`getReturnType` stack overflow when using recursive generic function with accumulated type argument

[StyleShit]

🔎 Search Terms

"getReturnType", "stack overflow", "Maximum call stack size exceeded", "recursive generic function"

🕗 Version & Regression Information

This is happening in v6 and tsgo (I didn't check prior versions)

⏯ Playground Link

No response

💻 Code

Coming from typescript-eslint/typescript-eslint#12705, I created a repro that's agnostic to ESLint:

// A generic function type whose call signature returns the same type,
// instantiated with an accumulated type argument.
type Recursive<T> = <U>() => Recursive<T & U>;

export declare const subject: Recursive<unknown>;

https://github.com/StyleShit/repros/tree/main/ts-getReturnType-stack-overflow

🙁 Actual behavior

Walking the function's signature and return type is failing with "Maximum call stack size exceeded" error

🙂 Expected behavior

Walking should not fail

Additional information about the issue

No response

[RyanCavanaugh]

This is your bug, not TypeScript's. It's the recurse function that is growing the stack:

  function recurse(type: ts.Type, depth: number) {
    console.log(`${depth}: ${checker.typeToString(type)}`); // <- added

3: Recursive<U & U & U>
4: Recursive<U & U & U & U>
4: Recursive<U & U & U & U>
5: Recursive<U & U & U & U & U>
6: Recursive<U & U & U & U & U & U>
7: Recursive<U & U & U & U & U & U & U>
8: Recursive<U & U & U & U & U & U & U & U>
9: Recursive<U & U & U & U & U & U & U & U & U>
10: Recursive<U & U & U & U & U & U & U & U & U & U>
11: Recursive<U & U & U & U & U & U & U & U & U & U & U>
12: Recursive<U & U & U & U & U & U & U & U & U & U & U & U>
13: Recursive<U & U & U & U & U & U & U & U & U & U & U & U & U>