(WIP) Private name class field transformation

.travis.yml

@@ -15,11 +15,7 @@ matrix:
 
 branches:
   only:
-  - master
-  - release-2.7
-  - release-2.8
-  - release-2.9
-  - release-3.0
+  - es-private-fields
 
 install:
   - npm uninstall typescript --no-save

src/compiler/binder.ts

@@ -266,6 +266,9 @@ namespace ts {
                     Debug.assert(isWellKnownSymbolSyntactically(nameExpression));
                     return getPropertyNameForKnownSymbolName(idText((<PropertyAccessExpression>nameExpression).name));
                 }
+                if (isPrivateName(node)) {
+                    return nodePosToString(node) as __String;
+                }
                 return isPropertyNameLiteral(name) ? getEscapedTextOfIdentifierOrLiteral(name) : undefined;
             }
             switch (node.kind) {
@@ -1394,7 +1397,7 @@ namespace ts {
             }
             if (node.expression.kind === SyntaxKind.PropertyAccessExpression) {
                 const propertyAccess = <PropertyAccessExpression>node.expression;
-                if (isNarrowableOperand(propertyAccess.expression) && isPushOrUnshiftIdentifier(propertyAccess.name)) {
+                if (isIdentifier(propertyAccess.name) && isNarrowableOperand(propertyAccess.expression) && isPushOrUnshiftIdentifier(propertyAccess.name)) {
                     currentFlow = createFlowArrayMutation(currentFlow, node);
                 }
             }
@@ -2359,7 +2362,7 @@ namespace ts {
                 return;
             }
             const lhs = node.left as PropertyAccessEntityNameExpression;
-            const symbol = forEachIdentifierInEntityName(lhs.expression, /*parent*/ undefined, (id, symbol) => {
+            const symbol = forEachIdentifierOrPrivateNameInEntityName(lhs.expression, /*parent*/ undefined, (id, symbol) => {
                 if (symbol) {
                     addDeclarationToSymbol(symbol, id, SymbolFlags.Module | SymbolFlags.JSContainer);
                 }
@@ -2518,7 +2521,7 @@ namespace ts {
                 // make symbols or add declarations for intermediate containers
                 const flags = SymbolFlags.Module | SymbolFlags.JSContainer;
                 const excludeFlags = SymbolFlags.ValueModuleExcludes & ~SymbolFlags.JSContainer;
-                namespaceSymbol = forEachIdentifierInEntityName(propertyAccess.expression, namespaceSymbol, (id, symbol, parent) => {
+                namespaceSymbol = forEachIdentifierOrPrivateNameInEntityName(propertyAccess.expression, namespaceSymbol, (id, symbol, parent) => {
                     if (symbol) {
                         addDeclarationToSymbol(symbol, id, flags);
                         return symbol;
@@ -2590,15 +2593,15 @@ namespace ts {
             }
         }
 
-        function forEachIdentifierInEntityName(e: EntityNameExpression, parent: Symbol | undefined, action: (e: Identifier, symbol: Symbol | undefined, parent: Symbol | undefined) => Symbol | undefined): Symbol | undefined {
+        function forEachIdentifierOrPrivateNameInEntityName(e: EntityNameExpression, parent: Symbol | undefined, action: (e: Identifier | PrivateName, symbol: Symbol | undefined, parent: Symbol | undefined) => Symbol | undefined): Symbol | undefined {
             if (isExportsOrModuleExportsOrAlias(file, e)) {
                 return file.symbol;
             }
             else if (isIdentifier(e)) {
                 return action(e, lookupSymbolForPropertyAccess(e), parent);
             }
             else {
-                const s = forEachIdentifierInEntityName(e.expression, parent, action);
+                const s = forEachIdentifierOrPrivateNameInEntityName(e.expression, parent, action);
                 if (!s || !s.exports) return Debug.fail();
                 return action(e.name, s.exports.get(e.name.escapedText), s);
             }
@@ -3308,6 +3311,11 @@ namespace ts {
             transformFlags |= TransformFlags.ContainsPropertyInitializer;
         }
 
+        // Private names are an ESNext feature.
+        if (isPrivateName(node.name)) {
+            transformFlags |= TransformFlags.AssertESNext;
+        }
+
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~TransformFlags.NodeExcludes;
     }
@@ -3445,6 +3453,11 @@ namespace ts {
             transformFlags |= TransformFlags.ContainsSuper;
         }
 
