duplicates:

• SR-1122 Failure to typecheck chain of binary operators on force-unwrapped values
• SR-2636 + Operator fails to infer type for more than 2 force unwrapped values

Issue Description:

This compiles:

        var d : [String:Double] = ["a" : 1]
        var total : Double = d["a"]! + d["a"]!

This doesn't compile:

        var d : [String:Double] = ["a" : 1]
        var total : Double = d["a"]! + d["a"]! + d["a"]!

The error message reads " Value of optional type 'Double?' not unwrapped; did you mean to use '!' or '?'?", and if you perform the Fix-It, you get a different error.

That makes no sense.