGURATIONS <config>...``
  Specify a list of build configurations for which the install rule
  applies (Debug, Release, etc.).

  If this option is used multiple times in a single call, its list
  of configurations accumulates.  If an ``install(TARGETS)``
  call uses <artifact-kind> arguments, a separate list of
  configurations is accumulated for each kind of artifact.

``COMPONENT <component>``
  Specify an installation component name with which the install rule
  is associated, such as ``Runtime`` or ``Development``.  During
  component-specific installation only install rules associated with
  the given component name will be executed.  During a full installation
  all components are installed unless marked with ``EXCLUDE_FROM_ALL``.
  If ``COMPONENT`` is not provided a default component "Unspecified" is
  created.  The default component name may be controlled with the
  ``CMAKE_INSTALL_DEFAULT_COMPONENT_NAME`` variable.

``EXCLUDE_FROM_ALL``
  .. versionadded:: 3.6

  Specify that the file is excluded from a full installation and only
  installed as part of a component-specific installation

``RENAME <name>``
  Specify a name for an installed file that may be different from the
  original file.  Renaming is allowed only when a single file is
  installed by the command.

``OPTIONAL``
  Specify that it is not an error if the file to be installed does
  not exist.

.. versionadded:: 3.1
  Command signatures that install files may print messages during
  installation.  Use the ``CMAKE_INSTALL_MESSAGE`` variable
  to control which messages are printed.

.. versionadded:: 3.11
  Many of the ``install()`` variants implicitly create the directories
  containing the installed files. If
  ``CMAKE_INSTALL_DEFAULT_DIRECTORY_PERMISSIONS`` is set, these
  directories will be created with the permissions specified. Otherwise,
  they will be created according to the uname rules on Unix-like platforms.
  Windows platforms are unaffected.

Signatures
^^^^^^^^^^

.. signature::
  install(TARGETS <target>... [...])

  Install target :ref:`Output Artifacts` and associated files:

  .. code-block:: cmake

    install(TARGETS <target>... [EXPORT <export-name>]
            [RUNTIME_DEPENDENCIES <arg>...|RUNTIME_DEPENDENCY_SET <set-name>]
            [<artifact-option>...]
            [<artifact-kind> <artifact-option>...]...
            [INCLUDES DESTINATION [<dir> ...]]
            )

  where ``<artifact-option>...`` group may contain:

  .. code-block:: cmake

    [DESTINATION <dir>]
    [PERMISSIONS <permission>...]
    [CONFIGURATIONS <config>...]
    [COMPONENT <component>]
    [NAMELINK_COMPONENT <component>]
    [OPTIONAL] [EXCLUDE_FROM_ALL]
    [NAMELINK_ONLY|NAMELINK_SKIP]

  The first ``<artifact-option>...`` group applies to target
  :ref:`Output Artifacts` that do not have a dedicated group specified
  later in the same call.

  .. _`<artifact-kind>`:

  Each ``<artifact-kind> <artifact-option>...`` group applies to
  :ref:`Output Artifacts` of the specified artifact kind:

  ``ARCHIVE``
    Target artifacts of this kind include:

    * *Static libraries*
      (except on macOS when marked as ``FRAMEWORK``, see below);
    * *DLL import libraries*
      (on all Windows-based systems including Cygwin; they have extension
      ``.lib``, in contrast to the ``.dll`` libraries that go to ``RUNTIME``);
    * On AIX, the *linker import file* created for executables with
      ``ENABLE_EXPORTS`` enabled.
    * On macOS, the *linker import file* created for shared libraries with
      ``ENABLE_EXPORTS`` enabled (except when marked as ``FRAMEWORK``,
      see below).

  ``LIBRARY``
    Target artifacts of this kind include:

    * *Shared libraries*, except

      - DLLs (these go to ``RUNTIME``, see below),
      - on macOS when marked as ``FRAMEWORK`` (see below).

  ``RUNTIME``
    Target artifacts of this kind include:

    * *Executables*
      (except on macOS when marked as ``MACOSX_BUNDLE``, see ``BUNDLE`` below);
    * DLLs (on all Windows-based systems including Cygwin; note that the
      accompanying import libraries are of kind ``ARCHIVE``).

  ``OBJECTS``
    .. versionadded:: 3.9

    Object files associated with *object libraries*.

  ``FRAMEWORK``
    Both static and shared libraries marked with the ``FRAMEWORK``
    property are treated as ``FRAMEWORK`` targets on macOS.

  ``BUNDLE``
    Executables marked with the ``MACOSX_BUNDLE`` property are treated as
    ``BUNDLE`` targets on macOS.

  ``PUBLIC_HEADER``
    Any ``PUBLIC_HEADER`` files associated with a library are installed in
    the destination specified by the ``PUBLIC_HEADER`` argument on non-Apple
    platforms. Rules defined by this argument are ignored for ``FRAMEWORK``
    libraries on Apple platforms because the associated files are installed
    into the appropriate locations inside the framework folder. See
    ``PUBLIC_HEADER`` for details.

  ``PRIVATE_HEADER``
    Similar to ``PUBLIC_HEADER``, but for ``PRIVATE_HEADER`` files. See
    ``PRIVATE_HEADER`` for details.

  ``RESOURCE``
    Similar to ``PUBLIC_HEADER`` and ``PRIVATE_HEADER``, but for
    ``RESOURCE`` files. See ``RESOURCE`` for details.

  ``FILE_SET <set-name>``
    .. versionadded:: 3.23

    File sets are defined by the ``target_sources(FILE_SET)`` command.
    If the file set ``<set-name>`` exists and is ``PUBLIC`` or ``INTERFACE``,
    any files in the set are installed under the destination (see below).
    The directory structure relative to the file set's base directories is
    preserved. For example, a file added to the file set as
    ``/blah/include/myproj/here.h`` with a base directory ``/blah/include``
    would be installed to ``myproj/here.h`` below the destination.

  ``CXX_MODULES_BMI``
    .. versionadded:: 3.28

    Any module files from C++ modules from ``PUBLIC`` sources in a file set of
    type ``CXX_MODULES`` will be installed to the given ``DESTINATION``. All
    modules are placed directly in the destination as no directory structure is
    derived from the names of the modules. An empty ``DESTINATION`` may be used
    to suppress installing these files (for use in generic code).

  For regular executables, static libraries and shared libraries, the
  ``DESTINATION`` argument is not required.  For these target types, when
  ``DESTINATION`` is omitted, a default destination will be taken from the
  appropriate variable from ``GNUInstallDirs``, or set to a built-in
  default value if that variable is not defined.  The same is true for file
  sets, and the public and private headers associated with the installed
  targets through the ``PUBLIC_HEADER`` and ``PRIVATE_HEADER``
  target properties. A destination must always be provided for module libraries,
  Apple bundles and frameworks.  A destination can be omitted for interface and
  object libraries, but they are handled differently (see the discussion of this
  topic toward the end of this section).

  For shared libraries on DLL platforms, if neither ``RUNTIME`` nor ``ARCHIVE``
  destinations are specified, both the ``RUNTIME`` and ``ARCHIVE`` components are
  installed to their default destinations. If either a ``RUNTIME`` or ``ARCHIVE``
  destination is specified, the component is installed to that destination, and
  the other component is not installed. If both ``RUNTIME`` and ``ARCHIVE``
  destinations are specified, then both components are installed to their
  respective destinations.

  The following table shows the target types with their associated variables and
  built-in defaults that apply when no destination is given:

  =============================== =============================== ======================
     Target Type                      GNUInstallDirs Variable        Built-In Default
  =============================== =============================== ======================
  ``RUNTIME``                     ``${CMAKE_INSTALL_BINDIR}``     ``bin``
  ``LIBRARY``                     ``${CMAKE_INSTALL_LIBDIR}``     ``lib``
  ``ARCHIVE``                     ``${CMAKE_INSTALL_LIBDIR}``     ``lib``
  ``PRIVATE_HEADER``              ``${CMAKE_INSTALL_INCLUDEDIR}`` ``include``
  ``PUBLIC_HEADER``               ``${CMAKE_INSTALL_INCLUDEDIR}`` ``include``
  ``FILE_SET`` (type ``HEADERS``) ``${CMAKE_INSTALL_INCLUDEDIR}`` ``include``
  =============================== =============================== ======================

  Projects wishing to follow the common practice of installing headers into a
  project-specific subdirectory may prefer using file sets with appropriate
  paths and base directories. Otherwise, they must provide a ``DESTINATION``
  instead of being able to rely on the above (see next example below).

  To make packages compliant with distribution filesystem layout policies, if
  projects must specify a ``DESTINATION``, it is strongly recommended that they use
  a path that begins with the appropriate relative ``GNUInstallDirs`` variable.
  This allows package maintainers to control the install destination by setting
  the appropriate cache variables.  The following example shows a static library
  being installed to the default destination provided by
  ``GNUInstallDirs``, but with its headers installed to a project-specific
  subdirectory without using file sets:

  .. code-block:: cmake

    add_library(mylib STATIC ...)
    set_target_properties(mylib PROPERTIES PUBLIC_HEADER mylib.h)
    include(GNUInstallDirs)
    install(TARGETS mylib
            PUBLIC_HEADER
              DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/myproj
    )

  In addition to the common options listed above, each target can accept
  the following additional arguments:

  ``NAMELINK_COMPONENT``
    .. versionadded:: 3.12

    On some platforms a versioned shared library has a symbolic link such
    as::

     lib<name>.so -> lib<name>.so.1

   where ``lib<name>.so.1`` is the soname of the library and ``lib<name>.so``
   is a "namelink" allowing linkers to find the library when given
   ``-l<name>``. The ``NAMELINK_COMPONENT`` option is similar to the
   ``COMPONENT`` option, but it changes the installation component of a shared
   library namelink if one is generated. If not specified, this defaults to the
   value of ``COMPONENT``. It is an error to use this parameter outside of a
   ``LIBRARY`` block.

   .. versionchanged:: 3.27
     This parameter is also usable for an ``ARCHIVE`` block to manage
     the linker import file created, on macOS, for shared libraries with
     :prop_tgt:`ENABLE_EXPORTS` enabled.

   See the `Example: Install Targets with Per-Artifact Components`_
   for an example using ``NAMELINK_COMPONENT``.

   This option is typically used for package managers that have separate
   runtime and development packages. For example, on Debian systems, the
   library is expected to be in the runtime package, and the headers and
   namelink are expected to be in the development package.

   See the :prop_tgt:`VERSION` and :prop_tgt:`SOVERSION` target properties for
   details on creating versioned shared libraries.

 ``NAMELINK_ONLY``
   This option causes the installation of only the namelink when a library
   target is installed. On platforms where versioned shared libraries do not
   have namelinks or when a library is not versioned, the ``NAMELINK_ONLY``
   option installs nothing. It is an error to use this parameter outside of a
   ``LIBRARY`` block.

   .. versionchanged:: 3.27
     This parameter is also usable for an ``ARCHIVE`` block to manage
     the linker import file created, on macOS, for shared libraries with
     :prop_tgt:`ENABLE_EXPORTS` enabled.

   When ``NAMELINK_ONLY`` is given, either ``NAMELINK_COMPONENT`` or
   ``COMPONENT`` may be used to specify the installation component of the
   namelink, but ``COMPONENT`` should generally be preferred.

 ``NAMELINK_SKIP``
   Similar to ``NAMELINK_ONLY``, but it has the opposite effect: it causes the
   installation of library files other than the namelink when a library target
   is installed. When neither ``NAMELINK_ONLY`` or ``NAMELINK_SKIP`` are given,
   both portions are installed. On platforms where versioned shared libraries
   do not have symlinks or when a library is not versioned, ``NAMELINK_SKIP``
   installs the library. It is an error to use this parameter outside of a
   ``LIBRARY`` block.

   .. versionchanged:: 3.27
     This parameter is also usable for an ``ARCHIVE`` block to manage
     the linker import file created, on macOS, for shared libraries with
     :prop_tgt:`ENABLE_EXPORTS` enabled.

   If ``NAMELINK_SKIP`` is specified, ``NAMELINK_COMPONENT`` has no effect. It
   is not recommended to use ``NAMELINK_SKIP`` in conjunction with
   ``NAMELINK_COMPONENT``.

 The :command:`install(TARGETS)` command can also accept the following
 options at the top level:

 ``EXPORT``
   This option associates the installed target files with an export called
   ``<export-name>``.  It must appear before any target options.
   To actually install the export file itself, call
   :command:`install(EXPORT)`, documented below.
   See documentation of the :prop_tgt:`EXPORT_NAME` target property to change
   the name of the exported target.

   If ``EXPORT`` is used and the targets include ``PUBLIC`` or ``INTERFACE``
   file sets, all of them must be specified with ``FILE_SET`` arguments. All
   ``PUBLIC`` or ``INTERFACE`` file sets associated with a target are included
   in the export.

 ``INCLUDES DESTINATION``
   This option specifies a list of directories which will be added to the
   :prop_tgt:`INTERFACE_INCLUDE_DIRECTORIES` target property of the
   ``<targets>`` when exported by the :command:`install(EXPORT)` command.
   If a relative path is specified, it is treated as relative to the
   :genex:`$<INSTALL_PREFIX>`.

 ``RUNTIME_DEPENDENCY_SET <set-name>``
   .. versionadded:: 3.21

   This option causes all runtime dependencies of installed executable, shared
   library, and module targets to be added to the specified runtime dependency
   set. This set can then be installed with an
   :command:`install(RUNTIME_DEPENDENCY_SET)` command.

   This keyword and the ``RUNTIME_DEPENDENCIES`` keyword are mutually
   exclusive.

 ``RUNTIME_DEPENDENCIES <arg>...``
   .. versionadded:: 3.21

   This option causes all runtime dependencies of installed executable, shared
   library, and module targets to be installed along with the targets
   themselves. The ``RUNTIME``, ``LIBRARY``, ``FRAMEWORK``, and generic
   arguments are used to determine the properties (``DESTINATION``,
   ``COMPONENT``, etc.) of the installation of these dependencies.

   ``RUNTIME_DEPENDENCIES`` is semantically equivalent to the following pair
   of calls:

   .. code-block:: cmake

     install(TARGETS ... RUNTIME_DEPENDENCY_SET <set-name>)
     install(RUNTIME_DEPENDENCY_SET <set-name> <arg>...)

   where ``<set-name>`` will be a randomly generated set name.
   ``<arg>...`` may include any of the following keywords supported by
   the :command:`install(RUNTIME_DEPENDENCY_SET)` command:

   * ``DIRECTORIES``
   * ``PRE_INCLUDE_REGEXES``
   * ``PRE_EXCLUDE_REGEXES``
   * ``POST_INCLUDE_REGEXES``
   * ``POST_EXCLUDE_REGEXES``
   * ``POST_INCLUDE_FILES``
   * ``POST_EXCLUDE_FILES``

   The ``RUNTIME_DEPENDENCIES`` and ``RUNTIME_DEPENDENCY_SET`` keywords are
   mutually exclusive.

 :ref:`Interface Libraries` may be listed among the targets to install.
 They install no artifacts but will be included in an associated ``EXPORT``.
 If :ref:`Object Libraries` are listed but given no destination for their
 object files, they will be exported as :ref:`Interface Libraries`.
 This is sufficient to satisfy transitive usage requirements of other
 targets that link to the object libraries in their implementation.

 Installing a target with the :prop_tgt:`EXCLUDE_FROM_ALL` target property
 set to ``TRUE`` has undefined behavior.

 .. versionadded:: 3.3
   An install destination given as a ``DESTINATION`` argument may
   use "generator expressions" with the syntax ``$<...>``.  See the
   :manual:`cmake-generator-expressions(7)` manual for available expressions.

 .. versionadded:: 3.13
   :command:`install(TARGETS)` can install targets that were created in
   other directories.  When using such cross-directory install rules, running
   ``make install`` (or similar) from a subdirectory will not guarantee that
   targets from other directories are up-to-date.  You can use
   :command:`target_link_libraries` or :command:`add_dependencies`
   to ensure that such out-of-directory targets are built before the
   subdirectory-specific install rules are run.

.. signature::
  install(IMPORTED_RUNTIME_ARTIFACTS <target>... [...])

  .. versionadded:: 3.21

  Install runtime artifacts of imported targets:

  .. code-block:: cmake

    install(IMPORTED_RUNTIME_ARTIFACTS <target>...
            [RUNTIME_DEPENDENCY_SET <set-name>]
            [[LIBRARY|RUNTIME|FRAMEWORK|BUNDLE]
             [DESTINATION <dir>]
             [PERMISSIONS <permission>...]
             [CONFIGURATIONS <config>...]
             [COMPONENT <component>]
             [OPTIONAL] [EXCLUDE_FROM_ALL]
            ] [...]
            )

  The ``IMPORTED_RUNTIME_ARTIFACTS`` form specifies rules for installing the
  runtime artifacts of imported targets. Projects may do this if they want to
  bundle outside executables or modules inside their installation. The
  ``LIBRARY``, ``RUNTIME``, ``FRAMEWORK``, and ``BUNDLE`` arguments have the
  same semantics that they do in the TARGETS mode. Only the runtime artifacts
  of imported targets are installed (except in the case of ``FRAMEWORK``
  libraries, ``MACOSX_BUNDLE`` executables, and ``BUNDLE``
  CFBundles.) For example, headers and import libraries associated with DLLs are
  not installed. In the case of ``FRAMEWORK`` libraries,
  ``MACOSX_BUNDLE`` executables, and ``BUNDLE`` CFBundles, the
  entire directory is installed.

  The ``RUNTIME_DEPENDENCY_SET`` option causes the runtime artifacts of the
  imported executable, shared library, and module library ``targets`` to be
  added to the ``<set-name>`` runtime dependency set. This set can then be
  installed with an ``install(RUNTIME_DEPENDENCY_SET)`` command.

.. signature::
  install(FILES <file>... [...])
  install(PROGRAMS <program>... [...])

  .. note::

   If installing header files, consider using file sets defined by
   :command:`target_sources(FILE_SET)` instead. File sets associate
   headers with a target and they install as part of the target.

 Install files or programs:

 .. code-block:: cmake

   install(<FILES|PROGRAMS> <file>...
           TYPE <type> | DESTINATION <dir>
           [PERMISSIONS <permission>...]
           [CONFIGURATIONS <config>...]
           [COMPONENT <component>]
           [RENAME <name>] [OPTIONAL] [EXCLUDE_FROM_ALL])

 The ``FILES`` form specifies rules for installing files for a project.
 File names given as relative paths are interpreted with respect to the
 current source directory.  Files installed by this form are by default
 given permissions ``OWNER_WRITE``, ``OWNER_READ``, ``GROUP_READ``, and
 ``WORLD_READ`` if no ``PERMISSIONS`` argument is given.

 The ``PROGRAMS`` form is identical to the ``FILES`` form except that the
 default permissions for the installed file also include ``OWNER_EXECUTE``,
 ``GROUP_EXECUTE``, and ``WORLD_EXECUTE``.  This form is intended to install
 programs that are not targets, such as shell scripts.  Use the ``TARGETS``
 form to install targets built within the project.

 The list of ``files...`` given to ``FILES`` or ``PROGRAMS`` may use
 "generator expressions" with the syntax ``$<...>``.  See the
 :manual:`cmake-generator-expressions(7)` manual for available expressions.
 However, if any item begins in a generator expression it must evaluate
 to a full path.

 Either a ``TYPE`` or a ``DESTINATION`` must be provided, but not both.
 A ``TYPE`` argument specifies the generic file type of the files being
 installed.  A destination will then be set automatically by taking the
 corresponding variable from :module:`GNUInstallDirs`, or by using a
 built-in default if that variable is not defined.  See the table below for
 the supported file types and their corresponding variables and built-in
 defaults.  Projects can provide a ``DESTINATION`` argument instead of a
 file type if they wish to explicitly define the install destination.

