kconfig: add CC_IS_CLANG and CLANG_VERSION

This will be useful to describe the clang version dependency.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

init/Kconfig

@@ -16,6 +16,13 @@ config GCC_VERSION
 	default $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//') if CC_IS_GCC
 	default 0
 
+config CC_IS_CLANG
+	def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
+
+config CLANG_VERSION
+	int
+	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
+
 config CONSTRUCTORS
 	bool
 	depends on !UML

scripts/clang-version.sh

@@ -10,24 +10,14 @@
 # clang-5.0.1 etc.
 #
 
-if [ "$1" = "-p" ] ; then
-	with_patchlevel=1;
-	shift;
-fi
-
 compiler="$*"
 
-if [ ${#compiler} -eq 0 ]; then
-	echo "Error: No compiler specified."
-	printf "Usage:\n\t$0 <clang-command>\n"
+if !( $compiler --version | grep -q clang) ; then
+	echo 0
 	exit 1
 fi
 
 MAJOR=$(echo __clang_major__ | $compiler -E -x c - | tail -n 1)
 MINOR=$(echo __clang_minor__ | $compiler -E -x c - | tail -n 1)
-if [ "x$with_patchlevel" != "x" ] ; then
-	PATCHLEVEL=$(echo __clang_patchlevel__ | $compiler -E -x c - | tail -n 1)
-	printf "%02d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
-else
-	printf "%02d%02d\\n" $MAJOR $MINOR
-fi
+PATCHLEVEL=$(echo __clang_patchlevel__ | $compiler -E -x c - | tail -n 1)
+printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL