Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Link to the rule's documentation

https://typescript-eslint.io/rules/no-unnecessary-type-parameters/

Description

For purposes of counting whether a generic type parameter is used twice, T[] / Array<T> should only count as using it once. I'm not aware of any realistic scenario where this would lead to a false positive.

We decided to defer this to a follow-up in the initial implementation (see links below). So here's an official request for the follow-up.

Fail

declare function getLength<T>(xs: readonly T[]): number;

Pass

declare function getLength(xs: readonly unknown[]): number;

Additional Info

See https://twitter.com/jfet97/status/1810703565280759964 and #8173 (comment) for context on why this doesn't work as expected today.

See #8173 (comment) for previous discussion of special-casing Array and friends.

See #8173 (review) for a contrived example of how this could yield a false positive for Map.