kbuild: clang: disable unused variable warnings only when constant

commit 0a5f41767444cc3b4fc5573921ab914b4f78baaa upstream.

Currently, GCC disables -Wunused-const-variable, but not
-Wunused-variable, so warns unused variables if they are
non-constant.

While, Clang does not warn unused variables at all regardless of
the const qualifier because -Wno-unused-const-variable is implied
by the stronger option -Wno-unused-variable.

Disable -Wunused-const-variable instead of -Wunused-variable so that
GCC and Clang work in the same way.

Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Makefile b/Makefile
index 50866f8..0b35e1a 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -706,7 +706,6 @@ KBUILD_CFLAGS += $(stackp-flag)
 
 ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
@@ -724,9 +723,9 @@ else
 # These warnings generated too much noise in a regular build.
 # Use make W=1 to enable them (see scripts/Makefile.extrawarn)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 endif
 
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS  += -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else