Merge branch 'master' into autohoist-default

src/compiler/binder.ts

@@ -1,3 +1,4 @@
+/// <reference path="utilities.ts"/>
 /// <reference path="parser.ts"/>
 
 /* @internal */
@@ -6,8 +7,8 @@ namespace ts {
 
     export const enum ModuleInstanceState {
         NonInstantiated = 0,
-        Instantiated    = 1,
-        ConstEnumOnly   = 2
+        Instantiated = 1,
+        ConstEnumOnly = 2
     }
 
     const enum Reachability {
@@ -138,6 +139,8 @@ namespace ts {
                 file.classifiableNames = classifiableNames;
             }
 
+            file = undefined;
+            options = undefined;
             parent = undefined;
             container = undefined;
             blockScopeContainer = undefined;
@@ -174,9 +177,14 @@ namespace ts {
                 symbol.members = {};
             }
 
-            if (symbolFlags & SymbolFlags.Value && !symbol.valueDeclaration) {
-                symbol.valueDeclaration = node;
-            }
+            if (symbolFlags & SymbolFlags.Value) {
+                const valueDeclaration = symbol.valueDeclaration;
+                if (!valueDeclaration ||
+                    (valueDeclaration.kind !== node.kind && valueDeclaration.kind === SyntaxKind.ModuleDeclaration)) {
+                    // other kinds of value declarations take precedence over modules
+                    symbol.valueDeclaration = node;
+                }
+        }
         }
 
         // Should not be called on a declaration with a computed property name,
@@ -188,6 +196,11 @@ namespace ts {
                 }
                 if (node.name.kind === SyntaxKind.ComputedPropertyName) {
                     const nameExpression = (<ComputedPropertyName>node.name).expression;
+                    // treat computed property names where expression is string/numeric literal as just string/numeric literal
+                    if (isStringOrNumericLiteral(nameExpression.kind)) {
+                        return (<LiteralExpression>nameExpression).text;
+                    }
+
                     Debug.assert(isWellKnownSymbolSyntactically(nameExpression));
                     return getPropertyNameForKnownSymbolName((<PropertyAccessExpression>nameExpression).name.text);
                 }
@@ -208,6 +221,9 @@ namespace ts {
                     return "__export";
                 case SyntaxKind.ExportAssignment:
                     return (<ExportAssignment>node).isExportEquals ? "export=" : "default";
+                case SyntaxKind.BinaryExpression:
+                    // Binary expression case is for JS module 'module.exports = expr'
+                    return "export=";
                 case SyntaxKind.FunctionDeclaration:
                 case SyntaxKind.ClassDeclaration:
                     return node.flags & NodeFlags.Default ? "default" : undefined;
@@ -441,7 +457,7 @@ namespace ts {
 
         /**
          * Returns true if node and its subnodes were successfully traversed.
-         * Returning false means that node was not examined and caller needs to dive into the node himself. 
+         * Returning false means that node was not examined and caller needs to dive into the node himself.
          */
         function bindReachableStatement(node: Node): void {
             if (checkUnreachable(node)) {
@@ -551,7 +567,7 @@ namespace ts {
         }
 
         function bindIfStatement(n: IfStatement): void {
-            // denotes reachability state when entering 'thenStatement' part of the if statement: 
+            // denotes reachability state when entering 'thenStatement' part of the if statement:
             // i.e. if condition is false then thenStatement is unreachable
             const ifTrueState = n.expression.kind === SyntaxKind.FalseKeyword ? Reachability.Unreachable : currentReachabilityState;
             // denotes reachability state when entering 'elseStatement':
@@ -1069,7 +1085,7 @@ namespace ts {
             return "__" + indexOf((<SignatureDeclaration>node.parent).parameters, node);
         }
 
