Why the recursive function's return type inferenced as any?

[nnnnoel]

Bug Report

when write recursive function via generator function or function,
return type inferenced as any.
the general purpose for recursive function, return type can be inferenced as correct return type.

🔎 Search Terms

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

Playground link with relevant code

💻 Code

function mock__fstat(name: string) {
    if (Math.random() > 0.5) {
        return {
            isDirectory: true,
            isFile: false,
        };
    }
    return {
        isDirectory: false,
        isFile: true,
    };
}
function* walk(dir: string) {
    if (mock__fstat(dir).isDirectory) {
        yield* walk(dir.split('/').slice(1).join('/'));
    }
    yield dir;
}
const a = walk('/a/b/c'); // will be AsyncGenerator<string>, but inferenced type is any

🙁 Actual behavior

walk function's return type is any

🙂 Expected behavior

walk function's return type is AsyncGenerator

[MartinJohns]

Your playground link does not work. Duplicate of #32523.

[nnnnoel]

@MartinJohns link updated!

[nnnnoel]

I thought #32523 is not focused on recursive function's type.

[RyanCavanaugh]

The error message tells you why?

because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions.

[nnnnoel]

@RyanCavanaugh but i cannot understand why this expression didn't inference type implicitly.
in this case, walk function returns AsyncGenerator<string> absolutely but recursive function call's return type inferenced as any.
why didn't skip the recursive function call in return type inference flow?

[fatcerberus]

why didn't skip the recursive function call in return type inference flow?

#53995 is probably relevant

[nnnnoel]

@fatcerberus omg thanks a lot!

[microsoft-github-policy-service]

This issue has been marked as 'Question' and has seen no recent activity. It has been automatically closed for house-keeping purposes. If you're still waiting on a response, questions are usually better suited to stackoverflow or the TypeScript Discord community.