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This commit is contained in:
Anders Hejlsberg 2019-07-26 13:12:44 -07:00
parent 00f41e5693
commit bb87332e73
1 changed files with 4 additions and 0 deletions
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src/compiler/checker.ts
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@ -15516,6 +15516,10 @@ namespace ts {
}
}
else if (target.flags & TypeFlags.Intersection && some((<IntersectionType>target).types, t => !!getInferenceInfoForType(t))) {
// We reduce intersection types only when they contain naked type parameters. For example, when
// inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and
// infer { extra: any } for T. But when inferring to 'string[] & Iterable<T>' we want to keep the
// string[] on the source side and infer string for T.
if (source.flags & TypeFlags.Intersection) {
// Infer between identically matching source and target constituents and remove the matching types.
const [sources, targets] = inferFromMatchingTypes((<IntersectionType>source).types, (<IntersectionType>target).types, isTypeIdenticalTo);