c++/9737: Partial template specialisation selection failure involving template parameter defaults
gccbugs@contacts.eelis.net
gccbugs@contacts.eelis.net
Mon Feb 17 23:26:00 GMT 2003
>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:
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