mirror of
https://github.com/reactos/CMake.git
synced 2024-11-24 12:09:48 +00:00
55df3954d3
Extend the change from commit 1d00ba9ccf (Find: find_package prefers
variable CMAKE_FIND_USE_REGISTRY, 2018-11-13, v3.16.0-rc1~461^2~1)
to cover the system package registry too.
Fixes: #19890
423 lines
19 KiB
ReStructuredText
423 lines
19 KiB
ReStructuredText
find_package
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------------
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.. only:: html
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.. contents::
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Find an external project, and load its settings.
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.. _`basic signature`:
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Basic Signature and Module Mode
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: cmake
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find_package(<PackageName> [version] [EXACT] [QUIET] [MODULE]
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[REQUIRED] [[COMPONENTS] [components...]]
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[OPTIONAL_COMPONENTS components...]
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[NO_POLICY_SCOPE])
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Finds and loads settings from an external project. ``<PackageName>_FOUND``
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will be set to indicate whether the package was found. When the
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package is found package-specific information is provided through
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variables and :ref:`Imported Targets` documented by the package itself. The
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``QUIET`` option disables informational messages, including those indicating
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that the package cannot be found if it is not ``REQUIRED``. The ``REQUIRED``
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option stops processing with an error message if the package cannot be found.
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A package-specific list of required components may be listed after the
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``COMPONENTS`` option (or after the ``REQUIRED`` option if present).
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Additional optional components may be listed after
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``OPTIONAL_COMPONENTS``. Available components and their influence on
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whether a package is considered to be found are defined by the target
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package.
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The ``[version]`` argument requests a version with which the package found
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should be compatible (format is ``major[.minor[.patch[.tweak]]]``). The
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``EXACT`` option requests that the version be matched exactly. If no
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``[version]`` and/or component list is given to a recursive invocation
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inside a find-module, the corresponding arguments are forwarded
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automatically from the outer call (including the ``EXACT`` flag for
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``[version]``). Version support is currently provided only on a
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package-by-package basis (see the `Version Selection`_ section below).
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See the :command:`cmake_policy` command documentation for discussion
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of the ``NO_POLICY_SCOPE`` option.
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The command has two modes by which it searches for packages: "Module"
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mode and "Config" mode. The above signature selects Module mode.
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If no module is found the command falls back to Config mode, described
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below. This fall back is disabled if the ``MODULE`` option is given.
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In Module mode, CMake searches for a file called ``Find<PackageName>.cmake``.
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The file is first searched in the :variable:`CMAKE_MODULE_PATH`,
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then among the :ref:`Find Modules` provided by the CMake installation.
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If the file is found, it is read and processed by CMake. It is responsible
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for finding the package, checking the version, and producing any needed
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messages. Some find-modules provide limited or no support for versioning;
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check the module documentation.
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If the ``MODULE`` option is not specfied in the above signature,
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CMake first searches for the package using Module mode. Then, if the
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package is not found, it searches again using Config mode. A user
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may set the variable :variable:`CMAKE_FIND_PACKAGE_PREFER_CONFIG` to
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``TRUE`` to direct CMake first search using Config mode before falling
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back to Module mode.
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Full Signature and Config Mode
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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User code should generally look for packages using the above `basic
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signature`_. The remainder of this command documentation specifies the
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full command signature and details of the search process. Project
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maintainers wishing to provide a package to be found by this command
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are encouraged to read on.
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The complete Config mode command signature is
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.. code-block:: cmake
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find_package(<PackageName> [version] [EXACT] [QUIET]
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[REQUIRED] [[COMPONENTS] [components...]]
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[OPTIONAL_COMPONENTS components...]
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[CONFIG|NO_MODULE]
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[NO_POLICY_SCOPE]
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[NAMES name1 [name2 ...]]
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[CONFIGS config1 [config2 ...]]
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[HINTS path1 [path2 ... ]]
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[PATHS path1 [path2 ... ]]
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[PATH_SUFFIXES suffix1 [suffix2 ...]]
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[NO_DEFAULT_PATH]
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[NO_PACKAGE_ROOT_PATH]
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[NO_CMAKE_PATH]
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[NO_CMAKE_ENVIRONMENT_PATH]
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[NO_SYSTEM_ENVIRONMENT_PATH]
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[NO_CMAKE_PACKAGE_REGISTRY]
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[NO_CMAKE_BUILDS_PATH] # Deprecated; does nothing.
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[NO_CMAKE_SYSTEM_PATH]
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[NO_CMAKE_SYSTEM_PACKAGE_REGISTRY]
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[CMAKE_FIND_ROOT_PATH_BOTH |
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ONLY_CMAKE_FIND_ROOT_PATH |
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NO_CMAKE_FIND_ROOT_PATH])
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The ``CONFIG`` option, the synonymous ``NO_MODULE`` option, or the use
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of options not specified in the `basic signature`_ all enforce pure Config
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mode. In pure Config mode, the command skips Module mode search and
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proceeds at once with Config mode search.
