swift

2757bd31 - [Executors ]dont use loc validity to determine if we should diagnose

[Executors ]dont use loc validity to determine if we should diagnose instead, error if all implementations are "default from stdlib" because end-user MUST implement at least one of them Don't trigger warnings about stdlib itself when user code might trigger them The standard library's enqueue() does not play by the same rules -- we provide "deprecated" implementations in order to remain source/binary compatible, and showing warnings about this when users make mistake will only be misleading.