Re: c++/9634: [3.4 regression] Problems with templates (SFINAE)

["Giovanni Bajo" <giovannibajo@libero.it>]

The following reply was made to PR c++/9634; it has been noted by GNATS.

From: "Giovanni Bajo" <giovannibajo@libero.it>
To: <gcc-gnats@gcc.gnu.org>,
	<gcc-bugs@gcc.gnu.org>,
	<nobody@gcc.gnu.org>,
	<gcc-prs@gcc.gnu.org>,
	<poschmid@lbl.gov>
Cc:  
Subject: Re: c++/9634: [3.4 regression] Problems with templates (SFINAE)
Date: Thu, 1 May 2003 15:59:01 +0200

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9634
 
 Yes, this is DR224
 (http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_defects.html#224), which is
 in WP status (so the resolution will be adopted in the next version of the
 standard). Basically, this PR can be sumed up in the following code:
 
 --------------------------------------
 template <typename T>
 struct A
 {
     typedef int Bar;
 
     template <typename>
     struct N {};
 
     typedef Bar          type1;
     typedef A::Bar       type2;
     typedef A<T>::Bar    type3;
 
     typedef N<int>       type4;
     typedef A::N<int>    type5;
     typedef A<T>::N<int> type6;
 };
 --------------------------------------
 pr9634.cpp:10: error: ISO C++ forbids declaration of `Bar' with no type
 pr9634.cpp:10: error: expected `;'
 pr9634.cpp:11: error: ISO C++ forbids declaration of `Bar' with no type
 pr9634.cpp:11: error: expected `;'
 pr9634.cpp:14: error: `N<int>' specified as declarator-id
 pr9634.cpp:14: error: expected `;'
 pr9634.cpp:15: error: `N<int>' specified as declarator-id
 pr9634.cpp:15: error: expected `;'
 
 The code is legal and should be accepted by GCC. It's rejected from 3.4
 (which first disables the implicit typename/template extensions).
 
 NOTE for the fixer: I suggest to prepare a testcase using the official
 examples present in the above link, which tests all the conditions for both
 success and failure.
 
 Giovanni Bajo