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Config mode search attempts to locate a configuration file provided by the
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package to be found. A cache entry called ``<PackageName>_DIR`` is created to
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hold the directory containing the file. By default the command
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searches for a package with the name ``<PackageName>``. If the ``NAMES`` option
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is given the names following it are used instead of ``<PackageName>``.
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The command searches for a file called ``<PackageName>Config.cmake`` or
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``<lower-case-package-name>-config.cmake`` for each name specified.
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A replacement set of possible configuration file names may be given
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using the ``CONFIGS`` option. The search procedure is specified below.
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Once found, the configuration file is read and processed by CMake.
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Since the file is provided by the package it already knows the
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location of package contents. The full path to the configuration file
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is stored in the cmake variable ``<PackageName>_CONFIG``.
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All configuration files which have been considered by CMake while
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searching for an installation of the package with an appropriate
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version are stored in the cmake variable ``<PackageName>_CONSIDERED_CONFIGS``,
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the associated versions in ``<PackageName>_CONSIDERED_VERSIONS``.
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If the package configuration file cannot be found CMake will generate
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an error describing the problem unless the ``QUIET`` argument is
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specified. If ``REQUIRED`` is specified and the package is not found a
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fatal error is generated and the configure step stops executing. If
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``<PackageName>_DIR`` has been set to a directory not containing a
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configuration file CMake will ignore it and search from scratch.
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Package maintainers providing CMake package configuration files are
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encouraged to name and install them such that the `Search Procedure`_
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outlined below will find them without requiring use of additional options.
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Version Selection
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^^^^^^^^^^^^^^^^^
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When the ``[version]`` argument is given Config mode will only find a
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version of the package that claims compatibility with the requested
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version (format is ``major[.minor[.patch[.tweak]]]``). If the ``EXACT``
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option is given only a version of the package claiming an exact match
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of the requested version may be found. CMake does not establish any
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convention for the meaning of version numbers. Package version
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numbers are checked by "version" files provided by the packages
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themselves. For a candidate package configuration file
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``<config-file>.cmake`` the corresponding version file is located next
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to it and named either ``<config-file>-version.cmake`` or
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``<config-file>Version.cmake``. If no such version file is available
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then the configuration file is assumed to not be compatible with any
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requested version. A basic version file containing generic version
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matching code can be created using the
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:module:`CMakePackageConfigHelpers` module. When a version file
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is found it is loaded to check the requested version number. The
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version file is loaded in a nested scope in which the following
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variables have been defined:
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``PACKAGE_FIND_NAME``
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the ``<PackageName>``
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``PACKAGE_FIND_VERSION``
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full requested version string
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``PACKAGE_FIND_VERSION_MAJOR``
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major version if requested, else 0
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``PACKAGE_FIND_VERSION_MINOR``
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minor version if requested, else 0
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``PACKAGE_FIND_VERSION_PATCH``
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patch version if requested, else 0
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``PACKAGE_FIND_VERSION_TWEAK``
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tweak version if requested, else 0
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``PACKAGE_FIND_VERSION_COUNT``
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number of version components, 0 to 4
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The version file checks whether it satisfies the requested version and
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sets these variables:
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``PACKAGE_VERSION``
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full provided version string
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``PACKAGE_VERSION_EXACT``
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true if version is exact match
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``PACKAGE_VERSION_COMPATIBLE``
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true if version is compatible
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``PACKAGE_VERSION_UNSUITABLE``
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true if unsuitable as any version
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These variables are checked by the ``find_package`` command to determine
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whether the configuration file provides an acceptable version. They
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are not available after the ``find_package`` call returns. If the version
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is acceptable the following variables are set:
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``<PackageName>_VERSION``
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full provided version string
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``<PackageName>_VERSION_MAJOR``
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major version if provided, else 0
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``<PackageName>_VERSION_MINOR``
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minor version if provided, else 0
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``<PackageName>_VERSION_PATCH``
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patch version if provided, else 0
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``<PackageName>_VERSION_TWEAK``
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tweak version if provided, else 0
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``<PackageName>_VERSION_COUNT``
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number of version components, 0 to 4
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and the corresponding package configuration file is loaded.
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When multiple package configuration files are available whose version files
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claim compatibility with the version requested it is unspecified which
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one is chosen: unless the variable :variable:`CMAKE_FIND_PACKAGE_SORT_ORDER`
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is set no attempt is made to choose a highest or closest version number.
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To control the order in which ``find_package`` checks for compatibility use
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the two variables :variable:`CMAKE_FIND_PACKAGE_SORT_ORDER` and
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:variable:`CMAKE_FIND_PACKAGE_SORT_DIRECTION`.