-        function bind(node: Node) {
+        function bind(node: Node): void {
             if (!node) {
                 return;
             }
@@ -1145,9 +1161,18 @@ namespace ts {
 
         function bindWorker(node: Node) {
             switch (node.kind) {
+                /* Strict mode checks */
                 case SyntaxKind.Identifier:
                     return checkStrictModeIdentifier(<Identifier>node);
                 case SyntaxKind.BinaryExpression:
+                    if (isInJavaScriptFile(node)) {
+                        if (isExportsPropertyAssignment(node)) {
+                            bindExportsPropertyAssignment(<BinaryExpression>node);
+                        }
+                        else if (isModuleExportsAssignment(node)) {
+                            bindModuleExportsAssignment(<BinaryExpression>node);
+                        }
+                    }
                     return checkStrictModeBinaryExpression(<BinaryExpression>node);
                 case SyntaxKind.CatchClause:
                     return checkStrictModeCatchClause(<CatchClause>node);
@@ -1161,7 +1186,7 @@ namespace ts {
                     return checkStrictModePrefixUnaryExpression(<PrefixUnaryExpression>node);
                 case SyntaxKind.WithStatement:
                     return checkStrictModeWithStatement(<WithStatement>node);
-                case SyntaxKind.ThisKeyword:
+                case SyntaxKind.ThisType:
                     seenThisKeyword = true;
                     return;
 
@@ -1213,6 +1238,14 @@ namespace ts {
                     checkStrictModeFunctionName(<FunctionExpression>node);
                     const bindingName = (<FunctionExpression>node).name ? (<FunctionExpression>node).name.text : "__function";
                     return bindAnonymousDeclaration(<FunctionExpression>node, SymbolFlags.Function, bindingName);
+
+                case SyntaxKind.CallExpression:
+                    if (isInJavaScriptFile(node)) {
+                        bindCallExpression(<CallExpression>node);
+                    }
+                    break;
+
+                // Members of classes, interfaces, and modules
                 case SyntaxKind.ClassExpression:
                 case SyntaxKind.ClassDeclaration:
                     return bindClassLikeDeclaration(<ClassLikeDeclaration>node);
@@ -1224,6 +1257,8 @@ namespace ts {
                     return bindEnumDeclaration(<EnumDeclaration>node);
                 case SyntaxKind.ModuleDeclaration:
                     return bindModuleDeclaration(<ModuleDeclaration>node);
+
+                // Imports and exports
                 case SyntaxKind.ImportEqualsDeclaration:
                 case SyntaxKind.NamespaceImport:
                 case SyntaxKind.ImportSpecifier:
@@ -1243,16 +1278,21 @@ namespace ts {
         function bindSourceFileIfExternalModule() {
             setExportContextFlag(file);
             if (isExternalModule(file)) {
-                bindAnonymousDeclaration(file, SymbolFlags.ValueModule, `"${removeFileExtension(file.fileName)}"`);
+                bindSourceFileAsExternalModule();
             }
         }
 
-        function bindExportAssignment(node: ExportAssignment) {
+        function bindSourceFileAsExternalModule() {
+            bindAnonymousDeclaration(file, SymbolFlags.ValueModule, `"${removeFileExtension(file.fileName) }"`);
+        }
+
+        function bindExportAssignment(node: ExportAssignment | BinaryExpression) {
+            const boundExpression = node.kind === SyntaxKind.ExportAssignment ? (<ExportAssignment>node).expression : (<BinaryExpression>node).right;
             if (!container.symbol || !container.symbol.exports) {
                 // Export assignment in some sort of block construct
                 bindAnonymousDeclaration(node, SymbolFlags.Alias, getDeclarationName(node));
             }
-            else if (node.expression.kind === SyntaxKind.Identifier) {
+            else if (boundExpression.kind === SyntaxKind.Identifier) {
                 // An export default clause with an identifier exports all meanings of that identifier
                 declareSymbol(container.symbol.exports, container.symbol, node, SymbolFlags.Alias, SymbolFlags.PropertyExcludes | SymbolFlags.AliasExcludes);
             }
@@ -1279,6 +1319,34 @@ namespace ts {
             }
         }
 
