Introduce the EntityNameExpression type

Author: Andy Hanson

src/compiler/checker.ts

@@ -944,28 +944,39 @@ namespace ts {
 
 
         function checkAndReportErrorForExtendingInterface(errorLocation: Node): boolean {
-            let parentClassExpression = errorLocation;
-            while (parentClassExpression) {
-                const kind = parentClassExpression.kind;
-                if (kind === SyntaxKind.Identifier || kind === SyntaxKind.PropertyAccessExpression) {
-                    parentClassExpression = parentClassExpression.parent;
-                    continue;
-                }
-                if (kind === SyntaxKind.ExpressionWithTypeArguments) {
-                    break;
-                }
+            const parentExpression = climbToSupportedExpressionWithTypeArguments(errorLocation);
+            if (!parentExpression) {
                 return false;
             }
-            if (!parentClassExpression) {
-                return false;
-            }
-            const expression = (<ExpressionWithTypeArguments>parentClassExpression).expression;
+            const expression = parentExpression.expression;
+
             if (resolveEntityName(expression, SymbolFlags.Interface, /*ignoreErrors*/ true)) {
                 error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, getTextOfNode(expression));
                 return true;
             }
             return false;
         }
+        /**
+         * Climbs up parents to a SupportedExpressionWIthTypeArguments.
+         * Does *not* just climb to an ExpressionWithTypeArguments; instead, ensures that this really is supported.
+         */
+        function climbToSupportedExpressionWithTypeArguments(node: Node): SupportedExpressionWithTypeArguments | undefined {
+            while (node) {
+                switch (node.kind) {
+                    case SyntaxKind.Identifier:
+                    case SyntaxKind.PropertyAccessExpression:
+                        node = node.parent;
+                        break;
+                    case SyntaxKind.ExpressionWithTypeArguments:
+                        Debug.assert(isSupportedExpressionWithTypeArguments(<ExpressionWithTypeArguments>node));
+                        return <SupportedExpressionWithTypeArguments>node;
+                    default:
+                        return undefined;
+                }
+            }
+            return undefined;
+        }
+
 
         function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void {
             Debug.assert((result.flags & SymbolFlags.BlockScopedVariable) !== 0);
@@ -1250,7 +1261,7 @@ namespace ts {
         }
 
         // Resolves a qualified name and any involved aliases
-        function resolveEntityName(name: EntityName | Expression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean): Symbol {
+        function resolveEntityName(name: EntityNameOrEntityNameExpression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean): Symbol | undefined {
             if (nodeIsMissing(name)) {
                 return undefined;
             }
@@ -1265,7 +1276,7 @@ namespace ts {
                 }
             }
             else if (name.kind === SyntaxKind.QualifiedName || name.kind === SyntaxKind.PropertyAccessExpression) {
-                const left = name.kind === SyntaxKind.QualifiedName ? (<QualifiedName>name).left : (<PropertyAccessExpression>name).expression;
+                const left = name.kind === SyntaxKind.QualifiedName ? (<QualifiedName>name).left : (<PropertyAccessEntityNameExpression>name).expression;
                 const right = name.kind === SyntaxKind.QualifiedName ? (<QualifiedName>name).right : (<PropertyAccessExpression>name).name;
 
                 const namespace = resolveEntityName(left, SymbolFlags.Namespace, ignoreErrors);
@@ -1814,7 +1825,7 @@ namespace ts {
             }
         }
 
-        function isEntityNameVisible(entityName: EntityName | Expression, enclosingDeclaration: Node): SymbolVisibilityResult {
+        function isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node): SymbolVisibilityResult {
             // get symbol of the first identifier of the entityName
             let meaning: SymbolFlags;
             if (entityName.parent.kind === SyntaxKind.TypeQuery || isExpressionWithTypeArgumentsInClassExtendsClause(entityName.parent)) {
@@ -4885,7 +4896,7 @@ namespace ts {
             return getDeclaredTypeOfSymbol(symbol);
         }
 
-        function getTypeReferenceName(node: TypeReferenceNode | ExpressionWithTypeArguments | JSDocTypeReference): LeftHandSideExpression | EntityName {
+        function getTypeReferenceName(node: TypeReferenceNode | ExpressionWithTypeArguments | JSDocTypeReference): EntityNameOrEntityNameExpression | undefined {
             switch (node.kind) {
                 case SyntaxKind.TypeReference:
                     return (<TypeReferenceNode>node).typeName;
@@ -4894,8 +4905,9 @@ namespace ts {
                 case SyntaxKind.ExpressionWithTypeArguments:
                     // We only support expressions that are simple qualified names. For other
                     // expressions this produces undefined.
-                    if (isSupportedExpressionWithTypeArguments(<ExpressionWithTypeArguments>node)) {
-                        return (<ExpressionWithTypeArguments>node).expression;
+                    const expr = <ExpressionWithTypeArguments>node;
+                    if (isSupportedExpressionWithTypeArguments(expr)) {
+                        return expr.expression;
                     }
 
