Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 9 Jan 2020 14:02:02 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Masami Hiramatsu <mhiramat@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Oleksandr Natalenko <oleksandr@redhat.com>, linux-mm@kvack.org,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Will Deacon <will@kernel.org>,
        Song Liu <songliubraving@fb.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Marc Zyngier <maz@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kallsyms: work around bogus -Wrestrict warning
Message-Id: <20200109140202.fd5488a2ac02f81b25d83b88@linux-foundation.org>
In-Reply-To: <20200108102602.43d4c5433eb495cdbf387e9b@kernel.org>
References: <20200107214042.855757-1-arnd@arndb.de>
        <20200108102602.43d4c5433eb495cdbf387e9b@kernel.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

> Hi Arnd,
> 
> On Tue,  7 Jan 2020 22:40:26 +0100
> Arnd Bergmann <arnd@arndb.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.