aaron.ballman added a comment. In D148700#4401451 <https://reviews.llvm.org/D148700#4401451>, @rsmith wrote:
> In D148700#4401353 <https://reviews.llvm.org/D148700#4401353>, @jyknight > wrote: > >> Yes, standard attributes aren't supposed to be used for things which affect >> the type system (although, we certainly have many, already, which do, since >> we expose most GCC-syntax attributes also as C++-standard attribute syntax!) > > The rule that standard attributes don't affect semantics only applies to > attributes specified by the language standard. There is no expectation that > vendor attributes avoid such effects. In particular, I'm concerned by this in > the description of this change: > > In D148700 <https://reviews.llvm.org/D148700>, @rsandifo-arm wrote: > >> Really, the “only” thing wrong with using standard attributes is that >> standard attributes cannot affect semantics. > > If the only reason for this patch series is an idea that vendor attributes > using `[[...]]` syntax can't affect program semantics, then I think this > change is not justified, because vendor attributes using `[[...]]` syntax can > and usually do affect program semantics. But the documentation change here > makes the point that using a keyword attribute may be as good idea in cases > where you would always want compilation to fail on a compiler that doesn't > understand the annotation, rather than the annotation being ignored (likely > with a warning), so maybe that's reasonable justification for this direction. That is the reason for this direction -- we have enough instances where people want to add a vendor attribute but it is not safe for other implementations to ignore it (due to ABI, correctness, etc). This feature allows adding the attribute as a keyword which can appear anywhere the attribute can appear. Due to it being expressed as a keyword in source, the other implementations will fail to accept the code, whereas use of a vendor-specified attribute would be (potentially silently) accepted with ill-effects. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D148700/new/ https://reviews.llvm.org/D148700 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
