Nonescaping parameter type spelling

[tera]

In the following fragment:

func foo(escaping: @escaping () -> (), nonescaping: () -> ()) {
    let a = escaping            // ok
    let b = nonescaping         // ok
    print(type(of: a))          // () -> ()
    print(type(of: b))          // () -> ()
    let c: () -> () = escaping  // ok
    let d: () -> () = nonescaping // 🛑 Using non-escaping parameter 'nonescaping' in a context expecting an @escaping closure
}

foo(escaping: {}, nonescaping: {})

both escaping and non escaping closure types are printed as () -> (), although this is apparently not the whole story and if I use this type in the explicit type position of a variable declaration the type doesn't match the nonescaping parameter. Is this type inexpressible in Swift?

[Tino]

I think it is comparable to let vs. var:
No different type, but some restriction on what you can do with the variable/value.

[anon9791410]

Do we have non-escaping local variable type?

In this recent thread: An odd error: "Escaping closure captures mutating 'self'" - #10 by Jens, I, (well, actually @Jens), just found out that this code compiles: func test(_ callback: () -> Void) { // Compiles, no need for it to be @escaping let x = callback x() } It baffles me because I don't think we have non-escaping closure types (yet). So my questions are Do we have it, and If so, how do we spell the type of x (or if it's actually a declaration attribute)? I confirmed that thi…