Default Values in a func are not working for func-parameters or to satisfy protocols

[cvogelbusch]

Description

A default parameter in a functions signature should mean this Parameter can be omitted. Sadly that only works in some situations which makes no sense for me - in my head this definition means that this function has multiple signatures kind of.

I found two cases where it does not work. When using the function as a parameter or when using it to satisfy a protocol.

Reproduction

import Foundation

struct TestA {
    var one: Int
    var two: Int
    
    init(one: Int, two: Int = 2) {
        self.one = one
        self.two = two
    }
    
    func needs(this: Int, and that: Int = 2) {
        print("This \(this), that \(that)")
    }
}

struct TestB {
    var one: Int
    var two: Int
    
    init(one: Int) {
        self.one = one
        self.two = 2
    }
    
    func needs(this: Int) {
        print("This \(this), that \(2)")
    }
}

let testA = (1...10).map(TestA.init)
let testB = (1...10).map(TestB.init)

protocol TestProtocol {
    func needs(this: Int)
}

extension TestA: TestProtocol {}
extension TestB: TestProtocol {}

//extension TestA {
//    func needs(this: Int) {
//        print("This \(this)")
//    }
//    init (one: Int) {
//        self.one = one
//        self.two = 0
//    }
//}

Expected behavior

I would expect that both TestA and TestB can do the mapping, because they their init can both be called with a single parameter of type Int.
Also I would assume TestA and TestB satisfies TestProtocol, because the function can be called as requested.

Actual Result:
Both do not "see" the function signature they need to call it with a single parameter
Line 31: Cannot convert value of type '@sendable (Int, Int) -> TestA' to expected argument type '(ClosedRange.Element) -> TestA' (aka '(Int) -> TestA')
Line 38: Type 'TestA' does not conform to protocol 'TestProtocol'

What is even weirder to me is I can declare the init and function with a single parameter (like in the comment), but not I do not know which one is called when I call the function with a single parameter in my code.

Environment

swift-driver version: 1.120.5 Apple Swift version 6.1.2 (swiftlang-6.1.2.1.2 clang-1700.0.13.5)
Target: arm64-apple-macosx15.0

Additional information

I really appreciate all you people working on Swift it is a lovely language and for no other language I would expect this to work, but Swift feels so clean to me that this should be working.