Re: [PATCH] bug: shut up format attribute warning for clang as well

[Brendan Jackman <jackmanb@google.com>]

On Fri Mar 20, 2026 at 9:14 PM UTC, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Like gcc, clang-22 now also warns about a function that it
> incorrectly identifies as a printf-style format:
>
> lib/bug.c:190:22: error: diagnostic behavior may be improved by adding the 'format(printf, 1, 0)' attribute to the declaration of '__warn_printf' [-Werror,-Wmissing-format-attribute]
>   179 | static void __warn_printf(const char *fmt, struct pt_regs *regs)
>       | __attribute__((format(printf, 1, 0)))
>   180 | {
>   181 |         if (!fmt)
>   182 |                 return;
>   183 |
>   184 | #ifdef HAVE_ARCH_BUG_FORMAT_ARGS
>   185 |         if (regs) {
>   186 |                 struct arch_va_list _args;
>   187 |                 va_list *args = __warn_args(&_args, regs);
>   188 |
>   189 |                 if (args) {
>   190 |                         vprintk(fmt, *args);
>       |                                           ^
>
> Turn off this warning for all compilers and versions.
>
> Fixes: d36067d6ea00 ("bug: Hush suggest-attribute=format for __warn_printf()")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  lib/bug.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/lib/bug.c b/lib/bug.c
> index bbc301097749..374feb144f0b 100644
> --- a/lib/bug.c
> +++ b/lib/bug.c
> @@ -174,8 +174,7 @@ struct bug_entry *find_bug(unsigned long bugaddr)
>  }
>  
>  __diag_push();
> -__diag_ignore(GCC, all, "-Wsuggest-attribute=format",
> -	      "Not a valid __printf() conversion candidate.");
> +__diag_ignore_all("-Wmissing-format-attribute", "Not a valid __printf() conversion candidate.");
>  static void __warn_printf(const char *fmt, struct pt_regs *regs)
>  {
>  	if (!fmt)

There is actually a superior fix for this warning that Andy Schevchenko
posted here (mine just happened to get merged first):

https://lore.kernel.org/all/20251208141618.2805983-1-andriy.shevchenko@linux.intel.com/T/#u

Should we just switch over to that? Looks like it should work for both
compilers.