+        function setCommonJsModuleIndicator(node: Node) {
+            if (!file.commonJsModuleIndicator) {
+                file.commonJsModuleIndicator = node;
+                bindSourceFileAsExternalModule();
+            }
+        }
+
+        function bindExportsPropertyAssignment(node: BinaryExpression) {
+            // When we create a property via 'exports.foo = bar', the 'exports.foo' property access
+            // expression is the declaration
+            setCommonJsModuleIndicator(node);
+            declareSymbol(file.symbol.exports, file.symbol, <PropertyAccessExpression>node.left, SymbolFlags.Property | SymbolFlags.Export, SymbolFlags.None);
+        }
+
+        function bindModuleExportsAssignment(node: BinaryExpression) {
+            // 'module.exports = expr' assignment
+            setCommonJsModuleIndicator(node);
+            bindExportAssignment(node);
+        }
+
+        function bindCallExpression(node: CallExpression) {
+            // We're only inspecting call expressions to detect CommonJS modules, so we can skip
+            // this check if we've already seen the module indicator
+            if (!file.commonJsModuleIndicator && isRequireCall(node)) {
+                setCommonJsModuleIndicator(node);
+            }
+        }
+
         function bindClassLikeDeclaration(node: ClassLikeDeclaration) {
             if (node.kind === SyntaxKind.ClassDeclaration) {
                 bindBlockScopedDeclaration(node, SymbolFlags.Class, SymbolFlags.ClassExcludes);
@@ -1467,7 +1535,7 @@ namespace ts {
 
                         // unreachable code is reported if
                         // - user has explicitly asked about it AND
-                        // - statement is in not ambient context (statements in ambient context is already an error 
+                        // - statement is in not ambient context (statements in ambient context is already an error
                         //   so we should not report extras) AND
                         //   - node is not variable statement OR
                         //   - node is block scoped variable statement OR

src/compiler/commandLineParser.ts

@@ -284,6 +284,11 @@ namespace ts {
             name: "allowSyntheticDefaultImports",
             type: "boolean",
             description: Diagnostics.Allow_default_imports_from_modules_with_no_default_export
+        },
+        {
+            name: "allowJs",
+            type: "boolean",
+            description: Diagnostics.Allow_javascript_files_to_be_compiled
         }
     ];
 
@@ -479,9 +484,10 @@ namespace ts {
       * @param basePath A root directory to resolve relative path entries in the config
       *    file to. e.g. outDir
       */
-    export function parseJsonConfigFileContent(json: any, host: ParseConfigHost, basePath: string): ParsedCommandLine {
-        const { options, errors } = convertCompilerOptionsFromJson(json["compilerOptions"], basePath);
+    export function parseJsonConfigFileContent(json: any, host: ParseConfigHost, basePath: string, existingOptions: CompilerOptions = {}): ParsedCommandLine {
+        const { options: optionsFromJsonConfigFile, errors } = convertCompilerOptionsFromJson(json["compilerOptions"], basePath);
 
+        const options = extend(existingOptions, optionsFromJsonConfigFile);
         return {
             options,
             fileNames: getFileNames(),
@@ -499,23 +505,32 @@ namespace ts {
                 }
             }
             else {
+                const filesSeen: Map<boolean> = {};
                 const exclude = json["exclude"] instanceof Array ? map(<string[]>json["exclude"], normalizeSlashes) : undefined;
-                const sysFiles = host.readDirectory(basePath, ".ts", exclude).concat(host.readDirectory(basePath, ".tsx", exclude));
-                for (let i = 0; i < sysFiles.length; i++) {
-                    const name = sysFiles[i];
-                    if (fileExtensionIs(name, ".d.ts")) {
-                        const baseName = name.substr(0, name.length - ".d.ts".length);
-                        if (!contains(sysFiles, baseName + ".tsx") && !contains(sysFiles, baseName + ".ts")) {
-                            fileNames.push(name);
+                const supportedExtensions = getSupportedExtensions(options);
+                Debug.assert(indexOf(supportedExtensions, ".ts") < indexOf(supportedExtensions, ".d.ts"), "Changed priority of extensions to pick");
+
+                // Get files of supported extensions in their order of resolution
+                for (const extension of supportedExtensions) {
+                    const filesInDirWithExtension = host.readDirectory(basePath, extension, exclude);
+                    for (const fileName of filesInDirWithExtension) {
+                        // .ts extension would read the .d.ts extension files too but since .d.ts is lower priority extension, 
+                        // lets pick them when its turn comes up
+                        if (extension === ".ts" && fileExtensionIs(fileName, ".d.ts")) {
+                            continue;
                         }
-                    }
-                    else if (fileExtensionIs(name, ".ts")) {
-                        if (!contains(sysFiles, name + "x")) {
-                            fileNames.push(name);
+
+                        // If this is one of the output extension (which would be .d.ts and .js if we are allowing compilation of js files)
+                        // do not include this file if we included .ts or .tsx file with same base name as it could be output of the earlier compilation
+                        if (extension === ".d.ts" || (options.allowJs && contains(supportedJavascriptExtensions, extension))) {
+                            const baseName = fileName.substr(0, fileName.length - extension.length);
+                            if (hasProperty(filesSeen, baseName + ".ts") || hasProperty(filesSeen, baseName + ".tsx")) {
+                                continue;
+                            }
                         }
-                    }
-                    else {
-                        fileNames.push(name);
+
+                        filesSeen[fileName] = true;
+                        fileNames.push(fileName);
                     }
                 }
             }

