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Re: may_alias attribute and type identity (PR c++/34935)

From: Jakub Jelinek <jakub at redhat dot com>
To: Richard Guenther <richard dot guenther at gmail dot com>
Cc: Doug Gregor <doug dot gregor at gmail dot com>, GCC Development <gcc at gcc dot gnu dot org>
Date: Thu, 24 Jan 2008 17:41:57 +0100
Subject: Re: may_alias attribute and type identity (PR c++/34935)
References: <24b520d20801240658t34a3fbf1gbcfabe24fdaa8dd7@mail.gmail.com> <84fc9c000801240706va25012fs19dadf5e2bd941dc@mail.gmail.com>
Reply-to: Jakub Jelinek <jakub at redhat dot com>

On Thu, Jan 24, 2008 at 04:06:47PM +0100, Richard Guenther wrote:
> On Jan 24, 2008 3:58 PM, Doug Gregor <doug.gregor@gmail.com> wrote:
> The middle-end type system (useless_type_conversion_p) says that
> pointers to int and pointers to int __attribute__((may_alias)) are
> distinct (you can't use one in place of the other without changning
> semantics) - because the pointed to types have different alias sets.
> 
> Now, for rvalues that doesn't matter, so indeed a value of type
> int and a value of type int __attribute__((may_alias)) can be used
> in place of each other.  So I stand corrected and they should indeed
> have the same canonical type.

See also http://gcc.gnu.org/PR34936.  Is int __attribute__((may_alias))
supposed to be mangled the same as int?  And if so, it should for cp/call.c
purposes be treated the same as well.

	Jakub

References:
- may_alias attribute and type identity (PR c++/34935)
  - From: Doug Gregor
- Re: may_alias attribute and type identity (PR c++/34935)
  - From: Richard Guenther

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