CMake Module for adding C compiler flags

Only adds the flag if it is supported

cmake/AddCCompilerFlag.cmake

@@ -0,0 +1,38 @@
+# - Adds a compiler flag if it is supported by the compiler
+#
+# This function checks that the supplied compiler flag is supported and then
+# adds it to the corresponding compiler flags
+#
+#  add_c_compiler_flag(<FLAG> [<VARIANT>])
+#
+# - Example
+#
+# include(AddCCompilerFlag)
+# add_c_compiler_flag(-Wall)
+# add_c_compiler_flag(-no-strict-aliasing RELEASE)
+# Requires CMake 2.6+
+
+if(__add_c_compiler_flag)
+  return()
+endif()
+set(__add_c_compiler_flag INCLUDED)
+
+include(CheckCCompilerFlag)
+
+function(add_c_compiler_flag FLAG)
+  string(TOUPPER "HAVE_C_FLAG_${FLAG}" SANITIZED_FLAG)
+  string(REPLACE "+" "X" SANITIZED_FLAG ${SANITIZED_FLAG})
+  string(REGEX REPLACE "[^A-Za-z_0-9]" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
+  string(REGEX REPLACE "_+" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
+  set(CMAKE_REQUIRED_FLAGS "${FLAG}")
+  check_c_compiler_flag("" ${SANITIZED_FLAG})
+  if(${SANITIZED_FLAG})
+    set(VARIANT ${ARGV1})
+    if(ARGV1)
+      string(REGEX REPLACE "[^A-Za-z_0-9]" "_" VARIANT "${VARIANT}")
+      string(TOUPPER "_${VARIANT}" VARIANT)
+    endif()
+    set(CMAKE_C_FLAGS${VARIANT} "${CMAKE_C_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
+  endif()
+endfunction()
+