On Tue, May 16, 2023 at 3:06 AM Florian Weimer via Gcc <gcc@gcc.gnu.org>
wrote:

> * Eric Gallager via Gcc:
>
> > I support this plan for using -Werror= and having it be split based on
> > whether -std= is set to a strict ANSI option or a GNU option; is there
> > a way to do that in the optfiles, or would it have to be handled at
> > the specs level instead?
>
> This isn't going to work well because -std=c17 (for example) disables
> _DEFAULT_SOURCE for glibc, so lots of declarations go missing from the
> glibc header files.  I don't see why these things should be tied
> together because as I see it, this is not about standards conformance
> (warnings make GCC conforming already), but programmer convenience.
>

Agreed, -std=c?? is supposed to disable only the extensions that conflict
with accepting all conforming code.  Diagnosing non-conforming code is the
job of -pedantic(-errors).

Can you explain again why upgrading -Wint-conversion (instead of
-Wimplicit) isn't the right solution for catching these bugs?  You
mentioned that this would need more changes to Fedora packages, but
wouldn't those cases also be fixing real bugs, unlike the changes needed to
avoid -Wimplicit in autoconf?

Jason