* Jakub Jelinek: > On Tue, Oct 10, 2023 at 12:30:52PM -0400, Jason Merrill via Gcc wrote: >> On Tue, Oct 10, 2023 at 7:30 AM Florian Weimer via Gcc <gcc@gcc.gnu.org> >> wrote: >> >> > Are these code fragments valid C89 code? >> > >> > int i1 = 1; >> > char *p1 = i; >> > >> > char c; >> > char *p2 = &c; >> > int i2 = p2; >> > >> > Or can we generate errors for them even with -std=gnu89? >> > >> > (It will still be possible to override this with -fpermissive or >> > -Wno-int-conversion.) >> > >> >> Given that C89 code is unlikely to be actively maintained, I think we >> should be permissive by default in that mode. People compiling with an old >> -std flag are presumably doing it to keep old code compiling, and it seems >> appropriate to respect that. > > Yeah, complete agreement here.
Okay. It helps with the test suite conversation because -std=gnu89 -w is available today, so I can post such patches separately. >> I'm also (though less strongly) inclined to be permissive in C99 mode, and >> only introduce the new strictness by default for C11/C17 modes. > > Especially when the default is -std=gnu17 that can be an option as well. > > There might be some code in the wild compiled with -std=gnu99 or -std=c99 just > because it wanted to use C99 features back 15-20 years ago and hasn't been > adjusted since then, but it might be better to adjust that if needed and keep > using those flags only when they are needed because the code isn't C11/C17/C2X > ready. Linux currently uses -std=gnu99 deliberately in a few places, I believe. It would be a shame if we defaulted to permissive mode over there. I would certainly prefer to restrict permissive mode to the C89/C90 language levels. We can have this discussion once I post my patch (which depends on Jason's permerror enhancement in several ways). Thanks, Florian
