On Tue, Mar 1, 2022 at 4:59 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> From: Mark Rutland <mark.rutland@xxxxxxx>
>
> In a subsequent patch we'll move the kernel from using `-std=gnu89` to
> `-std=gnu11`, permitting the use of additional C11 features such as
> for-loop initial declarations.
>
> One contentious aspect of C99 is that it permits mixed declarations and
> code, and for now at least, it seems preferable to enforce that
> declarations must come first.
>
> These warnings were already disabled in the kernel itself, but not
> for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses
> a separate set of CFLAGS.
>
> This patch fixes an existing violation in modpost.c, which is not
> reported because of the missing flag in KBUILD_USERCFLAGS:
>
> | scripts/mod/modpost.c: In function ‘match’:
> | scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
> | 837 | const char *endp = p + strlen(p) - 1;
> | | ^~~~~
>
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> [arnd: don't add a duplicate flag to the default set, update changelog]
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
I was able to build and boot on bare metal.
No new warnings in my build-log here after switching to -std=gnu11.
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> # LLVM/Clang v13.0.0 x86-64
- sed@ -
> ---
> Makefile | 3 ++-
> arch/arm64/kernel/vdso32/Makefile | 1 +
> scripts/mod/modpost.c | 4 +++-
> 3 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 94fa9a849a7a..37ef6a555dcd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -432,7 +432,8 @@ HOSTCXX = g++
> endif
>
> export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
> - -O2 -fomit-frame-pointer -std=gnu89
> + -O2 -fomit-frame-pointer -std=gnu89 \
> + -Wdeclaration-after-statement
> export KBUILD_USERLDFLAGS :=
>
> KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
> diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
> index 9378ea055bf2..ed181bedbffc 100644
> --- a/arch/arm64/kernel/vdso32/Makefile
> +++ b/arch/arm64/kernel/vdso32/Makefile
> @@ -68,6 +68,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
> -fno-strict-aliasing -fno-common \
> -Werror-implicit-function-declaration \
> -Wno-format-security \
> + -Wdeclaration-after-statement \
> -std=gnu11
> VDSO_CFLAGS += -O2
> # Some useful compiler-dependent flags from top-level Makefile
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 6bfa33217914..fe693304b120 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -833,8 +833,10 @@ static int match(const char *sym, const char * const pat[])
> {
> const char *p;
> while (*pat) {
> + const char *endp;
> +
> p = *pat++;
> - const char *endp = p + strlen(p) - 1;
> + endp = p + strlen(p) - 1;
>
> /* "*foo*" */
> if (*p == '*' && *endp == '*') {
> --
> 2.29.2
>
