4.5.0 regression - Maximum call stack size exceeded with recursive conditional types

[DetachHead]

Bug Report

🔎 Search Terms

maximum call stack size exceeded

🕗 Version & Regression Information

4.5.0-dev.20211012

• This changed between versions 4.4.3 and 4.5.0-beta

⏯ Playground Link

Playground link with relevant code

💻 Code

type _PrependNextNum<A extends Array<unknown>> = A['length'] extends infer T
    ? [T, ...A] extends [...infer X] 
        ? X
        : never
    : never
type _Enumerate<A extends Array<unknown>, N extends number> = N extends A['length']
    ? A
    : _Enumerate<_PrependNextNum<A>, N> & number

export type Enumerate<N extends number> = number extends N
    ? number
    : _Enumerate<[], N> extends (infer E)[]
    ? E
    : never

declare function foo<T extends unknown[]>(value: T): Enumerate<T['length']> {
    return value.length
}

🙁 Actual behavior

🙂 Expected behavior

no crash

[ahejlsberg]

@weswigham Another one caused by #41821, basically a duplicate of #46183. Issue again is an infinitely expanding recursive conditional type that should relate as Ternary.Maybe after five levels.

[weswigham]

Well, first problem is that we're actually stacking out rather than reporting the "infinitely expanding type" error. That would seem to imply that we're not incrementing the depth counter enough somewhere. Though, yes, once that's fixed, it is likely a duplicate of the other.