Teach gimple_canonical_types_compatible_p about incomplete types

[Joseph Myers]

On Tue, 2 Jun 2015, Jan Hubicka wrote:

> > On Sat, 30 May 2015, Jan Hubicka wrote:
> > 
> > > Joseph, does the attached testcase make sense for you? Is it defined? It is my
> > > first attempt to really interpret C standard to detail.
> > 
> > I suppose it's defined if unsigned int is the type chosen as compatible 
> > with that enum.  The test should be skipped for short_enums targets 
> > (arm-eabi bare metal) (you can't simply use -fno-short-enums as then that 
> > will fail the link-time compatibility checking).
> 
> thanks. I did not notice we have -fshort-enum by default targets. I suppose we want:
> /* { dg-xfail-if "" { arm-eabi-* } { "*" } { "" } } */

Well, not that (which matches "eabi" against the vendor part of the 
triplet), but skip for the short_enums effective-target keyword.

-- 
Joseph S. Myers
joseph@codesourcery.com