[Bug c++/51489] New: constexpr not working consistently

["dave at boostpro dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51489

             Bug #: 51489
           Summary: constexpr not working consistently
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dave@boostpro.com


I think this is a bug, and the program should compile.

  struct array
  {
      constexpr array() :x(0) {}
      constexpr int const* begin() { return &x; }
      int x;
  };
  constexpr array aa;
  constexpr auto b = aa.begin();
  static_assert(b-b == 0, "compiles just fine");
  static_assert(aa.begin()-aa.begin() == 0, "compiler thinks it's not a
constant expression");