Generics; ReturnType<Foo> != ReturnType<typeof foo>

TypeScript Version: Version 2.9.0-dev.20180516

Search Terms: generic function returntype

I couldn't think of a good title for this,

Code

type Delegate<T> = () => T;

function executeGeneric<
    X,
    DelegateT extends Delegate<X> 
>(delegate: DelegateT): ReturnType<DelegateT> {
    //Type 'X' is not assignable to type 'ReturnType<DelegateT>'.
    const x: ReturnType<typeof delegate> = delegate();
    //Type 'X' is not assignable to type 'ReturnType<DelegateT>'.
    const y: ReturnType<DelegateT> = delegate();
    //Type 'X' is not assignable to type 'ReturnType<DelegateT>'.
    return delegate();
}

Expected behavior:

Return successfully.

Intuitively, to me,

1. delegate is of typeDelegateT.
2. ReturnType<DelegateT> and ReturnType<typeof delegate> should be the same

However,

Actual behavior:

Type 'X' is not assignable to type 'ReturnType<DelegateT>'.

Playground Link: Here

Related Issues:

Start with the linked TypeScript Playground reproduction and compare the types of ReturnType and ReturnType in the generic function. Determine whether the reported assignment errors should be eliminated while preserving the stated generic relationship, then verify the reproduction no longer reports those errors.