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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CMakeFindDependencyMacro
------------------------
.. command:: find_dependency
The ``find_dependency()`` macro wraps a :command:`find_package` call for
a package dependency::
find_dependency(<dep> [...])
It is designed to be used in a
:ref:`Package Configuration File <Config File Packages>`
(``<PackageName>Config.cmake``). ``find_dependency`` forwards the correct
parameters for ``QUIET`` and ``REQUIRED`` which were passed to
the original :command:`find_package` call. Any additional arguments
specified are forwarded to :command:`find_package`.
If the dependency could not be found it sets an informative diagnostic
message and calls :command:`return` to end processing of the calling
package configuration file and return to the :command:`find_package`
command that loaded it.
.. note::
The call to :command:`return` makes this macro unsuitable to call
from :ref:`Find Modules`.
Package Dependency Search Optimizations
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If ``find_dependency`` is called with arguments identical to a previous
call in the same directory, perhaps due to diamond-shaped package
dependencies, the underlying call to :command:`find_package` is optimized
out. This optimization is important to support large package dependency
graphs while avoiding a combinatorial explosion of repeated searches.
However, the heuristic cannot account for ambient variables that
affect package behavior, such as ``<PackageName>_USE_STATIC_LIBS``,
offered by some packages. Therefore package configuration files should
avoid setting such variables before their calls to ``find_dependency``.
.. versionchanged:: 3.15
Previously, the underlying call to :command:`find_package` was always
optimized out if the package had already been found. CMake 3.15
removed the optimization to support cases in which ``find_dependency``
call arguments request different components.
.. versionchanged:: 3.26
The pre-3.15 optimization was restored, but with the above-described
heuristic to account for varying ``find_dependency`` call arguments.
#]=======================================================================]
macro(find_dependency dep)
string(SHA256 cmake_fd_call_hash "${dep};${ARGN};${${CMAKE_FIND_PACKAGE_NAME}_FIND_REQUIRED}")
if(_CMAKE_${dep}_${cmake_fd_call_hash}_FOUND)
unset(cmake_fd_call_hash)
else()
list(APPEND _CMAKE_${dep}_HASH_STACK ${cmake_fd_call_hash})
set(cmake_fd_quiet_arg)
if(${CMAKE_FIND_PACKAGE_NAME}_FIND_QUIETLY)
set(cmake_fd_quiet_arg QUIET)
endif()
set(cmake_fd_required_arg)
if(${CMAKE_FIND_PACKAGE_NAME}_FIND_REQUIRED)
set(cmake_fd_required_arg REQUIRED)
endif()
get_property(cmake_fd_alreadyTransitive GLOBAL PROPERTY
_CMAKE_${dep}_TRANSITIVE_DEPENDENCY
)
find_package(${dep} ${ARGN}
${cmake_fd_quiet_arg}
${cmake_fd_required_arg}
)
list(POP_BACK _CMAKE_${dep}_HASH_STACK cmake_fd_call_hash)
set("_CMAKE_${dep}_${cmake_fd_call_hash}_FOUND" "${${dep}_FOUND}")
if(NOT DEFINED cmake_fd_alreadyTransitive OR cmake_fd_alreadyTransitive)
set_property(GLOBAL PROPERTY _CMAKE_${dep}_TRANSITIVE_DEPENDENCY TRUE)
endif()
unset(cmake_fd_alreadyTransitive)
unset(cmake_fd_call_hash)
unset(cmake_fd_quiet_arg)
unset(cmake_fd_required_arg)
if (NOT ${dep}_FOUND)
set(${CMAKE_FIND_PACKAGE_NAME}_NOT_FOUND_MESSAGE "${CMAKE_FIND_PACKAGE_NAME} could not be found because dependency ${dep} could not be found.")
set(${CMAKE_FIND_PACKAGE_NAME}_FOUND False)
return()
endif()
endif()
endmacro()
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