Spread results in error with Interfaces

[dancrumb]

I would expect the following code to pass with no errors.

interface Baz {
  baz: string;
}

interface Foo extends Baz { 
  bar: number;
}

const foo: Foo = {bar: 2, baz: ''};
const qux: Foo = {...foo};        

However, it fails on the last line with

^ Cannot assign object literal to `qux` because property `baz` is missing in object literal [1] but exists in `Baz` [2].

I see comparable behaviour with Object.freeze and Object.assign.

Recreate: https://flow.org/try/#0JYOwLgpgTgZghgYwgAgEJwF7IN4ChnIBGmAXMgM5hSgDmA3LgL666iSyIoBiA9j8hAAekEABNyaTDmT4icKGRABXALaFoDZrgQ8QlZDD5le-ALw5iC5ACYANHIxkA5E8YMdesMgCOSwcb5kc2wAOjDDHjcCaOigA

[dancrumb]

I have seen similar issues concerning the spread operator in this repo, but they seem to focus on 'exact objects' and don't talk about interfaces.

[dancrumb]

FWIW, replacing the last line with this works:

const objectSafeClone: <S>(S) => S = function cloner<T>(o: T): T {
  return {...o};
};
  
const qux: Foo = objectSafeClone(foo);