Inference of recursive arrow function's return type is any

[hospotho]

🔎 Search Terms

recursive function arrow function

🕗 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

https://www.typescriptlang.org/play?ts=5.4.4#code/PTAEGMHsDsGcBdQDNKQFygBQEpQF4A+UAQ2gE8AoKORFSfLXQ0AbwtFAEsksBZY+AAsAdACdSAE0gBbHKCIAGYQFZcbDh1EBTeAFdR0ZKhztQAX1Pa9B0AooWKIZLujh4nGKABGxUTgzQutJeWqIUSC5uHoY+fmqm3HwCIuLQUrK4iirxGqBW+jG+JhwWmjoFtvYUQA

💻 Code

// const foo: () => any
const foo = () => {
  if (Math.random() > 0.5) {
    return foo()
  }
  return 0
}

// function bar(): number
function bar() {
  if (Math.random() > 0.5) {
    return bar()
  }
  return 0
}

🙁 Actual behavior

const foo: () => any
'foo' implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions.

🙂 Expected behavior

The inference should be const foo: () => number, even this inference is happened before the arrow function assign to foo

Additional information about the issue

No response

[MartinJohns]

Duplicate of #53978. Used search terms: recursive any in:title

[hospotho]

Duplicate of #53978. Used search terms: recursive any in:title

They mention a pull request (#53995) related to regular function with self tail calls. Maybe I can update the title to "Self tail calls of arrow function were not ignored"?