[Swift 5.8] Unexpected error "Cannot inherit from protocol type with generic argument"

[ensan-hcl]

Description
In Swift 5.8, when attempting to inherit from a protocol with primary associated types specified and providing a typealias for the associated type, the code fails to compile with the error "Cannot inherit from protocol type with generic argument 'P'."

Steps to reproduce

1. Define a protocol P with a primary associated type T.
2. Attempt to create a struct F that inherits from P<Int> and provide a typealias for the associated type.

protocol P<T> {
    associatedtype T
}

// Cannot inherit from protocol type with generic argument 'P<Int>'
struct F: P<Int> {}

Expected behavior
The code should compile without any errors, as mentioned in SE-0346

In the inheritance clause of a concrete type, for example:

struct Lines : Collection<String> { ... }

In this position it is sugar for specifying the associated type witness, similar to explicitly declaring a typealias:

struct Lines : Collection {
  typealias Element = String
}

Environment

• Swift compiler version info:
  swift-driver version: 1.75.2 Apple Swift version 5.8.1 (swiftlang-5.8.0.124.5 clang-1403.0.22.11.100)
  Target: x86_64-apple-macosx13.0

• Xcode version info:
  Xcode 14.3.1
  Build version 14E300c

• Deployment target: N/A

Other Information

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