[SR-9818] Compile error is wrong when calling generic function with an argument of the wrong type

[swift-ci]

Previous ID	SR-9818
Radar	None
Original Reporter	justin.garcia (JIRA User)
Type	Bug

Attachment: Download

Environment

Swift 4.2

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, KeyPaths, TypeChecker
Assignee	@xedin
Priority	Medium

md5: a9dabc9d51d41c18b92d4aa8090e6384

Issue Description:

When I try to call the generic function below, if I pass the wrong type for the second parameter (a String instead of an Int), the compile error is wrong. It says there is a problem with the first parameter.

The error is:
Key path value type 'Equipment?' cannot be converted to contextual type 'NSManagedObject?'

I think the error should be something like:
Cannot convert value of type 'String' to expected argument of type 'Int'

Here is the code (sorry if the formatting is wrong, there is also a playground attached):

import CoreData``class

Equipment: NSManagedObject {

{{}}}

class Injury {

{{ init() {}}

    }

{{ var equipment: Equipment?}}

{{ func set<T: NSManagedObject>(propertyAt keyPath: ReferenceWritableKeyPath<Injury, T?>, toValueWithServerID serverID: Int {}}

    }  

{{}}}

let injury = Injury()

injury.set(propertyAt: \Injury.equipment, toValueWithServerID: "foo")

[belkadan]

Still occurs on master. cc @xedin