Hello Swift Community,
The review of SE-0070: "Make Optional Requirements Objective-C-only” ran from April 25 ... May 2, 2016. The proposal is *accepted* for Swift 3. The feedback on the proposal mainly discussed other alternatives, but the core team felt that those approaches would be too invasive. SE-0070 is the minimal solution for clarifying optional requirements without making their important use cases overtly awkward. The core team requests that the diagnostics generated by mistakes using optional requirements be revised to make it clear that it is an Objective-C only feature.
Thank you to Doug Gregor for proposing this. I filed SR-1395 to track the implementation of this work (https://bugs.swift.org/browse/SR-1395) - this is a nice starter task in the compiler.