Typescript: Recursive type references are still disallowed in type parameter defaults

[falsandtru]

@ahejlsberg

TypeScript Version: master

Search Terms:

Code

type Tree<T, U extends Tree<T>[] = Tree<T>[]> = [T, U];

Expected behavior:
pass
Actual behavior:

$ node built/local/tsc --noEmit index.ts
index.ts:1:36 - error TS2716: Type parameter 'U' has a circular default.

1 type Tree<T, U extends Tree<T>[] = Tree<T>[]> = [T, U];
                                     ~~~~~~~~~


Found 1 error.

Playground Link:

Related Issues:

[jcalz]

From https://github.com/microsoft/TypeScript/issues/33616#issuecomment-541789058:

We need you to read those instructions completely, follow them, and then fill in all the fields in that template.

[falsandtru]

Looks like you've never seen other valid issues.

[jcalz]

Is there any way we can reset this conversation to remain civil? I'll start over: could you please fill out the template completely? It would improve the chances of your issue being addressed.

Edit: It has been pointed out to me that maybe there is a communication barrier here, so I'll be as explicit as possible. Please fill out the following fields from the template:

• search terms
• playground link
• related issues

The search terms and related issues are the most important as they provide context for everyone and make issues easier to find. This does take extra work on your part, but since Ryan specifically said that they are not able to take on such work themselves, it would be a good idea to comply with that request if you want your issue addressed.

In any case it's not my job to intervene, so I will disengage here unless anyone needs something specific from me. Good luck!

[RyanCavanaugh]

@falsandtru it'd be great if you would stop ccing people on post, follow the template completely, and otherwise behave a bit more constructively. I'd really appreciate it. If you continue to disregard these reasonable requests, we'll need to take other actions to ensure that everyone's able to meaningfully participate, which wouldn't be my preferred outcome.

This is an observation, not a bug report. Type aliases and type parameter defaults are separate things and enabling circular references in one doesn't change much in the other.

[falsandtru]

Since that this is an observation or not is unclear, you can't request correct judgement at all times. As I said before, other persons can't exactly know/predict your inner thoughts nor judgement without your mother. Don't make me say the same thing. I'm not your mom, right? And my cc basically specifies the correct person in charge especially when a problem is made by a new feature or a bug fix.