Remove optionality from the initial type of default-valued parameters
When narrowing, remove optionality from the initial type of parameters with initialisers. Note that the type of the initialiser is not used; its presence just means that the initial type of the parameter can't contain undefined. It could contain any other member of a declared union type.
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@ -3368,16 +3368,6 @@ namespace ts {
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return strictNullChecks && optional ? includeFalsyTypes(type, TypeFlags.Undefined) : type;
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}
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/** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */
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function removeOptionalityFromAnnotation(annotatedType: Type, declaration: VariableLikeDeclaration): Type {
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const annotationIncludesUndefined = strictNullChecks &&
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declaration.kind === SyntaxKind.Parameter &&
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declaration.initializer &&
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getFalsyFlags(annotatedType) & TypeFlags.Undefined &&
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!(getFalsyFlags(checkExpression(declaration.initializer)) & TypeFlags.Undefined);
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return annotationIncludesUndefined ? getNonNullableType(annotatedType) : annotatedType;
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}
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// Return the inferred type for a variable, parameter, or property declaration
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function getTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, includeOptionality: boolean): Type {
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if (declaration.flags & NodeFlags.JavaScriptFile) {
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@ -3412,7 +3402,7 @@ namespace ts {
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// Use type from type annotation if one is present
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if (declaration.type) {
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const declaredType = removeOptionalityFromAnnotation(getTypeFromTypeNode(declaration.type), declaration);
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const declaredType = getTypeFromTypeNode(declaration.type);
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return addOptionality(declaredType, /*optional*/ declaration.questionToken && includeOptionality);
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}
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@ -10248,14 +10238,12 @@ namespace ts {
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return false;
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}
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function getFlowTypeOfReference(reference: Node, declaredType: Type, assumeInitialized: boolean, flowContainer: Node) {
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let key: string;
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if (!reference.flowNode || assumeInitialized && !(declaredType.flags & TypeFlags.Narrowable)) {
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return declaredType;
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function isFlowNarrowable(reference: Node, type: Type, couldBeUninitialized?: boolean) {
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return reference.flowNode && (type.flags & TypeFlags.Narrowable || couldBeUninitialized);
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}
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const initialType = assumeInitialized ? declaredType :
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declaredType === autoType || declaredType === autoArrayType ? undefinedType :
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includeFalsyTypes(declaredType, TypeFlags.Undefined);
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function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node) {
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let key: string;
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const visitedFlowStart = visitedFlowCount;
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const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(reference.flowNode));
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visitedFlowCount = visitedFlowStart;
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@ -10934,6 +10922,16 @@ namespace ts {
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return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0 && getTypeOfSymbol(symbol) !== autoArrayType;
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}
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/** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */
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function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type {
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const annotationIncludesUndefined = strictNullChecks &&
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declaration.kind === SyntaxKind.Parameter &&
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declaration.initializer &&
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getFalsyFlags(declaredType) & TypeFlags.Undefined &&
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!(getFalsyFlags(checkExpression(declaration.initializer)) & TypeFlags.Undefined);
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return annotationIncludesUndefined ? getNonNullableType(declaredType) : declaredType;
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}
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function checkIdentifier(node: Identifier): Type {
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const symbol = getResolvedSymbol(node);
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if (symbol === unknownSymbol) {
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@ -11052,7 +11050,10 @@ namespace ts {
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const assumeInitialized = isParameter || isOuterVariable ||
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type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & TypeFlags.Any) !== 0 || isInTypeQuery(node)) ||
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isInAmbientContext(declaration);
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const flowType = getFlowTypeOfReference(node, type, assumeInitialized, flowContainer);
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const initialType = assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, getRootDeclaration(declaration) as VariableLikeDeclaration) : type) :
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type === autoType || type === autoArrayType ? undefinedType :
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includeFalsyTypes(type, TypeFlags.Undefined);
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const flowType = isFlowNarrowable(node, type, !assumeInitialized) ? getFlowTypeOfReference(node, type, initialType, flowContainer) : type;
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// A variable is considered uninitialized when it is possible to analyze the entire control flow graph
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// from declaration to use, and when the variable's declared type doesn't include undefined but the
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// control flow based type does include undefined.
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@ -11318,7 +11319,7 @@ namespace ts {
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if (isClassLike(container.parent)) {
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const symbol = getSymbolOfNode(container.parent);
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const type = hasModifier(container, ModifierFlags.Static) ? getTypeOfSymbol(symbol) : (<InterfaceType>getDeclaredTypeOfSymbol(symbol)).thisType;
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return getFlowTypeOfReference(node, type, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
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return isFlowNarrowable(node, type) ? getFlowTypeOfReference(node, type) : type;
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}
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if (isInJavaScriptFile(node)) {
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@ -13309,7 +13310,7 @@ namespace ts {
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!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
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return propType;
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}
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const flowType = getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
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const flowType = isFlowNarrowable(node, propType) ? getFlowTypeOfReference(node, propType) : propType;
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return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType;
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}
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