🔎 Search Terms

ReturnType, generic, default

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This changed in commit or PR _______
• 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

No response

💻 Code

const func = <Return = string>(): Return {
   //
}

type ShouldBeNumber = ReturnType<typeof func<number>>; // number
type ShouldBeString = ReturnType<typeof func>; // unknown

🙁 Actual behavior

ReturnType returns unknown.

🙂 Expected behavior

ReturnType returns default type.

Additional information about the issue

This was encountered when trying to write this kind of function:

const invoker  = <Endpoint extends (...args: any) => any>(endpoint: Endpoint, ...parameters: Parameters<Endpoint>): ReturnType<Endpoint> {
    // Perform some logic before endpoint function is called

    return endpoint(...parameters);
}