Note, this proposal includes some methods that are only useful in a generic context. For example, withUnsafeMutableBufferPointerIfSupported is pointless if you know you have an Array. Similarly, withUnsafeBufferPointer is pointless if you already have one.
These are probably more examples of the discussion we've had elsewhere of being able to fine-tune autocomplete suggestions and documentation depending on context, but should probably be discussed separately to this pitch itself.