Circular Reference with Generic Parameterization - error TS2456: Type alias 'Result' circularly references itself.

[AaronNGray]

🔎 Search Terms

Circular Reference, Generic Parameterization, error TS2456: Type alias 'Result' circularly references itself.

🕗 Version & Regression Information

Failing on Main 32ebd28

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/C4TwDgpgBAggdiAPAFShAHsCcAmBnKAeQCMArCAY2AD4oBeKAbwCgo2oBtAawhAC48wAE4BLOAHMAunyjIA3MwC+cqM2ahIUAEoQ8AVwA2welEGiJUAD7bdh4B0lXYCRDv1HqKgPRe0QoQD2QrIAygBMACwArABsMsjg0ACGBiJJBADkbnYZUBQiQhSGSUIGIFBCEABmEJVwFLpQIsB4EAZVAHTMQA

💻 Code

Fails :-

type Any<T extends Object> = {
    [key:string]: T;
}; 

type Result = string | Result[] | Any<Result>; // error TS2456: Type alias 'Result' circularly references itself.

Works :-

type ResultObject = {
    [key:string]: Result;
}; 

type Result = string | Result[] | ResultObject;

Fails :-

type ResultObject = {
    [key:string]: Result;
}; 

type ResultArray<T> = T[];
 
type Result = string | ResultArray<Result> | ResultObject;  // error TS2456: Type alias 'Result' circularly references itself.

It looks like it is a Generic Parameterization issue.

🙁 Actual behavior

Throwing Error on compilation error TS2456: Type alias 'Result' circularly references itself.

🙂 Expected behavior

Should not throw an error and demonstrates the type system is incomplete.

Additional information about the issue

No response

[jcalz]

duplicate of #41164

[AaronNGray]

Looks semantically totally different to me.

[jcalz]

Any<T> is the same as Record<string, T> and you have the same problem with it.

[AaronNGray]

So basically there is no support for recursive parameterized types and mutually recursive parameterized types in TypeScript.

This is a crazy limitation as so many programming patterns I use use this.

I need to find my feet with TypeScripts code base and see if I can implement this.

[jcalz]

You might want to read through the other issue thoroughly, especially the linked PR at #57293.