swift

2bf37b49 - disallow effectful getters for borrowed reads

disallow effectful getters for borrowed reads This means properties returning noncopyable types or those marked with `@_borrowed` can't have effects. The compiler never accepted the latter correctly before. The synthesized coroutine `read` calls the user-defined `get`, but coroutines don't support `async` or `throws`. resolves rdar://106260787