[Bug c++/20234] ambiguity with friend name injection and using directive

[bangerth at dealii dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|incorrect error: class has  |ambiguity with friend name
                   |not been declared           |injection and using
                   |                            |directive


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20234