linux-kernel - Re: [PATCH] kallsyms: work around bogus -Wrestrict warning

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Date:   Thu, 9 Jan 2020 14:02:02 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Oleksandr Natalenko <oleksandr@...hat.com>, linux-mm@...ck.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Will Deacon <will@...nel.org>,
        Song Liu <songliubraving@...com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kallsyms: work around bogus -Wrestrict warning

On Wed, 8 Jan 2020 10:26:02 +0900 Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Hi Arnd,
> 
> On Tue,  7 Jan 2020 22:40:26 +0100
> Arnd Bergmann <arnd@...db.de> wrote:
> 
> > gcc -O3 produces some really odd warnings for this file:
> > 
> > kernel/kallsyms.c: In function 'sprint_symbol':
> > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
> >    strcpy(buffer, name);
> >    ^~~~~~~~~~~~~~~~~~~~
> > kernel/kallsyms.c: In function 'sprint_symbol_no_offset':
> > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
> >    strcpy(buffer, name);
> >    ^~~~~~~~~~~~~~~~~~~~
> > kernel/kallsyms.c: In function 'sprint_backtrace':
> > kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
> >    strcpy(buffer, name);
> >    ^~~~~~~~~~~~~~~~~~~~
> > 
> > This obviously cannot be since it is preceded by an 'if (name != buffer)'
> > check.
> 
> Hmm, this looks like a bug in gcc.

Yes, we're getting a lot of such reports.  I don't think current gcc is
ready for this patch so I'll drop it, sorry.