                 // fall through;
@@ -4906,7 +4918,7 @@ namespace ts {
 
         function resolveTypeReferenceName(
             node: TypeReferenceNode | ExpressionWithTypeArguments | JSDocTypeReference,
-            typeReferenceName: LeftHandSideExpression | EntityName) {
+            typeReferenceName: EntityNameExpression | EntityName) {
 
             if (!typeReferenceName) {
                 return unknownSymbol;
@@ -4947,15 +4959,14 @@ namespace ts {
                     const typeReferenceName = getTypeReferenceName(node);
                     symbol = resolveTypeReferenceName(node, typeReferenceName);
                     type = getTypeReferenceType(node, symbol);
-
-                    links.resolvedSymbol = symbol;
-                    links.resolvedType = type;
                 }
                 else {
                     // We only support expressions that are simple qualified names. For other expressions this produces undefined.
-                    const typeNameOrExpression = node.kind === SyntaxKind.TypeReference ? (<TypeReferenceNode>node).typeName :
-                        isSupportedExpressionWithTypeArguments(<ExpressionWithTypeArguments>node) ? (<ExpressionWithTypeArguments>node).expression :
-                            undefined;
+                    const typeNameOrExpression: EntityNameOrEntityNameExpression = node.kind === SyntaxKind.TypeReference
+                        ? (<TypeReferenceNode>node).typeName
+                        : isSupportedExpressionWithTypeArguments(<ExpressionWithTypeArguments>node)
+                            ? (<SupportedExpressionWithTypeArguments>node).expression
+                            : undefined;
                     symbol = typeNameOrExpression && resolveEntityName(typeNameOrExpression, SymbolFlags.Type) || unknownSymbol;
                     type = symbol === unknownSymbol ? unknownType :
                         symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface) ? getTypeFromClassOrInterfaceReference(node, symbol) :
@@ -16594,20 +16605,21 @@ namespace ts {
             }
         }
 
-        function getFirstIdentifier(node: EntityName | Expression): Identifier {
-            while (true) {
-                if (node.kind === SyntaxKind.QualifiedName) {
-                    node = (<QualifiedName>node).left;
-                }
-                else if (node.kind === SyntaxKind.PropertyAccessExpression) {
-                    node = (<PropertyAccessExpression>node).expression;
-                }
-                else {
-                    break;
-                }
+        function getFirstIdentifier(node: EntityNameOrEntityNameExpression): Identifier {
+            switch (node.kind) {
+                case SyntaxKind.Identifier:
+                    return <Identifier>node;
+                case SyntaxKind.QualifiedName:
+                    do {
+                        node = (<QualifiedName>node).left;
+                    } while (node.kind !== SyntaxKind.Identifier);
+                    return <Identifier>node;
+                case SyntaxKind.PropertyAccessExpression:
+                    do {
+                        node = (<PropertyAccessEntityNameExpression>node).expression;
+                    } while (node.kind !== SyntaxKind.Identifier);
+                    return <Identifier>node;
             }
-            Debug.assert(node.kind === SyntaxKind.Identifier);
-            return <Identifier>node;
         }
 
         function checkExternalImportOrExportDeclaration(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration): boolean {
@@ -17306,7 +17318,7 @@ namespace ts {
             return getLeftSideOfImportEqualsOrExportAssignment(node) !== undefined;
         }
 
-        function getSymbolOfEntityNameOrPropertyAccessExpression(entityName: EntityName | PropertyAccessExpression): Symbol {
+        function getSymbolOfEntityNameOrPropertyAccessExpression(entityName: EntityName | PropertyAccessExpression): Symbol | undefined {
             if (isDeclarationName(entityName)) {
                 return getSymbolOfNode(entityName.parent);
             }
@@ -17325,8 +17337,8 @@ namespace ts {
                 }
             }
 
-            if (entityName.parent.kind === SyntaxKind.ExportAssignment) {
-                return resolveEntityName(<Identifier>entityName,
+            if (entityName.parent.kind === SyntaxKind.ExportAssignment && isEntityNameExpression(<Identifier | PropertyAccessExpression>entityName)) {
+                return resolveEntityName(<EntityNameExpression>entityName,
                     /*all meanings*/ SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias);
             }
 
