4f2fcce4b9
Prior to the existence of the if(DEFINED) condition, many of our Check
modules implemented the condition with a hack that takes advantage of
the auto-dereference behavior of the if() command to detect if a
variable is defined. The hack has the form:
if("${VAR} MATCHES "^${VAR}$")
where "${VAR}" is a macro argument reference. However, this does not
work when the variable named in the macro argument contains characters
that have special meaning in regular expressions, such as '+'. Run the
command
git grep -E 'if\("\$\{.*\}" MATCHES "\^\$\{.*\}\$"\)' -- Modules/Check*
to identify lines with this problem. Use if(NOT DEFINED) instead.
86 lines
3.2 KiB
CMake
86 lines
3.2 KiB
CMake
#.rst:
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# CheckFunctionExists
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# -------------------
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#
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# Check if a C function can be linked
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#
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# CHECK_FUNCTION_EXISTS(<function> <variable>)
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#
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# Check that the <function> is provided by libraries on the system and
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# store the result in a <variable>. This does not verify that any
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# system header file declares the function, only that it can be found at
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# link time (consider using CheckSymbolExists).
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#
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# The following variables may be set before calling this macro to modify
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# the way the check is run:
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#
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# ::
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#
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# CMAKE_REQUIRED_FLAGS = string of compile command line flags
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# CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
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# CMAKE_REQUIRED_INCLUDES = list of include directories
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# CMAKE_REQUIRED_LIBRARIES = list of libraries to link
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# CMAKE_REQUIRED_QUIET = execute quietly without messages
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#=============================================================================
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# Copyright 2002-2011 Kitware, Inc.
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#
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# Distributed under the OSI-approved BSD License (the "License");
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# see accompanying file Copyright.txt for details.
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#
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# This software is distributed WITHOUT ANY WARRANTY; without even the
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# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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# See the License for more information.
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#=============================================================================
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# (To distribute this file outside of CMake, substitute the full
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# License text for the above reference.)
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macro(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE)
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if(NOT DEFINED "${VARIABLE}")
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set(MACRO_CHECK_FUNCTION_DEFINITIONS
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"-DCHECK_FUNCTION_EXISTS=${FUNCTION} ${CMAKE_REQUIRED_FLAGS}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${FUNCTION}")
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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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try_compile(${VARIABLE}
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${CMAKE_BINARY_DIR}
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${CMAKE_ROOT}/Modules/CheckFunctionExists.c
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COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
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${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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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(STATUS "Looking for ${FUNCTION} - 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(STATUS "Looking for ${FUNCTION} - not found")
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endif()
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set(${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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