relates to:

• SR-1297 Method parameters list interpreted as a single tuple (tuple "unsplat"), making behavior disturbing

Issue Description:

See https://github.com/mikelehen/swift-ambiguous-use-bug for a repro.

Basically, SwiftBug.h defines a class with two versions of a "observeEventType" method:

• (void)observeEventType:(int)eventType withBlock:(void (^)(Thinger *thing))block;

• (void)observeEventType:(int)eventType andPreviousSiblingKeyWithBlock:(void (^)(Thinger *thing, NSString *key))block;

I'm able to inconsistently call this method with trailing closure syntax. And very strangely, the presence of an innocuous print statement causes compilation to fail:

        foo.observeEventType(0) { snap in
            // If you uncomment print("test") then compilation fails with "Ambiguous use of 'observeEventType(_:withBlock:)'"
            //print("test")
            
            snap.doThing()
        }

Can you:

1. Confirm there's a bug here and comment on if/when it might be fixed.
2. Comment on the best way to expose this method so that Swift trailing closure syntax works (ideally I would just expose the version that takes the block with two params, but I want both versions for Obj-C).

Thanks!