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Fix homomorphic type check in instantiateMappedType

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This commit is contained in:
Anders Hejlsberg
2016-12-30 18:27:38 -08:00
parent 69e0677ea1
commit a437c0a689
1 changed files with 13 additions and 11 deletions
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src/compiler/checker.ts
+13 -11
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@@ -6628,17 +6628,19 @@ namespace ts {
const constraintType = getConstraintTypeFromMappedType(type);
if (constraintType.flags & TypeFlags.Index) {
const typeVariable = (<IndexType>constraintType).type;
const mappedTypeVariable = instantiateType(typeVariable, mapper);
if (typeVariable !== mappedTypeVariable) {
return mapType(mappedTypeVariable, t => {
if (isMappableType(t)) {
const replacementMapper = createUnaryTypeMapper(typeVariable, t);
const combinedMapper = mapper.mappedTypes && mapper.mappedTypes.length === 1 ? replacementMapper : combineTypeMappers(replacementMapper, mapper);
combinedMapper.mappedTypes = mapper.mappedTypes;
return instantiateMappedObjectType(type, combinedMapper);
}
return t;
});
if (typeVariable.flags & TypeFlags.TypeParameter) {
const mappedTypeVariable = instantiateType(typeVariable, mapper);
if (typeVariable !== mappedTypeVariable) {
return mapType(mappedTypeVariable, t => {
if (isMappableType(t)) {
const replacementMapper = createUnaryTypeMapper(typeVariable, t);
const combinedMapper = mapper.mappedTypes && mapper.mappedTypes.length === 1 ? replacementMapper : combineTypeMappers(replacementMapper, mapper);
combinedMapper.mappedTypes = mapper.mappedTypes;
return instantiateMappedObjectType(type, combinedMapper);
}
return t;
});
}
}
}
return instantiateMappedObjectType(type, mapper);