This is the mail archive of the
gcc-prs@gcc.gnu.org
mailing list for the GCC project.
c++/10574: Partial specialization selection failure involving a default template parameter from inside a template
- From: gccbugs at contacts dot eelis dot net
- To: gcc-gnats at gcc dot gnu dot org
- Date: 30 Apr 2003 23:39:57 -0000
- Subject: c++/10574: Partial specialization selection failure involving a default template parameter from inside a template
- Reply-to: gccbugs at contacts dot eelis dot net
>Number: 10574
>Category: c++
>Synopsis: Partial specialization selection failure involving a default template parameter from inside a template
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: rejects-legal
>Submitter-Id: net
>Arrival-Date: Wed Apr 30 23:46:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: Eelis van der Weegen
>Release: gcc version 3.2.2
>Organization:
>Environment:
Configured with: ../gcc-3.2.2/configure --prefix=/usr --enable-shared --enable-threads=posix --enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose --target=i386-slackware-linux --host=i386-slackware-linux
Thread model: posix
>Description:
Consider the following code:
template <typename>
struct A
{
struct B {};
template <typename, typename T = B>
struct C
{
typename T::x y;
};
template <typename T>
struct C<T, B> {};
};
A<int>::C<int> t;
The last statement should instantiate C's partial specialization. However, the nonspecialized version is instantiated, resulting in a compiler error:
no type named `x' in `struct A<int>::B
When considering the specialization, it seems G++ fails to identify the automatically selected default parameter and the formal parameter of the specialization as the same B. Moving B outside A resolves the issue.
Comeau compiles the code without problems.
This problem seems to be related to PR9737, which was suspended due to possible change in the next version of the C++ standard. I think this problem is different enough for examination, especially since the current patch for 9737 does not cover this issue (it deals with template template parameter problems).
>How-To-Repeat:
Try compiling the code from the description.
>Fix:
No idea.
>Release-Note:
>Audit-Trail:
>Unformatted: