[SR-5984] Error message for accidentally calling function in #selector(foo()) could suggest removing parens

[huonw]

Previous ID	SR-5984
Radar	rdar://problem/34640740
Original Reporter	@huonw
Type	Bug
Status	In Progress
Resolution

Environment

Swift 4.0

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, DiagnosticsQoI, StarterBug, TypeChecker
Assignee	None
Priority	Medium

md5: 939952c8851f309540d6ce3aaa7d7c15

Issue Description:

import Foundation

class Foo {
    @objc func foo() {
        _ = #selector(foo())
    }
}

call-selector.swift:5:13: error: argument of '#selector' does not refer to an '@objc' method, property, or initializer
        _ = #selector(foo())
            ^         ~~~~~

This is close to the correct syntax (#selector(foo)) and the compiler could help guide the user to this. This probably comes up most often with selectors for methods with no arguments (https://bugs.swift.org/browse/SR-1016).

[huonw]

@swift-ci create

[jckarter]

I feel like we should just also accept the syntax with the parens. It's not ambiguous with anything.

[belkadan]

Resetting assignee for all Starter Bugs not modified since 2018.