350 lines
15 KiB
ReStructuredText
350 lines
15 KiB
ReStructuredText
find_package
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------------
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Load settings for an external project.
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::
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find_package(<package> [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. ``<package>_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 messages if the package cannot be found. The
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``MODULE`` option disables the second signature documented below. The
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``REQUIRED`` option stops processing with an error message if the package
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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 (details below).
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User code should generally look for packages using the above simple
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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 command has two modes by which it searches for packages: "Module"
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mode and "Config" mode. Module mode is available when the command is
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invoked with the above reduced signature. CMake searches for a file
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called ``Find<package>.cmake`` in the :variable:`CMAKE_MODULE_PATH`
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followed by the CMake installation. If the file is found, it is read
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and processed by CMake. It is responsible for finding the package,
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checking the version, and producing any needed messages. Many
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find-modules provide limited or no support for versioning; check
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the module documentation. If no module is found and the ``MODULE``
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option is not given the command proceeds to Config mode.
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The complete Config mode command signature is::
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find_package(<package> [version] [EXACT] [QUIET]
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[REQUIRED] [[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_CMAKE_ENVIRONMENT_PATH]
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[NO_CMAKE_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]
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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 may be used to skip Module mode explicitly and
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switch to Config mode. It is synonymous to using ``NO_MODULE``. Config
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mode is also implied by use of options not specified in the reduced
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signature.
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Config mode attempts to locate a configuration file provided by the
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package to be found. A cache entry called ``<package>_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 ``<package>``. If the ``NAMES`` option
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is given the names following it are used instead of ``<package>``. The
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command searches for a file called ``<name>Config.cmake`` or
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``<lower-case-name>-config.cmake`` for each name specified. A
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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 ``<package>_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 ``<package>_CONSIDERED_CONFIGS``,
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the associated versions in ``<package>_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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``<package>_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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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 ``<package>`` name
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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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``<package>_VERSION``
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full provided version string
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``<package>_VERSION_MAJOR``
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major version if provided, else 0
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``<package>_VERSION_MINOR``
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minor version if provided, else 0
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``<package>_VERSION_PATCH``
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patch version if provided, else 0
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``<package>_VERSION_TWEAK``
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tweak version if provided, else 0
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``<package>_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. When
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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. No attempt is made to choose a highest or closest
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version number.
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Config mode provides an elaborate interface and search procedure.
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Much of the interface is provided for completeness and for use
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internally by find-modules loaded by Module mode. Most user code
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should simply call::
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find_package(<package> [major[.minor]] [EXACT] [REQUIRED|QUIET])
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in order to find a package. Package maintainers providing CMake
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package configuration files are encouraged to name and install them
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such that the procedure outlined below will find them without
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requiring use of additional options.
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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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On systems supporting OS X Frameworks and Application Bundles the
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following directories are searched for frameworks or 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 (``<package>`` 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. If ``PATH_SUFFIXES``
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is specified the suffixes are appended to each (W) or (U) directory entry
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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 cmake variables
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``CMAKE_FIND_FRAMEWORK`` and ``CMAKE_FIND_APPBUNDLE``
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determine the order of preference as specified below.
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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 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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This can be skipped if ``NO_CMAKE_PATH`` is passed::
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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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2. 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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This can be skipped if ``NO_CMAKE_ENVIRONMENT_PATH`` is passed::
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<package>_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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3. 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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4. Search the standard system environment variables. This can be
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skipped if ``NO_SYSTEM_ENVIRONMENT_PATH`` is passed. 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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5. Search project build trees recently configured in a :manual:`cmake-gui(1)`.
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This can be skipped if ``NO_CMAKE_BUILDS_PATH`` is passed. It is intended
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for the case when a user is building multiple dependent projects one
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after another.
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(This step is implemented only on Windows.)
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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:`CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY`
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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::
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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
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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:: <package>
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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_MAC.txt
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.. include:: FIND_XXX_ROOT.txt
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.. include:: FIND_XXX_ORDER.txt
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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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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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``<package>_FIND_REQUIRED``
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true if ``REQUIRED`` option was given
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``<package>_FIND_QUIETLY``
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true if ``QUIET`` option was given
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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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``<package>_FIND_VERSION_EXACT``
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true if ``EXACT`` option was given
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``<package>_FIND_COMPONENTS``
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list of requested components
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``<package>_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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``<package>_FOUND`` to false to tell ``find_package`` that component
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requirements are not satisfied.
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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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