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Allow intersections (and substitutions) to be checks against discriminable unions (#36663)

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This commit is contained in:
Wesley Wigham
2020-02-10 15:26:46 -08:00
committed by GitHub
parent 70e6f5b8a0
commit aece8c06b0
5 changed files with 126 additions and 3 deletions
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6
src/compiler/checker.ts
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@@ -15901,7 +15901,7 @@ namespace ts {
// with respect to T. We do not report errors here, as we will use the existing
// error result from checking each constituent of the union.
if (source.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Union) {
const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object);
const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution);
if (objectOnlyTarget.flags & TypeFlags.Union) {
const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType);
if (result) {
@@ -15998,7 +15998,7 @@ namespace ts {
// NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts
// for examples.
const sourceProperties = getPropertiesOfObjectType(source);
const sourceProperties = getPropertiesOfType(source);
const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target);
if (!sourcePropertiesFiltered) return Ternary.False;
@@ -16037,7 +16037,7 @@ namespace ts {
outer: for (const type of target.types) {
for (let i = 0; i < sourcePropertiesFiltered.length; i++) {
const sourceProperty = sourcePropertiesFiltered[i];
const targetProperty = getPropertyOfObjectType(type, sourceProperty.escapedName);
const targetProperty = getPropertyOfType(type, sourceProperty.escapedName);
if (!targetProperty) continue outer;
if (sourceProperty === targetProperty) continue;
// We compare the source property to the target in the context of a single discriminant type.