Re: [PATCH] kbuild: fix duplicated flags in DEBUG_CFLAGS

Nathan Chancellor
2021-02-03T17:39:35Z

On Wed, Feb 03, 2021 at 04:52:39PM +0900, Masahiro Yamada wrote:
> Sedat Dilek noticed duplicated debug flags passed when building C
> files with CONFIG_DEBUG_INFO.
>
> I do not know much about his build environment, but yes, Kbuild
> recurses to the top Makefile with some build targets. For example,
> 'make CC=clang bindeb-pkg' reproduces the issue.
>
> With commit 121c5d08d53c ("kbuild: Only add -fno-var-tracking-assignments
> for old GCC versions") applied, DEBUG_CFLAGS is now reset only when
> CONFIG_CC_IS_GCC=y.
>
> Fix it to reset DEBUG_CFLAGS also when using Clang.
>
> Fixes: 121c5d08d53c ("kbuild: Only add -fno-var-tracking-assignments for old GCC versions")
> Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>
> Makefile | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 3d3f67b98ca2..769a38ee81b9 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -811,10 +811,12 @@ KBUILD_CFLAGS += -ftrivial-auto-var-init=zero
> KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
> endif
>
> +DEBUG_CFLAGS :=
> +
> # Workaround for GCC versions < 5.0
> # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
> ifdef CONFIG_CC_IS_GCC
> -DEBUG_CFLAGS := $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments))
> +DEBUG_CFLAGS += $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments))
> endif
>
> ifdef CONFIG_DEBUG_INFO
> --
> 2.27.0
>