Re: c++/8772: Segmentation fault on 3 lines of template code

[Gabriel Dos Reis <gdr@integrable-solutions.net>]

The following reply was made to PR c++/8772; it has been noted by GNATS.

From: Gabriel Dos Reis <gdr@integrable-solutions.net>
To: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
Cc: Volker Reichelt <reichelt@igpm.rwth-aachen.de>, gcc-gnats@gcc.gnu.org,
   <sneechy@hotmail.com>, <gcc-bugs@gcc.gnu.org>
Subject: Re: c++/8772: Segmentation fault on 3 lines of template code
Date: 18 Jan 2003 10:28:18 +0100

 Wolfgang Bangerth <bangerth@ticam.utexas.edu> writes:
 
 | > What are we going to do with the PR w.r.t. the how-to-make-to-code-legal
 | > issue? Leave it open, close it, suspend it, open a new PR?
 | 
 | Good question. Just to recall this briefly: this code
 | ---------------
 | template <int> struct A {
 |     template <int> struct B { enum { v = 1 }; };
 | };
 | 
 | template <template <int> class F> struct C {
 |     enum { v = F<1>::v || 2 };
 | };
 | 
 | template <int n> struct D {
 |     enum { v = C<A<n>::B>::v };
 | };
 | -----------------------
 | generated an ICE (now errors), and the question was: is in the last line
 |   C<A<n>::B> 
 | something meaningful? Wouldn't we have to write
 |   C<typename A<n>::B>
 | ? This doesn't compile either presently. 
 | 
 | Gaby's suggestion was that this needs to be further disambiguated as
 |   C<typename A<n>::template B>
 
 Actually I suggeted:
 
   C<A<n>::template B>
 
 | which would not be covered by the standard (the oversight Gaby spoke of), 
 | but be reasonable. However, this still doesn't compile presently:
 |   g/a> /home/bangerth/bin/gcc-3.4-pre/bin/gcc -c x.cc
 |   x.cc:10: error: template argument 1 is invalid
 | 
 | What does compile is (also with icc7, by the way)
 |   C<A<n>::template B>
 | 
 | Gaby, is the latter the syntax you had in mind to be legal, i.e. put 
 | differently: no need for "typename"?
 
 Yes, that is what I talking about.  Incidently, as I said, Iraised the
 issue ad John Spicer (EDG) tolad me that he already came across the
 same issue, made a (revised) suggestion that matches mine, see
 
    http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2000/n1231.html
 
 | 
 | If yes, then I would say gcc presently does its best and we should close 
 | the report.
 
 Well, the diagnostic is still incorrect; I believe we should rephrase
 teh synopsis to indicate that
 
 | If the inquire Gaby did with the ISO committee finds some 
 | other solution, then this will be put into a DR anyway, and there is no 
 | need to keep the report open presently anyway.
 
 This is already reported to committee and there seems to be agreement
 that the code should be made work with 'template' prefix.
 
 -- Gaby