linux-kernel - Re: [PATCH RESEND 1/1] perf build: Allow nested externs to enable BUILD

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Message-ID: <20201013190756.GA3100363@kernel.org>
Date:   Tue, 13 Oct 2020 16:07:56 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Vasily Gorbik <gor@...ux.ibm.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: [PATCH RESEND 1/1] perf build: Allow nested externs to enable
 BUILD_BUG() usage

Em Fri, Oct 09, 2020 at 02:41:11PM +0200, Jiri Olsa escreveu:
> On Fri, Oct 09, 2020 at 02:25:23PM +0200, Vasily Gorbik wrote:
> > Currently BUILD_BUG() macro is expanded to smth like the following:
> >    do {
> >            extern void __compiletime_assert_0(void)
> >                    __attribute__((error("BUILD_BUG failed")));
> >            if (!(!(1)))
> >                    __compiletime_assert_0();
> >    } while (0);
> > 
> > If used in a function body this obviously would produce build errors
> > with -Wnested-externs and -Werror.
> > 
> > To enable BUILD_BUG() usage in tools/arch/x86/lib/insn.c which perf
> > includes in intel-pt-decoder, build perf without -Wnested-externs.
> > 
> > Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> > Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
> 
> that one applied nicely ;-) thanks
> 
> Acked-by: Jiri Olsa <jolsa@...hat.com>



Thanks, applied.

- Arnaldo