[SR-1019] Can't use the new #selector syntax for generic types

[swift-ci]

Previous ID	SR-1019
Radar	None
Original Reporter	JamieWhite (JIRA User)
Type	Bug

Environment

xcode 7.3
Swift 2.2

Additional Detail from JIRA

Votes	2
Component/s	Compiler
Labels	Bug, StarterBug
Assignee	None
Priority	Medium

md5: 5685a8e13e6f20612a2c6754c850cfe2

Issue Description:

I have an example here: https://gist.github.com/JamieWhite/72e0f7406a33d8e52657/51032655f639d9f92042ed7c02d0ee6c9e22790f

You'll notice this:

addTarget(trampoline, action: #selector(ActionTrampoline.action(_:)), forControlEvents: events)

ActionTrampoline is generic type. How this should work is doing this:

addTarget(trampoline, action: #selector(ActionTrampoline<Self>.action(_:)), forControlEvents: events)

How I worked around this was typeAliasing ActionTrampoline<self> and using that in the #selector like this:

https://gist.github.com/JamieWhite/72e0f7406a33d8e52657/fb010c8c0403725e431880b9dc6253dafc0c3b35

[swift-ci]

Comment by Mark Sands (JIRA)

JamieWhite (JIRA User) You can specify the generic type in your selector. Add <UIControl> in the failing line:

addTarget(trampoline, action: #selector(ActionTrampoline<UIControl>.action(_:)), forControlEvents: events)

[swift-ci]

Comment by Mark Sands (JIRA)

I created a radar for Xcode here 26031273, or reach out to me on twitter @marksands if someone from Apple actually wants to provide feedback 😉

FYI, a very simple test case to break Xcode's current behavior is this:

import Foundation

class TestClass<T> {
    let testSelector: Selector = "action" // Xcode should convert to #selector(TestClass<T>.action)
    @objc func action() { }
}

[CodaFi]

I have a patch, but the worrying thing about fixing this is that the fixit is still "wrong" in a lot of cases. Where before (replace without the generic param list) we would complain about not knowing how to, say, instantiate T in TestClass, now we get a fully spelled out type with an undeclared generic type parameter in it. Essentially: In non-generic contexts the fixit is just shuffling one error around for another.