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

From: Masahiro Yamada
Date: Mon Dec 05 2022 - 23:07:54 EST


CONFIG_WERROR turns warnings into errors, which happens only for *.c
files because -Werror is added to KBUILD_CFLAGS.

Adding it to KBUILD_CPPFLAGS makes more sense because preprocessors
understand the -Werror option.

For example, you can put a #warning directive in any preprocessed code.

warning: #warning "this is a warning message" [-Wcpp]

If -Werror is added, it is promoted to an error.

error: #warning "this is a warning message" [-Werror=cpp]

This commit moves -Werror 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@xxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---

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

diff --git a/Makefile b/Makefile
index 53fa1a9fba8a..f84b57910667 100644
--- a/Makefile
+++ b/Makefile
@@ -869,7 +869,8 @@ 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_RUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
--
2.34.1