 ======================= ================================== =========================
    ``TYPE`` Argument         GNUInstallDirs Variable           Built-In Default
 ======================= ================================== =========================
 ``BIN``                 ``${CMAKE_INSTALL_BINDIR}``        ``bin``
 ``SBIN``                ``${CMAKE_INSTALL_SBINDIR}``       ``sbin``
 ``LIB``                 ``${CMAKE_INSTALL_LIBDIR}``        ``lib``
 ``INCLUDE``             ``${CMAKE_INSTALL_INCLUDEDIR}``    ``include``
 ``SYSCONF``             ``${CMAKE_INSTALL_SYSCONFDIR}``    ``etc``
 ``SHAREDSTATE``         ``${CMAKE_INSTALL_SHARESTATEDIR}`` ``com``
 ``LOCALSTATE``          ``${CMAKE_INSTALL_LOCALSTATEDIR}`` ``var``
 ``RUNSTATE``            ``${CMAKE_INSTALL_RUNSTATEDIR}``   ``<LOCALSTATE dir>/run``
 ``DATA``                ``${CMAKE_INSTALL_DATADIR}``       ``<DATAROOT dir>``
 ``INFO``                ``${CMAKE_INSTALL_INFODIR}``       ``<DATAROOT dir>/info``
 ``LOCALE``              ``${CMAKE_INSTALL_LOCALEDIR}``     ``<DATAROOT dir>/locale``
 ``MAN``                 ``${CMAKE_INSTALL_MANDIR}``        ``<DATAROOT dir>/man``
 ``DOC``                 ``${CMAKE_INSTALL_DOCDIR}``        ``<DATAROOT dir>/doc``
 ======================= ================================== =========================

 Projects wishing to follow the common practice of installing headers into a
 project-specific subdirectory will need to provide a destination rather than
 rely on the above. Using file sets for headers instead of ``install(FILES)``
 would be even better (see :command:`target_sources(FILE_SET)`).

 Note that some of the types' built-in defaults use the ``DATAROOT`` directory as
 a prefix. The ``DATAROOT`` prefix is calculated similarly to the types, with
 ``CMAKE_INSTALL_DATAROOTDIR`` as the variable and ``share`` as the built-in
 default. You cannot use ``DATAROOT`` as a ``TYPE`` parameter; please use
 ``DATA`` instead.

 To make packages compliant with distribution filesystem layout policies, if
 projects must specify a ``DESTINATION``, it is strongly recommended that they use
 a path that begins with the appropriate relative :module:`GNUInstallDirs` variable.
 This allows package maintainers to control the install destination by setting
 the appropriate cache variables.  The following example shows how to follow
 this advice while installing an image to a project-specific documentation
 subdirectory:

 .. code-block:: cmake

   include(GNUInstallDirs)
   install(FILES logo.png
           DESTINATION ${CMAKE_INSTALL_DOCDIR}/myproj
   )

 .. versionadded:: 3.4
   An install destination given as a ``DESTINATION`` argument may
   use "generator expressions" with the syntax ``$<...>``.  See the
   :manual:`cmake-generator-expressions(7)` manual for available expressions.

 .. versionadded:: 3.20
   An install rename given as a ``RENAME`` argument may
   use "generator expressions" with the syntax ``$<...>``.  See the
   :manual:`cmake-generator-expressions(7)` manual for available expressions.

.. signature::
  install(DIRECTORY <dir>... [...])

  .. note::

   To install a directory sub-tree of headers, consider using file sets
   defined by :command:`target_sources(FILE_SET)` instead. File sets not only
   preserve directory structure, they also associate headers with a target
   and install as part of the target.

 Install the contents of one or more directories:

 .. code-block:: cmake

   install(DIRECTORY dirs...
           TYPE <type> | DESTINATION <dir>
           [FILE_PERMISSIONS <permission>...]
           [DIRECTORY_PERMISSIONS <permission>...]
           [USE_SOURCE_PERMISSIONS] [OPTIONAL] [MESSAGE_NEVER]
           [CONFIGURATIONS <config>...]
           [COMPONENT <component>] [EXCLUDE_FROM_ALL]
           [FILES_MATCHING]
           [[PATTERN <pattern> | REGEX <regex>]
            [EXCLUDE] [PERMISSIONS <permission>...]] [...])

 The ``DIRECTORY`` form installs contents of one or more directories to a
 given destination.  The directory structure is copied verbatim to the
 destination.  The last component of each directory name is appended to
 the destination directory but a trailing slash may be used to avoid
 this because it leaves the last component empty.  Directory names
 given as relative paths are interpreted with respect to the current
 source directory.  If no input directory names are given the
 destination directory will be created but nothing will be installed
 into it.  The ``FILE_PERMISSIONS`` and ``DIRECTORY_PERMISSIONS`` options
 specify permissions given to files and directories in the destination.
 If ``USE_SOURCE_PERMISSIONS`` is specified and ``FILE_PERMISSIONS`` is not,
 file permissions will be copied from the source directory structure.
 If no permissions are specified files will be given the default
 permissions specified in the ``FILES`` form of the command, and the
 directories will be given the default permissions specified in the
 ``PROGRAMS`` form of the command.

 .. versionadded:: 3.1
   The ``MESSAGE_NEVER`` option disables file installation status output.

 Installation of directories may be controlled with fine granularity
 using the ``PATTERN`` or ``REGEX`` options.  These "match" options specify a
 globbing pattern or regular expression to match directories or files
 encountered within input directories.  They may be used to apply
 certain options (see below) to a subset of the files and directories
 encountered.  The full path to each input file or directory (with
 forward slashes) is matched against the expression.  A ``PATTERN`` will
 match only complete file names: the portion of the full path matching
 the pattern must occur at the end of the file name and be preceded by
 a slash.  A ``REGEX`` will match any portion of the full path but it may
 use ``/`` and ``$`` to simulate the ``PATTERN`` behavior.  By default all
 files and directories are installed whether or not they are matched.
 The ``FILES_MATCHING`` option may be given before the first match option
 to disable installation of files (but not directories) not matched by
 any expression.  For example, the code

 .. code-block:: cmake

   install(DIRECTORY src/ DESTINATION doc/myproj
           FILES_MATCHING PATTERN "*.png")

 will extract and install images from a source tree.

 Some options may follow a ``PATTERN`` or ``REGEX`` expression as described
 under :ref:`string(REGEX) <Regex Specification>` and are applied
 only to files or directories matching them.  The ``EXCLUDE`` option will
 skip the matched file or directory.  The ``PERMISSIONS`` option overrides
 the permissions setting for the matched file or directory.  For
 example the code

 .. code-block:: cmake

   install(DIRECTORY icons scripts/ DESTINATION share/myproj
           PATTERN "CVS" EXCLUDE
           PATTERN "scripts/*"
           PERMISSIONS OWNER_EXECUTE OWNER_WRITE OWNER_READ
                       GROUP_EXECUTE GROUP_READ)

 will install the ``icons`` directory to ``share/myproj/icons`` and the
 ``scripts`` directory to ``share/myproj``.  The icons will get default
 file permissions, the scripts will be given specific permissions, and any
 ``CVS`` directories will be excluded.

 Either a ``TYPE`` or a ``DESTINATION`` must be provided, but not both.
 A ``TYPE`` argument specifies the generic file type of the files within the
 listed directories being installed.  A destination will then be set
 automatically by taking the corresponding variable from
 :module:`GNUInstallDirs`, or by using a built-in default if that variable
 is not defined.  See the table below for the supported file types and their
 corresponding variables and built-in defaults.  Projects can provide a
 ``DESTINATION`` argument instead of a file type if they wish to explicitly
 define the install destination.

 ======================= ================================== =========================
    ``TYPE`` Argument         GNUInstallDirs Variable           Built-In Default
 ======================= ================================== =========================
 ``BIN``                 ``${CMAKE_INSTALL_BINDIR}``        ``bin``
 ``SBIN``                ``${CMAKE_INSTALL_SBINDIR}``       ``sbin``
 ``LIB``                 ``${CMAKE_INSTALL_LIBDIR}``        ``lib``
 ``INCLUDE``             ``${CMAKE_INSTALL_INCLUDEDIR}``    ``include``
 ``SYSCONF``             ``${CMAKE_INSTALL_SYSCONFDIR}``    ``etc``
 ``SHAREDSTATE``         ``${CMAKE_INSTALL_SHARESTATEDIR}`` ``com``
 ``LOCALSTATE``          ``${CMAKE_INSTALL_LOCALSTATEDIR}`` ``var``
 ``RUNSTATE``            ``${CMAKE_INSTALL_RUNSTATEDIR}``   ``<LOCALSTATE dir>/run``
 ``DATA``                ``${CMAKE_INSTALL_DATADIR}``       ``<DATAROOT dir>``
 ``INFO``                ``${CMAKE_INSTALL_INFODIR}``       ``<DATAROOT dir>/info``
 ``LOCALE``              ``${CMAKE_INSTALL_LOCALEDIR}``     ``<DATAROOT dir>/locale``
 ``MAN``                 ``${CMAKE_INSTALL_MANDIR}``        ``<DATAROOT dir>/man``
 ``DOC``                 ``${CMAKE_INSTALL_DOCDIR}``        ``<DATAROOT dir>/doc``
 ======================= ================================== =========================

 Note that some of the types' built-in defaults use the ``DATAROOT`` directory as
 a prefix. The ``DATAROOT`` prefix is calculated similarly to the types, with
 ``CMAKE_INSTALL_DATAROOTDIR`` as the variable and ``share`` as the built-in
 default. You cannot use ``DATAROOT`` as a ``TYPE`` parameter; please use
 ``DATA`` instead.

 To make packages compliant with distribution filesystem layout policies, if
 projects must specify a ``DESTINATION``, it is strongly recommended that they use
 a path that begins with the appropriate relative :module:`GNUInstallDirs` variable.
 This allows package maintainers to control the install destination by setting
 the appropriate cache variables.

 .. versionadded:: 3.4
   An install destination given as a ``DESTINATION`` argument may
   use "generator expressions" with the syntax ``$<...>``.  See the
   :manual:`cmake-generator-expressions(7)` manual for available expressions.

 .. versionadded:: 3.5
   The list of ``dirs...`` given to ``DIRECTORY`` may use
   "generator expressions" too.

.. signature::
  install(SCRIPT <file> [...])
  install(CODE <code> [...])

  Invoke CMake scripts or code during installation:

  .. code-block:: cmake

    install([[SCRIPT <file>] [CODE <code>]]
            [ALL_COMPONENTS | COMPONENT <component>]
            [EXCLUDE_FROM_ALL] [...])

  The ``SCRIPT`` form will invoke the given CMake script files during
  installation.  If the script file name is a relative path it will be
  interpreted with respect to the current source directory.  The ``CODE``
  form will invoke the given CMake code during installation.  Code is
  specified as a single argument inside a double-quoted string.  For
  example, the code

  .. code-block:: cmake

    install(CODE "MESSAGE(\"Sample install message.\")")

  will print a message during installation.

  .. versionadded:: 3.21
    When the ``ALL_COMPONENTS`` option is given, the custom installation
    script code will be executed for every component of a component-specific
    installation.  This option is mutually exclusive with the ``COMPONENT``
    option.

  .. versionadded:: 3.14
    ``<file>`` or ``<code>`` may use "generator expressions" with the syntax
    ``$<...>`` (in the case of ``<file>``, this refers to their use in the file
    name, not the file's contents).  See the
    ``cmake-generator-expressions(7)`` manual for available expressions.

.. signature::
  install(EXPORT <export-name> [...])

  Install a CMake file exporting targets for dependent projects:

  .. code-block:: cmake

    install(EXPORT <export-name> DESTINATION <dir>
            [NAMESPACE <namespace>] [FILE <name>.cmake]
            [PERMISSIONS <permission>...]
            [CONFIGURATIONS <config>...]
            [CXX_MODULES_DIRECTORY <directory>]
            [EXPORT_LINK_INTERFACE_LIBRARIES]
            [COMPONENT <component>]
            [EXCLUDE_FROM_ALL]
            [EXPORT_PACKAGE_DEPENDENCIES])
    install(EXPORT_ANDROID_MK <export-name> DESTINATION <dir> [...])

  The ``EXPORT`` form generates and installs a CMake file containing code to
  import targets from the installation tree into another project.
  Target installations are associated with the export ``<export-name>``
  using the ``EXPORT`` option of the ``install(TARGETS)`` signature
  documented above.  The ``NAMESPACE`` option will prepend ``<namespace>`` to
  the target names as they are written to the import file.  By default
  the generated file will be called ``<export-name>.cmake`` but the ``FILE``
  option may be used to specify a different name.  The value given to
  the ``FILE`` option must be a file name with the ``.cmake`` extension.
  If a ``CONFIGURATIONS`` option is given then the file will only be installed
  when one of the named configurations is installed.  Additionally, the
  generated import file will reference only the matching target
  configurations.  See the ``CMAKE_MAP_IMPORTED_CONFIG_<CONFIG>``
  variable to map configurations of dependent projects to the installed
  configurations.  The ``EXPORT_LINK_INTERFACE_LIBRARIES`` keyword, if
  present, causes the contents of the properties matching
  ``(IMPORTED_)?LINK_INTERFACE_LIBRARIES(_<CONFIG>)?`` to be exported, when
  policy ``CMP0022`` is ``NEW``.

  .. note::
    The installed ``<export-name>.cmake`` file may come with additional
    per-configuration ``<export-name>-*.cmake`` files to be loaded by
    globbing.  Do not use an export name that is the same as the package
    name in combination with installing a ``<package-name>-config.cmake``
    file or the latter may be incorrectly matched by the glob and loaded.

  When a ``COMPONENT`` option is given, the listed ``<component>`` implicitly
  depends on all components mentioned in the export set. The exported
  ``<name>.cmake`` file will require each of the exported components to be
  present in order for dependent projects to build properly. For example, a
  project may define components ``Runtime`` and ``Development``, with shared
  libraries going into the ``Runtime`` component and static libraries and
  headers going into the ``Development`` component. The export set would also
  typically be part of the ``Development`` component, but it would export
  targets from both the ``Runtime`` and ``Development`` components. Therefore,
  the ``Runtime`` component would need to be installed if the ``Development``
  component was installed, but not vice versa. If the ``Development`` component
  was installed without the ``Runtime`` component, dependent projects that try
  to link against it would have build errors. Package managers, such as APT and
  RPM, typically handle this by listing the ``Runtime`` component as a dependency
  of the ``Development`` component in the package metadata, ensuring that the
  library is always installed if the headers and CMake export file are present.

  .. versionadded:: 3.7
    In addition to cmake language files, the ``EXPORT_ANDROID_MK`` mode may be
    used to specify an export to the android ndk build system.  This mode
    accepts the same options as the normal export mode.  The Android
    NDK supports the use of prebuilt libraries, both static and shared. This
    allows cmake to build the libraries of a project and make them available
    to an ndk build system complete with transitive dependencies, include flags
    and defines required to use the libraries.

  ``CXX_MODULES_DIRECTORY``
    .. versionadded:: 3.28

    Specify a subdirectory to store C++ module information for targets in the
    export set. This directory will be populated with files which add the
    necessary target property information to the relevant targets. Note that
    without this information, none of the C++ modules which are part of the
    targets in the export set will support being imported in consuming targets.

  ``EXPORT_PACKAGE_DEPENDENCIES``
    .. note::

     Experimental. Gated by ``CMAKE_EXPERIMENTAL_EXPORT_PACKAGE_DEPENDENCIES``.

   Specify that :command:`find_dependency` calls should be exported. If this
   argument is specified, CMake examines all targets in the export set and
   gathers their ``INTERFACE`` link targets. If any such targets either were
   found with :command:`find_package` or have the
   :prop_tgt:`EXPORT_FIND_PACKAGE_NAME` property set, and such package
   dependency was not disabled by passing ``ENABLED OFF`` to
   :command:`export(SETUP)`, then a :command:`find_dependency` call is
   written with the target's corresponding package name, a ``REQUIRED``
   argument, and any additional arguments specified by the ``EXTRA_ARGS``
   argument of :command:`export(SETUP)`. Any package dependencies that were
   manually specified by passing ``ENABLED ON`` to :command:`export(SETUP)`
   are also added, even if the exported targets don't depend on any targets
   from them.

   The :command:`find_dependency` calls are written in the following order:

   1. Any package dependencies that were listed in :command:`export(SETUP)`
      are written in the order they were first specified, regardless of
      whether or not they contain ``INTERFACE`` dependencies of the
      exported targets.
   2. Any package dependencies that contain ``INTERFACE`` link dependencies
      of the exported targets and that were never specified in
      :command:`export(SETUP)` are written in the order they were first
      found.

 The ``EXPORT`` form is useful to help outside projects use targets built
 and installed by the current project.  For example, the code

 .. code-block:: cmake

   install(TARGETS myexe EXPORT myproj DESTINATION bin)
   install(EXPORT myproj NAMESPACE mp_ DESTINATION lib/myproj)
   install(EXPORT_ANDROID_MK myproj DESTINATION share/ndk-modules)

 will install the executable ``myexe`` to ``<prefix>/bin`` and code to import
 it in the file ``<prefix>/lib/myproj/myproj.cmake`` and
 ``<prefix>/share/ndk-modules/Android.mk``.  An outside project
 may load this file with the include command and reference the ``myexe``
 executable from the installation tree using the imported target name
 ``mp_myexe`` as if the target were built in its own tree.

.. signature::
  install(RUNTIME_DEPENDENCY_SET <set-name> [...])

  .. versionadded:: 3.21

  Installs a runtime dependency set:

  .. code-block:: cmake

    install(RUNTIME_DEPENDENCY_SET <set-name>
            [[LIBRARY|RUNTIME|FRAMEWORK]
             [DESTINATION <dir>]
             [PERMISSIONS <permission>...]
             [CONFIGURATIONS <config>...]
             [COMPONENT <component>]
             [NAMELINK_COMPONENT <component>]
             [OPTIONAL] [EXCLUDE_FROM_ALL]
            ] [...]
            [PRE_INCLUDE_REGEXES <regex>...]
            [PRE_EXCLUDE_REGEXES <regex>...]
            [POST_INCLUDE_REGEXES <regex>...]
            [POST_EXCLUDE_REGEXES <regex>...]
            [POST_INCLUDE_FILES <file>...]
            [POST_EXCLUDE_FILES <file>...]
            [DIRECTORIES <dir>...]
            )

  Installs a runtime dependency set previously created by one or more
  ``install(TARGETS)`` or ``install(IMPORTED_RUNTIME_ARTIFACTS)``
  commands.  The dependencies of targets belonging to a runtime dependency set
  are installed in the ``RUNTIME`` destination and component on DLL platforms,
  and in the ``LIBRARY`` destination and component on non-DLL platforms.
  macOS frameworks are installed in the ``FRAMEWORK`` destination and component.
  Targets built within the build tree will never be installed as runtime
  dependencies, nor will their own dependencies, unless the targets themselves
  are installed with ``install(TARGETS)``.

  The generated install script calls ``file(GET_RUNTIME_DEPENDENCIES)``
  on the build-tree files to calculate the runtime dependencies. The build-tree
  executable files are passed as the ``EXECUTABLES`` argument, the build-tree
  shared libraries as the ``LIBRARIES`` argument, and the build-tree modules as
  the ``MODULES`` argument. On macOS, if one of the executables is a
  ``MACOSX_BUNDLE``, that executable is passed as the
  ``BUNDLE_EXECUTABLE`` argument. At most one such bundle executable may be in
  the runtime dependency set on macOS. The ``MACOSX_BUNDLE`` property
  has no effect on other platforms. Note that
  ``file(GET_RUNTIME_DEPENDENCIES)`` only supports collecting the runtime
  dependencies for Windows, Linux and macOS platforms, so
  ``install(RUNTIME_DEPENDENCY_SET)`` has the same limitation.

  The following sub-arguments are forwarded through as the corresponding
  arguments to ``file(GET_RUNTIME_DEPENDENCIES)`` (for those that provide
  a non-empty list of directories, regular expressions or files).  They all
  support ``generator expressions``.

  * ``DIRECTORIES <dir>...``
  * ``PRE_INCLUDE_REGEXES <regex>...``
  * ``PRE_EXCLUDE_REGEXES <regex>...``
  * ``POST_INCLUDE_REGEXES <regex>...``
  * ``POST_EXCLUDE_REGEXES <regex>...``
  * ``POST_INCLUDE_FILES <file>...``
  * ``POST_EXCLUDE_FILES <file>...``

.. note::
  This command supersedes the ``install_targets()`` command and
  the ``PRE_INSTALL_SCRIPT`` and ``POST_INSTALL_SCRIPT``
  target properties.  It also replaces the ``FILES`` forms of the
  ``install_files()`` and ``install_programs()`` commands.
  The processing order of these install rules relative to
  those generated by ``install_targets()``,
  ``install_files()``, and ``install_programs()`` commands
  is not defined.