@@ -17340,7 +17352,7 @@ namespace ts {
             }
 
             if (isRightSideOfQualifiedNameOrPropertyAccess(entityName)) {
-                entityName = <QualifiedName | PropertyAccessExpression>entityName.parent;
+                entityName = <QualifiedName | PropertyAccessEntityNameExpression>entityName.parent;
             }
 
             if (isHeritageClauseElementIdentifier(<EntityName>entityName)) {
@@ -18053,7 +18065,7 @@ namespace ts {
             };
 
             // defined here to avoid outer scope pollution
-            function getTypeReferenceDirectivesForEntityName(node: EntityName | PropertyAccessExpression): string[] {
+            function getTypeReferenceDirectivesForEntityName(node: EntityNameOrEntityNameExpression): string[] {
                 // program does not have any files with type reference directives - bail out
                 if (!fileToDirective) {
                     return undefined;

src/compiler/declarationEmitter.ts

@@ -441,7 +441,7 @@ namespace ts {
                 }
             }
 
-            function emitEntityName(entityName: EntityName | PropertyAccessExpression) {
+            function emitEntityName(entityName: EntityNameOrEntityNameExpression) {
                 const visibilityResult = resolver.isEntityNameVisible(entityName,
                     // Aliases can be written asynchronously so use correct enclosing declaration
                     entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration ? entityName.parent : enclosingDeclaration);
@@ -454,7 +454,7 @@ namespace ts {
             function emitExpressionWithTypeArguments(node: ExpressionWithTypeArguments) {
                 if (isSupportedExpressionWithTypeArguments(node)) {
                     Debug.assert(node.expression.kind === SyntaxKind.Identifier || node.expression.kind === SyntaxKind.PropertyAccessExpression);
-                    emitEntityName(<Identifier | PropertyAccessExpression>node.expression);
+                    emitEntityName(node.expression);
                     if (node.typeArguments) {
                         write("<");
                         emitCommaList(node.typeArguments, emitType);

src/compiler/types.ts

@@ -981,13 +981,19 @@ namespace ts {
         multiLine?: boolean;
     }
 
+    export type EntityNameExpression = Identifier | PropertyAccessEntityNameExpression;
+    export type EntityNameOrEntityNameExpression = EntityName | EntityNameExpression;
+
     // @kind(SyntaxKind.PropertyAccessExpression)
     export interface PropertyAccessExpression extends MemberExpression, Declaration {
         expression: LeftHandSideExpression;
         name: Identifier;
     }
-
-    export type IdentifierOrPropertyAccess = Identifier | PropertyAccessExpression;
+    /** Brand for a PropertyAccessExpression which, like a QualifiedName, consists of a sequence of identifiers separated by dots. */
+    export interface PropertyAccessEntityNameExpression extends PropertyAccessExpression {
+        _propertyAccessExpressionLikeQualifiedNameBrand?: any;
+        expression: EntityNameExpression;
+    }
 
     // @kind(SyntaxKind.ElementAccessExpression)
     export interface ElementAccessExpression extends MemberExpression {
@@ -1007,6 +1013,10 @@ namespace ts {
         expression: LeftHandSideExpression;
         typeArguments?: NodeArray<TypeNode>;
     }
+    export interface SupportedExpressionWithTypeArguments extends ExpressionWithTypeArguments {
+        _supportedExpressionWithTypeArgumentsBrand?: any;
+        expression: EntityNameExpression;
+    }
 
     // @kind(SyntaxKind.NewExpression)
     export interface NewExpression extends CallExpression, PrimaryExpression { }
@@ -2019,7 +2029,7 @@ namespace ts {
         writeTypeOfExpression(expr: Expression, enclosingDeclaration: Node, flags: TypeFormatFlags, writer: SymbolWriter): void;
         writeBaseConstructorTypeOfClass(node: ClassLikeDeclaration, enclosingDeclaration: Node, flags: TypeFormatFlags, writer: SymbolWriter): void;
         isSymbolAccessible(symbol: Symbol, enclosingDeclaration: Node, meaning: SymbolFlags): SymbolAccessibilityResult;
-        isEntityNameVisible(entityName: EntityName | Expression, enclosingDeclaration: Node): SymbolVisibilityResult;
+        isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node): SymbolVisibilityResult;
         // Returns the constant value this property access resolves to, or 'undefined' for a non-constant
         getConstantValue(node: EnumMember | PropertyAccessExpression | ElementAccessExpression): number;
         getReferencedValueDeclaration(reference: Identifier): Declaration;
@@ -2028,7 +2038,7 @@ namespace ts {
         moduleExportsSomeValue(moduleReferenceExpression: Expression): boolean;
         isArgumentsLocalBinding(node: Identifier): boolean;
         getExternalModuleFileFromDeclaration(declaration: ImportEqualsDeclaration | ImportDeclaration | ExportDeclaration | ModuleDeclaration): SourceFile;
-        getTypeReferenceDirectivesForEntityName(name: EntityName | PropertyAccessExpression): string[];
+        getTypeReferenceDirectivesForEntityName(name: EntityNameOrEntityNameExpression): string[];
         getTypeReferenceDirectivesForSymbol(symbol: Symbol, meaning?: SymbolFlags): string[];
     }
 

