[Bug target/79671] [7 Regression] mapnik miscompilation on armv7hl since r235622

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79671

--- Comment #101 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to rguenther@suse.de from comment #100)
> On Tue, 4 Apr 2017, bernd.edlinger at hotmail dot de wrote:
> 
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79671
> > 
> > --- Comment #99 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
> > (In reply to rguenther@suse.de from comment #95)
> > > >
> > > >this would fix the remaining fall-out.
> > > 
> > > Because that is not how it was designed or documented to work :)
> > 
> > So yes, it seems I misunderstood what may_alias should do.
> > 
> > It is defined on the type, however it has only meaning on the
> > pointers to that type, but not on the instances.
> > 
> > But I wanted to have an attribute to express in the tree
> > that instances and pointers to that type may alias anything.
> > 
> > How about adding a new type attribute, that does what I meant,
> > like always_alias for instance?
> 
> That's what I proposed the C++ FE to do with a new tree type flag.  That
> could be exposed to users with an attribute as well, of course.

good.

I have all the bits together, I just have to rename the flag.