Re: [PATCH] clang: disable the gcc-compat warnings for read_atomic

From: "Jan Beulich" <JBeulich@suse.com>
To: Julien Grall <julien.grall@arm.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	xen-devel@lists.xenproject.org,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH] clang: disable the gcc-compat warnings for read_atomic
Date: Thu, 13 Apr 2017 09:11:56 -0600	[thread overview]
Message-ID: <58EFB15C0200007800150D5D@prv-mh.provo.novell.com> (raw)
In-Reply-To: <20170411075420.55018-1-roger.pau@citrix.com>

>>> On 11.04.17 at 09:54, <roger.pau@citrix.com> wrote:
> clang gcc-compat warnings can wrongly fire when certain constructions are used,
> at least the following flow:
> 
> switch ( ... )
> {
> case ...:
>     while ( ({ int x; switch ( foo ) { case 1: x = 1; break; } x }) )
>     {
>         ...
> 
> Will cause clang to emit the following warning "'break' is bound to loop, GCC
> binds it to switch", which is a false positive, and both gcc and clang bound
> the break to the inner switch. In order to workaround this issue, disable the
> gcc-compat checks for the usage of the read_atomic macro.
> 
> This has been reported upstream as 
> http://bugs.llvm.org/show_bug.cgi?id=32595.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Julien,

Roger forgot to Cc you on this - thoughts wrt 4.9 (without it Xen
won't build with clang aiui)?

Jan

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