From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-412724-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 12346 invoked by alias); 19 Jan 2013 20:11:25 -0000
Received: (qmail 12123 invoked by uid 48); 19 Jan 2013 20:11:00 -0000
From: "hstong at ca dot ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/56039] ICE in iterative_hash_template_arg, at cp/pt.c:1606
Date: Sat, 19 Jan 2013 20:11:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Keywords: ice-on-valid-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: hstong at ca dot ibm.com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-56039-4-Y5zkkyDz68@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-56039-4@http.gcc.gnu.org/bugzilla/>
References: <bug-56039-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2013-01/txt/msg01843.txt.bz2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56039

--- Comment #4 from Hubert Tong <hstong at ca dot ibm.com> 2013-01-19 20:10:59 UTC ---
(In reply to comment #3)
I seem to find that the expression in question
> 
> false && [](){}
> 
is valid because there is a implicit conversion sequence consisting of a
user-defined conversion to pointer-to-function followed by a conversion to bool
from the pointer type.

> I'm forwarding this problem to CWG. I don't think that any compiler change
> will be done before that decision, because the CWG group intentionally tried
> to forbid lambda expressions within template declarations because of some
> known technical problems.
Sure. While I may not have a full appreciation of the difficultly for having an
implementation which works with this, I am aware that there is at least the
issue with mangling hinted at by the note in 14.5.6.1 [temp.over.link] p7 with
regards to the linking of equivalent declarations.

I am not sure, though, that implementation difficulty is a good reason to
remove the ability to have SFINAE applied on statements such as the declaration
in the IsConstructibleImpl specialization above.