Wrong type narrowing to 'never' after 'in'

[JanKoehnlein]

Search Terms:
Type narrowing, 'in'

Code

interface Foo { 
    foo: boolean
}

interface Bar {
    bar: boolean
}

function isFooAndHasBar(foo: Foo): foo is Foo & Bar {
    return 'bar' in foo && foo.foo; 
}

Expected behavior:
No type error. Just because there is an additional property in a Foo, it should still have all props of Foo.

Actual behavior:
Error: Property 'foo' does not exist on type 'never'

Playground Link:
https://www.typescriptlang.org/play/index.html#src=interface%20Foo%20%7B%20%0D%0A%20%20%20%20foo%3A%20boolean%0D%0A%7D%0D%0A%0D%0Ainterface%20Bar%20%7B%0D%0A%20%20%20%20bar%3A%20boolean%0D%0A%7D%0D%0A%0D%0Afunction%20isFooAndHasBar(foo%3A%20Foo)%3A%20foo%20is%20Foo%20%26%20Bar%20%7B%0D%0A%20%20%20%20return%20'bar'%20in%20foo%20%26%26%20foo.foo%3B%0D%0A%7D

Related Issues:
#20583
Note that this is about the true branch (&&), and that foo itself is narrowed down to never (not foo.foo).
Current workaround: Switch operands. Had to do this in quite a few places in my codebase.

[niieani]

You are expecting foo of type Foo as the parameter. You need to use a generic and expect something that extends Foo:

function isFooAndHasBar<T extends Foo>(foo: T): foo is Foo & Bar {
    return 'bar' in foo && foo.foo;
}

Playground

[mhegazy]

duplicate of #21517.

[typescript-bot]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.