René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Can extends [any, any] but not generic which is exactly [any, any] (woks till 5.3.3 breaks from 5.4.5)","articleBody":"### 🔎 Search Terms\n\ngeneric, tuple extends\n\n### 🕗 Version \u0026 Regression Information\n\nThis 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)\n\n### ⏯ Playground Link\n\nhttps://www.typescriptlang.org/play/?ts=5.6.3#code/C4TwDgpgBAIghsOUC8UDacBcUCMAaKAI2wCYCA6SgY2wGY0BdBgWACg3RIoAVCAZ2DdwEHAB5uUCAA9gEAHYATPlDhyQjAHwoobKHp6SZ8pekrkAlnIBmEAE5QASodmLlGNQVUgGFSl8YMUAD8jlDYchAAbnYcwlCyAjjavAJCkGLwiBpsAPQ5+gB6QWyxXCmCwiTizsbK-j5QALJwfADWNa4qaoza7iCeagxaqLr6EtIuJmhmljb2ThO1TS2tvuT1gSFO4VExrJzQCcAkyfwVkFWZcNmseYVBQA\n\n### 💻 Code\n\n```ts\ntype Data = [a: 1, b: 2, ...c: 3[]]\n\ntype TestType1\u003cT extends any[]\u003e = \n    T extends [...infer R extends [any, any], ...any[]] ? R : never\ntype test1 = TestType1\u003cData\u003e\n//   ^?\n\ntype TestType2\u003cT extends any[], Mask extends any[] = [any, any]\u003e = \n    T extends [...infer R extends Mask, ...any[]] ? R : never\ntype test2 = TestType2\u003cData\u003e\n//   ^?\n```\n\n\n### 🙁 Actual behavior\n\nWhen 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`\n\n### 🙂 Expected behavior\n\nExpect 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\n\n### Additional information about the issue\n\n_No response_","author":{"url":"https://github.com/zedryas","@type":"Person","name":"zedryas"},"datePublished":"2024-10-21T15:13:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/60299/TypeScript/issues/60299"}