duplicates:

• SR-2316 typealias for block type not defaulting to @NoEscape

Issue Description:

I created a typealias for a sort descriptor:

typealias SortDescriptor<A> = (A, A) -> Bool

Now, when I try to create function that takes a sort descriptor and inverts it, the parameter should be marked as escaping, however, the compiler doesn't detect that, and worse, disallows it:

func invert<A>(_ x: SortDescriptor<A>) -> SortDescriptor<A> {
return { l, r in !x(l, r)
}

If I define the same function without the typealias, all is well:

// Exact same function, but now it needs to be marked as escaping... (which is correct)
func invert2<A>(_ x: @escaping (A,A) -> Bool) -> (A,A) -> Bool {
return { l, r in !x(l, r)
}

I can, however, call the first function just fine:

let gte: SortDescriptor<Int> = invert(<)