"Hashable" conformance can only be synthesized in case it's declared in the same file with the type.
Since the file you declare Hashable conformance for CGPoint in is different from the file where CGPoint is declared, conformance cannot be synthesized.
It's generally worth reporting unhelpful error messages on bugs.swift.org (there already is a report for this particular issue, but please try to report bad error messages when you encounter them; an unclear error message is always a bug).