Thank you for raising the question!
On our cxx_status page, we list coroutines as partial. Part of the reasoning given is “This feature requires further analysis of the C++ Standard to determine what work is necessary for conformance.” – do you have confidence that this analysis has been done and that we have sufficient test coverage to convince you that we’re conforming?
More broadly related to policy, I don’t think it’s practical to wait until a feature has no open issues before claiming we support the feature. However, the feature should be reasonably functional on all the targets we support (at least, the targets for which any given feature makes sense for). So an issue like wrong code due to incompatibility between C++20 coroutines and 32-bit Windows x86 ABI · Issue #59382 · llvm/llvm-project · GitHub does concern me – we support Windows and clang gets integrated into Visual Studio, so it’s not an uncommon target. So the final comment about coroutines having significant issues on Windows makes me think we’re not quite there yet for marking support as full. That said, perhaps it would be appropriate to update the Partial status to say it’s supported fully everywhere but on Windows targets?