erichkeane added a comment. In D143891#4125954 <https://reviews.llvm.org/D143891#4125954>, @erichkeane wrote:
> In D143891#4122731 <https://reviews.llvm.org/D143891#4122731>, @aaron.ballman > wrote: > >> In D143891#4122668 <https://reviews.llvm.org/D143891#4122668>, @royjacobson >> wrote: >> >>> In D143891#4122660 <https://reviews.llvm.org/D143891#4122660>, >>> @aaron.ballman wrote: >>> >>>> This is an ABI breaking change, isn't it? (The type trait now returns >>>> something different than it did before, which could change instantiations >>>> or object layout.) >>> >>> Technically it is, but it only affects code that relies on constrained >>> default constructors, which we're only going to support in Clang 16. So if >>> we backport this to 16 it's not very problematic. >> >> Hmmm, if it's true that this only changes the behavior of a type with a >> constrained default constructor, then I think it's fine despite being an ABI >> break (we never claimed full support for concepts, so anyone relying on a >> particular behavior was mistaken to do that). I can't quite convince myself >> this doesn't impact other cases though -- the logic for computing triviality >> is nontrivial itself (pun intended), so I'm really only concerned that >> `__is_trivial` and friends return a different value for a non-constrained >> type. However, I also can't come up with a test case whose behavior changes >> either. > > Avoiding hte rest of the discussion, because I cannot even: > ABI Breaks like this are typically OK, BUT we need to update the > ClangABIVersion stuff, which includes only implementing this in the newest > version. Aaron points out offline that this is Concepts specific, and can only be run into with a concept. I didn't realize on first read the 'ineligible' was 'disabled with a constraint'. If so, we don't really make any guarantees about ABI compat with Concepts yet, so the ClangABIVersion stuff is likely unnecessary. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D143891/new/ https://reviews.llvm.org/D143891 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
