Contextual type inference breaks on function parameters with explicit return

[evankim390]

Bug Report

🔎 Search Terms

contextual type inference function return generic

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about generics.

⏯ Playground Link

Playground link with relevant code

💻 Code

interface Options<K> {
    key: K;
    fn(key: K): any;
}

function id<K>(options: () => Options<K>) {
    throw 'unimplemented';
}

const breaks = id(() => {
    return {
        key: { id: 32 },
        fn(key) {
            // 'key' is of type 'unknown'.(18046)
            return key.id.toString();
        },
    };
});

const works = id(() => ({
    key: { id: 32 },
    fn(key) {
        return key.id.toString();
    },
}));

🙁 Actual behavior

The fn parameter type is only correctly inferred in the case where an arrow function is directly returning an object.

🙂 Expected behavior

I would expect for both cases to be handled consistently.

[RyanCavanaugh]

Duplicate #47599

[jcalz]

@RyanCavanaugh Is a block body context sensitive in a way that a concise body isn’t? I suspect as much but I’d love to hear official word since #47599 doesn’t seem to talk about that specifically.

[ahejlsberg]

This isn't related to #47599. Rather, it's an issue that was already fixed in #50903. The example works as expected in 5.1.

[ahejlsberg]

So, I'll call this a duplicate of #50687.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.