Type comparison incorrect with inherited string literals

[davewasmer]

TypeScript Version: 2.2.0

Code

class Foo {
    bar: "boop";
}
class Buzz extends Foo {
    bar = 'boop'
}

Playground Link

Expected behavior:

Compiles without error.

Actual behavior:

Class 'Buzz' incorrectly extends base class 'Foo'.
  Types of property 'bar' are incompatible.
    Type 'string' is not assignable to type '"boop"'.

---

Apologies if I'm missing something obvious, this is by design, or there are existing issues for this. I searched and didn't find anything like it.

[ahejlsberg]

See #6118. Ideally we'd have the declaration of bar in Buzz somehow contextually typed by the declaration of bar in Foo, but it turns out not to be an easy change.