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Date: Fri, 10 Jun 2011 08:53:00 -0000
From: Richard Guenther <rguenther@suse.de>
To: Jason Merrill <jason@redhat.com>
Cc: Richard Guenther <richard.guenther@gmail.com>,	gcc-patches List <gcc-patches@gcc.gnu.org>
Subject: Re: RFA (fold): PATCH for c++/49290 (folding *(T*)(ar+10))
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On Thu, 9 Jun 2011, Jason Merrill wrote:

> On 06/07/2011 10:24 AM, Jason Merrill wrote:
> > On 06/07/2011 10:05 AM, Richard Guenther wrote:
> > > In that case you could do what Jakub suggested - but only for rvalues
> > > of course.
> > 
> > Right, and I need to handle lvalues as well.
> > 
> > > Can't you instead adjust the type you feed to fold_indirect_ref_1 in
> > > the caller in the C++ FE?
> > 
> > Not without digging down into the operand to see what type it wants. At
> > that point I might as well just copy the whole function into the FE.
> 
> Ping?

I'm out of good suggestions ;)  You can do the same-qualifier matching
and simply have a mismatched array element vs. array-ref type.  We
could also argue that whoever calls fold_indirect_ref_1 with TYPE
that doesn't even have TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (op0 (!)))
== TYPE_MAIN_VARIANT (type) is broken.  Thus we could argue that
even ignoring qualifiers is ok - but I'd be worried about folding
*((volatile int *)&a[0] + 1) to a[1] with lost volatile qualification.

Richard.