# - Check whether the C compiler supports a given flag.
# CHECK_C_COMPILER_FLAG(<flag> <var>)
#  <flag> - the compiler flag
#  <var>  - variable to store the result
# This internally calls the check_c_source_compiles macro.
# See help for CheckCSourceCompiles for a listing of variables
# that can modify the build.

#=============================================================================
# Copyright 2006-2010 Kitware, Inc.
# Copyright 2006 Alexander Neundorf <neundorf@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(CheckCSourceCompiles)

# This could be replaced by a simple check_c_compiler_flag(<flag> <var>)
# https://cmake.org/cmake/help/v3.10/module/CheckCCompilerFlag.html?highlight=flags
macro (OTB_CHECK_C_COMPILER_FLAG _FLAG _RESULT)
   set(SAFE_CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS}")
   set(CMAKE_REQUIRED_DEFINITIONS "${_FLAG}")
   CHECK_C_SOURCE_COMPILES("int main(void) { return 0; }" ${_RESULT}
     # Some compilers do not fail with a bad flag
     FAIL_REGEX "warning: command line option .* is valid for .* but not for C"
                                                            # Apple gcc
     FAIL_REGEX "unrecognized .*option"                     # GNU
     FAIL_REGEX "unknown .*option"                          # Clang
     FAIL_REGEX "ignoring unknown option"                   # MSVC
     FAIL_REGEX "warning D9002"                             # MSVC, any lang
     FAIL_REGEX "[Uu]nknown option"                         # HP
     FAIL_REGEX "[Ww]arning: [Oo]ption"                     # SunPro
     FAIL_REGEX "command option .* is not recognized"       # XL
     FAIL_REGEX "warning #10156: ignoring option"       # INTEL compilers
     )
   set (CMAKE_REQUIRED_DEFINITIONS "${SAFE_CMAKE_REQUIRED_DEFINITIONS}")
endmacro ()