+        // Private names are an ESNext feature.
+        if (isPrivateName(node.name)) {
+            transformFlags |= TransformFlags.AssertESNext;
+        }
+
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~TransformFlags.PropertyAccessExcludes;
     }

src/compiler/checker.ts

@@ -14346,8 +14346,10 @@ namespace ts {
             const root = getReferenceRoot(node);
             const parent = root.parent;
             const isLengthPushOrUnshift = parent.kind === SyntaxKind.PropertyAccessExpression && (
-                (<PropertyAccessExpression>parent).name.escapedText === "length" ||
-                parent.parent.kind === SyntaxKind.CallExpression && isPushOrUnshiftIdentifier((<PropertyAccessExpression>parent).name));
+                (<PropertyAccessExpression>parent).name.escapedText === "length" || (
+                    parent.parent.kind === SyntaxKind.CallExpression
+                    && isIdentifier((parent as PropertyAccessExpression).name)
+                    && isPushOrUnshiftIdentifier((parent as PropertyAccessExpression).name as Identifier)));
             const isElementAssignment = parent.kind === SyntaxKind.ElementAccessExpression &&
                 (<ElementAccessExpression>parent).expression === root &&
                 parent.parent.kind === SyntaxKind.BinaryExpression &&
@@ -17972,7 +17974,7 @@ namespace ts {
             return checkPropertyAccessExpressionOrQualifiedName(node, node.left, node.right);
         }
 
-        function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, right: Identifier) {
+        function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, right: Identifier | PrivateName) {
             let propType: Type;
             const leftType = checkNonNullExpression(left);
             const parentSymbol = getNodeLinks(left).resolvedSymbol;
@@ -17990,7 +17992,7 @@ namespace ts {
             }
             if (!prop) {
                 const indexInfo = getIndexInfoOfType(apparentType, IndexKind.String);
-                if (!(indexInfo && indexInfo.type)) {
+                if (!(indexInfo && indexInfo.type) || isPrivateName(right)) {
                     if (isJSLiteralType(leftType)) {
                         return anyType;
                     }
@@ -18048,7 +18050,7 @@ namespace ts {
             return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType;
         }
 
-        function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier): void {
+        function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier | PrivateName): void {
             const { valueDeclaration } = prop;
             if (!valueDeclaration) {
                 return;
@@ -18118,7 +18120,7 @@ namespace ts {
             return getIntersectionType(x);
         }
 
-        function reportNonexistentProperty(propNode: Identifier, containingType: Type) {
+        function reportNonexistentProperty(propNode: Identifier | PrivateName, containingType: Type) {
             let errorInfo: DiagnosticMessageChain | undefined;
             let relatedInfo: Diagnostic | undefined;
             if (containingType.flags & TypeFlags.Union && !(containingType.flags & TypeFlags.Primitive)) {
@@ -18161,11 +18163,11 @@ namespace ts {
             return prop !== undefined && prop.valueDeclaration && hasModifier(prop.valueDeclaration, ModifierFlags.Static);
         }
 
-        function getSuggestedSymbolForNonexistentProperty(name: Identifier | string, containingType: Type): Symbol | undefined {
+        function getSuggestedSymbolForNonexistentProperty(name: Identifier | PrivateName | string, containingType: Type): Symbol | undefined {
             return getSpellingSuggestionForName(isString(name) ? name : idText(name), getPropertiesOfType(containingType), SymbolFlags.Value);
         }
 
-        function getSuggestionForNonexistentProperty(name: Identifier | string, containingType: Type): string | undefined {
+        function getSuggestionForNonexistentProperty(name: Identifier | PrivateName | string, containingType: Type): string | undefined {
             const suggestion = getSuggestedSymbolForNonexistentProperty(name, containingType);
             return suggestion && symbolName(suggestion);
         }
@@ -21876,6 +21878,9 @@ namespace ts {
             checkGrammarDecoratorsAndModifiers(node);
 
             checkVariableLikeDeclaration(node);
+            if (node.name && isIdentifier(node.name) && node.name.originalKeywordKind === SyntaxKind.PrivateName) {
+                error(node, Diagnostics.Private_names_cannot_be_used_as_parameters);
+            }
             const func = getContainingFunction(node)!;
             if (hasModifier(node, ModifierFlags.ParameterPropertyModifier)) {
                 if (!(func.kind === SyntaxKind.Constructor && nodeIsPresent(func.body))) {
@@ -23523,9 +23528,9 @@ namespace ts {
             }
         }
 