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For instance in order to select the highest version one can set
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.. code-block:: cmake
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SET(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
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SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)
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before calling ``find_package``.
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Search Procedure
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^^^^^^^^^^^^^^^^
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CMake constructs a set of possible installation prefixes for the
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package. Under each prefix several directories are searched for a
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configuration file. The tables below show the directories searched.
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Each entry is meant for installation trees following Windows (``W``), UNIX
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(``U``), or Apple (``A``) conventions::
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<prefix>/ (W)
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<prefix>/(cmake|CMake)/ (W)
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<prefix>/<name>*/ (W)
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<prefix>/<name>*/(cmake|CMake)/ (W)
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<prefix>/(lib/<arch>|lib*|share)/cmake/<name>*/ (U)
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<prefix>/(lib/<arch>|lib*|share)/<name>*/ (U)
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<prefix>/(lib/<arch>|lib*|share)/<name>*/(cmake|CMake)/ (U)
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<prefix>/<name>*/(lib/<arch>|lib*|share)/cmake/<name>*/ (W/U)
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<prefix>/<name>*/(lib/<arch>|lib*|share)/<name>*/ (W/U)
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<prefix>/<name>*/(lib/<arch>|lib*|share)/<name>*/(cmake|CMake)/ (W/U)
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On systems supporting macOS :prop_tgt:`FRAMEWORK` and :prop_tgt:`BUNDLE`, the
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following directories are searched for Frameworks or Application Bundles
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containing a configuration file::
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<prefix>/<name>.framework/Resources/ (A)
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<prefix>/<name>.framework/Resources/CMake/ (A)
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<prefix>/<name>.framework/Versions/*/Resources/ (A)
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<prefix>/<name>.framework/Versions/*/Resources/CMake/ (A)
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<prefix>/<name>.app/Contents/Resources/ (A)
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<prefix>/<name>.app/Contents/Resources/CMake/ (A)
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In all cases the ``<name>`` is treated as case-insensitive and corresponds
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to any of the names specified (``<PackageName>`` or names given by ``NAMES``).
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Paths with ``lib/<arch>`` are enabled if the
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:variable:`CMAKE_LIBRARY_ARCHITECTURE` variable is set. ``lib*`` includes one
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or more of the values ``lib64``, ``lib32``, ``libx32`` or ``lib`` (searched in
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that order).
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* Paths with ``lib64`` are searched on 64 bit platforms if the
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:prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS` property is set to ``TRUE``.
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* Paths with ``lib32`` are searched on 32 bit platforms if the
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:prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS` property is set to ``TRUE``.
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* Paths with ``libx32`` are searched on platforms using the x32 ABI
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if the :prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS` property is set to ``TRUE``.
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* The ``lib`` path is always searched.
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If ``PATH_SUFFIXES`` is specified, the suffixes are appended to each
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(``W``) or (``U``) directory entry one-by-one.
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This set of directories is intended to work in cooperation with
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projects that provide configuration files in their installation trees.
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Directories above marked with (``W``) are intended for installations on
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Windows where the prefix may point at the top of an application's
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installation directory. Those marked with (``U``) are intended for
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installations on UNIX platforms where the prefix is shared by multiple
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packages. This is merely a convention, so all (``W``) and (``U``) directories
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are still searched on all platforms. Directories marked with (``A``) are
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intended for installations on Apple platforms. The
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:variable:`CMAKE_FIND_FRAMEWORK` and :variable:`CMAKE_FIND_APPBUNDLE`
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variables determine the order of preference.
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The set of installation prefixes is constructed using the following
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steps. If ``NO_DEFAULT_PATH`` is specified all ``NO_*`` options are
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enabled.
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1. Search paths specified in the :variable:`<PackageName>_ROOT` CMake
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variable and the :envvar:`<PackageName>_ROOT` environment variable,
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where ``<PackageName>`` is the package to be found.
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The package root variables are maintained as a stack so if
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called from within a find module, root paths from the parent's find
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module will also be searched after paths for the current package.
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This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
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the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
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See policy :policy:`CMP0074`.
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2. Search paths specified in cmake-specific cache variables. These
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are intended to be used on the command line with a ``-DVAR=value``.
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The values are interpreted as :ref:`semicolon-separated lists <CMake Language Lists>`.
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This can be skipped if ``NO_CMAKE_PATH`` is passed or by setting the
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:variable:`CMAKE_FIND_USE_CMAKE_PATH` to ``FALSE``::
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CMAKE_PREFIX_PATH
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CMAKE_FRAMEWORK_PATH
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CMAKE_APPBUNDLE_PATH
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3. Search paths specified in cmake-specific environment variables.
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These are intended to be set in the user's shell configuration,
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and therefore use the host's native path separator
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(``;`` on Windows and ``:`` on UNIX).
