Bug Report

When trying to remove nils from a Tuple it resolves to an Tuple that do not extends to the identical Tuple (as represented by the compiler)

So in the example below the reult of a type is [a: 1, b?:2] which do not extends the type [a: 1, b?:2] ??

🔎 Search Terms

Identical type - Invalid Equality
tuple optional extends

🕗 Version & Regression Information

Discovered the issue today and it's referenced on the following stackoverflow
I did test it in the playground upto version 4.05 of typescript (syntax breaks in version prior)

⏯ Playground Link

playground

💻 Code

type UnNullify<T extends readonly unknown[]> = {
  [K in keyof T]: Exclude<T[K], null | undefined>
}

type Foo = UnNullify<[a: 1, b?: 2 | undefined]>
//   [a: 1, b?: 2]

type Test = [a: 1, b?: 2] extends Foo ? true : false
//   false ??

🙁 Actual behavior

Two types represented identical by the compiler do not extends each other

🙂 Expected behavior

Expected the two types to extends