Compiling without -O causes severe consequences that can easily be avoided, i.e. see the "wontfix" bug 25575.
people expect to have warnings for use of uninitialized variables, I dont know if this behaviour has always been the same across gcc versions but regardless, the user cant be expected to read the whole manual to stumble upon this one alarming detail. If there is no reason to ever compile without -O, then that should probably be completely disabled, otherwise there should be a warning I think "BEWARE!!! you are compiling without optimization - some warnings and errors will be missed" This would have saved me 2 weeks of tracking down the uninitialized bytes without the compiler's help. -- Summary: gcc should probably warn if users compile without -O Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tvb at gnome dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30719