Re: c++/9737: Partial template specialisation selection failure involving template parameter defaults

Re: c++/9737: Partial template specialisation selection failure involving template parameter defaults

[lerdsuwa]

Synopsis: Partial template specialisation selection failure involving template parameter defaults

State-Changed-From-To: analyzed->suspended
State-Changed-By: lerdsuwa
State-Changed-When: Thu Apr 24 16:05:31 2003
State-Changed-Why:
    Work suspended due to possible change in this area in the next version of the C++ standard.  In the mean time, you can use the supplied patch to get the desired behavior.  Here is the patch:
      http://gcc.gnu.org/ml/gcc-patches/2003-04/msg01410.html

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9737

Re: c++/9737: Partial template specialisation selection failure involving template parameter defaults

[Kriang Lerdsuwanakij]

The following reply was made to PR c++/9737; it has been noted by GNATS.

From: Kriang Lerdsuwanakij <lerdsuwa@users.sourceforge.net>
To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org, lerdsuwa@gcc.gnu.org,
        gcc-prs@gcc.gnu.org, gccbugs@contacts.eelis.net
Cc:  
Subject: Re: c++/9737: Partial template specialisation selection failure involving
 template parameter defaults
Date: Fri, 18 Apr 2003 21:59:49 +0700

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9737
 
 Patch submitted:
 
      http://gcc.gnu.org/ml/gcc-patches/2003-04/msg01410.html
 

Re: c++/9737: Partial template specialisation selection failure involving template parameter defaults

[lerdsuwa]

Synopsis: Partial template specialisation selection failure involving template parameter defaults

Responsible-Changed-From-To: unassigned->lerdsuwa
Responsible-Changed-By: lerdsuwa
Responsible-Changed-When: Fri Feb 21 15:28:41 2003
Responsible-Changed-Why:
    A change to this behavior is planned for 3.4.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9737

Re: c++/9737: Partial template specialisation selection failure involving template parameter defaults

[bangerth]

Synopsis: Partial template specialisation selection failure involving template parameter defaults

State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Tue Feb 18 00:13:22 2003
State-Changed-Why:
    Confirmed. Default arguments must not affect the signature
    of template classes.
    
    Behavior is same since 2.95 and through to today's CVS.
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9737

c++/9737: Partial template specialisation selection failure involving template parameter defaults

[gccbugs]

>Number:         9737
>Category:       c++
>Synopsis:       Partial template specialisation selection failure involving template parameter defaults
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 17 23:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     gccbugs@contacts.eelis.net
>Release:        gcc version 3.2 (mingw special 20020817-1)
>Organization:
>Environment:
Configured with: ../gcc/configure --with-gcc --with-gnu-ld --with-gnu-as --host=mingw32 --target=mingw32 --prefix=/mingw --enable-threads --disable-nls --enable-languages=f77,c++,objc,ada --disable-win32-registry --disable-shared
Thread model: win32
gcc version 3.2 (mingw special 20020817-1)
>Description:
G++ fails to perform correct partial template specialisation selection when the template parameter either depends on or is equal to a default type or value:

// a simple template:

  template <typename> struct T {};

// two partial specializations:

  template <template <typename> class A, typename B>
  struct T<A<B> > {};

  template <template <typename, typename> class A, typename B, typename C>
  struct T<A<B, C> > {};

// the subject type that we will try to match (note the default):

  template <typename, typename A = void> struct P;

// now let's try to instantiate T with P:

  T<P<float, int > > a; // ok
  T<P<float, void> > b; // ambiguous instantiation
  T<P<float      > > c; // ambiguous instantiation

Comeau has no problems compiling any of this.
>How-To-Repeat:
Try compiling the code from the description.
>Fix:
No idea.
>Release-Note:
>Audit-Trail:
>Unformatted: