http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54388
--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-09-09 17:56:15 UTC --- (In reply to comment #10) > Can the compiler warn about the original (buggy) code? It already does: c.cc: In function ‘A& get(int)’: c.cc:3:43: error: invalid initialization of non-const reference of type ‘A&’ from an rvalue of type ‘A’ A& get(int i) { return i == 0 ? a : throw 1; } ^ But warnings are suppressed in system headers.