On Fri, 6 Sept 2024 at 16:40, Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > This was brought up to GCC at one point and they considered its current > behavior as working as intended from my understanding: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91432 Their argument seems to be "the missing fallthrough has no effect". Which is true. But they seem to be missing that it has no effect *NOW*. One major problem case is that people tend to add new cases to the end of a switch() statement, not counting that final "default: break". So the "it doesn't have any effect NOW" is true, but the next time somebody edits that and doesn't check warnings, it *will* have very strange behavior, and it won't be affecting the newly added case, but some entirely unrelated previous case. So I really think the lack of warnings is a gcc mis-feature. It leaves code in a bad situation going forward. Oh well. Many times I have had to disable warnings entirely because they have too many false positives, so I guess the occasional "doesn't warn enough" is still a better problem to have. And at least we have (a) clang warning about it and (b) require the warnings going forward and use -Werror, so at least for the kernel the "when somebody edits that code, you get surprising behavior" case _will_ get noticed. Linus
