# CheckLinkerFlag
# ------------------
#
# Checks whether a compiler supports a given linker flag.
#

include(CheckCSourceCompiles)
include(CheckCXXSourceCompiles)
include(CheckFortranSourceCompiles)

include(CMakeCheckCompilerFlagCommonPatterns)

# FLAG: the linker flag to check
# LANGUAGE: the language to test it on.  C, CXX, or Fortran
# RESULT: return variable

macro(check_linker_flag LANGUAGE FLAG RESULT)
    if (NOT DEFINED ${RESULT})
        set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
        set(CMAKE_REQUIRED_FLAGS "${FLAG}")
        # Normalize locale during test compilation.
        set(_CheckLinkerFlag_LOCALE_VARS LC_ALL LC_MESSAGES LANG)
        foreach (v ${_CheckLinkerFlag_LOCALE_VARS})
            set(_CheckLinkerFlag_SAVED_${v} "$ENV{${v}}")
            set(ENV{${v}} C)
        endforeach ()

        CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckLinkerFlag_COMMON_PATTERNS)

        if ("${LANGUAGE}" STREQUAL C)

            CHECK_C_SOURCE_COMPILES(
                    "int main(void) { return 0; }" ${RESULT}
                    # Some compilers do not fail with a bad flag
                    FAIL_REGEX "command line option .* is valid for .* but not for C" # GNU
                    ${_CheckLinkerFlag_COMMON_PATTERNS}
            )
        elseif ("${LANGUAGE}" STREQUAL CXX)
            check_cxx_source_compiles(
                    "int main(void) { return 0; }" ${RESULT}
                    # Some compilers do not fail with a bad flag
                    FAIL_REGEX "command line option .* is valid for .* but not for C" # GNU
                    ${_CheckLinkerFlag_COMMON_PATTERNS}
            )
        elseif ("${LANGUAGE}" STREQUAL Fortran)
            check_fortran_source_compiles(
                    "program test
			print *, \'Hello, world\'
			end program test"
                    ${RESULT}
                    # Some compilers do not fail with a bad flag
                    FAIL_REGEX "command line option .* is valid for .* but not for Fortran" # GNU
                    ${_CheckLinkerFlag_COMMON_PATTERNS})
        else ()
            message(FATAL_ERROR "Invalid LANGUAGE argument ${LANGUAGE}")
        endif ()

        foreach (v ${_CheckCCompilerFlag_LOCALE_VARS})
            set(ENV{${v}} ${_CheckCCompilerFlag_SAVED_${v}})
            unset(_CheckCCompilerFlag_SAVED_${v})
        endforeach ()
        unset(_CheckCCompilerFlag_LOCALE_VARS)
        unset(_CheckCCompilerFlag_COMMON_PATTERNS)

        set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_DEFINITIONS}")
    endif ()
endmacro(check_linker_flag)