http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57242
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to etherice from comment #0) > I put a #warning in the my_pch.hpp file to be sure of when PCH were being > ignored (though, the long delay also made it quite obvious). You can use -Winvalid-pch for that instead.