Type Instantiation is Excessively Deep Error Regression in #37348

🔎 Search Terms

type instantiation is excessively deep, unused type parameter, unused tuple element, #37348

🕗 Version & Regression Information

This changed in PR #37348

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/CYUwxgNghgTiAEkoGdnwPoEkB2AXEM2UEAKgJ4AOIAIlLlALID2oE8A3gFDw-wVwVYNAgEsAbiGC16ALngBtKNjIAaeErIBdANycAvrs6gkcRNFTxyVaYxYgIAHm68A9C-iYAZvFwALEWi4lAiCMFAAtiD4MPAB8KxRkj6+CGAiMGAArtAwIkHwAOZMIGhQAO5QZAB0zjwAqtiZyJIqtfDUohJSdFCtAHzwIAAe+NjAaFh4BESkwTbMrBxt-CChwrldNnJ+ccOj45ZzPQv2DhpqItieBO2dkjZ9bbzwAPzwbpb+aM1gTGODEBAkTwsWwyQQuEyFEBsVKEGQTHg2HAJWQsDI8E8TBiCMi8DgKD+NWeJN48h2yDUGk0T14cg0uj0QA

💻 Code

declare class _InternalTypeDataModel {
    prepareDerivedData: [any, any];
};

declare class TypeDataModel<
    // If this type parameter is deleted the circularity goes away.
    Unused,
    DerivedData,
> extends _InternalTypeDataModel {
    prepareDerivedData: this extends TypeDataModel<any, infer DerivedData>
        ? // This second element in the tuple is also necessary for some reason.
            [this, any]
        : any;
}

🙁 Actual behavior

Type instantiation is excessively deep and possibly infinite.

🙂 Expected behavior

No error.

Additional information about the issue

I understand the weirdness in this minimized code but the actual code I was reducing actually does useful things and doesn't really seem so contrived in context. In actual code all type parameters and tuple elements actually do useful things but this reproduction shows it doesn't matter if they're used, just that they exist, for some reason.

Inizia con la riproduzione fornita in Playground e confronta il suo comportamento con la modifica introdotta da PR #37348. Segui il percorso di istanziazione dei tipi responsabile della diagnostica di profondità eccessiva, quindi verifica che questo esempio e la regressione segnalata non producano più un errore.