Typo of any vs Any resulted in an unhelpful error message

[mattmassicotte]

Motivation

I was experimenting with some features from SE-420, and I made a typo. I found it quite hard to figure out what was going on from the error message produced. I have no idea if such a thing is possible to handle more gracefully, but I thought I'd point it out anyways.

protocol Thingy {
	func doThing(isolation: isolated (any Actor)?)
}

actor MyActor {
	var value = 1
}

extension Thingy {
	func doThing(isolation: isolated (Any Actor)? = #isolation) {
		print(value)
	}
}

And here are the warnings being produced:

test.swift:10:45: error: expected ':' following argument label and parameter name
 8 | 
 9 | extension Thingy {
10 | 	func doThing(isolation: isolated (Any Actor)? = #isolation) {
   |                                             `- error: expected ':' following argument label and parameter name
11 | 		print(value)
12 | 	}

test.swift:10:45: error: expected type
 8 | 
 9 | extension Thingy {
10 | 	func doThing(isolation: isolated (Any Actor)? = #isolation) {
   |                                             `- error: expected type
11 | 		print(value)
12 | 	}

test.swift:10:26: error: 'isolated' parameter type '()?' does not conform to 'Actor' or 'DistributedActor'
 8 | 
 9 | extension Thingy {
10 | 	func doThing(isolation: isolated (Any Actor)? = #isolation) {
   |                          `- error: 'isolated' parameter type '()?' does not conform to 'Actor' or 'DistributedActor'
11 | 		print(value)
12 | 	}

test.swift:11:9: error: cannot find 'value' in scope
 9 | extension Thingy {
10 | 	func doThing(isolation: isolated (Any Actor)? = #isolation) {
11 | 		print(value)
   |         `- error: cannot find 'value' in scope
12 | 	}
13 | }

Proposed solution

I think it would be great if I could get some feedback about the possibility that I just typoed here. Especially in this specific example, I think Any is actually totally invalid. But, it would be even cooler if it could be solved more generally.

Alternatives considered

No response

Additional information

No response