aaron.ballman added a comment. In D140860#4045224 <https://reviews.llvm.org/D140860#4045224>, @dblaikie wrote:
> In D140860#4044937 <https://reviews.llvm.org/D140860#4044937>, @aaron.ballman > wrote: > >> In D140860#4031872 <https://reviews.llvm.org/D140860#4031872>, @dblaikie >> wrote: >> >>> The risk now is that this might significantly regress/add new findings for >>> this warning that may not be sufficiently bug-finding to be worth immediate >>> cleanup, causing users to have to choose between extensive lower-value >>> cleanup and disabling the warning entirely. >>> >>> Have you/could you run this over a significant codebase to see what sort of >>> new findings the modified warning finds, to see if they're high quality bug >>> finding, or mostly noise/check for whether this starts to detect certain >>> idioms we want to handle differently? >>> >>> It might be hard to find a candidate codebase that isn't already >>> warning-clean with GCC (at least Clang/LLVM wouldn't be a good candidate >>> because of this) & maybe that's sufficient justification to not worry too >>> much about this outcome... >>> >>> @aaron.ballman curious what your take on this might be >> >> Thank you for the ping (and the patience waiting on my response)! >> >> I think there's a design here that could make sense to me. >> >> Issuing the diagnostic when there is a literal is silly because the literal >> value is never going to change. However, with a constant expression, the >> value could change depending on configuration. This begs the question of: >> what do we do with literals that are expanded from a macro? It looks like we >> elide the diagnostic in that case, but macros also imply potential >> configurability. So I think the design that would make sense to me is to >> treat macro expansions and constant expressions the same way (diagnose) and >> only elide the diagnostic when there's a (possibly string) literal. WDYT? > > Yeah, I'm OK with that - though I also wouldn't feel strongly about ensuring > we warn on the macro case too - if the incremental improvement to do > constexpr values is enough for now and a note is left to let someone know > they could expand it to handle macros. > > But equally it's probably not super difficult to check if the literal is from > a macro source location that differs from the source location of either of > the operators, I guess? (I guess that check would be needed, so it doesn't > warn when the macro is literally 'x && y || true' or the like. I mostly don't want to insist on dealing with macros in this patch, but it does leave the diagnostic behavior somewhat inconsistent to my mind. I think I can live without the macro functionality though, as this is still forward progress. And yes, you'd need to check the macro location against the operator location, I believe. Testing for a macro expansion is done with `SourceLocation::isMacroID()`, in case @hazohelet wants to try to implement that functionality as well. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D140860/new/ https://reviews.llvm.org/D140860 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
