74 lines
2.4 KiB
CMake
74 lines
2.4 KiB
CMake
# 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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# CheckVariableExists
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# -------------------
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#
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# Check if the variable exists.
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#
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# ::
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#
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# CHECK_VARIABLE_EXISTS(VAR VARIABLE)
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#
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#
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#
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# ::
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#
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# VAR - the name of the variable
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# VARIABLE - variable to store the result
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# Will be created as an internal cache variable.
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#
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#
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# This macro is only for C variables.
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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_LIBRARIES = list of libraries to link
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# CMAKE_REQUIRED_QUIET = execute quietly without messages
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macro(CHECK_VARIABLE_EXISTS VAR VARIABLE)
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if(NOT DEFINED "${VARIABLE}")
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set(MACRO_CHECK_VARIABLE_DEFINITIONS
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"-DCHECK_VARIABLE_EXISTS=${VAR} ${CMAKE_REQUIRED_FLAGS}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR}")
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endif()
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if(CMAKE_REQUIRED_LIBRARIES)
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set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES
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LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
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else()
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set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES)
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endif()
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try_compile(${VARIABLE}
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${CMAKE_BINARY_DIR}
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${CMAKE_ROOT}/Modules/CheckVariableExists.c
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COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
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${CHECK_VARIABLE_EXISTS_ADD_LIBRARIES}
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CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_VARIABLE_DEFINITIONS}
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OUTPUT_VARIABLE OUTPUT)
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if(${VARIABLE})
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set(${VARIABLE} 1 CACHE INTERNAL "Have variable ${VAR}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR} - 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 variable ${VAR} exists passed with the following output:\n"
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"${OUTPUT}\n\n")
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else()
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set(${VARIABLE} "" CACHE INTERNAL "Have variable ${VAR}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR} - not found")
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endif()
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file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
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"Determining if the variable ${VAR} exists failed with the following output:\n"
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"${OUTPUT}\n\n")
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endif()
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endif()
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endmacro()
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