[Bug c++/96082] New: GCC rejects the template disambiguator with "typename"

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96082

            Bug ID: 96082
           Summary: GCC rejects the template disambiguator with "typename"
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

Hi, all.

This code, test.cc, GCC rejects it in versions from 9.1 to trunk, but accepts
it from 8.3 to 4.8 versions. 

$cat test.cc
template <class> class A {};
int main () { 
    typename :: template A <int> a;
}

$g++ test.cc
test.cc: In function ‘int main()’:
test.cc:3:26: error: ‘template’ must follow a nested-name-specifier
    3 |     typename :: template A <int> a;
      |                          ^~~~~~~
test.cc:3:26: error: expected ‘(’
    3 |     typename :: template A <int> a;
      |                          ^~~~~~~
      |                    

I also tested in clang, icc, and msvc, they all accept this code.