Type Inference Crash

playground.swift

import Foundation
import UIKit

// If defined here in the same module, no issue
// However, if defined in a separate module + used, will cause compiler crash
// public typealias GenericResult<T> = Result<T, NSError>


func testFunction<T>(withCompletion completion: (Result<T, NSError>) -> Void)
{
    // Do Stuff
}


// This works
testFunction { (result: Result<Data, NSError>) in }

// This crashes the compiler if GenericResult<T> is defined in another module :(
testFunction { (result: GenericResult<Data>) in }


print("Hello World")

result.swift

// NOTE: This must be compiled in a separate module for the crash to manifest

import Foundation

public enum Result<T, U: ErrorProtocol>
{
    case success(T)
    case failure(U)
}

public typealias GenericResult<T> = Result<T, NSError>