Examples
^^^^^^^^

Example: Install Targets with Per-Artifact Components
"""""""""""""""""""""""""""""""""""""""""""""""""""""

Consider a project that defines targets with different artifact kinds:

 add_executable(myExe myExe.c)
 add_library(myStaticLib STATIC myStaticLib.c)
 target_sources(myStaticLib PUBLIC FILE_SET HEADERS FILES myStaticLib.h)
 add_library(mySharedLib SHARED mySharedLib.c)
 target_sources(mySharedLib PUBLIC FILE_SET HEADERS FILES mySharedLib.h)
 set_property(TARGET mySharedLib PROPERTY SOVERSION 1)

We may call ``install(TARGETS)`` with <artifact-kind> arguments
to specify different options for each kind of artifact:

 install(TARGETS
           myExe
           mySharedLib
           myStaticLib
         RUNTIME           # Following options apply to runtime artifacts.
           COMPONENT Runtime
         LIBRARY           # Following options apply to library artifacts.
           COMPONENT Runtime
           NAMELINK_COMPONENT Development
         ARCHIVE           # Following options apply to archive artifacts.
           COMPONENT Development
           DESTINATION lib/static
         FILE_SET HEADERS  # Following options apply to file set HEADERS.
           COMPONENT Development
         )

This will:

* Install ``myExe`` to ``<prefix>/bin``, the default RUNTIME artifact
  destination, as part of the ``Runtime`` component.

* On non-DLL platforms:

  * Install ``libmySharedLib.so.1`` to ``<prefix>/lib``, the default
    LIBRARY artifact destination, as part of the ``Runtime`` component.

  * Install the ``libmySharedLib.so`` "namelink" (symbolic link) to
    ``<prefix>/lib``, the default LIBRARY artifact destination, as part
    of the ``Development`` component.

* On DLL platforms:

  * Install ``mySharedLib.dll`` to ``<prefix>/bin``, the default RUNTIME
    artifact destination, as part of the ``Runtime`` component.

  * Install ``mySharedLib.lib`` to ``<prefix>/lib/static``, the specified
    ARCHIVE artifact destination, as part of the ``Development`` component.

* Install ``myStaticLib`` to ``<prefix>/lib/static``, the specified
  ARCHIVE artifact destination, as part of the ``Development`` component.

* Install ``mySharedLib.h`` and ``myStaticLib.h`` to ``<prefix>/include``,
  the default destination for a file set of type HEADERS, as part of the
  ``Development`` component.

Example: Install Targets to Per-Config Destinations
"""""""""""""""""""""""""""""""""""""""""""""""""""

Each ``install(TARGETS)`` call installs a given target
:ref:`output artifact <Output Artifacts>` to at most one ``DESTINATION``,
but the install rule itself may be filtered by the ``CONFIGURATIONS`` option.
In order to install to a different destination for each configuration, one
call per configuration is needed.  For example, the code:

 install(TARGETS myExe
         CONFIGURATIONS Debug
         RUNTIME
           DESTINATION Debug/bin
         )
 install(TARGETS myExe
         CONFIGURATIONS Release
         RUNTIME
           DESTINATION Release/bin
         )

will install ``myExe`` to ``<prefix>/Debug/bin`` in the Debug configuration,
and to ``<prefix>/Release/bin`` in the Release configuration.

Generated Installation Script
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. note::

  Use of this feature is not recommended. Please consider using the
  :option:`cmake --install` instead.

The ``install()`` command generates a file, ``cmake_install.cmake``, inside
the build directory, which is used internally by the generated install target
and by CPack. You can also invoke this script manually with
:option:`cmake -P`. This script accepts several variables:

``COMPONENT``
  Set this variable to install only a single CPack component as opposed to all
  of them. For example, if you only want to install the ``Development``
  component, run ``cmake -DCOMPONENT=Development -P cmake_install.cmake``.

``BUILD_TYPE``
  Set this variable to change the build type if you are using a multi-config
  generator. For example, to install with the ``Debug`` configuration, run
  ``cmake -DBUILD_TYPE=Debug -P cmake_install.cmake``.

``DESTDIR``
  This is an environment variable rather than a CMake variable. It allows you
  to change the installation prefix on UNIX systems. See ``DESTDIR`` for
  details.

link_directories
----------------

Add directories in which the linker will look for libraries.

 link_directories([AFTER|BEFORE] directory1 [directory2 ...])

Adds the paths in which the linker should search for libraries.
Relative paths given to this command are interpreted as relative to
the current source directory, see ``CMP0015``.

The command will apply only to targets created after it is called.

.. versionadded:: 3.13
  The directories are added to the ``LINK_DIRECTORIES`` directory
  property for the current ``CMakeLists.txt`` file, converting relative
  paths to absolute as needed.  See the ``cmake-buildsystem(7)``
  manual for more on defining buildsystem properties.

.. versionadded:: 3.13
  By default the directories specified are appended onto the current list of
  directories.  This default behavior can be changed by setting
  ``CMAKE_LINK_DIRECTORIES_BEFORE`` to ``ON``.  By using
  ``AFTER`` or ``BEFORE`` explicitly, you can select between appending and
  prepending, independent of the default.

.. versionadded:: 3.13
  Arguments to ``link_directories`` may use "generator expressions" with
  the syntax "$<...>".  See the ``cmake-generator-expressions(7)``
  manual for available expressions.

.. note::

  This command is rarely necessary and should be avoided where there are
  other choices.  Prefer to pass full absolute paths to libraries where
  possible, since this ensures the correct library will always be linked.
  The ``find_library()`` command provides the full path, which can
  generally be used directly in calls to ``target_link_libraries()``.
  Situations where a library search path may be needed include:

  - Project generators like Xcode where the user can switch target
    architecture at build time, but a full path to a library cannot
    be used because it only provides one architecture (i.e. it is not
    a universal binary).
  - Libraries may themselves have other private library dependencies
    that expect to be found via ``RPATH`` mechanisms, but some linkers
    are not able to fully decode those paths (e.g. due to the presence
    of things like ``$ORIGIN``).

  If a library search path must be provided, prefer to localize the effect
  where possible by using the ``target_link_directories()`` command
  rather than ``link_directories()``.  The target-specific command can also
  control how the search directories propagate to other dependent targets.

See Also
^^^^^^^^

* ``target_link_directories()``
* ``target_link_libraries()``

link_libraries
--------------

Link libraries to all targets added later.

 link_libraries([item1 [item2 [...]]]
                [[debug|optimized|general] <item>] ...)

Specify libraries or flags to use when linking any targets created later in
the current directory or below by commands such as ``add_executable()``
or ``add_library()``.  See the ``target_link_libraries()`` command
for meaning of arguments.

.. note::
  The ``target_link_libraries()`` command should be preferred whenever
  possible.  Library dependencies are chained automatically, so directory-wide
  specification of link libraries is rarely needed.

load_cache
----------

Load in the values from another project's CMake cache.

 load_cache(pathToBuildDirectory READ_WITH_PREFIX prefix entry1...)

Reads the cache and store the requested entries in variables with their
name prefixed with the given prefix.  This only reads the values, and
does not create entries in the local project's cache.

 load_cache(pathToBuildDirectory [EXCLUDE entry1...]
            [INCLUDE_INTERNALS entry1...])

Loads in the values from another cache and store them in the local
project's cache as internal entries.  This is useful for a project
that depends on another project built in a different tree.  ``EXCLUDE``
option can be used to provide a list of entries to be excluded.
``INCLUDE_INTERNALS`` can be used to provide a list of internal entries to
be included.  Normally, no internal entries are brought in.  Use of
this form of the command is strongly discouraged, but it is provided
for backward compatibility.

project
-------

Set the name of the project.

Synopsis
^^^^^^^^

 project(<PROJECT-NAME> [<language-name>...])
 project(<PROJECT-NAME>
         [VERSION <major>[.<minor>[.<patch>[.<tweak>]]]]
         [DESCRIPTION <project-description-string>]
         [HOMEPAGE_URL <url-string>]
         [LANGUAGES <language-name>...])

Sets the name of the project, and stores it in the variable
``PROJECT_NAME``. When called from the top-level
``CMakeLists.txt`` also stores the project name in the
variable ``CMAKE_PROJECT_NAME``.

Also sets the variables:

``PROJECT_SOURCE_DIR``, ``<PROJECT-NAME>_SOURCE_DIR``
  Absolute path to the source directory for the project.

``PROJECT_BINARY_DIR``, ``<PROJECT-NAME>_BINARY_DIR``
  Absolute path to the binary directory for the project.

``PROJECT_IS_TOP_LEVEL``, ``<PROJECT-NAME>_IS_TOP_LEVEL``
  .. versionadded:: 3.21

  Boolean value indicating whether the project is top-level.

Further variables are set by the optional arguments described in the following.
If any of these arguments is not used, then the corresponding variables are
set to the empty string.

Options
^^^^^^^

The options are:

``VERSION <version>``
  Optional; may not be used unless policy ``CMP0048`` is
  set to ``NEW``.

  Takes a ``<version>`` argument composed of non-negative integer components,
  i.e. ``<major>[.<minor>[.<patch>[.<tweak>]]]``,
  and sets the variables

  * ``PROJECT_VERSION``,
    ``<PROJECT-NAME>_VERSION``
  * ``PROJECT_VERSION_MAJOR``,
    ``<PROJECT-NAME>_VERSION_MAJOR``
  * ``PROJECT_VERSION_MINOR``,
    ``<PROJECT-NAME>_VERSION_MINOR``
  * ``PROJECT_VERSION_PATCH``,
    ``<PROJECT-NAME>_VERSION_PATCH``
  * ``PROJECT_VERSION_TWEAK``,
    ``<PROJECT-NAME>_VERSION_TWEAK``.

  .. versionadded:: 3.12
    When the ``project()`` command is called from the top-level
    ``CMakeLists.txt``, then the version is also stored in the variable
    ``CMAKE_PROJECT_VERSION``.

``DESCRIPTION <project-description-string>``
  .. versionadded:: 3.9

  Optional.
  Sets the variables

  * ``PROJECT_DESCRIPTION``, ``<PROJECT-NAME>_DESCRIPTION``

  to ``<project-description-string>``.
  It is recommended that this description is a relatively short string,
  usually no more than a few words.

  When the ``project()`` command is called from the top-level ``CMakeLists.txt``,
  then the description is also stored in the variable ``CMAKE_PROJECT_DESCRIPTION``.

  .. versionadded:: 3.12
    Added the ``<PROJECT-NAME>_DESCRIPTION`` variable.

``HOMEPAGE_URL <url-string>``
  .. versionadded:: 3.12

  Optional.
  Sets the variables

  * ``PROJECT_HOMEPAGE_URL``, ``<PROJECT-NAME>_HOMEPAGE_URL``

  to ``<url-string>``, which should be the canonical home URL for the project.

  When the ``project()`` command is called from the top-level ``CMakeLists.txt``,
  then the URL also is stored in the variable ``CMAKE_PROJECT_HOMEPAGE_URL``.

``LANGUAGES <language-name>...``
  Optional.
  Can also be specified without ``LANGUAGES`` keyword per the first, short signature.

  Selects which programming languages are needed to build the project.


Supported languages are ``C``, ``CXX`` (i.e.  C++), ``CSharp`` (i.e.  C#), ``CUDA``,
``OBJC`` (i.e. Objective-C), ``OBJCXX`` (i.e. Objective-C++), ``Fortran``, ``HIP``,
``ISPC``, ``Swift``, ``ASM``, ``ASM_NASM``, ``ASM_MARMASM``, ``ASM_MASM``, and ``ASM-ATT``.

  .. versionadded:: 3.8
    Added ``CSharp`` and ``CUDA`` support.

  .. versionadded:: 3.15
    Added ``Swift`` support.

  .. versionadded:: 3.16
    Added ``OBJC`` and ``OBJCXX`` support.

  .. versionadded:: 3.18
    Added ``ISPC`` support.

  .. versionadded:: 3.21
    Added ``HIP`` support.

  .. versionadded:: 3.26
    Added ``ASM_MARMASM`` support.

If enabling ``ASM``, list it last so that CMake can check whether
compilers for other languages like ``C`` work for assembly too.

By default ``C`` and ``CXX`` are enabled if no language options are given.
Specify language ``NONE``, or use the ``LANGUAGES`` keyword and list no languages,
to skip enabling any languages.

The variables set through the ``VERSION``, ``DESCRIPTION`` and ``HOMEPAGE_URL``
options are intended for use as default values in package metadata and documentation.

Code Injection
^^^^^^^^^^^^^^

A number of variables can be defined by the user to specify files to include
at different points during the execution of the ``project()`` command.
The following outlines the steps performed during a ``project()`` call:

* .. versionadded:: 3.15
    For every ``project()`` call regardless of the project
    name, include the file(s) and module(s) named by
    ``CMAKE_PROJECT_INCLUDE_BEFORE``, if set.

* .. versionadded:: 3.17
    If the ``project()`` command specifies ``<PROJECT-NAME>`` as its project
    name, include the file(s) and module(s) named by
    ``CMAKE_PROJECT_<PROJECT-NAME>_INCLUDE_BEFORE``, if set.

* Set the various project-specific variables detailed in the Synopsis
  and Options sections above.

* For the very first ``project()`` call only:

  * If ``CMAKE_TOOLCHAIN_FILE`` is set, read it at least once.
    It may be read multiple times and it may also be read again when
    enabling languages later (see below).

  * Set the variables describing the host and target platforms.
    Language-specific variables might or might not be set at this point.
    On the first run, the only language-specific variables that might be
    defined are those a toolchain file may have set. On subsequent runs,
    language-specific variables cached from a previous run may be set.

  * .. versionadded:: 3.24
      Include each file listed in ``CMAKE_PROJECT_TOP_LEVEL_INCLUDES``,
      if set. The variable is ignored by CMake thereafter.

* Enable any languages specified in the call, or the default languages if
  none were provided. The toolchain file may be re-read when enabling a
  language for the first time.

* .. versionadded:: 3.15
    For every ``project()`` call regardless of the project
    name, include the file(s) and module(s) named by
    ``CMAKE_PROJECT_INCLUDE``, if set.

* If the ``project()`` command specifies ``<PROJECT-NAME>`` as its project
  name, include the file(s) and module(s) named by
  ``CMAKE_PROJECT_<PROJECT-NAME>_INCLUDE``, if set.

Usage
^^^^^

The top-level ``CMakeLists.txt`` file for a project must contain a
literal, direct call to the ``project()`` command; loading one
through the ``include()`` command is not sufficient.  If no such
call exists, CMake will issue a warning and pretend there is a
``project(Project)`` at the top to enable the default languages
(``C`` and ``CXX``).

.. note::
  Call the ``project()`` command near the top of the top-level
  ``CMakeLists.txt``, but *after* calling ``cmake_minimum_required()``.
  It is important to establish version and policy settings before invoking
  other commands whose behavior they may affect and for this reason the
  ``project()`` command will issue a warning if this order is not kept.
  See also policy ``CMP0000``.

remove_definitions
------------------

Remove -D define flags added by ``add_definitions()``.

 remove_definitions(-DFOO -DBAR ...)

Removes flags (added by ``add_definitions()``) from the compiler
command line for sources in the current directory and below.

set_source_files_properties
---------------------------

Source files can have properties that affect how they are built.

 set_source_files_properties(<files> ...
                             [DIRECTORY <dirs> ...]
                             [TARGET_DIRECTORY <targets> ...]
                             PROPERTIES <prop1> <value1>
                             [<prop2> <value2>] ...)

Sets properties associated with source files using a key/value paired
list.

.. versionadded:: 3.18
  By default, source file properties are only visible to targets added in the
  same directory (``CMakeLists.txt``).  Visibility can be set in other directory
  scopes using one or both of the following options:

``DIRECTORY <dirs>...``
  The source file properties will be set in each of the ``<dirs>``
  directories' scopes.  CMake must already know about each of these
  source directories, either by having added them through a call to
  ``add_subdirectory()`` or it being the top level source directory.
  Relative paths are treated as relative to the current source directory.

``TARGET_DIRECTORY <targets>...``
  The source file properties will be set in each of the directory scopes
  where any of the specified ``<targets>`` were created (the ``<targets>``
  must therefore already exist).

Use ``get_source_file_property()`` to get property values.
See also the ``set_property(SOURCE)`` command.

.. note::

  The ``GENERATED`` source file property may be globally visible.
  See its documentation for details.

See Also
^^^^^^^^

* ``define_property()``
* ``get_source_file_property()``
* :ref:`Source File Properties` for the list of properties known
  to CMake

set_target_properties
---------------------

Targets can have properties that affect how they are built.

 set_target_properties(<targets> ...
                       PROPERTIES <prop1> <value1>
                       [<prop2> <value2>] ...)

Sets properties on targets.  The syntax for the command is to list all
the targets you want to change, and then provide the values you want to
set next.  You can use any prop value pair you want and extract it
later with the ``get_property()`` or ``get_target_property()``
command.

:ref:`Alias Targets` do not support setting target properties.

See Also
^^^^^^^^

* ``define_property()``
* ``get_target_property()``
* the more general ``set_property()`` command
* :ref:`Target Properties` for the list of properties known to CMake

set_tests_properties
--------------------

Set a property of the tests.

 set_tests_properties(<tests>...
                      [DIRECTORY <dir>]
                      PROPERTIES <prop1> <value1>
                      [<prop2> <value2>]...)

Sets a property for the tests.  If the test is not found, CMake
will report an error.

Test property values may be specified using
``generator expressions``
for tests created by the ``add_test(NAME)`` signature.

.. versionadded:: 3.28
  Visibility can be set in other directory scopes using the following option:

  ``DIRECTORY <dir>``
    The test properties will be set in the ``<dir>`` directory's scope.
    CMake must already know about this directory, either by having added it
    through a call to ``add_subdirectory()`` or it being the top level
    source directory. Relative paths are treated as relative to the current
    source directory. ``<dir>`` may reference a binary directory.

See Also
^^^^^^^^

* ``add_test()``
* ``define_property()``
* the more general ``set_property()`` command
* :ref:`Test Properties` for the list of properties known to CMake

source_group
------------

Define a grouping for source files in IDE project generation.
There are two different signatures to create source groups.

 source_group(<name> [FILES <src>...] [REGULAR_EXPRESSION <regex>])
 source_group(TREE <root> [PREFIX <prefix>] [FILES <src>...])

Defines a group into which sources will be placed in project files.
This is intended to set up file tabs in Visual Studio.
The group is scoped in the directory where the command is called,
and applies to sources in targets created in that directory.

The options are:

``TREE``
 .. versionadded:: 3.8

 CMake will automatically detect, from ``<src>`` files paths, source groups
 it needs to create, to keep structure of source groups analogically to the
 actual files and directories structure in the project. Paths of ``<src>``
 files will be cut to be relative to ``<root>``. The command fails if the
 paths within ``src`` do not start with ``root``.

``PREFIX``
 .. versionadded:: 3.8

 Source group and files located directly in ``<root>`` path, will be placed
 in ``<prefix>`` source groups.

``FILES``
 Any source file specified explicitly will be placed in group
 ``<name>``.  Relative paths are interpreted with respect to the
 current source directory.

``REGULAR_EXPRESSION``
 Any source file whose name matches the regular expression will
 be placed in group ``<name>``.

If a source file matches multiple groups, the *last* group that
explicitly lists the file with ``FILES`` will be favored, if any.
If no group explicitly lists the file, the *last* group whose
regular expression matches the file will be favored.

The ``<name>`` of the group and ``<prefix>`` argument may contain forward
slashes or backslashes to specify subgroups.  Backslashes need to be escaped
appropriately:

 source_group(base/subdir ...)
 source_group(outer\\inner ...)
 source_group(TREE <root> PREFIX sources\\inc ...)

.. versionadded:: 3.18
  Allow using forward slashes (``/``) to specify subgroups.

