[Bug c++/55992] New: constexpr static member function not recognised in templated using statement

["wd11 at leicester dot ac.uk" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55992

             Bug #: 55992
           Summary: constexpr static member function not recognised in
                    templated using statement
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: wd11@leicester.ac.uk


The compiler fails to resolve a static constexpr member function which is used
in a templated using directive. For example, the following valid code
---------------------------------------------------------------------------------
#include <array>

template<unsigned MaxP, typename Type>
struct test
{
  static constexpr unsigned pole(unsigned P)
  { return P>MaxP? MaxP:P; }

  template<unsigned P>
  using my_array = std::array<Type,pole(P)>;    // causing error

  template<unsigned P>
  void do_something(my_array<P> const&, my_array<P>);
};
---------------------------------------------------------------------------------
produces (when compiling via g++ -c -std=c++11 test.cc using gcc 4.7.1 or
4.7.2)
---------------------------------------------------------------------------------
test.cc:10:42: error: âpoleâ was not declared in this scope
---------------------------------------------------------------------------------
The compiler can be made happy by explicitly resolving ("test::pole" in line
10) or by not using my_array<> (ie. without the do_something() member)