Microsoft/TypeScript
Nested destructuring does not narrow dependent parameters
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#48,378 opened on 2022/03/22
BugDomain: check: Control FlowHelp Wanted
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説明
Bug Report
🔎 Search Terms
destructuring destructured dependent parameters nested control flow analysis
🕗 Version & Regression Information
- This changed between versions 4.5.5 and 4.6
⏯ Playground Link
Playground link with relevant code
💻 Code
declare const Tuple: [true, string] | [false, number];
const [[val1, val2]] = [Tuple];
if (val1) {
val2 // string | number
}
🙁 Actual behavior
TypeScript does not correctly narrow val2 when narrowing val1 if it's in any type of nested destructuring.
🙂 Expected behavior
I expect it to behave the same as directly destructuring the object.