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120 lines
4.3 KiB
120 lines
4.3 KiB
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file Copyright.txt or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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CheckFunctionExists
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-------------------
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Check if a C function can be linked
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.. command:: check_function_exists
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.. code-block:: cmake
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check_function_exists(<function> <variable>)
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Checks that the ``<function>`` is provided by libraries on the system and store
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the result in a ``<variable>``, which will be created as an internal
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cache variable.
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The following variables may be set before calling this macro to modify the
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way the check is run:
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``CMAKE_REQUIRED_FLAGS``
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string of compile command line flags.
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``CMAKE_REQUIRED_DEFINITIONS``
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a :ref:`;-list <CMake Language Lists>` of macros to define (-DFOO=bar).
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``CMAKE_REQUIRED_INCLUDES``
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a :ref:`;-list <CMake Language Lists>` of header search paths to pass to
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the compiler.
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``CMAKE_REQUIRED_LINK_OPTIONS``
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.. versionadded:: 3.14
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a :ref:`;-list <CMake Language Lists>` of options to add to the link command.
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``CMAKE_REQUIRED_LIBRARIES``
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a :ref:`;-list <CMake Language Lists>` of libraries to add to the link
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command. See policy :policy:`CMP0075`.
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``CMAKE_REQUIRED_QUIET``
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.. versionadded:: 3.1
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execute quietly without messages.
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.. note::
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Prefer using :Module:`CheckSymbolExists` instead of this module,
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for the following reasons:
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* ``check_function_exists()`` can't detect functions that are inlined
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in headers or specified as a macro.
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* ``check_function_exists()`` can't detect anything in the 32-bit
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versions of the Win32 API, because of a mismatch in calling conventions.
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* ``check_function_exists()`` only verifies linking, it does not verify
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that the function is declared in system headers.
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#]=======================================================================]
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include_guard(GLOBAL)
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macro(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE)
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if(NOT DEFINED "${VARIABLE}" OR "x${${VARIABLE}}" STREQUAL "x${VARIABLE}")
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set(MACRO_CHECK_FUNCTION_DEFINITIONS
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"-DCHECK_FUNCTION_EXISTS=${FUNCTION} ${CMAKE_REQUIRED_FLAGS}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(CHECK_START "Looking for ${FUNCTION}")
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endif()
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if(CMAKE_REQUIRED_LINK_OPTIONS)
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set(CHECK_FUNCTION_EXISTS_ADD_LINK_OPTIONS
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LINK_OPTIONS ${CMAKE_REQUIRED_LINK_OPTIONS})
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else()
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set(CHECK_FUNCTION_EXISTS_ADD_LINK_OPTIONS)
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endif()
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if(CMAKE_REQUIRED_LIBRARIES)
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set(CHECK_FUNCTION_EXISTS_ADD_LIBRARIES
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LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
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else()
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set(CHECK_FUNCTION_EXISTS_ADD_LIBRARIES)
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endif()
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if(CMAKE_REQUIRED_INCLUDES)
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set(CHECK_FUNCTION_EXISTS_ADD_INCLUDES
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"-DINCLUDE_DIRECTORIES:STRING=${CMAKE_REQUIRED_INCLUDES}")
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else()
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set(CHECK_FUNCTION_EXISTS_ADD_INCLUDES)
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endif()
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if(CMAKE_C_COMPILER_LOADED)
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set(_cfe_source CheckFunctionExists.c)
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elseif(CMAKE_CXX_COMPILER_LOADED)
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set(_cfe_source CheckFunctionExists.cxx)
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else()
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message(FATAL_ERROR "CHECK_FUNCTION_EXISTS needs either C or CXX language enabled")
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endif()
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try_compile(${VARIABLE}
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SOURCE_FROM_FILE "${_cfe_source}" "${CMAKE_ROOT}/Modules/CheckFunctionExists.c"
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COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
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${CHECK_FUNCTION_EXISTS_ADD_LINK_OPTIONS}
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${CHECK_FUNCTION_EXISTS_ADD_LIBRARIES}
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CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_FUNCTION_DEFINITIONS}
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"${CHECK_FUNCTION_EXISTS_ADD_INCLUDES}"
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OUTPUT_VARIABLE OUTPUT)
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unset(_cfe_source)
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if(${VARIABLE})
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set(${VARIABLE} 1 CACHE INTERNAL "Have function ${FUNCTION}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(CHECK_PASS "found")
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endif()
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file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
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"Determining if the function ${FUNCTION} exists passed with the following output:\n"
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"${OUTPUT}\n\n")
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else()
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if(NOT CMAKE_REQUIRED_QUIET)
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message(CHECK_FAIL "not found")
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endif()
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set(${VARIABLE} "" CACHE INTERNAL "Have function ${FUNCTION}")
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file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
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"Determining if the function ${FUNCTION} exists failed with the following output:\n"
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"${OUTPUT}\n\n")
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endif()
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endif()
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endmacro()
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