[PATCH 4.4 25/70] kbuild: clang: disable unused variable warnings only when constant

From: Greg Kroah-Hartman
Date: Mon Nov 26 2018 - 05:54:30 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Sodagudi Prasad <psodagud@xxxxxxxxxxxxxx>

commit 0a5f41767444cc3b4fc5573921ab914b4f78baaa upstream.

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

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@xxxxxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Makefile | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- 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)

+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls