Re: [PATCH 2/3] treewide: use -Wdeclaration-after-statement

[Masahiro Yamada]

On Tue, Mar 1, 2022 at 11:52 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


Precisely speaking,
"In a subsequent patch we'll move the userspace tools ..."

The kernel part was done by 1/3.



> `-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

Is this the opposite?

"These warnings were already _enabled_ in the kernel itself, ..."




If you have a chance to resend this,
can you please rebase on top of kbuild/for-next?

This is not applicable due to the conflict with:
https://patchwork.kernel.org/project/linux-kbuild/patch/20220201213542.2808035-1-quic_eberman@xxxxxxxxxxx/






> 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>
> ---
>  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
>


-- 
Best Regards
Masahiro Yamada