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Merged
merged 2 commits into from
Apr 27, 2016
Merged

Properly display narrowed types when hovering in IDE #8324

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700435b
Properly display narrowed types when hovering in IDE
ahejlsberg Apr 27, 2016
65edb52
Adding fourslash test
ahejlsberg Apr 27, 2016
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72 changes: 30 additions & 42 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -7358,12 +7358,6 @@ namespace ts {
return flowTypeCaches[flow.id] || (flowTypeCaches[flow.id] = {});
}

function isNarrowableReference(expr: Node): boolean {
return expr.kind === SyntaxKind.Identifier ||
expr.kind === SyntaxKind.ThisKeyword ||
expr.kind === SyntaxKind.PropertyAccessExpression && isNarrowableReference((<PropertyAccessExpression>expr).expression);
}

function typeMaybeAssignableTo(source: Type, target: Type) {
if (!(source.flags & TypeFlags.Union)) {
return isTypeAssignableTo(source, target);
Expand Down Expand Up @@ -7554,30 +7548,12 @@ namespace ts {
getInitialTypeOfBindingElement(<BindingElement>node);
}

function getNarrowedTypeOfReference(type: Type, reference: Node) {
if (!(type.flags & TypeFlags.Narrowable) || !isNarrowableReference(reference)) {
return type;
}
const leftmostNode = getLeftmostIdentifierOrThis(reference);
if (!leftmostNode) {
return type;
}
if (leftmostNode.kind === SyntaxKind.Identifier) {
const leftmostSymbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(<Identifier>leftmostNode));
if (!leftmostSymbol) {
return type;
}
const declaration = leftmostSymbol.valueDeclaration;
if (!declaration || declaration.kind !== SyntaxKind.VariableDeclaration && declaration.kind !== SyntaxKind.Parameter && declaration.kind !== SyntaxKind.BindingElement) {
return type;
}
}
return getFlowTypeOfReference(reference, type, type);
}

function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType: Type) {
let key: string;
return reference.flowNode ? getTypeAtFlowNode(reference.flowNode) : declaredType;
if (!reference.flowNode || declaredType === initialType && !(declaredType.flags & TypeFlags.Narrowable)) {
return declaredType;
}
return getTypeAtFlowNode(reference.flowNode);

function getTypeAtFlowNode(flow: FlowNode): Type {
while (true) {
Expand Down Expand Up @@ -7885,19 +7861,18 @@ namespace ts {
}

function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) {
// The language service will always care about the narrowed type of a symbol, because that is
// the type the language says the symbol should have.
const type = getTypeOfSymbol(symbol);
// If we have an identifier or a property access at the given location, if the location is
// an dotted name expression, and if the location is not an assignment target, obtain the type
// of the expression (which will reflect control flow analysis). If the expression indeed
// resolved to the given symbol, return the narrowed type.
if (location.kind === SyntaxKind.Identifier) {
if (isRightSideOfQualifiedNameOrPropertyAccess(location)) {
location = location.parent;
}
// If location is an identifier or property access that references the given
// symbol, use the location as the reference with respect to which we narrow.
if (isExpression(location) && !isAssignmentTarget(location)) {
checkExpression(<Expression>location);
const type = checkExpression(<Expression>location);
if (getExportSymbolOfValueSymbolIfExported(getNodeLinks(location).resolvedSymbol) === symbol) {
return getNarrowedTypeOfReference(type, <IdentifierOrPropertyAccess>location);
return type;
}
}
}
Expand All @@ -7906,7 +7881,7 @@ namespace ts {
// to it at the given location. Since we have no control flow information for the
// hypotherical reference (control flow information is created and attached by the
// binder), we simply return the declared type of the symbol.
return type;
return getTypeOfSymbol(symbol);
}