-        function getIdentifierFromEntityNameExpression(node: Identifier | PropertyAccessExpression): Identifier;
-        function getIdentifierFromEntityNameExpression(node: Expression): Identifier | undefined;
-        function getIdentifierFromEntityNameExpression(node: Expression): Identifier | undefined {
+        function getIdentifierFromEntityNameExpression(node: Identifier | PropertyAccessExpression): Identifier | PrivateName;
+        function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateName | undefined;
+        function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateName | undefined {
             switch (node.kind) {
                 case SyntaxKind.Identifier:
                     return node as Identifier;
@@ -29288,6 +29293,10 @@ namespace ts {
                 checkESModuleMarker(node.name);
             }
 
+            if (isIdentifier(node.name) && node.name.originalKeywordKind === SyntaxKind.PrivateName) {
+                return grammarErrorOnNode(node.name, Diagnostics.Private_names_are_not_allowed_in_variable_declarations);
+            }
+
             const checkLetConstNames = (isLet(node) || isVarConst(node));
 
             // 1. LexicalDeclaration : LetOrConst BindingList ;

src/compiler/diagnosticMessages.json

@@ -4166,6 +4166,14 @@
         "category": "Error",
         "code": 18003
     },
+    "Private names are not allowed in variable declarations.": {
+        "category": "Error",
+        "code": 18004
+    },
+    "Private names cannot be used as parameters": {
+        "category": "Error",
+        "code": 18005
+    },
 
     "File is a CommonJS module; it may be converted to an ES6 module.": {
         "category": "Suggestion",

src/compiler/emitter.ts

@@ -609,6 +609,10 @@ namespace ts {
                     case SyntaxKind.Identifier:
                         return emitIdentifier(<Identifier>node);
 
+                    // PrivateNames
+                    case SyntaxKind.PrivateName:
+                        return emitPrivateName(node as PrivateName);
+
                     // Parse tree nodes
 
                     // Names
@@ -878,6 +882,10 @@ namespace ts {
                     case SyntaxKind.Identifier:
                         return emitIdentifier(<Identifier>node);
 
+                    // Private Names
+                    case SyntaxKind.PrivateName:
+                        return emitPrivateName(node as PrivateName);
+
                     // Reserved words
                     case SyntaxKind.FalseKeyword:
                     case SyntaxKind.NullKeyword:
@@ -1067,6 +1075,12 @@ namespace ts {
             emitList(node, node.typeArguments, ListFormat.TypeParameters); // Call emitList directly since it could be an array of TypeParameterDeclarations _or_ type arguments
         }
 
+        function emitPrivateName(node: PrivateName) {
+            const writeText = node.symbol ? writeSymbol : write;
+            writeText(getTextOfNode(node, /*includeTrivia*/ false), node.symbol);
+            emitList(node, /*typeArguments*/ undefined, ListFormat.TypeParameters); // Call emitList directly since it could be an array of TypeParameterDeclarations _or_ type arguments
+        }
+
         //
         // Names
         //
@@ -3302,7 +3316,7 @@ namespace ts {
         function getLiteralTextOfNode(node: LiteralLikeNode): string {
             if (node.kind === SyntaxKind.StringLiteral && (<StringLiteral>node).textSourceNode) {
                 const textSourceNode = (<StringLiteral>node).textSourceNode!;
-                if (isIdentifier(textSourceNode)) {
+                if (isIdentifierOrPrivateName(textSourceNode)) {
                     return getEmitFlags(node) & EmitFlags.NoAsciiEscaping ?
                         `"${escapeString(getTextOfNode(textSourceNode))}"` :
                         `"${escapeNonAsciiString(getTextOfNode(textSourceNode))}"`;

src/compiler/factory.ts

@@ -105,7 +105,7 @@ namespace ts {
         return node;
     }
 
-    function createLiteralFromNode(sourceNode: PropertyNameLiteral): StringLiteral {
+    function createLiteralFromNode(sourceNode: Exclude<PropertyNameLiteral, PrivateName>): StringLiteral {
         const node = createStringLiteral(getTextOfIdentifierOrLiteral(sourceNode));
         node.textSourceNode = sourceNode;
         return node;
@@ -995,15 +995,15 @@ namespace ts {
             : node;
     }
 
