118 lines
4.2 KiB
ReStructuredText
118 lines
4.2 KiB
ReStructuredText
try_compile
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-----------
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.. only:: html
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.. contents::
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Try building some code.
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Try Compiling Whole Projects
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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::
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try_compile(RESULT_VAR <bindir> <srcdir>
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<projectName> [<targetName>] [CMAKE_FLAGS <flags>...]
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[OUTPUT_VARIABLE <var>])
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Try building a project. The success or failure of the ``try_compile``,
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i.e. ``TRUE`` or ``FALSE`` respectively, is returned in ``RESULT_VAR``.
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In this form, ``<srcdir>`` should contain a complete CMake project with a
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``CMakeLists.txt`` file and all sources. The ``<bindir>`` and ``<srcdir>``
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will not be deleted after this command is run. Specify ``<targetName>`` to
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build a specific target instead of the ``all`` or ``ALL_BUILD`` target. See
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below for the meaning of other options.
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Try Compiling Source Files
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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::
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try_compile(RESULT_VAR <bindir> <srcfile|SOURCES srcfile...>
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[CMAKE_FLAGS <flags>...]
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[COMPILE_DEFINITIONS <defs>...]
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[LINK_LIBRARIES <libs>...]
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[OUTPUT_VARIABLE <var>]
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[COPY_FILE <fileName> [COPY_FILE_ERROR <var>]])
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Try building an executable from one or more source files. The success or
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failure of the ``try_compile``, i.e. ``TRUE`` or ``FALSE`` respectively, is
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returned in ``RESULT_VAR``.
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In this form the user need only supply one or more source files that include a
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definition for ``main``. CMake will create a ``CMakeLists.txt`` file to build
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the source(s) as an executable that looks something like this::
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add_definitions(<expanded COMPILE_DEFINITIONS from caller>)
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include_directories(${INCLUDE_DIRECTORIES})
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link_directories(${LINK_DIRECTORIES})
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add_executable(cmTryCompileExec <srcfile>...)
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target_link_libraries(cmTryCompileExec ${LINK_LIBRARIES})
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The options are:
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``CMAKE_FLAGS <flags>...``
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Specify flags of the form ``-DVAR:TYPE=VALUE`` to be passed to
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the ``cmake`` command-line used to drive the test build.
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The above example shows how values for variables
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``INCLUDE_DIRECTORIES``, ``LINK_DIRECTORIES``, and ``LINK_LIBRARIES``
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are used.
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``COMPILE_DEFINITIONS <defs>...``
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Specify ``-Ddefinition`` arguments to pass to ``add_definitions``
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in the generated test project.
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``COPY_FILE <fileName>``
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Copy the linked executable to the given ``<fileName>``.
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``COPY_FILE_ERROR <var>``
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Use after ``COPY_FILE`` to capture into variable ``<var>`` any error
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message encountered while trying to copy the file.
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``LINK_LIBRARIES <libs>...``
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Specify libraries to be linked in the generated project.
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The list of libraries may refer to system libraries and to
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:ref:`Imported Targets <Imported Targets>` from the calling project.
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If this option is specified, any ``-DLINK_LIBRARIES=...`` value
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given to the ``CMAKE_FLAGS`` option will be ignored.
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``OUTPUT_VARIABLE <var>``
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Store the output from the build process the given variable.
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In this version all files in ``<bindir>/CMakeFiles/CMakeTmp`` will be
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cleaned automatically. For debugging, ``--debug-trycompile`` can be
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passed to ``cmake`` to avoid this clean. However, multiple sequential
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``try_compile`` operations reuse this single output directory. If you use
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``--debug-trycompile``, you can only debug one ``try_compile`` call at a time.
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The recommended procedure is to protect all ``try_compile`` calls in your
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project by ``if(NOT DEFINED RESULT_VAR)`` logic, configure with cmake
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all the way through once, then delete the cache entry associated with
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the try_compile call of interest, and then re-run cmake again with
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``--debug-trycompile``.
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Other Behavior Settings
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^^^^^^^^^^^^^^^^^^^^^^^
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If set, the following variables are passed in to the generated
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try_compile CMakeLists.txt to initialize compile target properties with
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default values:
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* :variable:`CMAKE_ENABLE_EXPORTS`
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* :variable:`CMAKE_LINK_SEARCH_START_STATIC`
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* :variable:`CMAKE_LINK_SEARCH_END_STATIC`
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* :variable:`CMAKE_POSITION_INDEPENDENT_CODE`
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If :policy:`CMP0056` is set to ``NEW``, then
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:variable:`CMAKE_EXE_LINKER_FLAGS` is passed in as well.
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The current setting of :policy:`CMP0065` is set in the generated project.
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Set the :variable:`CMAKE_TRY_COMPILE_CONFIGURATION` variable to choose
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a build configuration.
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Set the :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` variable to specify
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the type of target used for the source file signature.
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