On Sun, Feb 27, 2022 at 2:09 AM Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> wrote: > > So imo we should just never do this by default, not just if the nasty > -fwrapv or nastier -fno-strict-overflow is used, just like we suggest > in our own documentation. The only valid reason -Wshift-negative-value > is in -Wextra is it warns for situations that always are undefined > behaviour (even if not in GCC). Ok, I just realized that this is specific to the i915 driver because that, unlike most of the kernel builds with -Wextra by default. -Wextra is enabled when users ask for a 'make W=1' build in linux, and i915 is one of just three drivers that enable an equivalent set of warnings, the other ones being greybus and btrfs. This means to work around the extra warnings, we also just need to disable it in the W=1 part of scripts/Makefile.extrawarn, as well as the three drivers that copy those options, but not the default warnings that don't include them. > Could you open a GCC PR for this? The current situation is quite > suboptimal, and what we document as our implementation choice is much > more useful! I hope I managed to capture the issue in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104711 Arnd