For backwards compatibility, the short-hand signature

 source_group(<name> <regex>)

is equivalent to

 source_group(<name> REGULAR_EXPRESSION <regex>)

target_compile_definitions
--------------------------

Add compile definitions to a target.

 target_compile_definitions(<target>
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Specifies compile definitions to use when compiling a given ``<target>``.  The
named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the following arguments.
``PRIVATE`` and ``PUBLIC`` items will populate the ``COMPILE_DEFINITIONS``
property of ``<target>``. ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_COMPILE_DEFINITIONS`` property of ``<target>``.
The following arguments specify compile definitions.  Repeated calls for the
same ``<target>`` append items in the order called.

.. versionadded:: 3.11
  Allow setting ``INTERFACE`` items on :ref:`IMPORTED targets <Imported Targets>`.

Arguments to ``target_compile_definitions`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Any leading ``-D`` on an item will be removed.  Empty items are ignored.
For example, the following are all equivalent:

 target_compile_definitions(foo PUBLIC FOO)
 target_compile_definitions(foo PUBLIC -DFOO)  # -D removed
 target_compile_definitions(foo PUBLIC "" FOO) # "" ignored
 target_compile_definitions(foo PUBLIC -D FOO) # -D becomes "", then ignored

Definitions may optionally have values:

 target_compile_definitions(foo PUBLIC FOO=1)

Note that many compilers treat ``-DFOO`` as equivalent to ``-DFOO=1``, but
other tools may not recognize this in all circumstances (e.g. IntelliSense).

See Also
^^^^^^^^

* ``add_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

target_compile_features
-----------------------

.. versionadded:: 3.1

Add expected compiler features to a target.

 target_compile_features(<target> <PRIVATE|PUBLIC|INTERFACE> <feature> [...])

Specifies compiler features required when compiling a given target.  If the
feature is not listed in the ``CMAKE_C_COMPILE_FEATURES``,
``CMAKE_CUDA_COMPILE_FEATURES``, or ``CMAKE_CXX_COMPILE_FEATURES``
variables, then an error will be reported by CMake.  If the use of the feature requires
an additional compiler flag, such as ``-std=gnu++11``, the flag will be added
automatically.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the scope of the features.  ``PRIVATE`` and ``PUBLIC`` items will
populate the ``COMPILE_FEATURES`` property of ``<target>``.
``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_COMPILE_FEATURES`` property of ``<target>``.
Repeated calls for the same ``<target>`` append items.

.. versionadded:: 3.11
  Allow setting ``INTERFACE`` items on :ref:`IMPORTED targets <Imported Targets>`.

The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

Arguments to ``target_compile_features`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-compile-features(7)`` manual for information on compile features and a list of supported compilers.See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

See Also
^^^^^^^^

* ``target_compile_definitions()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

target_compile_options
----------------------

Add compile options to a target.

 target_compile_options(<target> [BEFORE]
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Adds options to the ``COMPILE_OPTIONS`` or
``INTERFACE_COMPILE_OPTIONS`` target properties. These options
are used when compiling the given ``<target>``, which must have been
created by a command such as ``add_executable()`` or
``add_library()`` and must not be an :ref:`ALIAS target <Alias Targets>`.

.. note::

  These options are not used when linking the target.
  See the ``target_link_options()`` command for that.

Arguments
^^^^^^^^^

If ``BEFORE`` is specified, the content will be prepended to the property
instead of being appended.  See policy ``CMP0101`` which affects
whether ``BEFORE`` will be ignored in certain cases.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the following arguments.
``PRIVATE`` and ``PUBLIC`` items will populate the ``COMPILE_OPTIONS``
property of ``<target>``.  ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_COMPILE_OPTIONS`` property of ``<target>``.
The following arguments specify compile options.  Repeated calls for the same
``<target>`` append items in the order called.

.. versionadded:: 3.11
  Allow setting ``INTERFACE`` items on :ref:`IMPORTED targets <Imported Targets>`.

Arguments to ``target_compile_options`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Option De-duplication
^^^^^^^^^^^^^^^^^^^^^

The final set of options used for a target is constructed by
accumulating options from the current target and the usage requirements of
its dependencies.  The set of options is de-duplicated to avoid repetition.

.. versionadded:: 3.12
  While beneficial for individual options, the de-duplication step can break
  up option groups.  For example, ``-option A -option B`` becomes
  ``-option A B``.  One may specify a group of options using shell-like
  quoting along with a ``SHELL:`` prefix.  The ``SHELL:`` prefix is dropped,
  and the rest of the option string is parsed using the
  ``separate_arguments()`` ``UNIX_COMMAND`` mode. For example,
  ``"SHELL:-option A" "SHELL:-option B"`` becomes ``-option A -option B``.

See Also
^^^^^^^^

* This command can be used to add any options. However, for adding
  preprocessor definitions and include directories it is recommended
  to use the more specific commands ``target_compile_definitions()``
  and ``target_include_directories()``.

* For directory-wide settings, there is the command ``add_compile_options()``.

* For file-specific settings, there is the source file property ``COMPILE_OPTIONS``.

* This command adds compile options for all languages in a target.
  Use the ``COMPILE_LANGUAGE`` generator expression to specify
  per-language compile options.

* ``target_compile_features()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

* ``CMAKE_<LANG>_FLAGS`` and ``CMAKE_<LANG>_FLAGS_<CONFIG>``
  add language-wide flags passed to all invocations of the compiler.
  This includes invocations that drive compiling and those that drive linking.

target_include_directories
--------------------------

Add include directories to a target.

 target_include_directories(<target> [SYSTEM] [AFTER|BEFORE]
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Specifies include directories to use when compiling a given target.
The named ``<target>`` must have been created by a command such
as ``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

By using ``AFTER`` or ``BEFORE`` explicitly, you can select between appending
and prepending, independent of the default.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to specify
the :ref:`scope <Target Command Scope>` of the following arguments.
``PRIVATE`` and ``PUBLIC`` items will populate the ``INCLUDE_DIRECTORIES``
property of ``<target>``. ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_INCLUDE_DIRECTORIES`` property of ``<target>``.
The following arguments specify include directories.

.. versionadded:: 3.11
  Allow setting ``INTERFACE`` items on :ref:`IMPORTED targets <Imported Targets>`.

Repeated calls for the same ``<target>`` append items in the order called.

If ``SYSTEM`` is specified, the compiler will be told the directories
are meant as system include directories on some platforms.  This may
have effects such as suppressing warnings or skipping the contained
headers in dependency calculations (see compiler documentation).
Additionally, system include directories are searched after normal
include directories regardless of the order specified.

If ``SYSTEM`` is used together with ``PUBLIC`` or ``INTERFACE``, the
``INTERFACE_SYSTEM_INCLUDE_DIRECTORIES`` target property will be
populated with the specified directories.

Arguments to ``target_include_directories`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Specified include directories may be absolute paths or relative paths.
A relative path will be interpreted as relative to the current source
directory (i.e. ``CMAKE_CURRENT_SOURCE_DIR``) and converted to an
absolute path before storing it in the associated target property.
If the path starts with a generator expression, it will always be assumed
to be an absolute path (with one exception noted below) and will be used
unmodified.

Include directories usage requirements commonly differ between the build-tree
and the install-tree.  The ``BUILD_INTERFACE`` and
``INSTALL_INTERFACE`` generator expressions can be used to describe
separate usage requirements based on the usage location.  Relative paths
are allowed within the ``INSTALL_INTERFACE`` expression and are
interpreted as relative to the installation prefix.  Relative paths should not
be used in ``BUILD_INTERFACE`` expressions because they will not be
converted to absolute.  For example:

 target_include_directories(mylib PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/mylib>
   $<INSTALL_INTERFACE:include/mylib>  # <prefix>/include/mylib
 )

Creating Relocatable Packages
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Note that it is not advisable to populate the ``INSTALL_INTERFACE`` of
the ``INTERFACE_INCLUDE_DIRECTORIES`` of a target with absolute paths to the include
directories of dependencies.  That would hard-code into installed packages
the include directory paths for dependencies
**as found on the machine the package was made on**.

The ``INSTALL_INTERFACE`` of the ``INTERFACE_INCLUDE_DIRECTORIES`` is only
suitable for specifying the required include directories for headers
provided with the target itself, not those provided by the transitive
dependencies listed in its ``INTERFACE_LINK_LIBRARIES`` target
property.  Those dependencies should themselves be targets that specify
their own header locations in ``INTERFACE_INCLUDE_DIRECTORIES``.

See the :ref:`Creating Relocatable Packages` section of the
``cmake-packages(7)`` manual for discussion of additional care
that must be taken when specifying usage requirements while creating
packages for redistribution.

See Also
^^^^^^^^

* ``include_directories()``
* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

target_link_directories
-----------------------

.. versionadded:: 3.13

Add link directories to a target.

 target_link_directories(<target> [BEFORE]
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Specifies the paths in which the linker should search for libraries when
linking a given target.  Each item can be an absolute or relative path,
with the latter being interpreted as relative to the current source
directory.  These items will be added to the link command.

The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the items that follow
them. ``PRIVATE`` and ``PUBLIC`` items will populate the
``LINK_DIRECTORIES`` property of ``<target>``.  ``PUBLIC`` and
``INTERFACE`` items will populate the ``INTERFACE_LINK_DIRECTORIES``
property of ``<target>`` (:ref:`IMPORTED targets <Imported Targets>` only
support ``INTERFACE`` items).
Each item specifies a link directory and will be converted to an absolute
path if necessary before adding it to the relevant property.  Repeated
calls for the same ``<target>`` append items in the order called.

If ``BEFORE`` is specified, the content will be prepended to the relevant
property instead of being appended.

Arguments to ``target_link_directories`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

.. note::

  This command is rarely necessary and should be avoided where there are
  other choices.  Prefer to pass full absolute paths to libraries where
  possible, since this ensures the correct library will always be linked.
  The ``find_library()`` command provides the full path, which can
  generally be used directly in calls to ``target_link_libraries()``.
  Situations where a library search path may be needed include:

  - Project generators like Xcode where the user can switch target
    architecture at build time, but a full path to a library cannot
    be used because it only provides one architecture (i.e. it is not
    a universal binary).
  - Libraries may themselves have other private library dependencies
    that expect to be found via ``RPATH`` mechanisms, but some linkers
    are not able to fully decode those paths (e.g. due to the presence
    of things like ``$ORIGIN``).

See Also
^^^^^^^^

* ``link_directories()``
* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

target_link_libraries
---------------------

Specify libraries or flags to use when linking a given target and/or
its dependents.  :ref:`Usage requirements <Target Usage Requirements>`
from linked library targets will be propagated.  Usage requirements
of a target's dependencies affect compilation of its own sources.

Overview
^^^^^^^^

This command has several signatures as detailed in subsections below.
All of them have the general form

 target_link_libraries(<target> ... <item>... ...)

The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.  If policy ``CMP0079`` is not
set to ``NEW`` then the target must have been created in the current
directory.  Repeated calls for the same ``<target>`` append items in
the order called.

.. versionadded:: 3.13
  The ``<target>`` doesn't have to be defined in the same directory as the
  ``target_link_libraries`` call.

Each ``<item>`` may be:

* **A library target name**: The generated link line will have the
  full path to the linkable library file associated with the target.
  The buildsystem will have a dependency to re-link ``<target>`` if
  the library file changes.

  The named target must be created by ``add_library()`` within
  the project or as an :ref:`IMPORTED library <Imported Targets>`.
  If it is created within the project an ordering dependency will
  automatically be added in the build system to make sure the named
  library target is up-to-date before the ``<target>`` links.

  If an imported library has the ``IMPORTED_NO_SONAME``
  target property set, CMake may ask the linker to search for
  the library instead of using the full path
  (e.g. ``/usr/lib/libfoo.so`` becomes ``-lfoo``).

  The full path to the target's artifact will be quoted/escaped for
  the shell automatically.

* **A full path to a library file**: The generated link line will
  normally preserve the full path to the file. The buildsystem will
  have a dependency to re-link ``<target>`` if the library file changes.

  There are some cases where CMake may ask the linker to search for
  the library (e.g. ``/usr/lib/libfoo.so`` becomes ``-lfoo``), such
  as when a shared library is detected to have no ``SONAME`` field.
  See policy ``CMP0060`` for discussion of another case.

  If the library file is in a macOS framework, the ``Headers`` directory
  of the framework will also be processed as a
  :ref:`usage requirement <Target Usage Requirements>`.  This has the same
  effect as passing the framework directory as an include directory.

  .. versionadded:: 3.28

    The library file may point to a ``.xcframework`` folder on Apple platforms.
    If it does, the target will get the selected library's ``Headers``
    directory as a usage requirement.

  .. versionadded:: 3.8
    On :ref:`Visual Studio Generators` for VS 2010 and above, library files
    ending in ``.targets`` will be treated as MSBuild targets files and
    imported into generated project files.  This is not supported by other
    generators.

  The full path to the library file will be quoted/escaped for
  the shell automatically.

* **A plain library name**: The generated link line will ask the linker
  to search for the library (e.g. ``foo`` becomes ``-lfoo`` or ``foo.lib``).

  The library name/flag is treated as a command-line string fragment and
  will be used with no extra quoting or escaping.

* **A link flag**: Item names starting with ``-``, but not ``-l`` or
  ``-framework``, are treated as linker flags.  Note that such flags will
  be treated like any other library link item for purposes of transitive
  dependencies, so they are generally safe to specify only as private link
  items that will not propagate to dependents.

  Link flags specified here are inserted into the link command in the same
  place as the link libraries. This might not be correct, depending on
  the linker. Use the ``LINK_OPTIONS`` target property or
  ``target_link_options()`` command to add link
  flags explicitly. The flags will then be placed at the toolchain-defined
  flag position in the link command.

  .. versionadded:: 3.13
    ``LINK_OPTIONS`` target property and ``target_link_options()``
    command.  For earlier versions of CMake, use ``LINK_FLAGS``
    property instead.

  The link flag is treated as a command-line string fragment and
  will be used with no extra quoting or escaping.

* **A generator expression**: A ``$<...>`` :manual:`generator expression
  <cmake-generator-expressions(7)>` may evaluate to any of the above
  items or to a :ref:`semicolon-separated list <CMake Language Lists>` of them.
  If the ``...`` contains any ``;`` characters, e.g. after evaluation
  of a ``${list}`` variable, be sure to use an explicitly quoted
  argument ``"$<...>"`` so that this command receives it as a
  single ``<item>``.

  Additionally, a generator expression may be used as a fragment of
  any of the above items, e.g. ``foo$<1:_d>``.

  Note that generator expressions will not be used in OLD handling of
  policy ``CMP0003`` or policy ``CMP0004``.

* A ``debug``, ``optimized``, or ``general`` keyword immediately followed
  by another ``<item>``.  The item following such a keyword will be used
  only for the corresponding build configuration.  The ``debug`` keyword
  corresponds to the ``Debug`` configuration (or to configurations named
  in the ``DEBUG_CONFIGURATIONS`` global property if it is set).
  The ``optimized`` keyword corresponds to all other configurations.  The
  ``general`` keyword corresponds to all configurations, and is purely
  optional.  Higher granularity may be achieved for per-configuration
  rules by creating and linking to
  :ref:`IMPORTED library targets <Imported Targets>`.
  These keywords are interpreted immediately by this command and therefore
  have no special meaning when produced by a generator expression.

Items containing ``::``, such as ``Foo::Bar``, are assumed to be
:ref:`IMPORTED <Imported Targets>` or :ref:`ALIAS <Alias Targets>` library
target names and will cause an error if no such target exists.
See policy ``CMP0028``.

See the ``cmake-buildsystem(7)`` manual for more on defining
buildsystem properties.

Libraries for a Target and/or its Dependents
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 target_link_libraries(<target>
                       <PRIVATE|PUBLIC|INTERFACE> <item>...
                      [<PRIVATE|PUBLIC|INTERFACE> <item>...]...)

The ``PUBLIC``, ``PRIVATE`` and ``INTERFACE``
:ref:`scope <Target Command Scope>` keywords can be used to
specify both the link dependencies and the link interface in one command.

Libraries and targets following ``PUBLIC`` are linked to, and are made
part of the link interface.  Libraries and targets following ``PRIVATE``
are linked to, but are not made part of the link interface.  Libraries
following ``INTERFACE`` are appended to the link interface and are not
used for linking ``<target>``.

Libraries for both a Target and its Dependents
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 target_link_libraries(<target> <item>...)

Library dependencies are transitive by default with this signature.
When this target is linked into another target then the libraries
linked to this target will appear on the link line for the other
target too.  This transitive "link interface" is stored in the
``INTERFACE_LINK_LIBRARIES`` target property and may be overridden
by setting the property directly.  When ``CMP0022`` is not set to
``NEW``, transitive linking is built in but may be overridden by the
``LINK_INTERFACE_LIBRARIES`` property.  Calls to other signatures
of this command may set the property making any libraries linked
exclusively by this signature private.

Libraries for a Target and/or its Dependents (Legacy)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 target_link_libraries(<target>
                       <LINK_PRIVATE|LINK_PUBLIC> <lib>...
                      [<LINK_PRIVATE|LINK_PUBLIC> <lib>...]...)

The ``LINK_PUBLIC`` and ``LINK_PRIVATE`` modes can be used to specify both
the link dependencies and the link interface in one command.

This signature is for compatibility only.  Prefer the ``PUBLIC`` or
``PRIVATE`` keywords instead.

Libraries and targets following ``LINK_PUBLIC`` are linked to, and are
made part of the ``INTERFACE_LINK_LIBRARIES``.  If policy
``CMP0022`` is not ``NEW``, they are also made part of the
``LINK_INTERFACE_LIBRARIES``.  Libraries and targets following
``LINK_PRIVATE`` are linked to, but are not made part of the
``INTERFACE_LINK_LIBRARIES`` (or ``LINK_INTERFACE_LIBRARIES``).

Libraries for Dependents Only (Legacy)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 target_link_libraries(<target> LINK_INTERFACE_LIBRARIES <item>...)

The ``LINK_INTERFACE_LIBRARIES`` mode appends the libraries to the
``INTERFACE_LINK_LIBRARIES`` target property instead of using them
for linking.  If policy ``CMP0022`` is not ``NEW``, then this mode
also appends libraries to the ``LINK_INTERFACE_LIBRARIES`` and its
per-configuration equivalent.

This signature is for compatibility only.  Prefer the ``INTERFACE`` mode
instead.

Libraries specified as ``debug`` are wrapped in a generator expression to
correspond to debug builds.  If policy ``CMP0022`` is
not ``NEW``, the libraries are also appended to the
``LINK_INTERFACE_LIBRARIES_DEBUG``
property (or to the properties corresponding to configurations listed in
the ``DEBUG_CONFIGURATIONS`` global property if it is set).
Libraries specified as ``optimized`` are appended to the
``INTERFACE_LINK_LIBRARIES`` property.  If policy ``CMP0022``
is not ``NEW``, they are also appended to the
``LINK_INTERFACE_LIBRARIES`` property.  Libraries specified as
``general`` (or without any keyword) are treated as if specified for both
``debug`` and ``optimized``.

Linking Object Libraries
^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.12

:ref:`Object Libraries` may be used as the ``<target>`` (first) argument
of ``target_link_libraries`` to specify dependencies of their sources
on other libraries.  For example, the code

 add_library(A SHARED a.c)
 target_compile_definitions(A PUBLIC A)

 add_library(obj OBJECT obj.c)
 target_compile_definitions(obj PUBLIC OBJ)
 target_link_libraries(obj PUBLIC A)

compiles ``obj.c`` with ``-DA -DOBJ`` and establishes usage requirements
for ``obj`` that propagate to its dependents.

Normal libraries and executables may link to :ref:`Object Libraries`
to get their objects and usage requirements.  Continuing the above
example, the code

 add_library(B SHARED b.c)
 target_link_libraries(B PUBLIC obj)

compiles ``b.c`` with ``-DA -DOBJ``, creates shared library ``B``
with object files from ``b.c`` and ``obj.c``, and links ``B`` to ``A``.
Furthermore, the code

 add_executable(main main.c)
 target_link_libraries(main B)

compiles ``main.c`` with ``-DA -DOBJ`` and links executable ``main``
to ``B`` and ``A``.  The object library's usage requirements are
propagated transitively through ``B``, but its object files are not.

:ref:`Object Libraries` may "link" to other object libraries to get
usage requirements, but since they do not have a link step nothing
is done with their object files.  Continuing from the above example,
the code:

 add_library(obj2 OBJECT obj2.c)
 target_link_libraries(obj2 PUBLIC obj)

 add_executable(main2 main2.c)
 target_link_libraries(main2 obj2)

compiles ``obj2.c`` with ``-DA -DOBJ``, creates executable ``main2``
with object files from ``main2.c`` and ``obj2.c``, and links ``main2``
to ``A``.

