support QualifiedName when narrowing inside loops #43592
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| if (foo.a.b) { | ||
| type B = typeof foo.a.b; | ||
| ~~~~~ | ||
| !!! error TS2532: Object is possibly 'undefined'. |
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IMO, this is a bug. Should it be fixed in this PR?
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Yes, I'm pretty sure that possibly-undefined errors also use control flow, so this is a sign that something else needs to be fixed.
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case SyntaxKind.QualifiedName:
- if (currentFlow && parent.kind === SyntaxKind.TypeQuery) {
+ if (currentFlow && isPartOfTypeQuery(node)) {
node.flowNode = currentFlow;
}binding children of QualifiedName fixed it.
src/compiler/checker.ts
Outdated
| case SyntaxKind.QualifiedName: | ||
| const left = getFlowCacheKey((<QualifiedName>node).left, declaredType, initialType, flowContainer); | ||
| const right = (<QualifiedName>node).right.escapedText; | ||
| return `${left}.${right}`; |
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This should use the same structure as the property/element access code below. Specifically, getFlowCacheKey can return undefined.
The way that isMatchingReference looks is probably the right way to copy the code, but it might also be possible to unify the handling of all three node kinds into one code path by finding/making more functions like getAccessedPropertyName.
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🤔 I think I gonna just copy from isMatchingReference because the structure of QualifiedName is kinda different from ElementAccessExpression
| if (foo.a.b) { | ||
| type B = typeof foo.a.b; | ||
| ~~~~~ | ||
| !!! error TS2532: Object is possibly 'undefined'. |
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Yes, I'm pretty sure that possibly-undefined errors also use control flow, so this is a sign that something else needs to be fixed.
| properties.foo; // type is { aaa: string; bbb: string; } | ||
| for (const x of [1, 2, 3]) { | ||
| properties.foo; // type is { aaa: string; bbb: string; } | ||
| type FooOrUndefined = typeof properties.foo; //type is { aaa: string; bbb: string; } | undefined |
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can you remove this comment or change it to be "type should be { aaa: string, bbb: string }", now that the bug is fixed?
Fixes #43411