+function(add_flag_or_print_warning flag)
+ check_c_compiler_flag(${flag} C_SUPPORTS_FLAG)
+ check_cxx_compiler_flag(${flag} CXX_SUPPORTS_FLAG)
+ if (C_SUPPORTS_FLAG AND CXX_SUPPORTS_FLAG)
+ message(STATUS "Building with ${flag}")
+ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}" PARENT_SCOPE)
+ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${flag}" PARENT_SCOPE)
+ else()
+ message(WARNING "${flag} is not supported.")
+ endif()
+endfunction()
+
+function(append value)
+ foreach(variable ${ARGN})
+ set(${variable} "${${variable}} ${value}" PARENT_SCOPE)
+ endforeach(variable)
+endfunction()
+
+function(append_if condition value)
+ if (${condition})
+ foreach(variable ${ARGN})
+ set(${variable} "${${variable}} ${value}" PARENT_SCOPE)
+ endforeach(variable)
+ endif()
+endfunction()
+
+macro(add_flag_if_supported flag)
+ check_c_compiler_flag(${flag} C_SUPPORTS_FLAG)
+ append_if(C_SUPPORTS_FLAG "${flag}" CMAKE_C_FLAGS)
+ check_cxx_compiler_flag(${flag} CXX_SUPPORTS_FLAG)
+ append_if(CXX_SUPPORTS_FLAG "${flag}" CMAKE_CXX_FLAGS)
+endmacro()
+