In other words, when :ref:`Object Libraries` appear in a target's
``INTERFACE_LINK_LIBRARIES`` property they will be
treated as :ref:`Interface Libraries`, but when they appear in
a target's ``LINK_LIBRARIES`` property their object files
will be included in the link too.

Linking Object Libraries via ``$<TARGET_OBJECTS>``
""""""""""""""""""""""""""""""""""""""""""""""""""

.. versionadded:: 3.21

The object files associated with an object library may be referenced
by the ``$<TARGET_OBJECTS>`` generator expression.  Such object
files are placed on the link line *before* all libraries, regardless
of their relative order.  Additionally, an ordering dependency will be
added to the build system to make sure the object library is up-to-date
before the dependent target links.  For example, the code

 add_library(obj3 OBJECT obj3.c)
 target_compile_definitions(obj3 PUBLIC OBJ3)

 add_executable(main3 main3.c)
 target_link_libraries(main3 PRIVATE a3 $<TARGET_OBJECTS:obj3> b3)

links executable ``main3`` with object files from ``main3.c``
and ``obj3.c`` followed by the ``a3`` and ``b3`` libraries.
``main3.c`` is *not* compiled with usage requirements from ``obj3``,
such as ``-DOBJ3``.

This approach can be used to achieve transitive inclusion of object
files in link lines as usage requirements.  Continuing the above
example, the code

 add_library(iface_obj3 INTERFACE)
 target_link_libraries(iface_obj3 INTERFACE obj3 $<TARGET_OBJECTS:obj3>)

creates an interface library ``iface_obj3`` that forwards the ``obj3``
usage requirements and adds the ``obj3`` object files to dependents'
link lines.  The code

 add_executable(use_obj3 use_obj3.c)
 target_link_libraries(use_obj3 PRIVATE iface_obj3)

compiles ``use_obj3.c`` with ``-DOBJ3`` and links executable ``use_obj3``
with object files from ``use_obj3.c`` and ``obj3.c``.

This also works transitively through a static library.  Since a static
library does not link, it does not consume the object files from
object libraries referenced this way.  Instead, the object files
become transitive link dependencies of the static library.
Continuing the above example, the code

 add_library(static3 STATIC static3.c)
 target_link_libraries(static3 PRIVATE iface_obj3)

 add_executable(use_static3 use_static3.c)
 target_link_libraries(use_static3 PRIVATE static3)

compiles ``static3.c`` with ``-DOBJ3`` and creates ``libstatic3.a``
using only its own object file.  ``use_static3.c`` is compiled *without*
``-DOBJ3`` because the usage requirement is not transitive through
the private dependency of ``static3``.  However, the link dependencies
of ``static3`` are propagated, including the ``iface_obj3`` reference
to ``$<TARGET_OBJECTS:obj3>``.  The ``use_static3`` executable is
created with object files from ``use_static3.c`` and ``obj3.c``, and
linked to library ``libstatic3.a``.

When using this approach, it is the project's responsibility to avoid
linking multiple dependent binaries to ``iface_obj3``, because they will
all get the ``obj3`` object files on their link lines.

.. note::

  Referencing ``$<TARGET_OBJECTS>`` in ``target_link_libraries``
  calls worked in versions of CMake prior to 3.21 for some cases,
  but was not fully supported:

  * It did not place the object files before libraries on link lines.
  * It did not add an ordering dependency on the object library.
  * It did not work in Xcode with multiple architectures.

Cyclic Dependencies of Static Libraries
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The library dependency graph is normally acyclic (a DAG), but in the case
of mutually-dependent ``STATIC`` libraries CMake allows the graph to
contain cycles (strongly connected components).  When another target links
to one of the libraries, CMake repeats the entire connected component.
For example, the code

 add_library(A STATIC a.c)
 add_library(B STATIC b.c)
 target_link_libraries(A B)
 target_link_libraries(B A)
 add_executable(main main.c)
 target_link_libraries(main A)

links ``main`` to ``A B A B``.  While one repetition is usually
sufficient, pathological object file and symbol arrangements can require
more.  One may handle such cases by using the
``LINK_INTERFACE_MULTIPLICITY`` target property or by manually
repeating the component in the last ``target_link_libraries`` call.
However, if two archives are really so interdependent they should probably
be combined into a single archive, perhaps by using :ref:`Object Libraries`.

Creating Relocatable Packages
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Note that it is not advisable to populate the
``INTERFACE_LINK_LIBRARIES`` of a target with absolute paths to dependencies.
That would hard-code into installed packages the library file paths
for dependencies **as found on the machine the package was made on**.

See the :ref:`Creating Relocatable Packages` section of the
``cmake-packages(7)`` manual for discussion of additional care
that must be taken when specifying usage requirements while creating
packages for redistribution.

See Also
^^^^^^^^

* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``
* ``target_sources()``

target_link_options
-------------------

.. versionadded:: 3.13

Add options to the link step for an executable, shared library or module
library target.

 target_link_options(<target> [BEFORE]
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

This command can be used to add any link options, but alternative commands
exist to add libraries (``target_link_libraries()`` or
``link_libraries()``).  See documentation of the
``directory`` and
``target`` ``LINK_OPTIONS`` properties.

.. note::

  This command cannot be used to add options for static library targets,
  since they do not use a linker.  To add archiver or MSVC librarian flags,
  see the ``STATIC_LIBRARY_OPTIONS`` target property.

If ``BEFORE`` is specified, the content will be prepended to the property
instead of being appended.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the following arguments.
``PRIVATE`` and ``PUBLIC`` items will populate the ``LINK_OPTIONS``
property of ``<target>``.  ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_LINK_OPTIONS`` property of ``<target>``.
The following arguments specify link options.  Repeated calls for the same
``<target>`` append items in the order called.

.. note::
  :ref:`IMPORTED targets <Imported Targets>` only support ``INTERFACE`` items.

Arguments to ``target_link_options`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

Host And Device Specific Link Options
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.18
  When a device link step is involved, which is controlled by
  ``CUDA_SEPARABLE_COMPILATION`` and
  ``CUDA_RESOLVE_DEVICE_SYMBOLS`` properties and policy ``CMP0105``,
  the raw options will be delivered to the host and device link steps (wrapped in
  ``-Xcompiler`` or equivalent for device link). Options wrapped with
  ``$<DEVICE_LINK:...>`` generator expression will be used
  only for the device link step. Options wrapped with ``$<HOST_LINK:...>``
  generator expression will be used only for the host link step.

Option De-duplication
^^^^^^^^^^^^^^^^^^^^^

The final set of options used for a target is constructed by
accumulating options from the current target and the usage requirements of
its dependencies.  The set of options is de-duplicated to avoid repetition.

.. versionadded:: 3.12
  While beneficial for individual options, the de-duplication step can break
  up option groups.  For example, ``-option A -option B`` becomes
  ``-option A B``.  One may specify a group of options using shell-like
  quoting along with a ``SHELL:`` prefix.  The ``SHELL:`` prefix is dropped,
  and the rest of the option string is parsed using the
  ``separate_arguments()`` ``UNIX_COMMAND`` mode. For example,
  ``"SHELL:-option A" "SHELL:-option B"`` becomes ``-option A -option B``.

Handling Compiler Driver Differences
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To pass options to the linker tool, each compiler driver has its own syntax.
The ``LINKER:`` prefix and ``,`` separator can be used to specify, in a portable
way, options to pass to the linker tool. ``LINKER:`` is replaced by the
appropriate driver option and ``,`` by the appropriate driver separator.
The driver prefix and driver separator are given by the values of the
``CMAKE_<LANG>_LINKER_WRAPPER_FLAG`` and
``CMAKE_<LANG>_LINKER_WRAPPER_FLAG_SEP`` variables.

For example, ``"LINKER:-z,defs"`` becomes ``-Xlinker -z -Xlinker defs`` for
``Clang`` and ``-Wl,-z,defs`` for ``GNU GCC``.

The ``LINKER:`` prefix can be specified as part of a ``SHELL:`` prefix
expression.

The ``LINKER:`` prefix supports, as an alternative syntax, specification of
arguments using the ``SHELL:`` prefix and space as separator. The previous
example then becomes ``"LINKER:SHELL:-z defs"``.

.. note::

  Specifying the ``SHELL:`` prefix anywhere other than at the beginning of the
  ``LINKER:`` prefix is not supported.

See Also
^^^^^^^^

* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_precompile_headers()``
* ``target_sources()``

* ``CMAKE_<LANG>_FLAGS`` and ``CMAKE_<LANG>_FLAGS_<CONFIG>``
  add language-wide flags passed to all invocations of the compiler.
  This includes invocations that drive compiling and those that drive linking.

target_precompile_headers
-------------------------

.. versionadded:: 3.16

Add a list of header files to precompile.

Precompiling header files can speed up compilation by creating a partially
processed version of some header files, and then using that version during
compilations rather than repeatedly parsing the original headers.

Main Form
^^^^^^^^^

 target_precompile_headers(<target>
   <INTERFACE|PUBLIC|PRIVATE> [header1...]
   [<INTERFACE|PUBLIC|PRIVATE> [header2...] ...])

The command adds header files to the ``PRECOMPILE_HEADERS`` and/or
``INTERFACE_PRECOMPILE_HEADERS`` target properties of ``<target>``.
The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the following arguments.
``PRIVATE`` and ``PUBLIC`` items will populate the ``PRECOMPILE_HEADERS``
property of ``<target>``.  ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_PRECOMPILE_HEADERS`` property of ``<target>``
(:ref:`IMPORTED targets <Imported Targets>` only support ``INTERFACE`` items).
Repeated calls for the same ``<target>`` will append items in the order called.

Projects should generally avoid using ``PUBLIC`` or ``INTERFACE`` for targets
that will be ``exported``, or they should at least use
the ``$<BUILD_INTERFACE:...>`` generator expression to prevent precompile
headers from appearing in an installed exported target.  Consumers of a target
should typically be in control of what precompile headers they use, not have
precompile headers forced on them by the targets being consumed (since
precompile headers are not typically usage requirements).  A notable exception
to this is where an :ref:`interface library <Interface Libraries>` is created
to define a commonly used set of precompile headers in one place and then other
targets link to that interface library privately.  In this case, the interface
library exists specifically to propagate the precompile headers to its
consumers and the consumer is effectively still in control, since it decides
whether to link to the interface library or not.

The list of header files is used to generate a header file named
``cmake_pch.h|xx`` which is used to generate the precompiled header file
(``.pch``, ``.gch``, ``.pchi``) artifact.  The ``cmake_pch.h|xx`` header
file will be force included (``-include`` for GCC, ``/FI`` for MSVC) to
all source files, so sources do not need to have ``#include "pch.h"``.

Header file names specified with angle brackets (e.g. ``<unordered_map>``) or
explicit double quotes (escaped for the ``cmake-language(7)``,
e.g. ``[["other_header.h"]]``) will be treated as is, and include directories
must be available for the compiler to find them.  Other header file names
(e.g. ``project_header.h``) are interpreted as being relative to the current
source directory (e.g. ``CMAKE_CURRENT_SOURCE_DIR``) and will be
included by absolute path.  For example:

 target_precompile_headers(myTarget
   PUBLIC
     project_header.h
   PRIVATE
     [["other_header.h"]]
     <unordered_map>
 )

Arguments to ``target_precompile_headers`` may use generator expressions
with the syntax ``$<...>``. See the ``cmake-generator-expressions(7)``
manual for available expressions.  The ``$<COMPILE_LANGUAGE:...>`` generator expression is particularly useful for specifying a language-specific header to precompile for only one language (e.g. ``CXX`` and not ``C``).  In this case, header file names that are not explicitly in double quotes or angle brackets must be specified by absolute path.  Also, when specifying angle brackets inside a generator expression, be sure to encode the closing ``>`` as ``$<ANGLE-R>``.  For example:See the ``cmake-buildsystem(7)`` manual for more on defining buildsystem properties.

 target_precompile_headers(mylib PRIVATE
   "$<$<COMPILE_LANGUAGE:CXX>:${CMAKE_CURRENT_SOURCE_DIR}/cxx_only.h>"
   "$<$<COMPILE_LANGUAGE:C>:<stddef.h$<ANGLE-R>>"
   "$<$<COMPILE_LANGUAGE:CXX>:<cstddef$<ANGLE-R>>"
 )

Reusing Precompile Headers
^^^^^^^^^^^^^^^^^^^^^^^^^^

The command also supports a second signature which can be used to specify that
one target reuses a precompiled header file artifact from another target
instead of generating its own:

 target_precompile_headers(<target> REUSE_FROM <other_target>)

This form sets the ``PRECOMPILE_HEADERS_REUSE_FROM`` property to
``<other_target>`` and adds a dependency such that ``<target>`` will depend
on ``<other_target>``.  CMake will halt with an error if the
``PRECOMPILE_HEADERS`` property of ``<target>`` is already set when
the ``REUSE_FROM`` form is used.

.. note::

  The ``REUSE_FROM`` form requires the same set of compiler options,
  compiler flags and compiler definitions for both ``<target>`` and
  ``<other_target>``.  Some compilers (e.g. GCC) may issue a warning if the
  precompiled header file cannot be used (``-Winvalid-pch``).

See Also
^^^^^^^^

* To disable precompile headers for specific targets, see the
  ``DISABLE_PRECOMPILE_HEADERS`` target property.

* To prevent precompile headers from being used when compiling a specific
  source file, see the ``SKIP_PRECOMPILE_HEADERS`` source file property.

* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_sources()``

target_sources
--------------

.. versionadded:: 3.1

Add sources to a target.

 target_sources(<target>
   <INTERFACE|PUBLIC|PRIVATE> [items1...]
   [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Specifies sources to use when building a target and/or its dependents.
The named ``<target>`` must have been created by a command such as
``add_executable()`` or ``add_library()`` or
``add_custom_target()`` and must not be an
:ref:`ALIAS target <Alias Targets>`.  The ``<items>`` may use
``generator expressions``.

.. versionadded:: 3.20
  ``<target>`` can be a custom target.

The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
specify the :ref:`scope <Target Command Scope>` of the source file paths
(``<items>``) that follow them.  ``PRIVATE`` and ``PUBLIC`` items will
populate the ``SOURCES`` property of ``<target>``, which are used when
building the target itself. ``PUBLIC`` and ``INTERFACE`` items will populate the
``INTERFACE_SOURCES`` property of ``<target>``, which are used
when building dependents.  A target created by ``add_custom_target()``
can only have ``PRIVATE`` scope.

Repeated calls for the same ``<target>`` append items in the order called.

.. versionadded:: 3.3
  Allow exporting targets with ``INTERFACE_SOURCES``.

.. versionadded:: 3.11
  Allow setting ``INTERFACE`` items on
  :ref:`IMPORTED targets <Imported Targets>`.

.. versionchanged:: 3.13
  Relative source file paths are interpreted as being relative to the current
  source directory (i.e. ``CMAKE_CURRENT_SOURCE_DIR``).
  See policy ``CMP0076``.

A path that begins with a generator expression is left unmodified.
When a target's ``SOURCE_DIR`` property differs from
``CMAKE_CURRENT_SOURCE_DIR``, use absolute paths in generator
expressions to ensure the sources are correctly assigned to the target.

 # WRONG: starts with generator expression, but relative path used
 target_sources(MyTarget PRIVATE "$<$<CONFIG:Debug>:dbgsrc.cpp>")

 # CORRECT: absolute path used inside the generator expression
 target_sources(MyTarget PRIVATE "$<$<CONFIG:Debug>:${CMAKE_CURRENT_SOURCE_DIR}/dbgsrc.cpp>")

See the ``cmake-buildsystem(7)`` manual for more on defining
buildsystem properties.

File Sets
^^^^^^^^^

.. versionadded:: 3.23

 target_sources(<target>
   [<INTERFACE|PUBLIC|PRIVATE>
    [FILE_SET <set> [TYPE <type>] [BASE_DIRS <dirs>...] [FILES <files>...]]...
   ]...)

Adds a file set to a target, or adds files to an existing file set. Targets
have zero or more named file sets. Each file set has a name, a type, a scope of
``INTERFACE``, ``PUBLIC``, or ``PRIVATE``, one or more base directories, and
files within those directories. The acceptable types include:

``HEADERS``

  Sources intended to be used via a language's ``#include`` mechanism.

``CXX_MODULES``
  .. versionadded:: 3.28

  Sources which contain C++ interface module or partition units (i.e., those
  using the ``export`` keyword). This file set type may not have an
  ``INTERFACE`` scope except on ``IMPORTED`` targets.

The optional default file sets are named after their type. The target may not
be a custom target or ``FRAMEWORK`` target.

Files in a ``PRIVATE`` or ``PUBLIC`` file set are marked as source files for
the purposes of IDE integration. Additionally, files in ``HEADERS`` file sets
have their ``HEADER_FILE_ONLY`` property set to ``TRUE``. Files in an
``INTERFACE`` or ``PUBLIC`` file set can be installed with the
``install(TARGETS)`` command, and exported with the
``install(EXPORT)`` and ``export()`` commands.

Each ``target_sources(FILE_SET)`` entry starts with ``INTERFACE``, ``PUBLIC``, or
``PRIVATE`` and accepts the following arguments:

``FILE_SET <set>``

  The name of the file set to create or add to. It must contain only letters,
  numbers and underscores. Names starting with a capital letter are reserved
  for built-in file sets predefined by CMake. The only predefined set names
  are those matching the acceptable types. All other set names must not start
  with a capital letter or
  underscore.

``TYPE <type>``

  Every file set is associated with a particular type of file. Only types
  specified above may be used and it is an error to specify anything else. As
  a special case, if the name of the file set is one of the types, the type
  does not need to be specified and the ``TYPE <type>`` arguments can be
  omitted. For all other file set names, ``TYPE`` is required.

``BASE_DIRS <dirs>...``

  An optional list of base directories of the file set. Any relative path
  is treated as relative to the current source directory
  (i.e. ``CMAKE_CURRENT_SOURCE_DIR``). If no ``BASE_DIRS`` are
  specified when the file set is first created, the value of
  ``CMAKE_CURRENT_SOURCE_DIR`` is added. This argument supports
  ``generator expressions``.

  No two base directories for a file set may be sub-directories of each other.
  This requirement must be met across all base directories added to a file set,
  not just those within a single call to ``target_sources()``.

``FILES <files>...``

  An optional list of files to add to the file set. Each file must be in
  one of the base directories, or a subdirectory of one of the base
  directories. This argument supports
  ``generator expressions``.

  If relative paths are specified, they are considered relative to
  ``CMAKE_CURRENT_SOURCE_DIR`` at the time ``target_sources()`` is
  called. An exception to this is a path starting with ``$<``. Such paths
  are treated as relative to the target's source directory after evaluation
  of generator expressions.

The following target properties are set by ``target_sources(FILE_SET)``,
but they should not generally be manipulated directly:

For file sets of type ``HEADERS``:

* ``HEADER_SETS``
* ``INTERFACE_HEADER_SETS``
* ``HEADER_SET``
* ``HEADER_SET_<NAME>``
* ``HEADER_DIRS``
* ``HEADER_DIRS_<NAME>``

For file sets of type ``CXX_MODULES``:

* ``CXX_MODULE_SETS``
* ``INTERFACE_CXX_MODULE_SETS``
* ``CXX_MODULE_SET``
* ``CXX_MODULE_SET_<NAME>``
* ``CXX_MODULE_DIRS``
* ``CXX_MODULE_DIRS_<NAME>``

Target properties related to include directories are also modified by
``target_sources(FILE_SET)`` as follows:

``INCLUDE_DIRECTORIES``

  If the ``TYPE`` is ``HEADERS``, and the scope of the file set is ``PRIVATE``
  or ``PUBLIC``, all of the ``BASE_DIRS`` of the file set are wrapped in
  ``$<BUILD_INTERFACE>`` and appended to this property.

``INTERFACE_INCLUDE_DIRECTORIES``

  If the ``TYPE`` is ``HEADERS``, and the scope of the file set is
  ``INTERFACE`` or ``PUBLIC``, all of the ``BASE_DIRS`` of the file set are
  wrapped in ``$<BUILD_INTERFACE>`` and appended to this property.

