erik.pilkington added a comment. In D63856#1561112 <https://reviews.llvm.org/D63856#1561112>, @rjmccall wrote:
> In D63856#1560213 <https://reviews.llvm.org/D63856#1560213>, @erik.pilkington > wrote: > > > In D63856#1560180 <https://reviews.llvm.org/D63856#1560180>, @rjmccall > > wrote: > > > > > This only applies to relational operators, right? I'm a little > > > uncomfortable with calling this "tautological" since it's not like it's > > > *undefined behavior* to have `(BOOL) 2`, it's just *unwise*. But as long > > > as we aren't warning about reasonable idioms that are intended to handle > > > unfortunate situations — like other code that might have left a > > > non-`{0,1}` value in the `BOOL` — I think this is fine. > > > > > > I think the party line is that it is undefined behaviour (in some sense), > > since UBSan will happily crash if you try to load a non-boolean value from > > a BOOL. > > > What? Since when? https://reviews.llvm.org/D27607 > > >> It is a bit unfortunate that "defensive" code will start warning here though >> :/. Maybe we can try to detect and permit something like `B < NO || B > >> YES`, or emit a note with some canonical way of checking for non-boolean >> BOOLs. Even if we end up having to disable it default, I think its still a >> good diagnostic to have. A warning on stores to BOOL would probably be a lot >> higher value, though. > > I'm not sure this is a problem because I'm not sure there's any reason to > write defensive code besides `B != NO` or `B == NO`. It's potentially > problematic if someone writes `B == YES`, though. I was thinking about something like the following, which probably isn't worth warning on. Another way of handling it would be only emitting the diagnostic if `!InRange`. Not exactly sure how common that pattern actually is though. void myAPI(BOOL DoAThing) { if (DoAThing > YES || DoAThing < NO) DoAThing = YES; // ... } Repository: rC Clang CHANGES SINCE LAST ACTION https://reviews.llvm.org/D63856/new/ https://reviews.llvm.org/D63856 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
