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Merge pull request #25115 from Microsoft/matchingTypeRefs

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Improved errors using type reference targets
This commit is contained in:
Daniel Rosenwasser
2018-06-21 13:46:21 -07:00
committed by GitHub
parent 51e7ae0813 6d755aa301
commit 72068e22af
7 changed files with 543 additions and 6 deletions
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24
src/compiler/checker.ts
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@@ -10823,12 +10823,32 @@ namespace ts {
}
}
if (reportErrors) {
const discriminantType = findMatchingDiscriminantType(source, target);
isRelatedTo(source, discriminantType || targetTypes[targetTypes.length - 1], /*reportErrors*/ true);
const bestMatchingType =
findMatchingDiscriminantType(source, target) ||
findMatchingTypeReferenceOrTypeAliasReference(source, target);
isRelatedTo(source, bestMatchingType || targetTypes[targetTypes.length - 1], /*reportErrors*/ true);
}
return Ternary.False;
}
function findMatchingTypeReferenceOrTypeAliasReference(source: Type, unionTarget: UnionOrIntersectionType) {
if (source.flags & TypeFlags.Object && (source as ObjectType).objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous) && unionTarget.flags & TypeFlags.Union) {
return find(unionTarget.types, target => {
if (target.flags & TypeFlags.Object) {
if ((source as ObjectType).objectFlags & (target as ObjectType).objectFlags & ObjectFlags.Reference) {
return (source as TypeReference).target === (target as TypeReference).target;
}
if ((source as ObjectType).objectFlags & (target as ObjectType).objectFlags & ObjectFlags.Anonymous) {
return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol;
}
}
return false;
});
}
}
// Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly
function findMatchingDiscriminantType(source: Type, target: UnionOrIntersectionType) {
let match: Type | undefined;