ldionne added a comment. In https://reviews.llvm.org/D50534#1194664, @timshen wrote:
> I'm not fully equipped with the context right now, but something doesn't add > up. if `__neg_chars_.empty()` check is removed, the `(__neg_mask_ == 0)` > above should be removed too. They have to be consistent. > > However, there is more weirdness in it. The comment above describes the > intention: > > union(complement(union(__neg_chars_, __neg_mask_)), other cases...) > > > With the `__neg_chars_.empty()` and `(__neg_mask_ == 0)` removed, I believe > that the code exactly matches the comment. Let's see what happens when users > don't specify any negative class or chars. `__neg_chars_` and `__neg_mask_` > will be empty sets, and `union(complement(union(__neg_chars_, __neg_mask_)), > other cases...)` always evaluate to full set, which means it always matches > all characters. This can't be right. > > It's likely that the comment description doesn't fully describe the intended > behavior. I think we need to figure that out first. Yes, I think you were right. I think what was missing is that the comment does not apply when there's no `neg_mask` and no `neg_chars`. Otherwise we get into that situation where we're taking the complement of an empty set, and we match everything, which is not what we want. Repository: rCXX libc++ https://reviews.llvm.org/D50534 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
