experimental/coroutine
I think that is only in C++20. It is going to be a while before clang supports that.
partially answering myself: i had to specify -fcoroutines-ts in other C++ flags, after that the following test worked:
https://wandbox.org/permlink/Dth1IO5q8Oe31ew2
ftm, i also specified C++17 and libc++ in compiler settings
anyone has a woring example that uses co_await in Xcode?
i was able to do that specifying -fcoroutines-ts in other C++ flags of Xcode. C++17