Microsoft/TypeScript
Voir sur GitHubA tuple containing a spread not at the trailing edge has its minimum length calculated incorrectly
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#52 688 ouverte le 8 févr. 2023
BugDomain: check: Type InferenceHelp Wanted
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Description
Bug Report
🔎 Search Terms
- tuple
- spread
🕗 Version & Regression Information
It happens in v4.9.5, no idea about other versions.
⏯ Playground Link
💻 Code
type FN1 <T> = (...args: string[]) => T;
type FN2 <T> = ( ...args: [consumed: string, ...groups: string[], input: string, index: string] ) => T;
const fn1: FN1<number> = ( a, b ) => 0;
const fn2: FN2<number> = ( a, b ) => 0;
🙁 Actual behavior
TS complains about my fn2, with the following error:
Type '(a: string, b: string) => number' is not assignable to type 'FN2<number>'.
Types of parameters 'b' and 'groups' are incompatible.
Type '[...groups: string[], input: string, index: string]' is not assignable to type '[b: string]'.
Source has 2 element(s) but target allows only 1.(2322)
If I'm interpreting it correctly it is saying like "hey you defined two arguments, but maybe this tuple only has one item in it.
🙂 Expected behavior
If I'm interpreting the error correctly then the error is wrong because there's no scenario where that tuple has just one item in it, minimum it will always have 3.