[Bug libstdc++/52942] [4.7 Regression] using std::ref with a std::unordered_map fails to compile

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52942

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-04-12 
09:08:33 UTC ---
(In reply to comment #5)
> I see, thanks. Then, short term shall we just change the derivation to public

Hmm, that might be ok ... it would be the least invasive change, certainly