[Bug libstdc++/52942] [4.7/4.8 Regression] using std::ref with a std::unordered_map fails to compile

[paolo.carlini at oracle dot com]

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

--- Comment #12 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-12 
10:27:16 UTC ---
Created attachment 27139
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27139
Draft I'm testing