[cfe]Does Clang support heterogeneous lookup on unordered_map now?

Hey guys,
I just read this proposal:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0919r2.html

and I got to know it has been merged into C++20, So does Clang support heterogeneous lookup on unordered_map now?
If so, any examples on how to use it?