[Bug c++/64259] New: Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

["rutsky.vladimir at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64259

            Bug ID: 64259
           Summary: Erroneous "declaration 'struct ...' does not declare
                    anything" when using "typename"
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rutsky.vladimir at gmail dot com

Consider following example:

$ cat /tmp/test.cpp 
class A;

namespace details
{
    struct B {};
}

using BB = typename details::B;

$ g++-4.9 -std=c++11 -c /tmp/test.cpp 
/tmp/test.cpp:8:30: warning: declaration 'struct details::B' does not declare
anything
 using BB = typename details::B;
                              ^
$ g++-4.9 --version
g++-4.9 (Ubuntu 4.9.2-0ubuntu1~14.04) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Code compiles without warnings with clang 3.5.


If I remove (uneeded) typename:

using BB = details::B;

code compiles with GCC without warnings.