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Add missing check in getIndexedAccessForMappedType

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This commit is contained in:
Anders Hejlsberg 2017-07-27 09:50:57 -07:00
parent 62ddc99a49
commit b6ec951207
1 changed files with 10 additions and 4 deletions
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14
src/compiler/checker.ts
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@ -7573,10 +7573,16 @@ namespace ts {
}
function getIndexedAccessForMappedType(type: MappedType, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode) {
const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? <ElementAccessExpression>accessNode : undefined;
if (accessExpression && isAssignmentTarget(accessExpression) && type.declaration.readonlyToken) {
error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(type));
return unknownType;
if (accessNode) {
// Check if the index type is assignable to 'keyof T' for the object type.
if (!isTypeAssignableTo(indexType, getIndexType(type))) {
error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(type));
return unknownType;
}
if (accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && type.declaration.readonlyToken) {
error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(type));
return unknownType;
}
}
const mapper = createTypeMapper([getTypeParameterFromMappedType(type)], [indexType]);
const templateMapper = type.mapper ? combineTypeMappers(type.mapper, mapper) : mapper;