Generic parameter 'τ_0_0' could not be inferred

[ios-blacksmith]

Description
Generic parameter 'τ_0_0' could not be inferred.

Steps to reproduce
Open playgrounds and paste the following code:

import SwiftUI
enum Fruit {

    case apple
    case orange

    var icon: (some View)? {
        switch self {
        case .apple: return Image(systemName: "applelogo")
        case .orange: return nil
        }
    }

}

Expected behavior
No error. The "(some View)?" type should be acceptable since either of the return types are in line with it.

Environment

• Swift compiler version info swift-driver version: 1.62.15 Apple Swift version 5.7.2 (swiftlang-5.7.2.135.5 clang-1400.0.29.51)
  Target: arm64-apple-macosx13.0

• Xcode version info Xcode 14.2
  Build version 14C18

• Deployment target: N/A - swift playgrounds

Opening the issues here as per: #53242 (comment)

[LucianoPAlmeida]

I think this is a duplicate from #62787. The diagnostics part we improved on main recently.

[xedin]

@LucianoPAlmeida is right, the diagnostic should be improved and this situation is indeed an error because nil does not provide a value for opaque type.

[AnthonyLatsis]

this situation is indeed an error because nil does not provide a value for opaque type.

In time, though, could we not do a type join or something to infer the nil’s wrapped type from the other return statement?