type C1 = abstract new (a: 1) => 1
type C2 = new (a: 2) => 2

interface A extends C1, C2 {} // Error: Cannot assign an abstract constructor type to a non-abstract constructor type.
interface B extends C2, C1 {} // Ok

declare let a: A
declare let b: B

// These are both effectively abstract
new a(1), new a(2), new b(1), new b(2)

a = b // Ok
b = a // Error: Cannot assign an abstract constructor type to a non-abstract constructor type.

type AbstractFirst = C1 & C2
type AbstractLast = C2 & C1

declare let abstractFirst: AbstractFirst
declare let abstractLast: AbstractLast

// These are assignable to each oher
abstractFirst = abstractLast
abstractLast = abstractFirst

b = abstractFirst // Error: Cannot assign an abstract constructor type to a non-abstract constructor type.
abstractFirst = b // Ok

b = abstractLast // Ok
abstractLast = b // Ok