See Also
^^^^^^^^

* ``add_executable()``
* ``add_library()``
* ``target_compile_definitions()``
* ``target_compile_features()``
* ``target_compile_options()``
* ``target_include_directories()``
* ``target_link_libraries()``
* ``target_link_directories()``
* ``target_link_options()``
* ``target_precompile_headers()``

try_compile
-----------

Try building some code.

Try Compiling Whole Projects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 try_compile(<compileResultVar> PROJECT <projectName>
             SOURCE_DIR <srcdir>
             [BINARY_DIR <bindir>]
             [TARGET <targetName>]
             [LOG_DESCRIPTION <text>]
             [NO_CACHE]
             [NO_LOG]
             [CMAKE_FLAGS <flags>...]
             [OUTPUT_VARIABLE <var>])

.. versionadded:: 3.25

Try building a project.  Build success returns ``TRUE`` and build failure
returns ``FALSE`` in ``<compileResultVar>``.

In this form, ``<srcdir>`` should contain a complete CMake project with a
``CMakeLists.txt`` file and all sources.  The ``<bindir>`` and ``<srcdir>``
will not be deleted after this command is run.  Specify ``<targetName>`` to
build a specific target instead of the ``all`` or ``ALL_BUILD`` target.  See
below for the meaning of other options.

.. versionchanged:: 3.24
  CMake variables describing platform settings, and those listed by the
  ``CMAKE_TRY_COMPILE_PLATFORM_VARIABLES`` variable, are propagated
  into the project's build configuration.  See policy ``CMP0137``.
  Previously this was only done by the
  :ref:`source file <Try Compiling Source Files>` signature.

.. versionadded:: 3.26
  This command records a
  :ref:`configure-log try_compile event <try_compile configure-log event>`
  if the ``NO_LOG`` option is not specified.

.. versionadded:: 3.30
  If the ``PROPAGATE_TOP_LEVEL_INCLUDES_TO_TRY_COMPILE`` global
  property is set to true, ``CMAKE_PROJECT_TOP_LEVEL_INCLUDES`` is
  propagated into the project's build configuration.

This command supports an alternate signature for CMake older than 3.25.
The signature above is recommended for clarity.

 try_compile(<compileResultVar> <bindir> <srcdir>
             <projectName> [<targetName>]
             [CMAKE_FLAGS <flags>...]
             [OUTPUT_VARIABLE <var>])

Try Compiling Source Files
^^^^^^^^^^^^^^^^^^^^^^^^^^

 try_compile(<compileResultVar>
             [SOURCES_TYPE <type>]
             <SOURCES <srcfile...>                 |
              SOURCE_FROM_CONTENT <name> <content> |
              SOURCE_FROM_VAR <name> <var>         |
              SOURCE_FROM_FILE <name> <path>       >...
             [LOG_DESCRIPTION <text>]
             [NO_CACHE]
             [NO_LOG]
             [CMAKE_FLAGS <flags>...]
             [COMPILE_DEFINITIONS <defs>...]
             [LINK_OPTIONS <options>...]
             [LINK_LIBRARIES <libs>...]
             [LINKER_LANGUAGE <lang>]
             [OUTPUT_VARIABLE <var>]
             [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
             [<LANG>_STANDARD <std>]
             [<LANG>_STANDARD_REQUIRED <bool>]
             [<LANG>_EXTENSIONS <bool>]
             )

.. versionadded:: 3.25

Try building an executable or static library from one or more source files
(which one is determined by the ``CMAKE_TRY_COMPILE_TARGET_TYPE``
variable). Build success returns ``TRUE`` and build failure returns ``FALSE``
in ``<compileResultVar>``.

In this form, one or more source files must be provided. Additionally, one of
``SOURCES`` and/or ``SOURCE_FROM_*`` must precede other keywords.

If ``CMAKE_TRY_COMPILE_TARGET_TYPE`` is unset or is set to
``EXECUTABLE``, the sources must include a definition for ``main`` and CMake
will create a ``CMakeLists.txt`` file to build the source(s) as an executable.
If ``CMAKE_TRY_COMPILE_TARGET_TYPE`` is set to ``STATIC_LIBRARY``,
a static library will be built instead and no definition for ``main`` is
required.  For an executable, the generated ``CMakeLists.txt`` file would
contain something like the following:

 add_definitions(<expanded COMPILE_DEFINITIONS from caller>)
 include_directories(${INCLUDE_DIRECTORIES})
 link_directories(${LINK_DIRECTORIES})
 add_executable(cmTryCompileExec <srcfile>...)
 target_link_options(cmTryCompileExec PRIVATE <LINK_OPTIONS from caller>)
 target_link_libraries(cmTryCompileExec ${LINK_LIBRARIES})

CMake automatically generates, for each ``try_compile`` operation, a
unique directory under ``${CMAKE_BINARY_DIR}/CMakeFiles/CMakeScratch``
with an unspecified name.  These directories are cleaned automatically unless
:option:`--debug-trycompile <cmake --debug-trycompile>` is passed to :program:`cmake`.
Such directories from previous runs are also unconditionally cleaned at the
beginning of any :program:`cmake` execution.

This command supports an alternate signature for CMake older than 3.25.
The signature above is recommended for clarity.

 try_compile(<compileResultVar> <bindir> <srcfile|SOURCES srcfile...>
             [CMAKE_FLAGS <flags>...]
             [COMPILE_DEFINITIONS <defs>...]
             [LINK_OPTIONS <options>...]
             [LINK_LIBRARIES <libs>...]
             [OUTPUT_VARIABLE <var>]
             [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
             [<LANG>_STANDARD <std>]
             [<LANG>_STANDARD_REQUIRED <bool>]
             [<LANG>_EXTENSIONS <bool>]
             )

In this version, ``try_compile`` will use ``<bindir>/CMakeFiles/CMakeTmp`` for
its operation, and all such files will be cleaned automatically.
For debugging, :option:`--debug-trycompile <cmake --debug-trycompile>` can be
passed to :program:`cmake` to avoid this clean.  However, multiple sequential
``try_compile`` operations, if given the same ``<bindir>``, will reuse this
single output directory, such that you can only debug one such ``try_compile``
call at a time.  Use of the newer signature is recommended to simplify
debugging of multiple ``try_compile`` operations.

Options
^^^^^^^

The options for the above signatures are:

``CMAKE_FLAGS <flags>...``
  Specify flags of the form :option:`-DVAR:TYPE=VALUE <cmake -D>` to be passed
  to the ``cmake(1)`` command-line used to drive the test build.
  The above example shows how values for variables
  ``COMPILE_DEFINITIONS``, ``INCLUDE_DIRECTORIES``, ``LINK_DIRECTORIES``,
  ``LINK_LIBRARIES``, and ``LINK_OPTIONS`` are used. Compiler options
  can be passed in like `CMAKE_FLAGS -DCOMPILE_DEFINITIONS=-Werror`.

``COMPILE_DEFINITIONS <defs>...``
  Specify ``-Ddefinition`` arguments to pass to ``add_definitions()``
  in the generated test project.

``COPY_FILE <fileName>``
  Copy the built executable or static library to the given ``<fileName>``.

``COPY_FILE_ERROR <var>``
  Use after ``COPY_FILE`` to capture into variable ``<var>`` any error
  message encountered while trying to copy the file.

``LINK_LIBRARIES <libs>...``
  Specify libraries to be linked in the generated project.
  The list of libraries may refer to system libraries and to
  :ref:`Imported Targets <Imported Targets>` from the calling project.

  If this option is specified, any ``-DLINK_LIBRARIES=...`` value
  given to the ``CMAKE_FLAGS`` option will be ignored.

  .. versionadded:: 3.29
    Alias targets to imported libraries are also supported.

``LINK_OPTIONS <options>...``
  .. versionadded:: 3.14

  Specify link step options to pass to ``target_link_options()`` or to
  set the ``STATIC_LIBRARY_OPTIONS`` target property in the generated
  project, depending on the ``CMAKE_TRY_COMPILE_TARGET_TYPE`` variable.

``LINKER_LANGUAGE <lang>``
  .. versionadded:: 3.29

  Specify the ``LINKER_LANGUAGE`` target property of the generated
  project.  When using multiple source files with different languages, set
  this to the language of the source file containing the program entry point,
  e.g., ``main``.

``LOG_DESCRIPTION <text>``
  .. versionadded:: 3.26

  Specify a non-empty text description of the purpose of the check.
  This is recorded in the ``cmake-configure-log(7)`` entry.

``NO_CACHE``
  .. versionadded:: 3.25

  The result will be stored in a normal variable rather than a cache entry.

  The result variable is normally cached so that a simple pattern can be used
  to avoid repeating the test on subsequent executions of CMake:

  .. code-block:: cmake

    if(NOT DEFINED RESULTVAR)
      # ...(check-specific setup code)...
      try_compile(RESULTVAR ...)
      # ...(check-specific logging and cleanup code)...
    endif()

  If the guard variable and result variable are not the same (for example, if
  the test is part of a larger inspection), ``NO_CACHE`` may be useful to avoid
  leaking the intermediate result variable into the cache.

``NO_LOG``
  .. versionadded:: 3.26

  Do not record a ``cmake-configure-log(7)`` entry for this call.

``OUTPUT_VARIABLE <var>``
  Store the output from the build process in the given variable.

``SOURCE_FROM_CONTENT <name> <content>``
  .. versionadded:: 3.25

  Write ``<content>`` to a file named ``<name>`` in the operation directory.
  This can be used to bypass the need to separately write a source file when
  the contents of the file are dynamically specified. The specified ``<name>``
  is not allowed to contain path components.

  ``SOURCE_FROM_CONTENT`` may be specified multiple times.

``SOURCE_FROM_FILE <name> <path>``
  .. versionadded:: 3.25

  Copy ``<path>`` to a file named ``<name>`` in the operation directory. This
  can be used to consolidate files into the operation directory, which may be
  useful if a source which already exists (i.e. as a stand-alone file in a
  project's source repository) needs to refer to other file(s) created by
  ``SOURCE_FROM_*``. (Otherwise, ``SOURCES`` is usually more convenient.) The
  specified ``<name>`` is not allowed to contain path components.

``SOURCE_FROM_VAR <name> <var>``
  .. versionadded:: 3.25

  Write the contents of ``<var>`` to a file named ``<name>`` in the operation
  directory. This is the same as ``SOURCE_FROM_CONTENT``, but takes the
  contents from the specified CMake variable, rather than directly, which may
  be useful when passing arguments through a function which wraps
  ``try_compile``. The specified ``<name>`` is not allowed to contain path
  components.

  ``SOURCE_FROM_VAR`` may be specified multiple times.

``SOURCES_TYPE <type>``
  .. versionadded:: 3.28

  Sources may be classified using the ``SOURCES_TYPE`` argument. Once
  specified, all subsequent sources specified will be treated as that type
  until another ``SOURCES_TYPE`` is given. Available types are:

  ``NORMAL``
    Sources are not added to any ``FILE_SET`` in the generated project.

  ``CXX_MODULE``
    .. versionadded:: 3.28

    Sources are added to a ``FILE_SET`` of type ``CXX_MODULES`` in the
    generated project.

  The default type of sources is ``NORMAL``.

``<LANG>_STANDARD <std>``
  .. versionadded:: 3.8

  Specify the ``C_STANDARD``, ``CXX_STANDARD``,
  ``OBJC_STANDARD``, ``OBJCXX_STANDARD``,
  or ``CUDA_STANDARD`` target property of the generated project.

``<LANG>_STANDARD_REQUIRED <bool>``
  .. versionadded:: 3.8

  Specify the ``C_STANDARD_REQUIRED``,
  ``CXX_STANDARD_REQUIRED``, ``OBJC_STANDARD_REQUIRED``,
  ``OBJCXX_STANDARD_REQUIRED``,or ``CUDA_STANDARD_REQUIRED``
  target property of the generated project.

``<LANG>_EXTENSIONS <bool>``
  .. versionadded:: 3.8

  Specify the ``C_EXTENSIONS``, ``CXX_EXTENSIONS``,
  ``OBJC_EXTENSIONS``, ``OBJCXX_EXTENSIONS``,
  or ``CUDA_EXTENSIONS`` target property of the generated project.

Other Behavior Settings
^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.4
  If set, the following variables are passed in to the generated
  try_compile CMakeLists.txt to initialize compile target properties with
  default values:

  * ``CMAKE_CUDA_RUNTIME_LIBRARY``
  * ``CMAKE_ENABLE_EXPORTS``
  * ``CMAKE_LINK_SEARCH_START_STATIC``
  * ``CMAKE_LINK_SEARCH_END_STATIC``
  * ``CMAKE_MSVC_RUNTIME_LIBRARY``
  * ``CMAKE_POSITION_INDEPENDENT_CODE``
  * ``CMAKE_WATCOM_RUNTIME_LIBRARY``

  If ``CMP0056`` is set to ``NEW``, then
  ``CMAKE_EXE_LINKER_FLAGS`` is passed in as well.

.. versionchanged:: 3.14
  If ``CMP0083`` is set to ``NEW``, then in order to obtain correct
  behavior at link time, the ``check_pie_supported()`` command from the
  ``CheckPIESupported`` module must be called before using the
  ``try_compile`` command.

The current settings of ``CMP0065`` and ``CMP0083`` are propagated
through to the generated test project.

Set variable ``CMAKE_TRY_COMPILE_CONFIGURATION`` to choose a build
configuration:

* For multi-config generators, this selects which configuration to build.

* For single-config generators, this sets ``CMAKE_BUILD_TYPE`` in
  the test project.

.. versionadded:: 3.6
  Set the ``CMAKE_TRY_COMPILE_TARGET_TYPE`` variable to specify
  the type of target used for the source file signature.

.. versionadded:: 3.6
  Set the ``CMAKE_TRY_COMPILE_PLATFORM_VARIABLES`` variable to specify
  variables that must be propagated into the test project.  This variable is
  meant for use only in toolchain files and is only honored by the
  ``try_compile()`` command for the source files form, not when given a whole
  project.

.. versionchanged:: 3.8
  If ``CMP0067`` is set to ``NEW``, or any of the ``<LANG>_STANDARD``,
  ``<LANG>_STANDARD_REQUIRED``, or ``<LANG>_EXTENSIONS`` options are used,
  then the language standard variables are honored:

  * ``CMAKE_C_STANDARD``
  * ``CMAKE_C_STANDARD_REQUIRED``
  * ``CMAKE_C_EXTENSIONS``
  * ``CMAKE_CXX_STANDARD``
  * ``CMAKE_CXX_STANDARD_REQUIRED``
  * ``CMAKE_CXX_EXTENSIONS``
  * ``CMAKE_OBJC_STANDARD``
  * ``CMAKE_OBJC_STANDARD_REQUIRED``
  * ``CMAKE_OBJC_EXTENSIONS``
  * ``CMAKE_OBJCXX_STANDARD``
  * ``CMAKE_OBJCXX_STANDARD_REQUIRED``
  * ``CMAKE_OBJCXX_EXTENSIONS``
  * ``CMAKE_CUDA_STANDARD``
  * ``CMAKE_CUDA_STANDARD_REQUIRED``
  * ``CMAKE_CUDA_EXTENSIONS``

  Their values are used to set the corresponding target properties in
  the generated project (unless overridden by an explicit option).

.. versionchanged:: 3.14
  For the ``Green Hills MULTI`` generator, the GHS toolset and target
  system customization cache variables are also propagated into the test
  project.

.. versionadded:: 3.24
  The ``CMAKE_TRY_COMPILE_NO_PLATFORM_VARIABLES`` variable may be
  set to disable passing platform variables into the test project.

.. versionadded:: 3.25
  If ``CMP0141`` is set to ``NEW``, one can use
  ``CMAKE_MSVC_DEBUG_INFORMATION_FORMAT`` to specify the MSVC debug
  information format.

.. versionadded:: 3.30
  If the ``PROPAGATE_TOP_LEVEL_INCLUDES_TO_TRY_COMPILE`` global
  property is set to true, ``CMAKE_PROJECT_TOP_LEVEL_INCLUDES`` is
  propagated into the test project's build configuration when using the
  :ref:`whole-project signature <Try Compiling Whole Projects>`.

See Also
^^^^^^^^

* ``try_run()``

try_run
-------

Try compiling and then running some code.

Try Compiling and Running Source Files
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 try_run(<runResultVar> <compileResultVar>
         [SOURCES_TYPE <type>]
         <SOURCES <srcfile...>                 |
          SOURCE_FROM_CONTENT <name> <content> |
          SOURCE_FROM_VAR <name> <var>         |
          SOURCE_FROM_FILE <name> <path>       >...
         [LOG_DESCRIPTION <text>]
         [NO_CACHE]
         [NO_LOG]
         [CMAKE_FLAGS <flags>...]
         [COMPILE_DEFINITIONS <defs>...]
         [LINK_OPTIONS <options>...]
         [LINK_LIBRARIES <libs>...]
         [COMPILE_OUTPUT_VARIABLE <var>]
         [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
         [<LANG>_STANDARD <std>]
         [<LANG>_STANDARD_REQUIRED <bool>]
         [<LANG>_EXTENSIONS <bool>]
         [RUN_OUTPUT_VARIABLE <var>]
         [RUN_OUTPUT_STDOUT_VARIABLE <var>]
         [RUN_OUTPUT_STDERR_VARIABLE <var>]
         [WORKING_DIRECTORY <var>]
         [ARGS <args>...]
         )

.. versionadded:: 3.25

Try building an executable from one or more source files.  Build success
returns ``TRUE`` and build failure returns ``FALSE`` in ``<compileResultVar>``.
If the build succeeds, this runs the executable and stores the exit code in
``<runResultVar>``.  If the executable was built, but failed to run, then
``<runResultVar>`` will be set to ``FAILED_TO_RUN``.  See command
``try_compile()`` for documentation of options common to both commands,
and for information on how the test project is constructed to build the source
file.

One or more source files must be provided. Additionally, one of ``SOURCES``
and/or ``SOURCE_FROM_*`` must precede other keywords.

.. versionadded:: 3.26
  This command records a
  :ref:`configure-log try_run event <try_run configure-log event>`
  if the ``NO_LOG`` option is not specified.

This command supports an alternate signature for CMake older than 3.25.
The signature above is recommended for clarity.

 try_run(<runResultVar> <compileResultVar>
         <bindir> <srcfile|SOURCES srcfile...>
         [CMAKE_FLAGS <flags>...]
         [COMPILE_DEFINITIONS <defs>...]
         [LINK_OPTIONS <options>...]
         [LINK_LIBRARIES <libs>...]
         [LINKER_LANGUAGE <lang>]
         [COMPILE_OUTPUT_VARIABLE <var>]
         [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
         [<LANG>_STANDARD <std>]
         [<LANG>_STANDARD_REQUIRED <bool>]
         [<LANG>_EXTENSIONS <bool>]
         [RUN_OUTPUT_VARIABLE <var>]
         [OUTPUT_VARIABLE <var>]
         [WORKING_DIRECTORY <var>]
         [ARGS <args>...]
         )

Options
^^^^^^^

The options specific to ``try_run`` are:

``COMPILE_OUTPUT_VARIABLE <var>``
  Report the compile step build output in a given variable.

``OUTPUT_VARIABLE <var>``
  Report the compile build output and the output from running the executable
  in the given variable.  This option exists for legacy reasons and is only
  supported by the old ``try_run`` signature.
  Prefer ``COMPILE_OUTPUT_VARIABLE`` and ``RUN_OUTPUT_VARIABLE`` instead.

``RUN_OUTPUT_VARIABLE <var>``
  Report the output from running the executable in a given variable.

``RUN_OUTPUT_STDOUT_VARIABLE <var>``
  .. versionadded:: 3.25

  Report the output of stdout from running the executable in a given variable.

``RUN_OUTPUT_STDERR_VARIABLE <var>``
  .. versionadded:: 3.25

  Report the output of stderr from running the executable in a given variable.

``WORKING_DIRECTORY <var>``
  .. versionadded:: 3.20

  Run the executable in the given directory. If no ``WORKING_DIRECTORY`` is
  specified, the executable will run in ``<bindir>`` or the current build
  directory.

``ARGS <args>...``
  Additional arguments to pass to the executable when running it.

