[PATCH 1/2] kbuild: move -Werror from KBUILD_CFLAGS to KBUILD_CPPFLAGS

[Masahiro Yamada <masahiroy@kernel.org>]

CONFIG_WERROR makes warnings into errors, but it only happens for *.c
files because -Werror is added to KBUILD_CFLAGS.

For example, you can put a #warning directive in any preprocessed
source file:

    #warning "blah blah ..."

If it is placed in a *.c file, it emits a warning by default, and it
is promoted to an error when CONFIG_WERROR is enabled:

    error: #warning "blah blah ..." [-Werror=cpp]

If it is placed in a *.S file, it is still a warning.

Move it to KBUILD_CPPFLAGS, so it works in the same way for *.c,
*.S, *.lds.S or whatever needs preprocessing.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index ebcb75442d7f..027d9163eff6 100644
--- a/Makefile
+++ b/Makefile
@@ -788,7 +788,8 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 
 KBUILD_CFLAGS += $(stackp-flags-y)
 
-KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
+KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
+KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
 
-- 
2.34.1