src/compiler/utilities.ts

@@ -1033,14 +1033,14 @@ namespace ts {
             && (<PropertyAccessExpression | ElementAccessExpression>node).expression.kind === SyntaxKind.SuperKeyword;
     }
 
-
-    export function getEntityNameFromTypeNode(node: TypeNode): EntityName | Expression {
+    export function getEntityNameFromTypeNode(node: TypeNode): EntityNameOrEntityNameExpression {
         if (node) {
             switch (node.kind) {
                 case SyntaxKind.TypeReference:
                     return (<TypeReferenceNode>node).typeName;
                 case SyntaxKind.ExpressionWithTypeArguments:
-                    return (<ExpressionWithTypeArguments>node).expression;
+                    Debug.assert(isSupportedExpressionWithTypeArguments(<ExpressionWithTypeArguments>node));
+                    return (<SupportedExpressionWithTypeArguments>node).expression;
                 case SyntaxKind.Identifier:
                 case SyntaxKind.QualifiedName:
                     return (<EntityName><Node>node);
@@ -2680,24 +2680,28 @@ namespace ts {
             isClassLike(node.parent.parent);
     }
 
-    // Returns false if this heritage clause element's expression contains something unsupported
-    // (i.e. not a name or dotted name).
-    export function isSupportedExpressionWithTypeArguments(node: ExpressionWithTypeArguments): boolean {
-        return isSupportedExpressionWithTypeArgumentsRest(node.expression);
+    export function isSupportedExpressionWithTypeArguments(node: ExpressionWithTypeArguments): node is SupportedExpressionWithTypeArguments {
+        return isEntityNameExpression(node.expression);
     }
 
-    function isSupportedExpressionWithTypeArgumentsRest(node: Expression): boolean {
-        if (node.kind === SyntaxKind.Identifier) {
-            return true;
-        }
-        else if (isPropertyAccessExpression(node)) {
-            return isSupportedExpressionWithTypeArgumentsRest(node.expression);
-        }
-        else {
-            return false;
+    export function isEntityNameExpression(node: Expression): node is EntityNameExpression {
+        for (; ; ) {
+            switch (node.kind) {
+                case SyntaxKind.Identifier:
+                    return true;
+                case SyntaxKind.PropertyAccessExpression:
+                    node = (<PropertyAccessExpression>node).expression;
+                    break;
+                default:
+                    return false;
+            }
         }
     }
 
+    export function isPropertyAccessAnEntityNameExpression(node: PropertyAccessExpression): node is PropertyAccessEntityNameExpression {
+        return isEntityNameExpression(node.expression);
+    }
+
     export function isRightSideOfQualifiedNameOrPropertyAccess(node: Node) {
         return (node.parent.kind === SyntaxKind.QualifiedName && (<QualifiedName>node.parent).right === node) ||
             (node.parent.kind === SyntaxKind.PropertyAccessExpression && (<PropertyAccessExpression>node.parent).name === node);

tests/baselines/reference/exportDefaultProperty.js

@@ -0,0 +1,8 @@
+//// [exportDefaultProperty.ts]
+export default "".length
+
+
+//// [exportDefaultProperty.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = "".length;

tests/baselines/reference/exportDefaultProperty.symbols

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/exportDefaultProperty.ts ===
+export default "".length
+>"".length : Symbol(String.length, Decl(lib.d.ts, --, --))
+>length : Symbol(String.length, Decl(lib.d.ts, --, --))
+

tests/baselines/reference/exportDefaultProperty.types

@@ -0,0 +1,6 @@
+=== tests/cases/compiler/exportDefaultProperty.ts ===
+export default "".length
+>"".length : number
+>"" : string
+>length : number
+

tests/cases/compiler/exportDefaultProperty.ts

@@ -0,0 +1 @@
+export default "".length