Description
I found an odd case where the compiler will refuse to compile an extension of a generic type's subtype, with the subtype using the same type parameters as its container type.

Steps to reproduce
Try building the following on current released tooling (Xcode 14.2, Swift 5.7):

struct Property<Value: Equatable> { var value: Value } enum Namespace<Value: Equatable> { typealias Prop = Property<Value> } extension Namespace.Prop { static func buildOne(initialValue: Value) -> Self { return .init(value: initialValue) } }

I get the following error:
<path to file>:<line>:<column> Reference to generic type ‘Namespace’ requires arguments in <...>

Using extension Property instead will compile.

Expected behavior
I'm reasonably sure it should build. Even if I'm wrong about that, the error emitted doesn't make sense.

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)
• Xcode version info Xcode 14.2 Build version 14C18
• Deployment target: macOS 13.3