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



>>> On 11.04.17 at 09:54, <roger.pau@xxxxxxxxxx> 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

bind (I think)

> 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.

Hmm, so far it wasn't clear to me that this is also needing an outer
switch() - can you confirm switch inside the while control expression
alone does not trigger the warning?

> This has been reported upstream as 
> http://bugs.llvm.org/show_bug.cgi?id=32595.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

The patch itself is fine with me, i.e.
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

but besides wanting to wait for above confirmation, I'd also like
to allow some time for others to voice objections to this new
approach.

Jan

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