type Data = [a: 1, b: 2, ...c: 3[]]
type TestType1<T extends any[]> =
T extends [...infer R extends [any, any], ...any[]] ? R : never
type test1 = TestType1<Data>
// ^?
type TestType2<T extends any[], Mask extends any[] = [any, any]> =
T extends [...infer R extends Mask, ...any[]] ? R : never
type test2 = TestType2<Data>
// ^?
🙁 Actual behavior
When passing the Mask as a generic and trying to extends the tuple with it to extract the relevant part, the resulting tuple is well formed, but item types are replaced with any
🙂 Expected behavior
Expect that constraint on infer to works wether as an explicit form or a generic holding a type with the exact same form, which used to be the case priori to typescript 5.4 bu breaks since
🔎 Search Terms
generic, tuple extends
🕗 Version & Regression Information
This code works in the playground with typescript version 5.3.3 but breaks since version 5.4.5 (version between are not available in the playground)
⏯ Playground Link
https://www.typescriptlang.org/play/?ts=5.6.3#code/C4TwDgpgBAIghsOUC8UDacBcUCMAaKAI2wCYCA6SgY2wGY0BdBgWACg3RIoAVCAZ2DdwEHAB5uUCAA9gEAHYATPlDhyQjAHwoobKHp6SZ8pekrkAlnIBmEAE5QASodmLlGNQVUgGFSl8YMUAD8jlDYchAAbnYcwlCyAjjavAJCkGLwiBpsAPQ5+gB6QWyxXCmCwiTizsbK-j5QALJwfADWNa4qaoza7iCeagxaqLr6EtIuJmhmljb2ThO1TS2tvuT1gSFO4VExrJzQCcAkyfwVkFWZcNmseYVBQA
💻 Code
🙁 Actual behavior
When passing the
Mask
as a generic and trying to extends the tuple with it to extract the relevant part, the resulting tuple is well formed, but item types are replaced withany
🙂 Expected behavior
Expect that constraint on infer to works wether as an explicit form or a generic holding a type with the exact same form, which used to be the case priori to typescript 5.4 bu breaks since
Additional information about the issue
No response