aaron.ballman added a comment. In D131479#3753586 <https://reviews.llvm.org/D131479#3753586>, @Mordante wrote:
> In D131479#3753533 <https://reviews.llvm.org/D131479#3753533>, @aaron.ballman > wrote: > >> In D131479#3753462 <https://reviews.llvm.org/D131479#3753462>, @Mordante >> wrote: >> >>> This change breaks the libc++ test >>> `libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/move.fail.cpp`. >>> >>> (https://buildkite.com/llvm-project/libcxx-ci/builds/13149#0182d0d4-341a-4b41-b67f-12937f41e6d5) >>> >>> Looking at the description of this patch it should only affect `consteval` >>> functions, but it seems to affect `constexpr` functions too. Can you have a >>> look? >> >> Agreed that we should take a look, but it's interesting to note that >> libstdc++ seems to have a different behavior than libc++ here: >> https://godbolt.org/z/6cWhf6GYj (the last three compiler panes show Clang 14 >> libstd++, Clang 14 libc++, and Clang trunk libc++). How sure are you that >> the libc++ test is actually correct, because (without checking the standard, >> so take with a giant grain of salt) this seems like it might have fixed a >> bug in libc++? The release note says this is expected to impact constexpr >> and consteval default special member functions, so behavioral changes to >> `constexpr` aren't unexpected (though I agree that the commit message didn't >> mention `constexpr` so the changes may seem surprising). > > Thanks for confirming it's indeed intended to affect `constexpr` too! It was > a bit confusing since it also referred to C++14, which didn't have > `consteval`. I wasn't entirely sure about the status of libc++, but since the > patch gave of a mixed message I wanted make sure that `constexpr` was > intended. It was a good question to bring up! > I've done some further digging and according to cppreference the paper > P0602R4 was a DR against C++20. This was proposed in the paper. > Looking at the changes in the addressing this paper I see no C++ version > checks https://reviews.llvm.org/D32385 > In a followup introduces tests using C++ version checks > https://reviews.llvm.org/D54772 > The failing test was introduced in 308624127fd6cc36558b6eee4d4ffa4e215a074e > before the paper was voted in > > So I think there's indeed a bug in libc++ which was hidden since Clang hadn't > implemented some DRs. I will look at the libc++ side what needs to be done to > fix the CI failures. Great sleuth work! Thank you for the investigation! Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D131479/new/ https://reviews.llvm.org/D131479 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
