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infer extends number in conditional type handles '\n' incorrectly

See original GitHub issue

Bug Report

🔎 Search Terms

infer extends number

🕗 Version & Regression Information

4.8.0-beta (in playground)

⏯ Playground Link

Playground link with relevant code

A simple type-level JSON parser encounters this issue

💻 Code

// number
type Foo = '\n' extends `${infer T extends number}${infer R}` ? T : never;

🙁 Actual behavior

Foo is number

🙂 Expected behavior

Foo should be never

Issue Analytics

State:
Created a year ago
Comments:9 (6 by maintainers)

Top GitHub Comments

2reactions

whzx5bybcommented, Aug 2, 2022

@fatcerberus You are looking for https://github.com/microsoft/TypeScript/issues/46124#issuecomment-930388594 ?

1reaction

Josh-Cenacommented, Aug 2, 2022

Not just parseInt()—but Number(). It uses the StringNumericLiteral production, which means 0b111 is a `${number}` as well. (Disclaimer: didn’t read that source code; this is based on experiment).

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