module for saving compiler flags to cache

modules/save_flags.cmake

@@ -0,0 +1,43 @@
+#.rst:
+#
+# Take care of updating the cache for fresh configurations.
+#
+# Variables modified (provided the corresponding language is enabled)::
+#
+#   DEFAULT_Fortran_FLAGS_SET
+#   DEFAULT_C_FLAGS_SET
+#   DEFAULT_CXX_FLAGS_SET
+
+macro(save_compiler_flags lang)
+    if (NOT DEFINED DEFAULT_${lang}_FLAGS_SET)
+        mark_as_advanced(DEFAULT_${lang}_FLAGS_SET)
+
+        set (DEFAULT_${lang}_FLAGS_SET ON
+            CACHE INTERNAL
+            "Flag that the default ${lang} compiler flags have been set.")
+
+        set(CMAKE_${lang}_FLAGS "${CMAKE_${lang}_FLAGS}"
+            CACHE STRING
+            "Flags used by the compiler during all builds." FORCE)
+
+        set(CMAKE_${lang}_FLAGS_DEBUG "${CMAKE_${lang}_FLAGS_DEBUG}"
+            CACHE STRING
+            "Flags used by the compiler during debug builds." FORCE)
+
+        set(CMAKE_${lang}_FLAGS_RELEASE "${CMAKE_${lang}_FLAGS_RELEASE}"
+            CACHE STRING
+            "Flags used by the compiler during release builds." FORCE)
+    endif()
+endmacro()
+
+if(DEFINED CMAKE_Fortran_COMPILER_ID)
+    save_compiler_flags(Fortran)
+endif()
+
+if(DEFINED CMAKE_C_COMPILER_ID)
+    save_compiler_flags(C)
+endif()
+
+if(DEFINED CMAKE_CXX_COMPILER_ID)
+    save_compiler_flags(CXX)
+endif()