protocol AProtocol {
    associatedtype V
    func a(_ v: V)
}

extension AProtocol {
    func v(_ v: V) {}
}

class AClass<V>: AProtocol {
    func a(_ v: V) {} 

    init() {}

    convenience init(_ w: V) {
        self.init()
        v(w) // Cannot convert value of type 'V' to expected argument type 'Self.V'
    }
    
    init(_ w: V, _ w2: V) {
        v(w) // This works
    }
}