Protocol conformance ignored when Self used

[vojtarylko]

Description

Compiler behaves in surprising ways when stating protocols using Self and/or typealias.

Reproduction

// Arbitrary protocol
protocol P1 { func someFunc() }

// Unexpected: Compiles fine even though we don't implement `someFunc()`
//
struct S1: Self.Conforms {
    typealias Conforms = P1
}

// Regresion: Fails to compile for Swift 6.1 with confusing
// error message:
//
// Swift 5.10 fails with:
//   `error: type 'S2' does not conform to protocol 'P1'`
//
//
// Swift 6.1 (84e93a26ea8ccf5) fails with:
//
//    struct S2: S2.Conforms {
//           `- note: through reference here
//        typealias Conforms = P1
//                  |- error: circular reference
//                  `- note: through reference here
//    }
//
struct S2: S2.Conforms {
    typealias Conforms = P1
}

Expected behavior

There shouldn't be difference between struct S1: Self.Conforms and struct S1: S1.Conforms

Environment

1. swift-driver version: 1.90.11.1 Apple Swift version 5.10 (swiftlang-5.10.0.13 clang-1500.3.9.4)
2. Swift version 6.1-dev (LLVM b5c60054ab3ee7b, Swift 84e93a26ea8ccf5)

Additional information

No response