linux-kernel - Re: [PATCH] lib/test_printf.c: fix clang -Wformat warnings

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Message-ID: <CAHp75VdQws+Q8aoh0BZkq1K4Grw0ugo_=NZ1uYO0g38xFjT9Lw@mail.gmail.com>
Date:   Thu, 30 Jun 2022 10:13:34 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        llvm@...ts.linux.dev
Subject: Re: [PATCH] lib/test_printf.c: fix clang -Wformat warnings

On Thu, Jun 30, 2022 at 2:11 AM Justin Stitt <justinstitt@...gle.com> wrote:
>
> see warnings:
> | lib/test_printf.c:157:52: error: format specifies type 'unsigned char'
> | but the argument has type 'int' [-Werror,-Wformat] test("0|1|1|128|255",
> | "%hhu|%hhu|%hhu|%hhu|%hhu", 0, 1, 257, 128, -1);
> -
> | lib/test_printf.c:158:55: error: format specifies type 'char' but the
> | argument has type 'int' [-Werror,-Wformat] test("0|1|1|-128|-1",
> | "%hhd|%hhd|%hhd|%hhd|%hhd", 0, 1, 257, 128, -1);
> -
> | lib/test_printf.c:159:41: error: format specifies type 'unsigned short'
> | but the argument has type 'int' [-Werror,-Wformat]
> | test("2015122420151225", "%ho%ho%#ho", 1037, 5282, -11627);
>
> There's an ongoing movement to eventually enable the -Wformat flag for
> clang. Previous patches have targeted incorrect usage of
> format specifiers. In this case, however, the "incorrect" format
> specifiers are intrinsically part of the test cases. Hence, fixing them
> would be misaligned with their intended purpose. My proposed fix is to
> simply disable the warnings so that one day a clean build of the kernel
> with clang (and -Wformat enabled) would be possible. It would also keep
> us in the green for alot of the CI bots.

a lot

...

>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+ blank line

> +#define DO_PRAGMA(x) _Pragma(#x)
> +#define NOWARN(warnoption, ...)
> +           DO_PRAGMA(GCC diagnostic push)
> +                   DO_PRAGMA(GCC diagnostic ignored #warnoption)
> +                           __VA_ARGS__
> +                                   DO_PRAGMA(GCC diagnostic pop)

Is it deliberately a broken indentation here?

...

> +       /* disable -Wformat for this chunk */
> +       NOWARN(-Wformat,
>         test("0|1|1|128|255", "%hhu|%hhu|%hhu|%hhu|%hhu", 0, 1, 257, 128, -1);
>         test("0|1|1|-128|-1", "%hhd|%hhd|%hhd|%hhd|%hhd", 0, 1, 257, 128, -1);
>         test("2015122420151225", "%ho%ho%#ho", 1037, 5282, -11627);

Perhaps shift right the lines as well?

> +       )
> +       /* end chunk */

-- 
With Best Regards,
Andy Shevchenko