function skipParenthesizedNodes(expression: Expression): Expression {
Expand Down Expand Up @@ -7975,9 +7950,6 @@ namespace ts {
const defaultsToDeclaredType = !strictNullChecks || type.flags & TypeFlags.Any || !declaration ||
declaration.kind === SyntaxKind.Parameter || isInAmbientContext(declaration) ||
getContainingFunctionOrModule(declaration) !== getContainingFunctionOrModule(node);
if (defaultsToDeclaredType && !(type.flags & TypeFlags.Narrowable)) {
return type;
}
const flowType = getFlowTypeOfReference(node, type, defaultsToDeclaredType ? type : undefinedType);
if (strictNullChecks && !(type.flags & TypeFlags.Any) && !(getNullableKind(type) & TypeFlags.Undefined) && getNullableKind(flowType) & TypeFlags.Undefined) {
error(node, Diagnostics.Variable_0_is_used_before_being_assigned, symbolToString(symbol));
Expand Down Expand Up @@ -8220,7 +8192,7 @@ namespace ts {
if (isClassLike(container.parent)) {
const symbol = getSymbolOfNode(container.parent);
const type = container.flags & NodeFlags.Static ? getTypeOfSymbol(symbol) : (<InterfaceType>getDeclaredTypeOfSymbol(symbol)).thisType;
return getNarrowedTypeOfReference(type, node);
return getFlowTypeOfReference(node, type, type);
}

if (isInJavaScriptFile(node)) {
Expand Down Expand Up @@ -9784,8 +9756,24 @@ namespace ts {
}

const propType = getTypeOfSymbol(prop);
return node.kind === SyntaxKind.PropertyAccessExpression && prop.flags & (SymbolFlags.Variable | SymbolFlags.Property) && !isAssignmentTarget(node) ?
getNarrowedTypeOfReference(propType, <PropertyAccessExpression>node) : propType;
if (node.kind !== SyntaxKind.PropertyAccessExpression || !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property)) || isAssignmentTarget(node)) {
return propType;
}
const leftmostNode = getLeftmostIdentifierOrThis(node);
if (!leftmostNode) {
return propType;
}
if (leftmostNode.kind === SyntaxKind.Identifier) {
const leftmostSymbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(<Identifier>leftmostNode));
if (!leftmostSymbol) {
return propType;
}
const declaration = leftmostSymbol.valueDeclaration;
if (!declaration || declaration.kind !== SyntaxKind.VariableDeclaration && declaration.kind !== SyntaxKind.Parameter && declaration.kind !== SyntaxKind.BindingElement) {
return propType;
}
}
return getFlowTypeOfReference(node, propType, propType);
}

function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName, propertyName: string): boolean {
Expand Down
21 changes: 21 additions & 0 deletions tests/cases/fourslash/quickInfoOnNarrowedType.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
/// <reference path='fourslash.ts'/>

// @strictNullChecks: true

////function foo(strOrNum: string | number) {
//// if (typeof /*1*/strOrNum === "number") {
//// return /*2*/strOrNum;
Expand All @@ -9,6 +11,13 @@
//// }
////}

////function bar() {
//// let s: string | undefined;
//// /*4*/s;
//// /*5*/s = "abc";
//// /*6*/s;
////}

goTo.marker('1');
verify.quickInfoIs('(parameter) strOrNum: string | number');
verify.completionListContains("strOrNum", "(parameter) strOrNum: string | number");
Expand All @@ -20,3 +29,15 @@ verify.completionListContains("strOrNum", "(parameter) strOrNum: number");
goTo.marker('3');
verify.quickInfoIs('(parameter) strOrNum: string');
verify.completionListContains("strOrNum", "(parameter) strOrNum: string");

goTo.marker('4');
verify.quickInfoIs('let s: undefined');
verify.completionListContains("s", "let s: undefined");

goTo.marker('5');
verify.quickInfoIs('let s: string | undefined');
verify.completionListContains("s", "let s: string | undefined");

goTo.marker('6');
verify.quickInfoIs('let s: string');
verify.completionListContains("s", "let s: string");