Other Behavior Settings
^^^^^^^^^^^^^^^^^^^^^^^

Set variable ``CMAKE_TRY_COMPILE_CONFIGURATION`` to choose a build
configuration:

* For multi-config generators, this selects which configuration to build.

* For single-config generators, this sets ``CMAKE_BUILD_TYPE`` in
  the test project.

Behavior when Cross Compiling
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.3
  Use ``CMAKE_CROSSCOMPILING_EMULATOR`` when running cross-compiled binaries.

When cross compiling, the executable compiled in the first step
usually cannot be run on the build host.  The ``try_run`` command checks
the ``CMAKE_CROSSCOMPILING`` variable to detect whether CMake is in
cross-compiling mode.  If that is the case, it will still try to compile
the executable, but it will not try to run the executable unless the
``CMAKE_CROSSCOMPILING_EMULATOR`` variable is set.  Instead it
will create cache variables which must be filled by the user or by
presetting them in some CMake script file to the values the executable
would have produced if it had been run on its actual target platform.
These cache entries are:

``<runResultVar>``
  Exit code if the executable were to be run on the target platform.

``<runResultVar>__TRYRUN_OUTPUT``
  Output from stdout and stderr if the executable were to be run on
  the target platform.  This is created only if the
  ``RUN_OUTPUT_VARIABLE`` or ``OUTPUT_VARIABLE`` option was used.

In order to make cross compiling your project easier, use ``try_run``
only if really required.  If you use ``try_run``, use the
``RUN_OUTPUT_STDOUT_VARIABLE``, ``RUN_OUTPUT_STDERR_VARIABLE``,
``RUN_OUTPUT_VARIABLE`` or ``OUTPUT_VARIABLE`` options only if really
required.  Using them will require that when cross-compiling, the cache
variables will have to be set manually to the output of the executable.
You can also "guard" the calls to ``try_run`` with an ``if()``
block checking the ``CMAKE_CROSSCOMPILING`` variable and
provide an easy-to-preset alternative for this case.

CTest Commands
==============

These commands are available only in CTest scripts.

ctest_build
-----------

Perform the :ref:`CTest Build Step` as a :ref:`Dashboard Client`.

 ctest_build([BUILD <build-dir>] [APPEND]
             [CONFIGURATION <config>]
             [PARALLEL_LEVEL <parallel>]
             [FLAGS <flags>]
             [PROJECT_NAME <project-name>]
             [TARGET <target-name>]
             [NUMBER_ERRORS <num-err-var>]
             [NUMBER_WARNINGS <num-warn-var>]
             [RETURN_VALUE <result-var>]
             [CAPTURE_CMAKE_ERROR <result-var>]
             )

Build the project and store results in ``Build.xml``
for submission with the ``ctest_submit()`` command.

The ``CTEST_BUILD_COMMAND`` variable may be set to explicitly
specify the build command line.  Otherwise the build command line is
computed automatically based on the options given.

The options are:

``BUILD <build-dir>``
  Specify the top-level build directory.  If not given, the
  ``CTEST_BINARY_DIRECTORY`` variable is used.

``APPEND``
  Mark ``Build.xml`` for append to results previously submitted to a
  dashboard server since the last ``ctest_start()`` call.
  Append semantics are defined by the dashboard server in use.
  This does *not* cause results to be appended to a ``.xml`` file
  produced by a previous call to this command.

``CONFIGURATION <config>``
  Specify the build configuration (e.g. ``Debug``).  If not
  specified the ``CTEST_BUILD_CONFIGURATION`` variable will be checked.
  Otherwise the :option:`-C \<cfg\> <ctest -C>` option given to the
  ``ctest(1)`` command will be used, if any.

``PARALLEL_LEVEL <parallel>``
  .. versionadded:: 3.21

  Specify the parallel level of the underlying build system.  If not
  specified, the ``CMAKE_BUILD_PARALLEL_LEVEL`` environment
  variable will be checked.

``FLAGS <flags>``
  Pass additional arguments to the underlying build command.
  If not specified the ``CTEST_BUILD_FLAGS`` variable will be checked.
  This can, e.g., be used to trigger a parallel build using the
  ``-j`` option of ``make``. See the ``ProcessorCount`` module
  for an example.

``PROJECT_NAME <project-name>``
  Ignored since CMake 3.0.

  .. versionchanged:: 3.14
    This value is no longer required.

``TARGET <target-name>``
  Specify the name of a target to build.  If not specified the
  ``CTEST_BUILD_TARGET`` variable will be checked.  Otherwise the
  default target will be built.  This is the "all" target
  (called ``ALL_BUILD`` in :ref:`Visual Studio Generators`).

``NUMBER_ERRORS <num-err-var>``
  Store the number of build errors detected in the given variable.

``NUMBER_WARNINGS <num-warn-var>``
  Store the number of build warnings detected in the given variable.

``RETURN_VALUE <result-var>``
  Store the return value of the native build tool in the given variable.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.7

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``QUIET``
  .. versionadded:: 3.3

  Suppress any CTest-specific non-error output that would have been
  printed to the console otherwise.  The summary of warnings / errors,
  as well as the output from the native build tool is unaffected by
  this option.

ctest_configure
---------------

Perform the :ref:`CTest Configure Step` as a :ref:`Dashboard Client`.

 ctest_configure([BUILD <build-dir>] [SOURCE <source-dir>] [APPEND]
                 [OPTIONS <options>] [RETURN_VALUE <result-var>] [QUIET]
                 [CAPTURE_CMAKE_ERROR <result-var>])

Configure the project build tree and record results in ``Configure.xml``
for submission with the ``ctest_submit()`` command.

The options are:

``BUILD <build-dir>``
  Specify the top-level build directory.  If not given, the
  ``CTEST_BINARY_DIRECTORY`` variable is used.

``SOURCE <source-dir>``
  Specify the source directory.  If not given, the
  ``CTEST_SOURCE_DIRECTORY`` variable is used.

``APPEND``
  Mark ``Configure.xml`` for append to results previously submitted to a
  dashboard server since the last ``ctest_start()`` call.
  Append semantics are defined by the dashboard server in use.
  This does *not* cause results to be appended to a ``.xml`` file
  produced by a previous call to this command.

``OPTIONS <options>``
  Specify command-line arguments to pass to the configuration tool.

``RETURN_VALUE <result-var>``
  Store in the ``<result-var>`` variable the return value of the native
  configuration tool.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.7

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``QUIET``
  .. versionadded:: 3.3

  Suppress any CTest-specific non-error messages that would have
  otherwise been printed to the console.  Output from the underlying
  configure command is not affected.

ctest_coverage
--------------

Perform the :ref:`CTest Coverage Step` as a :ref:`Dashboard Client`.

 ctest_coverage([BUILD <build-dir>] [APPEND]
                [LABELS <label>...]
                [RETURN_VALUE <result-var>]
                [CAPTURE_CMAKE_ERROR <result-var>]
                [QUIET]
                )

Collect coverage tool results and stores them in ``Coverage.xml``
for submission with the ``ctest_submit()`` command.

The options are:

``BUILD <build-dir>``
  Specify the top-level build directory.  If not given, the
  ``CTEST_BINARY_DIRECTORY`` variable is used.

``APPEND``
  Mark ``Coverage.xml`` for append to results previously submitted to a
  dashboard server since the last ``ctest_start()`` call.
  Append semantics are defined by the dashboard server in use.
  This does *not* cause results to be appended to a ``.xml`` file
  produced by a previous call to this command.

``LABELS``
  Filter the coverage report to include only source files labeled
  with at least one of the labels specified.

``RETURN_VALUE <result-var>``
  Store in the ``<result-var>`` variable ``0`` if coverage tools
  ran without error and non-zero otherwise.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.7

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``QUIET``
  .. versionadded:: 3.3

  Suppress any CTest-specific non-error output that would have been
  printed to the console otherwise.  The summary indicating how many
  lines of code were covered is unaffected by this option.

ctest_empty_binary_directory
----------------------------

empties the binary directory

 ctest_empty_binary_directory(<directory>)

Removes a binary directory.  This command will perform some checks
prior to deleting the directory in an attempt to avoid malicious or
accidental directory deletion.

ctest_memcheck
--------------

Perform the :ref:`CTest MemCheck Step` as a :ref:`Dashboard Client`.

 ctest_memcheck([BUILD <build-dir>] [APPEND]
                [START <start-number>]
                [END <end-number>]
                [STRIDE <stride-number>]
                [EXCLUDE <exclude-regex>]
                [INCLUDE <include-regex>]
                [EXCLUDE_LABEL <label-exclude-regex>]
                [INCLUDE_LABEL <label-include-regex>]
                [EXCLUDE_FIXTURE <regex>]
                [EXCLUDE_FIXTURE_SETUP <regex>]
                [EXCLUDE_FIXTURE_CLEANUP <regex>]
                [PARALLEL_LEVEL <level>]
                [RESOURCE_SPEC_FILE <file>]
                [TEST_LOAD <threshold>]
                [SCHEDULE_RANDOM <ON|OFF>]
                [STOP_ON_FAILURE]
                [STOP_TIME <time-of-day>]
                [RETURN_VALUE <result-var>]
                [CAPTURE_CMAKE_ERROR <result-var>]
                [REPEAT <mode>:<n>]
                [OUTPUT_JUNIT <file>]
                [DEFECT_COUNT <defect-count-var>]
                [QUIET]
                )

Run tests with a dynamic analysis tool and store results in
``MemCheck.xml`` for submission with the ``ctest_submit()``
command.

Most options are the same as those for the ``ctest_test()`` command.

The options unique to this command are:

``DEFECT_COUNT <defect-count-var>``
  .. versionadded:: 3.8

  Store in the ``<defect-count-var>`` the number of defects found.

ctest_read_custom_files
-----------------------

read CTestCustom files.

 ctest_read_custom_files(<directory>...)

Read all the CTestCustom.ctest or CTestCustom.cmake files from the
given directory.

By default, invoking ``ctest(1)`` without a script will read custom
files from the binary directory.

ctest_run_script
----------------

runs a :option:`ctest -S` script

 ctest_run_script([NEW_PROCESS] script_file_name script_file_name1
             script_file_name2 ... [RETURN_VALUE var])

Runs a script or scripts much like if it was run from :option:`ctest -S`.
If no argument is provided then the current script is run using the current
settings of the variables.  If ``NEW_PROCESS`` is specified then each
script will be run in a separate process.If ``RETURN_VALUE`` is specified
the return value of the last script run will be put into ``var``.

ctest_sleep
-----------

sleeps for some amount of time

 ctest_sleep(<seconds>)

Sleep for given number of seconds.

 ctest_sleep(<time1> <duration> <time2>)

Sleep for t=(time1 + duration - time2) seconds if t > 0.

ctest_start
-----------

Starts the testing for a given model

 ctest_start(<model> [<source> [<binary>]] [GROUP <group>] [QUIET])

 ctest_start([<model> [<source> [<binary>]]] [GROUP <group>] APPEND [QUIET])

Starts the testing for a given model.  The command should be called
after the binary directory is initialized.

The parameters are as follows:

``<model>``
  Set the dashboard model. Must be one of ``Experimental``, ``Continuous``, or
  ``Nightly``. This parameter is required unless ``APPEND`` is specified.

``<source>``
  Set the source directory. If not specified, the value of
  ``CTEST_SOURCE_DIRECTORY`` is used instead.

``<binary>``
  Set the binary directory. If not specified, the value of
  ``CTEST_BINARY_DIRECTORY`` is used instead.

``GROUP <group>``
  If ``GROUP`` is used, the submissions will go to the specified group on the
  CDash server. If no ``GROUP`` is specified, the name of the model is used by
  default.

  .. versionchanged:: 3.16
    This replaces the deprecated option ``TRACK``. Despite the name
    change its behavior is unchanged.

``APPEND``
  If ``APPEND`` is used, the existing ``TAG`` is used rather than creating a new
  one based on the current time stamp. If you use ``APPEND``, you can omit the
  ``<model>`` and ``GROUP <group>`` parameters, because they will be read from
  the generated ``TAG`` file. For example:

  .. code-block:: cmake

    ctest_start(Experimental GROUP GroupExperimental)

  Later, in another :option:`ctest -S` script:

  .. code-block:: cmake

    ctest_start(APPEND)

  When the second script runs ``ctest_start(APPEND)``, it will read the
  ``Experimental`` model and ``GroupExperimental`` group from the ``TAG`` file
  generated by the first ``ctest_start()`` command. Please note that if you
  call ``ctest_start(APPEND)`` and specify a different model or group than
  in the first ``ctest_start()`` command, a warning will be issued, and the
  new model and group will be used.

``QUIET``
  .. versionadded:: 3.3

  If ``QUIET`` is used, CTest will suppress any non-error messages that it
  otherwise would have printed to the console.

The parameters for ``ctest_start()`` can be issued in any order, with the
exception that ``<model>``, ``<source>``, and ``<binary>`` have to appear
in that order with respect to each other. The following are all valid and
equivalent:

 ctest_start(Experimental path/to/source path/to/binary GROUP SomeGroup QUIET APPEND)

 ctest_start(GROUP SomeGroup Experimental QUIET path/to/source APPEND path/to/binary)

 ctest_start(APPEND QUIET Experimental path/to/source GROUP SomeGroup path/to/binary)

However, for the sake of readability, it is recommended that you order your
parameters in the order listed at the top of this page.

If the ``CTEST_CHECKOUT_COMMAND`` variable (or the
``CTEST_CVS_CHECKOUT`` variable) is set, its content is treated as
command-line.  The command is invoked with the current working directory set
to the parent of the source directory, even if the source directory already
exists.  This can be used to create the source tree from a version control
repository.

ctest_submit
------------

Perform the :ref:`CTest Submit Step` as a :ref:`Dashboard Client`.

 ctest_submit([PARTS <part>...] [FILES <file>...]
              [SUBMIT_URL <url>]
              [BUILD_ID <result-var>]
              [HTTPHEADER <header>]
              [RETRY_COUNT <count>]
              [RETRY_DELAY <delay>]
              [RETURN_VALUE <result-var>]
              [CAPTURE_CMAKE_ERROR <result-var>]
              [QUIET]
              )

Submit results to a dashboard server.
By default all available parts are submitted.

The options are:

``PARTS <part>...``
  Specify a subset of parts to submit.  Valid part names are::

 Start      = nothing
 Update     = ctest_update results, in Update.xml
 Configure  = ctest_configure results, in Configure.xml
 Build      = ctest_build results, in Build.xml
 Test       = ctest_test results, in Test.xml
 Coverage   = ctest_coverage results, in Coverage.xml
 MemCheck   = ctest_memcheck results, in DynamicAnalysis.xml and
              DynamicAnalysis-Test.xml
 Notes      = Files listed by CTEST_NOTES_FILES, in Notes.xml
 ExtraFiles = Files listed by CTEST_EXTRA_SUBMIT_FILES
 Upload     = Files prepared for upload by ctest_upload(), in Upload.xml
 Submit     = nothing
 Done       = Build is complete, in Done.xml

``FILES <file>...``
  Specify an explicit list of specific files to be submitted.
  Each individual file must exist at the time of the call.

``SUBMIT_URL <url>``
  .. versionadded:: 3.14

  The ``http`` or ``https`` URL of the dashboard server to send the submission
  to.  If not given, the ``CTEST_SUBMIT_URL`` variable is used.

``BUILD_ID <result-var>``
  .. versionadded:: 3.15

  Store in the ``<result-var>`` variable the ID assigned to this build by
  CDash.

``HTTPHEADER <HTTP-header>``
  .. versionadded:: 3.9

  Specify HTTP header to be included in the request to CDash during submission.
  For example, CDash can be configured to only accept submissions from
  authenticated clients. In this case, you should provide a bearer token in your
  header:

  .. code-block:: cmake

    ctest_submit(HTTPHEADER "Authorization: Bearer <auth-token>")

  This suboption can be repeated several times for multiple headers.

``RETRY_COUNT <count>``
  Specify how many times to retry a timed-out submission.

``RETRY_DELAY <delay>``
  Specify how long (in seconds) to wait after a timed-out submission
  before attempting to re-submit.

``RETURN_VALUE <result-var>``
  Store in the ``<result-var>`` variable ``0`` for success and
  non-zero on failure.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.13

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``QUIET``
  .. versionadded:: 3.3

  Suppress all non-error messages that would have otherwise been
  printed to the console.

Submit to CDash Upload API
^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.2

 ctest_submit(CDASH_UPLOAD <file> [CDASH_UPLOAD_TYPE <type>]
              [SUBMIT_URL <url>]
              [BUILD_ID <result-var>]
              [HTTPHEADER <header>]
              [RETRY_COUNT <count>]
              [RETRY_DELAY <delay>]
              [RETURN_VALUE <result-var>]
              [QUIET])

This second signature is used to upload files to CDash via the CDash
file upload API. The API first sends a request to upload to CDash along
with a content hash of the file. If CDash does not already have the file,
then it is uploaded. Along with the file, a CDash type string is specified
to tell CDash which handler to use to process the data.

This signature interprets options in the same way as the first one.

.. versionadded:: 3.8
  Added the ``RETRY_COUNT``, ``RETRY_DELAY``, ``QUIET`` options.

.. versionadded:: 3.9
  Added the ``HTTPHEADER`` option.

.. versionadded:: 3.13
  Added the ``RETURN_VALUE`` option.

.. versionadded:: 3.14
  Added the ``SUBMIT_URL`` option.

.. versionadded:: 3.15
  Added the ``BUILD_ID`` option.

ctest_test
----------

Perform the :ref:`CTest Test Step` as a :ref:`Dashboard Client`.

 ctest_test([BUILD <build-dir>] [APPEND]
            [START <start-number>]
            [END <end-number>]
            [STRIDE <stride-number>]
            [EXCLUDE <exclude-regex>]
            [INCLUDE <include-regex>]
            [EXCLUDE_LABEL <label-exclude-regex>]
            [INCLUDE_LABEL <label-include-regex>]
            [EXCLUDE_FROM_FILE <filename>]
            [INCLUDE_FROM_FILE <filename>]
            [EXCLUDE_FIXTURE <regex>]
            [EXCLUDE_FIXTURE_SETUP <regex>]
            [EXCLUDE_FIXTURE_CLEANUP <regex>]
            [PARALLEL_LEVEL [<level>]]
            [RESOURCE_SPEC_FILE <file>]
            [TEST_LOAD <threshold>]
            [SCHEDULE_RANDOM <ON|OFF>]
            [STOP_ON_FAILURE]
            [STOP_TIME <time-of-day>]
            [RETURN_VALUE <result-var>]
            [CAPTURE_CMAKE_ERROR <result-var>]
            [REPEAT <mode>:<n>]
            [OUTPUT_JUNIT <file>]
            [QUIET]
            )

Run tests in the project build tree and store results in
``Test.xml`` for submission with the ``ctest_submit()`` command.

The options are:

``BUILD <build-dir>``
  Specify the top-level build directory.  If not given, the
  ``CTEST_BINARY_DIRECTORY`` variable is used.

``APPEND``
  Mark ``Test.xml`` for append to results previously submitted to a
  dashboard server since the last ``ctest_start()`` call.
  Append semantics are defined by the dashboard server in use.
  This does *not* cause results to be appended to a ``.xml`` file
  produced by a previous call to this command.

``START <start-number>``
  Specify the beginning of a range of test numbers.

``END <end-number>``
  Specify the end of a range of test numbers.

``STRIDE <stride-number>``
  Specify the stride by which to step across a range of test numbers.

``EXCLUDE <exclude-regex>``
  Specify a regular expression matching test names to exclude.

``INCLUDE <include-regex>``
  Specify a regular expression matching test names to include.
  Tests not matching this expression are excluded.

``EXCLUDE_LABEL <label-exclude-regex>``
  Specify a regular expression matching test labels to exclude.

``INCLUDE_LABEL <label-include-regex>``
  Specify a regular expression matching test labels to include.
  Tests not matching this expression are excluded.

``EXCLUDE_FROM_FILE <filename>``
  .. versionadded:: 3.29

  Do NOT run tests listed with their exact name in the given file.

``INCLUDE_FROM_FILE <filename>``
  .. versionadded:: 3.29

  Only run the tests listed with their exact name in the given file.

