[Concurrency] Evolving the Concurrency design and proposals

[Douglas_Gregor]

@Michael_Ilseman

If we ban overloading, then what situation does this overload-resolution rule apply to? Would this be Clang importer magic or am I misunderstanding the change? Would the overload-resolution rule interact with implicit promotion to async (it that is ever added)?

Please see [Concurrency] Asynchronous functions - #140 by Douglas_Gregor