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This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed or by setting
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the :variable:`CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH` to ``FALSE``::
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<PackageName>_DIR
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CMAKE_PREFIX_PATH
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CMAKE_FRAMEWORK_PATH
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CMAKE_APPBUNDLE_PATH
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4. Search paths specified by the ``HINTS`` option. These should be paths
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computed by system introspection, such as a hint provided by the
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location of another item already found. Hard-coded guesses should
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be specified with the ``PATHS`` option.
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5. Search the standard system environment variables. This can be
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skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed or by setting the
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:variable:`CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH` to ``FALSE``. Path entries
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ending in ``/bin`` or ``/sbin`` are automatically converted to their
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parent directories::
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PATH
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6. Search paths stored in the CMake :ref:`User Package Registry`.
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This can be skipped if ``NO_CMAKE_PACKAGE_REGISTRY`` is passed or by
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setting the variable :variable:`CMAKE_FIND_USE_PACKAGE_REGISTRY`
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to ``FALSE`` or the deprecated variable
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:variable:`CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY` to ``TRUE``.
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See the :manual:`cmake-packages(7)` manual for details on the user
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package registry.
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7. Search cmake variables defined in the Platform files for the
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current system. This can be skipped if ``NO_CMAKE_SYSTEM_PATH`` is
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passed or by setting the :variable:`CMAKE_FIND_USE_CMAKE_SYSTEM_PATH`
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to ``FALSE``::
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CMAKE_SYSTEM_PREFIX_PATH
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CMAKE_SYSTEM_FRAMEWORK_PATH
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CMAKE_SYSTEM_APPBUNDLE_PATH
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8. Search paths stored in the CMake :ref:`System Package Registry`.
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This can be skipped if ``NO_CMAKE_SYSTEM_PACKAGE_REGISTRY`` is passed
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or by setting the :variable:`CMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY`
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variable to ``FALSE`` or the deprecated variable
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:variable:`CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY` to ``TRUE``.
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See the :manual:`cmake-packages(7)` manual for details on the system
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package registry.
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9. Search paths specified by the ``PATHS`` option. These are typically
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hard-coded guesses.
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.. |FIND_XXX| replace:: find_package
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.. |FIND_ARGS_XXX| replace:: <PackageName>
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.. |CMAKE_FIND_ROOT_PATH_MODE_XXX| replace::
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:variable:`CMAKE_FIND_ROOT_PATH_MODE_PACKAGE`
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.. include:: FIND_XXX_ROOT.txt
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.. include:: FIND_XXX_ORDER.txt
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By default the value stored in the result variable will be the path at
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which the file is found. The :variable:`CMAKE_FIND_PACKAGE_RESOLVE_SYMLINKS`
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variable may be set to ``TRUE`` before calling ``find_package`` in order
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to resolve symbolic links and store the real path to the file.
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Every non-REQUIRED ``find_package`` call can be disabled by setting the
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:variable:`CMAKE_DISABLE_FIND_PACKAGE_<PackageName>` variable to ``TRUE``.
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Package File Interface Variables
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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When loading a find module or package configuration file ``find_package``
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defines variables to provide information about the call arguments (and
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restores their original state before returning):
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``CMAKE_FIND_PACKAGE_NAME``
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the ``<PackageName>`` which is searched for
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``<PackageName>_FIND_REQUIRED``
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true if ``REQUIRED`` option was given
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``<PackageName>_FIND_QUIETLY``
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true if ``QUIET`` option was given
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``<PackageName>_FIND_VERSION``
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full requested version string
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``<PackageName>_FIND_VERSION_MAJOR``
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major version if requested, else 0
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``<PackageName>_FIND_VERSION_MINOR``
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minor version if requested, else 0
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``<PackageName>_FIND_VERSION_PATCH``
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patch version if requested, else 0
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``<PackageName>_FIND_VERSION_TWEAK``
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tweak version if requested, else 0
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``<PackageName>_FIND_VERSION_COUNT``
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number of version components, 0 to 4
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``<PackageName>_FIND_VERSION_EXACT``
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true if ``EXACT`` option was given
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``<PackageName>_FIND_COMPONENTS``
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list of requested components
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``<PackageName>_FIND_REQUIRED_<c>``
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true if component ``<c>`` is required,
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false if component ``<c>`` is optional
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In Module mode the loaded find module is responsible to honor the
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request detailed by these variables; see the find module for details.
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In Config mode ``find_package`` handles ``REQUIRED``, ``QUIET``, and
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``[version]`` options automatically but leaves it to the package
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configuration file to handle components in a way that makes sense
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for the package. The package configuration file may set
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``<PackageName>_FOUND`` to false to tell ``find_package`` that component
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requirements are not satisfied.
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