[Bug libstdc++/56468] Clang exposes bug with unexpected forward-declaration of type_info

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56468

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-27 09:33:27 UTC ---
It's because of the implicit declaration of std::type_info, G++ correctly
diagnoses similar cases with altered namespace names or type names, it only
happens for std::type_info.  I see no harm in adding an explicit declaration to
the libstdc++ header so it works with clang and other compilers that don't
declare std::type_info automatically.