``EXCLUDE_FIXTURE <regex>``
  .. versionadded:: 3.7

  If a test in the set of tests to be executed requires a particular fixture,
  that fixture's setup and cleanup tests would normally be added to the test
  set automatically. This option prevents adding setup or cleanup tests for
  fixtures matching the ``<regex>``. Note that all other fixture behavior is
  retained, including test dependencies and skipping tests that have fixture
  setup tests that fail.

``EXCLUDE_FIXTURE_SETUP <regex>``
  .. versionadded:: 3.7

  Same as ``EXCLUDE_FIXTURE`` except only matching setup tests are excluded.

``EXCLUDE_FIXTURE_CLEANUP <regex>``
  .. versionadded:: 3.7

  Same as ``EXCLUDE_FIXTURE`` except only matching cleanup tests are excluded.

``PARALLEL_LEVEL [<level>]``
  Run tests in parallel, limited to a given level of parallelism.

  .. versionadded:: 3.29

    The ``<level>`` may be omitted, or ``0``, to let ctest use a default
    level of parallelism, or unbounded parallelism, respectively, as
    documented by the :option:`ctest --parallel` option.

``RESOURCE_SPEC_FILE <file>``
  .. versionadded:: 3.16

  Specify a
  :ref:`resource specification file <ctest-resource-specification-file>`. See
  :ref:`ctest-resource-allocation` for more information.

``TEST_LOAD <threshold>``
  .. versionadded:: 3.4

  While running tests in parallel, try not to start tests when they
  may cause the CPU load to pass above a given threshold.  If not
  specified the ``CTEST_TEST_LOAD`` variable will be checked,
  and then the :option:`--test-load <ctest --test-load>` command-line
  argument to ``ctest(1)``. See also the ``TestLoad`` setting
  in the :ref:`CTest Test Step`.

``REPEAT <mode>:<n>``
  .. versionadded:: 3.17

  Run tests repeatedly based on the given ``<mode>`` up to ``<n>`` times.
  The modes are:

  ``UNTIL_FAIL``
    Require each test to run ``<n>`` times without failing in order to pass.
    This is useful in finding sporadic failures in test cases.

  ``UNTIL_PASS``
    Allow each test to run up to ``<n>`` times in order to pass.
    Repeats tests if they fail for any reason.
    This is useful in tolerating sporadic failures in test cases.

  ``AFTER_TIMEOUT``
    Allow each test to run up to ``<n>`` times in order to pass.
    Repeats tests only if they timeout.
    This is useful in tolerating sporadic timeouts in test cases
    on busy machines.

``SCHEDULE_RANDOM <ON|OFF>``
  Launch tests in a random order.  This may be useful for detecting
  implicit test dependencies.

``STOP_ON_FAILURE``
  .. versionadded:: 3.18

  Stop the execution of the tests once one has failed.

``STOP_TIME <time-of-day>``
  Specify a time of day at which the tests should all stop running.

``RETURN_VALUE <result-var>``
  Store in the ``<result-var>`` variable ``0`` if all tests passed.
  Store non-zero if anything went wrong.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.7

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``OUTPUT_JUNIT <file>``
  .. versionadded:: 3.21

  Write test results to ``<file>`` in JUnit XML format. If ``<file>`` is a
  relative path, it will be placed in the build directory. If ``<file>``
  already exists, it will be overwritten. Note that the resulting JUnit XML
  file is **not** uploaded to CDash because it would be redundant with
  CTest's ``Test.xml`` file.

``QUIET``
  .. versionadded:: 3.3

  Suppress any CTest-specific non-error messages that would have otherwise
  been printed to the console.  Output from the underlying test command is not
  affected.  Summary info detailing the percentage of passing tests is also
  unaffected by the ``QUIET`` option.

See also the ``CTEST_CUSTOM_MAXIMUM_PASSED_TEST_OUTPUT_SIZE``,
``CTEST_CUSTOM_MAXIMUM_FAILED_TEST_OUTPUT_SIZE`` and
``CTEST_CUSTOM_TEST_OUTPUT_TRUNCATION`` variables, along with their
corresponding ``ctest(1)`` command line options
:option:`--test-output-size-passed <ctest --test-output-size-passed>`,
:option:`--test-output-size-failed <ctest --test-output-size-failed>`, and
:option:`--test-output-truncation <ctest --test-output-truncation>`.

Additional Test Measurements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

CTest can parse the output of your tests for extra measurements to report
to CDash.

When run as a :ref:`Dashboard Client`, CTest will include these custom
measurements in the ``Test.xml`` file that gets uploaded to CDash.

Check the `CDash test measurement documentation
<https://github.com/Kitware/CDash/blob/master/docs/test_measurements.md>`_
for more information on the types of test measurements that CDash recognizes.

The following example demonstrates how to output a variety of custom test
measurements.

 std::cout <<
   "<CTestMeasurement type=\"numeric/double\" name=\"score\">28.3</CTestMeasurement>"
   << std::endl;

 std::cout <<
   "<CTestMeasurement type=\"text/string\" name=\"color\">red</CTestMeasurement>"
   << std::endl;

 std::cout <<
   "<CTestMeasurement type=\"text/link\" name=\"CMake URL\">https://cmake.org</CTestMeasurement>"
   << std::endl;

 std::cout <<
   "<CTestMeasurement type=\"text/preformatted\" name=\"Console Output\">" <<
   "line 1.\n" <<
   "  \033[31;1m line 2. Bold red, and indented!\033[0;0ml\n" <<
   "line 3. Not bold or indented...\n" <<
   "</CTestMeasurement>" << std::endl;

Image Measurements
""""""""""""""""""

The following example demonstrates how to upload test images to CDash.

 std::cout <<
   "<CTestMeasurementFile type=\"image/jpg\" name=\"TestImage\">" <<
   "/dir/to/test_img.jpg</CTestMeasurementFile>" << std::endl;

 std::cout <<
   "<CTestMeasurementFile type=\"image/gif\" name=\"ValidImage\">" <<
   "/dir/to/valid_img.gif</CTestMeasurementFile>" << std::endl;

 std::cout <<
   "<CTestMeasurementFile type=\"image/png\" name=\"AlgoResult\">" <<
   "/dir/to/img.png</CTestMeasurementFile>"
   << std::endl;

Images will be displayed together in an interactive comparison mode on CDash
if they are provided with two or more of the following names.

* ``TestImage``
* ``ValidImage``
* ``BaselineImage``
* ``DifferenceImage2``

By convention, ``TestImage`` is the image generated by your test, and
``ValidImage`` (or ``BaselineImage``) is basis of comparison used to determine
if the test passed or failed.

If another image name is used it will be displayed by CDash as a static image
separate from the interactive comparison UI.

Attached Files
""""""""""""""

.. versionadded:: 3.21

The following example demonstrates how to upload non-image files to CDash.

 std::cout <<
   "<CTestMeasurementFile type=\"file\" name=\"TestInputData1\">" <<
   "/dir/to/data1.csv</CTestMeasurementFile>\n"                   <<
   "<CTestMeasurementFile type=\"file\" name=\"TestInputData2\">" <<
   "/dir/to/data2.csv</CTestMeasurementFile>"                     << std::endl;

If the name of the file to upload is known at configure time, you can use the
``ATTACHED_FILES`` or ``ATTACHED_FILES_ON_FAIL`` test
properties instead.

Custom Details
""""""""""""""

.. versionadded:: 3.21

The following example demonstrates how to specify a custom value for the
``Test Details`` field displayed on CDash.

 std::cout <<
   "<CTestDetails>My Custom Details Value</CTestDetails>" << std::endl;

Additional Labels
"""""""""""""""""

.. versionadded:: 3.22

The following example demonstrates how to add additional labels to a test
at runtime.

 std::cout <<
   "<CTestLabel>Custom Label 1</CTestLabel>\n" <<
   "<CTestLabel>Custom Label 2</CTestLabel>"   << std::endl;

Use the ``LABELS`` test property instead for labels that can be
determined at configure time.

ctest_update
------------

Perform the :ref:`CTest Update Step` as a :ref:`Dashboard Client`.

 ctest_update([SOURCE <source-dir>]
              [RETURN_VALUE <result-var>]
              [CAPTURE_CMAKE_ERROR <result-var>]
              [QUIET])

Update the source tree from version control and record results in
``Update.xml`` for submission with the ``ctest_submit()`` command.

The options are:

``SOURCE <source-dir>``
  Specify the source directory.  If not given, the
  ``CTEST_SOURCE_DIRECTORY`` variable is used.

``RETURN_VALUE <result-var>``
  Store in the ``<result-var>`` variable the number of files
  updated or ``-1`` on error.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.13

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

``QUIET``
  .. versionadded:: 3.3

  Tell CTest to suppress most non-error messages that it would
  have otherwise printed to the console.  CTest will still report
  the new revision of the repository and any conflicting files
  that were found.

The update always follows the version control branch currently checked
out in the source directory.  See the :ref:`CTest Update Step`
documentation for information about variables that change the behavior
of ``ctest_update()``.

ctest_upload
------------

Upload files to a dashboard server as a :ref:`Dashboard Client`.

 ctest_upload(FILES <file>... [QUIET] [CAPTURE_CMAKE_ERROR <result-var>])

The options are:

``FILES <file>...``
  Specify a list of files to be sent along with the build results to the
  dashboard server.

``QUIET``
  .. versionadded:: 3.3

  Suppress any CTest-specific non-error output that would have been
  printed to the console otherwise.

``CAPTURE_CMAKE_ERROR <result-var>``
  .. versionadded:: 3.7

  Store in the ``<result-var>`` variable -1 if there are any errors running
  the command and prevent ctest from returning non-zero if an error occurs.

Deprecated Commands
===================

These commands are deprecated and are only made available to maintain
backward compatibility.  The documentation of each command states the
CMake version in which it was deprecated.  Do not use these commands
in new code.

build_name
----------

Disallowed since version 3.0.  See CMake Policy ``CMP0036``.

Use ``${CMAKE_SYSTEM}`` and ``${CMAKE_CXX_COMPILER}`` instead.

 build_name(variable)

Sets the specified variable to a string representing the platform and
compiler settings.  These values are now available through the
``CMAKE_SYSTEM`` and
``CMAKE_CXX_COMPILER`` variables.

exec_program
------------

.. versionchanged:: 3.28
  This command is available only if policy ``CMP0153`` is not set to ``NEW``.
  Port projects to the ``execute_process()`` command.

Run an executable program during the processing of the CMakeList.txt
file.

 exec_program(Executable [directory in which to run]
              [ARGS <arguments to executable>]
              [OUTPUT_VARIABLE <var>]
              [RETURN_VALUE <var>])

The executable is run in the optionally specified directory.  The
executable can include arguments if it is double quoted, but it is
better to use the optional ``ARGS`` argument to specify arguments to the
program.  This is because cmake will then be able to escape spaces in
the executable path.  An optional argument ``OUTPUT_VARIABLE`` specifies a
variable in which to store the output.  To capture the return value of
the execution, provide a ``RETURN_VALUE``.  If ``OUTPUT_VARIABLE`` is
specified, then no output will go to the stdout/stderr of the console
running cmake.

export_library_dependencies
---------------------------

Disallowed since version 3.0.  See CMake Policy ``CMP0033``.

Use ``install(EXPORT)`` or ``export()`` command.

This command generates an old-style library dependencies file.
Projects requiring CMake 2.6 or later should not use the command.  Use
instead the ``install(EXPORT)`` command to help export targets from an
installation tree and the ``export()`` command to export targets from a
build tree.

The old-style library dependencies file does not take into account
per-configuration names of libraries or the
``LINK_INTERFACE_LIBRARIES`` target property.

 export_library_dependencies(<file> [APPEND])

Create a file named ``<file>`` that can be included into a CMake listfile
with the INCLUDE command.  The file will contain a number of SET
commands that will set all the variables needed for library dependency
information.  This should be the last command in the top level
CMakeLists.txt file of the project.  If the ``APPEND`` option is
specified, the SET commands will be appended to the given file instead
of replacing it.

install_files
-------------

This command has been superseded by the ``install()`` command.  It is
provided for compatibility with older CMake code.  The ``FILES`` form is
directly replaced by the ``FILES`` form of the ``install()``
command.  The regexp form can be expressed more clearly using the ``GLOB``
form of the ``file()`` command.

 install_files(<dir> extension file file ...)

Create rules to install the listed files with the given extension into
the given directory.  Only files existing in the current source tree
or its corresponding location in the binary tree may be listed.  If a
file specified already has an extension, that extension will be
removed first.  This is useful for providing lists of source files
such as foo.cxx when you want the corresponding foo.h to be installed.
A typical extension is ``.h``.

 install_files(<dir> regexp)

Any files in the current source directory that match the regular
expression will be installed.

 install_files(<dir> FILES file file ...)

Any files listed after the ``FILES`` keyword will be installed explicitly
from the names given.  Full paths are allowed in this form.

The directory ``<dir>`` is relative to the installation prefix, which is
stored in the variable ``CMAKE_INSTALL_PREFIX``.

install_programs
----------------

This command has been superseded by the ``install()`` command.  It is
provided for compatibility with older CMake code.  The ``FILES`` form is
directly replaced by the ``PROGRAMS`` form of the ``install()``
command.  The regexp form can be expressed more clearly using the ``GLOB``
form of the ``file()`` command.

 install_programs(<dir> file1 file2 [file3 ...])
 install_programs(<dir> FILES file1 [file2 ...])

Create rules to install the listed programs into the given directory.
Use the ``FILES`` argument to guarantee that the file list version of the
command will be used even when there is only one argument.

 install_programs(<dir> regexp)

In the second form any program in the current source directory that
matches the regular expression will be installed.

This command is intended to install programs that are not built by
cmake, such as shell scripts.  See the ``TARGETS`` form of the
``install()`` command to create installation rules for targets built
by cmake.

The directory ``<dir>`` is relative to the installation prefix, which is
stored in the variable ``CMAKE_INSTALL_PREFIX``.

install_targets
---------------

This command has been superseded by the ``install()`` command.  It is
provided for compatibility with older CMake code.

 install_targets(<dir> [RUNTIME_DIRECTORY dir] target target)

Create rules to install the listed targets into the given directory.
The directory ``<dir>`` is relative to the installation prefix, which is
stored in the variable ``CMAKE_INSTALL_PREFIX``.  If
``RUNTIME_DIRECTORY`` is specified, then on systems with special runtime
files (Windows DLL), the files will be copied to that directory.

load_command
------------

Disallowed since version 3.0.  See CMake Policy ``CMP0031``.

Load a command into a running CMake.

 load_command(COMMAND_NAME <loc1> [loc2 ...])

The given locations are searched for a library whose name is
cmCOMMAND_NAME.  If found, it is loaded as a module and the command is
added to the set of available CMake commands.  Usually,
``try_compile()`` is used before this command to compile the
module.  If the command is successfully loaded a variable named

 CMAKE_LOADED_COMMAND_<COMMAND_NAME>

will be set to the full path of the module that was loaded.  Otherwise
the variable will not be set.

make_directory
--------------

 make_directory(directory)

Creates the specified directory.  Full paths should be given.  Any
parent directories that do not exist will also be created.  Use with
care.

output_required_files
---------------------

Disallowed since version 3.0.  See CMake Policy ``CMP0032``.

Approximate C preprocessor dependency scanning.

This command exists only because ancient CMake versions provided it.
CMake handles preprocessor dependency scanning automatically using a
more advanced scanner.

 output_required_files(srcfile outputfile)

Outputs a list of all the source files that are required by the
specified ``srcfile``.  This list is written into ``outputfile``.  This is
similar to writing out the dependencies for ``srcfile`` except that it
jumps from ``.h`` files into ``.cxx``, ``.c`` and ``.cpp`` files if possible.

qt_wrap_cpp
-----------

Manually create Qt Wrappers.

 qt_wrap_cpp(resultingLibraryName DestName SourceLists ...)

Produces moc files for all the .h files listed in the SourceLists.  The
moc files will be added to the library using the ``DestName`` source list.

Consider updating the project to use the ``AUTOMOC`` target property
instead for a more automated way of invoking the ``moc`` tool.

qt_wrap_ui
----------

Manually create Qt user interfaces Wrappers.

 qt_wrap_ui(resultingLibraryName HeadersDestName
            SourcesDestName SourceLists ...)

Produces .h and .cxx files for all the .ui files listed in the
``SourceLists``.  The .h files will be added to the library using the
``HeadersDestNamesource`` list.  The .cxx files will be added to the
library using the ``SourcesDestNamesource`` list.

Consider updating the project to use the ``AUTOUIC`` target property
instead for a more automated way of invoking the ``uic`` tool.

remove
------

 remove(VAR VALUE VALUE ...)

Removes ``VALUE`` from the variable ``VAR``.  This is typically used to
remove entries from a vector (e.g.  semicolon separated list).  ``VALUE``
is expanded.

subdir_depends
--------------

Disallowed since version 3.0.  See CMake Policy ``CMP0029``.

Does nothing.

 subdir_depends(subdir dep1 dep2 ...)

Does not do anything.  This command used to help projects order
parallel builds correctly.  This functionality is now automatic.

subdirs
-------

Add a list of subdirectories to the build.

 subdirs(dir1 dir2 ...[EXCLUDE_FROM_ALL exclude_dir1 exclude_dir2 ...]
         [PREORDER] )

Add a list of subdirectories to the build.  The ``add_subdirectory()``
command should be used instead of ``subdirs`` although ``subdirs`` will still
work.  This will cause any CMakeLists.txt files in the sub directories
to be processed by CMake.  Any directories after the ``PREORDER`` flag are
traversed first by makefile builds, the ``PREORDER`` flag has no effect on
IDE projects.  Any directories after the ``EXCLUDE_FROM_ALL`` marker will
not be included in the top level makefile or project file.  This is
useful for having CMake create makefiles or projects for a set of
examples in a project.  You would want CMake to generate makefiles or
project files for all the examples at the same time, but you would not
want them to show up in the top level project or be built each time
make is run from the top.

use_mangled_mesa
----------------

Disallowed since version 3.0.  See CMake Policy ``CMP0030``.

Copy mesa headers for use in combination with system GL.

 use_mangled_mesa(PATH_TO_MESA OUTPUT_DIRECTORY)

The path to mesa includes, should contain ``gl_mangle.h``.  The mesa
headers are copied to the specified output directory.  This allows
mangled mesa headers to override other GL headers by being added to
the include directory path earlier.

utility_source
--------------

Disallowed since version 3.0.  See CMake Policy ``CMP0034``.

Specify the source tree of a third-party utility.

 utility_source(cache_entry executable_name
                path_to_source [file1 file2 ...])

When a third-party utility's source is included in the distribution,
this command specifies its location and name.  The cache entry will
not be set unless the ``path_to_source`` and all listed files exist.  It
is assumed that the source tree of the utility will have been built
before it is needed.

When cross compiling CMake will print a warning if a ``utility_source()``
command is executed, because in many cases it is used to build an
executable which is executed later on.  This doesn't work when cross
compiling, since the executable can run only on their target platform.
So in this case the cache entry has to be adjusted manually so it
points to an executable which is runnable on the build host.

variable_requires
-----------------

Disallowed since version 3.0.  See CMake Policy ``CMP0035``.

Use the ``if()`` command instead.

Assert satisfaction of an option's required variables.

 variable_requires(TEST_VARIABLE RESULT_VARIABLE
                   REQUIRED_VARIABLE1
                   REQUIRED_VARIABLE2 ...)

The first argument (``TEST_VARIABLE``) is the name of the variable to be
tested, if that variable is false nothing else is done.  If
``TEST_VARIABLE`` is true, then the next argument (``RESULT_VARIABLE``)
is a variable that is set to true if all the required variables are set.
The rest of the arguments are variables that must be true or not set
to ``NOTFOUND`` to avoid an error.  If any are not true, an error is
reported.

write_file
----------

 write_file(filename "message to write"... [APPEND])

The first argument is the file name, the rest of the arguments are
messages to write.  If the argument ``APPEND`` is specified, then the
message will be appended.

NOTE 1: ``file(WRITE)``  and ``file(APPEND)``  do exactly
the same as this one but add some more functionality.

NOTE 2: When using ``write_file`` the produced file cannot be used as an
input to CMake (CONFIGURE_FILE, source file ...) because it will lead
to an infinite loop.  Use ``configure_file()`` if you want to
generate input files to CMake.