-    export function createPropertyAccess(expression: Expression, name: string | Identifier | undefined) {
+    export function createPropertyAccess(expression: Expression, name: string | Identifier | PrivateName | undefined) {
         const node = <PropertyAccessExpression>createSynthesizedNode(SyntaxKind.PropertyAccessExpression);
         node.expression = parenthesizeForAccess(expression);
         node.name = asName(name)!; // TODO: GH#18217
         setEmitFlags(node, EmitFlags.NoIndentation);
         return node;
     }
 
-    export function updatePropertyAccess(node: PropertyAccessExpression, expression: Expression, name: Identifier) {
+    export function updatePropertyAccess(node: PropertyAccessExpression, expression: Expression, name: Identifier | PrivateName) {
         // Because we are updating existed propertyAccess we want to inherit its emitFlags
         // instead of using the default from createPropertyAccess
         return node.expression !== expression
@@ -2714,7 +2714,7 @@ namespace ts {
 
     // Utilities
 
-    function asName<T extends Identifier | BindingName | PropertyName | EntityName | ThisTypeNode | undefined>(name: string | T): T | Identifier {
+    function asName<T extends Identifier | PrivateName | BindingName | PropertyName | EntityName | ThisTypeNode | undefined>(name: string | T): T | Identifier {
         return isString(name) ? createIdentifier(name) : name;
     }
 
@@ -3099,7 +3099,7 @@ namespace ts {
         }
         else {
             const expression = setTextRange(
-                isIdentifier(memberName)
+                (isIdentifier(memberName) || isPrivateName(memberName))
                     ? createPropertyAccess(target, memberName)
                     : createElementAccess(target, memberName),
                 memberName
@@ -3529,7 +3529,7 @@ namespace ts {
         }
     }
 
-    export function createExpressionForPropertyName(memberName: PropertyName): Expression {
+    export function createExpressionForPropertyName(memberName: Exclude<PropertyName, PrivateName>): Expression {
         if (isIdentifier(memberName)) {
             return createLiteral(memberName);
         }
@@ -3541,11 +3541,17 @@ namespace ts {
         }
     }
 
+    /**
+     * accessor declaration that can be converted to an expression (`name` field cannot be a `PrivateName`)
+     */
+    type ExpressionableAccessorDeclaration = AccessorDeclaration & {name: Exclude<PropertyName, PrivateName>};
+
     export function createExpressionForObjectLiteralElementLike(node: ObjectLiteralExpression, property: ObjectLiteralElementLike, receiver: Expression): Expression | undefined {
         switch (property.kind) {
             case SyntaxKind.GetAccessor:
             case SyntaxKind.SetAccessor:
-                return createExpressionForAccessorDeclaration(node.properties, property, receiver, !!node.multiLine);
+                // type assertion `as ExpressionableAccessorDeclaration` is safe because PrivateNames are not allowed in object literals
+                return createExpressionForAccessorDeclaration(node.properties, property as ExpressionableAccessorDeclaration, receiver, !!node.multiLine);
             case SyntaxKind.PropertyAssignment:
                 return createExpressionForPropertyAssignment(property, receiver);
             case SyntaxKind.ShorthandPropertyAssignment:
@@ -3555,7 +3561,7 @@ namespace ts {
         }
     }
 
-    function createExpressionForAccessorDeclaration(properties: NodeArray<Declaration>, property: AccessorDeclaration, receiver: Expression, multiLine: boolean) {
+    function createExpressionForAccessorDeclaration(properties: NodeArray<Declaration>, property: ExpressionableAccessorDeclaration, receiver: Expression, multiLine: boolean) {
         const { firstAccessor, getAccessor, setAccessor } = getAllAccessorDeclarations(properties, property);
         if (property === firstAccessor) {
             const properties: ObjectLiteralElementLike[] = [];