[Bug c++/54972] O2 breaks something in 4.6.3

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54972



--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-18 
12:01:22 UTC ---

(In reply to comment #4)

> You need -Wstrict-aliasing=2. 



And -O2



If the optimization passes don't run then they can't produce warnings.