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Narrow property access from string index signatures

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Previously these accesses did not use control flow to narrow property
accesses of undefined properties that are resolved from a string index
signature. Now the use control flow to narrow these just like normal
properties.
This commit is contained in:
Nathan Shively-Sanders 2017-11-08 09:48:36 -08:00
parent 62eeb7254c
commit d73fb3acdd
1 changed files with 14 additions and 9 deletions
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23
src/compiler/checker.ts
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@ -15221,7 +15221,7 @@ namespace ts {
if (indexInfo.isReadonly && (isAssignmentTarget(node) || isDeleteTarget(node))) {
error(node, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(apparentType));
}
return indexInfo.type;
return getFlowTypeOfPropertyAccess(node, /*prop*/ undefined, indexInfo.type, getAssignmentTargetKind(node));
}
if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) {
reportNonexistentProperty(right, type.flags & TypeFlags.TypeParameter && (type as TypeParameter).isThisType ? apparentType : type);
@ -15246,16 +15246,21 @@ namespace ts {
return unknownType;
}
}
return getFlowTypeOfPropertyAccess(node, prop, propType, assignmentKind);
}
// Only compute control flow type if this is a property access expression that isn't an
// assignment target, and the referenced property was declared as a variable, property,
// accessor, or optional method.
if (node.kind !== SyntaxKind.PropertyAccessExpression || assignmentKind === AssignmentKind.Definite ||
!(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) &&
!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
/**
* Only compute control flow type if this is a property access expression that isn't an
* assignment target, and the referenced property was declared as a variable, property,
* accessor, or optional method.
*/
function getFlowTypeOfPropertyAccess(node: PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, type: Type, assignmentKind: AssignmentKind) {
if (node.kind !== SyntaxKind.PropertyAccessExpression ||
assignmentKind === AssignmentKind.Definite ||
prop && !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) && !(prop.flags & SymbolFlags.Method && type.flags & TypeFlags.Union)) {
return type;
}
const flowType = getFlowTypeOfReference(node, propType);
const flowType = getFlowTypeOfReference(node, type);
return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType;
}