On Thu, Sep 13, 2018 at 4:13 PM Richard Yao <r...@gentoo.org> wrote: > > On Sep 13, 2018, at 12:03 PM, Fabian Groffen <grob...@gentoo.org> wrote: > > > >> On 13-09-2018 07:36:09 -0400, Richard Yao wrote: > >> > >> > >>>> On Sep 12, 2018, at 6:55 PM, Thomas Deutschmann <whi...@gentoo.org> > >>>> wrote: > >>>> > >>>> On 2018-09-12 16:50, Rich Freeman wrote: > >>>> There is also the case where we want these warnings to block > >>>> installation, because the risk of there being a problem is too great. > >>> > >>> I really disagree with that. So many devs have already said multiple > >>> times in this thread that "-Werror" is only turning existing warnings > >>> into fatal errors but "-Werror" itself doesn't add any new checks and > >>> more often requires "-O3" to be useful. > >> The way that compilers work is that the warnings are generated in the > >> front end while the optimization level affects the backend. That means > >> that -O3 has no effect on the code that does error generation. This remark > >> about -O3 being needed to make -Werror useful is just plain wrong. > > > > Huh? -O3 enables more checks, which can generate more warnings. > > What checks are those? -O3 affects backend optimization while warnings are > generated by the front end. Once the immediate representation is generated, > there are no other warnings aside from those from the linker.
https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html Search for "depend on" -> [...] estimated based on heuristics that depend on thelevel argument and on optimization -> Because these warnings depend on optimization [...] Yes, warnings are dependent on optimization level.
