linux-kernel - Re: New -Werror=restrict error with incremental gcc

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Date:   Fri, 16 Mar 2018 17:56:28 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Wang Nan <wangnan0@...wei.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: New -Werror=restrict error with incremental gcc

On 03/15/2018 08:11 PM, Josh Poimboeuf wrote:
> On Thu, Mar 15, 2018 at 08:06:26AM -0700, Laura Abbott wrote:
>> This only showed up with the very latest rawhide snapshot, .17 worked and
>> .18 started failing. I had to download .18 manually to test locally
>> https://koji.fedoraproject.org/koji/packageinfo?packageID=40
> 
> I also see the error with the latest gcc master branch.  The code is
> harmless, but maybe the warning is useful in other places, so here's one
> way to fix it.
> 

Works for me, you can add

Tested-by: Laura Abbott <labbott@...hat.com>

> ----
> 
> From: Josh Poimboeuf <jpoimboe@...hat.com>
> Subject: [PATCH] objtool, perf: Fix GCC 8 -Wrestrict error
> 
> Starting with recent GCC 8 builds, objtool and perf fail to build with
> the following error:
> 
>    ../str_error_r.c: In function ‘str_error_r’:
>    ../str_error_r.c:25:3: error: passing argument 1 to restrict-qualified parameter aliases with argument 5 [-Werror=restrict]
>       snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
> 
> The code seems harmless, but there's probably no benefit in printing the
> 'buf' pointer in this situation anyway, so just remove it to make GCC
> happy.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> ---
>   tools/lib/str_error_r.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/lib/str_error_r.c b/tools/lib/str_error_r.c
> index d6d65537b0d9..6aad8308a0ac 100644
> --- a/tools/lib/str_error_r.c
> +++ b/tools/lib/str_error_r.c
> @@ -22,6 +22,6 @@ char *str_error_r(int errnum, char *buf, size_t buflen)
>   {
>   	int err = strerror_r(errnum, buf, buflen);
>   	if (err)
> -		snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
> +		snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, [buf], %zd)=%d", errnum, buflen, err);
>   	return buf;
>   }
>