sindresorhus/type-fest

Remove redundant code for compatibility with older versions of typescript

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#1,142 opened on May 16, 2025

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enhancementgood first issue

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Description

In some previously supported but now unsupported versions of typescript, there would be some incorrect circular check, and in order to bypass the circular check, we have to add some non-essential code, for example:

type A<T> = 
 SomeToolType<T> extends infer B 
  ? B
  : never // Never happen

The above code can be simplified now:

type A<T> = SomeToolType<T>

Contributor guide

Research direction
Find type definitions that use the pattern `type A<T> = SomeToolType<T> extends infer B ? B : never` and replace them with `type A<T> = SomeToolType<T>`.
Tech stack
typescript
Domain
developer experience
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
1
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80