`@dynamicMemberLookup` static subscripts do not work with unprefixed dot syntax

[matt-curtis]

Describe the bug @dynamicMemberLookup static subscripts do not work with unprefixed dot syntax.

Demonstration:

struct Color {

    let red: Double
    let green: Double
    let blue: Double
    let alpha: Double

}

@dynamicMemberLookup
struct Prop {

    static subscript<T>(dynamicMember member: KeyPath<Color, T>) -> Self { Prop() }

}

_ = Prop.red // works
let prop: Prop = .red // does not work

Steps To Reproduce Steps to reproduce the behavior:

1. Define a static dynamicMember subscript
2. Observe that it does not work with unprefixed dot syntax

Expected behavior Dynamic properties are inferred the same way as other unprefixed properties are.

Environment (please fill out the following information)

• OS: macOS 12.5
• Xcode Version: 13.4.1 (13F100)

Additional context Swift forums thread post discussing this issue.

[soumyamahunt]

Looking forward for this to be fixed as well.