zygoloid wrote: > Would it be possible to provide better fine grained control over the > `-Wsign-compare` so the clang could still flag the the cases like the one in > the summary but ignore the cases where implicit conversion has no side > effects or UB?
The warning being produced is a `-Wimplicit-int-conversion` warning, not a `-Wsign-compare` warning, caused by us now noticing that if `shift` is `-128`, `-shift` will be `(int)128`, and the conversion back to `int8_t` changes the value. I could be wrong, but I don't think `-Wimplicit-int-conversion` flags any cases where the conversion has UB or side effects, so you could perhaps work around this by turning off that flag. That said, it looks strange that this warns: ```c++ int8_t n = ...; n = -n; ``` but this does not: ```c++ int8_t n = ...; n = n + 1; ``` Both have the property that the right-hand side is sometimes 128, and if so, it gets implicitly wrapped to `-128` by the conversion back to `int8_t`. Perhaps we should look at what `+` and `-` are doing and make `-n` behave the same as `0 - n`? https://github.com/llvm/llvm-project/pull/126846 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
