TypeScript/tests/baselines/reference/intersectionOfUnionNarrowing.types
caojoshua acdf62fa1e
Fix "Union types are not being narrowed down correctly in 4.3 #44401" (#44771)
* Fix "Union types are not being narrowed down correctly in 4.3 #44401"

* On undefined constraint, add the original type to constraints.
2021-07-13 11:02:18 -07:00

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=== tests/cases/conformance/types/intersection/intersectionOfUnionNarrowing.ts ===
interface X {
a?: { aProp: string };
>a : { aProp: string; } | undefined
>aProp : string
b?: { bProp: string };
>b : { bProp: string; } | undefined
>bProp : string
}
type AorB = { a: object; b: undefined } | { a: undefined; b: object };
>AorB : AorB
>a : object
>b : undefined
>a : undefined
>b : object
declare const q: X & AorB;
>q : X & AorB
if (q.a !== undefined) {
>q.a !== undefined : boolean
>q.a : ({ aProp: string; } & object) | undefined
>q : X & AorB
>a : ({ aProp: string; } & object) | undefined
>undefined : undefined
q.a.aProp;
>q.a.aProp : string
>q.a : { aProp: string; } & object
>q : X & { a: object; b: undefined; }
>a : { aProp: string; } & object
>aProp : string
} else {
// q.b is previously incorrectly inferred as potentially undefined
q.b.bProp;
>q.b.bProp : string
>q.b : { bProp: string; } & object
>q : X & { a: undefined; b: object; }
>b : { bProp: string; } & object
>bProp : string
}