[Bug c++/58538] Injected class-name treated as type-name instead of template-name when used as a template-argument for a template template-parameter

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58538

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
cp/pt.c convert_template_argument has this code:

  /* Deal with an injected-class-name used as a template template arg.  */
  if (requires_tmpl_type && CLASS_TYPE_P (arg))
    {
      tree t = maybe_get_template_decl_from_type_decl (TYPE_NAME (arg));
      if (TREE_CODE (t) == TEMPLATE_DECL)
        {
          if (cxx_dialect >= cxx11)
            /* OK under DR 1004.  */;
          else if (complain & tf_warning_or_error)
            pedwarn (input_location, OPT_Wpedantic, "injected-class-name %qD"
                     " used as template template argument", TYPE_NAME (arg));
          else if (flag_pedantic_errors)
            t = arg;

          arg = t;
        }
    }

So cp/semantics.c check_template_template_default_arg needs something similar.