Add utility to purge compiler flags for a given language

Author: awnawab

cmake/ecbuild_compiler_flags.cmake

@@ -72,6 +72,45 @@ macro( ecbuild_compiler_flags _lang )
 
 endmacro()
 
+##############################################################################
+#.rst:
+#
+# ecbuild_purge_compiler_flags
+# ======================
+#
+# Purge compiler flags for a given language ::
+#
+#   ecbuild_purge_compiler_flags( <lang> )
+#
+##############################################################################
+
+macro( ecbuild_purge_compiler_flags _lang )
+
+    set( options WARN )
+    set( oneValueArgs "" )
+    set( multiValueArgs "" )
+
+    cmake_parse_arguments( _PAR "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN} )
+
+    if( CMAKE_${_lang}_COMPILER_LOADED )
+
+      # Clear default compilation flags potentially inherited from parent scope
+      # when using custom compilation flags
+      if( ECBUILD_SOURCE_FLAGS OR ECBUILD_COMPILE_FLAGS )
+        set(CMAKE_${_lang}_FLAGS "")
+        foreach(_btype ALL RELEASE RELWITHDEBINFO PRODUCTION BIT DEBUG)
+          set(CMAKE_${_lang}_FLAGS_${_btype} "")
+        endforeach()
+      endif()
+
+    endif()
+
+    if( ${_PAR_WARN} )
+      ecbuild_warn( "Purging compiler flags set for ${_lang}" )
+    endif()
+
+endmacro()
+
 ##############################################################################
 #.rst:
 #
@@ -189,10 +228,7 @@ foreach( _lang C CXX Fortran )
     # Clear default compilation flags potentially inherited from parent scope
     # when using custom compilation flags
     if( ECBUILD_SOURCE_FLAGS OR ECBUILD_COMPILE_FLAGS )
-      set(CMAKE_${_lang}_FLAGS "")
-      foreach(_btype ALL RELEASE RELWITHDEBINFO PRODUCTION BIT DEBUG)
-        set(CMAKE_${_lang}_FLAGS_${_btype} "")
-      endforeach()
+      ecbuild_purge_compiler_flags( ${_lang} )
     # Load default compilation flags only if custom compilation flags not enabled
     else()
       ecbuild_compiler_flags( ${_lang} )