Re: c++/9990: locale_facets.h contains invalid typedef

[Nathan Sidwell <nathan.sidwell@blueyonder.co.uk>]

The following reply was made to PR c++/9990; it has been noted by GNATS.

From: Nathan Sidwell <nathan.sidwell@blueyonder.co.uk>
To: paolo@gcc.gnu.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
   nasgaard@ca.ibm.com, nathan@gcc.gnu.org, nobody@gcc.gnu.org,
   gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c++/9990: locale_facets.h contains invalid typedef
Date: Sun, 09 Mar 2003 15:53:28 +0000

 I can't tell if this is well formed or not.
 
 typename ctype::mask is looked up at instantiation time. Now does it find the
 typedef in ctype, or does it find the typedef in ctype_base? If this were
 not a template class, it would find the latter, ctype::mask not being in scope
 at the point of parsing the decl-spec.
 
 I believe class template instantiation should behave as closely as possible
 to the non-template equivalent. In which case the typename will find
 the name in the base class, and then insert the typedef into the instantiated
 class's scope. The standard doesn't specify precisely how instantiation
 happens. There are (sort of) two choices
 1) build up the instantiated class and its members much like a non-template
 class definition is constructed. I.e. what I've described above
 2) bind all the names declared, to types, functions, fields or whatever,
 then instantiate each of those declared things.
 
 IIRC gcc kind of does a mixture of the two :(
 
 Anyway, even if we do 1, do we fall foul of [3.3.6]/2? I think we do.
 note no diagnostic is required for such a violation. We also fail to issue one
 for the non-template case of N being a qualified id. Such as,
 	struct B { typedef int X;};
 	struct C : B { typedef C::X Y;
 	int X;
 	};
 
 I think this is really a 'request for change'
 
 nathan
 
 -- 
 Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
           The voices in my head said this was stupid too
 nathan@codesourcery.com : http://www.cs.bris.ac.uk/~nathan/ : nathan@acm.org