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



Hi Jan,

On 13/04/17 16:11, Jan Beulich wrote:
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
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@xxxxxxxxxx>

Julien,

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

On the basis that it will break Xen build with clang:

Release-acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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