#.rst:
# CheckFortranCompilerFlag
# ------------------------
#
# Check whether the Fortran compiler supports a given flag.
#
# CHECK_Fortran_COMPILER_FLAG(<flag> <var>)
#
# ::
#
#   <flag> - the compiler flag
#   <var>  - variable to store the result
#            Will be created as an internal cache variable.
#
# This internally calls the check_fortran_source_compiles macro and
# sets CMAKE_REQUIRED_FLAGS to <flag>.  See help for
# CheckFortranSourceCompiles for a listing of variables that can
# otherwise modify the build.  The result only tells that the compiler
# does not give an error message when it encounters the flag.  If the
# flag has any effect or even a specific one is beyond the scope of
# this module.

#=============================================================================
# Copyright 2015 Nicolas Bock <nicolasbock@gmail.com>
# Copyright 2006-2011 Kitware, Inc.
# Copyright 2006 Alexander Neundorf <neundorf@kde.org>
# Copyright 2011 Matthias Kretz <kretz@kde.org>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
#  License text for the above reference.)

include(CheckFortranSourceCompiles)
include(CMakeCheckCompilerFlagCommonPatterns)

macro (CHECK_Fortran_COMPILER_FLAG _FLAG _RESULT)
  set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
  set(CMAKE_REQUIRED_FLAGS "${_FLAG}")

  # Normalize locale during test compilation.
  set(_CheckFortranCompilerFlag_LOCALE_VARS LC_ALL LC_MESSAGES LANG)
  foreach(v ${_CheckFortranCompilerFlag_LOCALE_VARS})
    set(_CheckFortranCompilerFlag_SAVED_${v} "$ENV{${v}}")
    set(ENV{${v}} C)
  endforeach()
  CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckFortranCompilerFlag_COMMON_PATTERNS)
  CHECK_Fortran_SOURCE_COMPILES("       program test\n       stop\n       end program" ${_RESULT}
    # Some compilers do not fail with a bad flag
    FAIL_REGEX "command line option .* is valid for .* but not for Fortran" # GNU
    ${_CheckFortranCompilerFlag_COMMON_PATTERNS}
    )
  foreach(v ${_CheckFortranCompilerFlag_LOCALE_VARS})
    set(ENV{${v}} ${_CheckFortranCompilerFlag_SAVED_${v}})
    unset(_CheckFortranCompilerFlag_SAVED_${v})
  endforeach()
  unset(_CheckFortranCompilerFlag_LOCALE_VARS)
  unset(_CheckFortranCompilerFlag_COMMON_PATTERNS)

  set (CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
endmacro ()
