Bug Report

Default iterator TReturn type is any. This causes code which works with iterators without a defined TReturn type to return any when getting next().value.

const set1 = new Set<string>();

// Should be `string | undefined` but is `any`
const e1 = set1.values().next().value;
//    ^?

Playground

🔎 Search Terms

iterator, set, treturn, next any

🕗 Version & Regression Information

• This is the behavior in every version I tried. Seems like it was introduced in Improve type checking and inference for Generators and Async Generators #30790

⏯ Playground Link

Playground link with relevant code

💻 Code

const set1 = new Set<string>();

// Should be `string | undefined` but is `any`
const e1 = set1.values().next().value;
//    ^?

🙁 Actual behavior

e1 should be string | undefined

🙂 Expected behavior

e1 is any