src/compiler/core.ts

@@ -297,8 +297,8 @@ namespace ts {
         return <T>result;
     }
 
-    export function extend<T1, T2>(first: Map<T1>, second: Map<T2>): Map<T1 & T2> {
-        const result: Map<T1 & T2> = {};
+    export function extend<T1 extends Map<{}>, T2 extends Map<{}>>(first: T1 , second: T2): T1 & T2 {
+        const result: T1 & T2 = <any>{};
         for (const id in first) {
             (result as any)[id] = first[id];
         }
@@ -714,7 +714,7 @@ namespace ts {
     }
 
     export function getBaseFileName(path: string) {
-        if (!path) {
+        if (path === undefined) {
             return undefined;
         }
         const i = path.lastIndexOf(directorySeparator);
@@ -738,18 +738,18 @@ namespace ts {
     /**
      *  List of supported extensions in order of file resolution precedence.
      */
-    export const supportedExtensions = [".ts", ".tsx", ".d.ts"];
-    /**
-     *  List of extensions that will be used to look for external modules.
-     *  This list is kept separate from supportedExtensions to for cases when we'll allow to include .js files in compilation,
-     *  but still would like to load only TypeScript files as modules 
-     */
-    export const moduleFileExtensions = supportedExtensions;
+    export const supportedTypeScriptExtensions = [".ts", ".tsx", ".d.ts"];
+    export const supportedJavascriptExtensions = [".js", ".jsx"];
+    const allSupportedExtensions  = supportedTypeScriptExtensions.concat(supportedJavascriptExtensions);
 
-    export function isSupportedSourceFileName(fileName: string) {
+    export function getSupportedExtensions(options?: CompilerOptions): string[] {
+        return options && options.allowJs ? allSupportedExtensions : supportedTypeScriptExtensions;
+    }
+
+    export function isSupportedSourceFileName(fileName: string, compilerOptions?: CompilerOptions) {
         if (!fileName) { return false; }
 
-        for (const extension of supportedExtensions) {
+        for (const extension of getSupportedExtensions(compilerOptions)) {
             if (fileExtensionIs(fileName, extension)) {
                 return true;
             }
@@ -847,7 +847,7 @@ namespace ts {
         }
 
         export function fail(message?: string): void {
-            Debug.assert(false, message);
+            Debug.assert(/*expression*/ false, message);
         }
     }
 

src/compiler/declarationEmitter.ts

@@ -31,13 +31,17 @@ namespace ts {
     }
 
     export function getDeclarationDiagnostics(host: EmitHost, resolver: EmitResolver, targetSourceFile: SourceFile): Diagnostic[] {
-        const diagnostics: Diagnostic[] = [];
-        const jsFilePath = getOwnEmitOutputFilePath(targetSourceFile, host, ".js");
-        emitDeclarations(host, resolver, diagnostics, jsFilePath, targetSourceFile);
-        return diagnostics;
+        const declarationDiagnostics = createDiagnosticCollection();
+        forEachExpectedEmitFile(host, getDeclarationDiagnosticsFromFile, targetSourceFile);
+        return declarationDiagnostics.getDiagnostics(targetSourceFile.fileName);
+
+        function getDeclarationDiagnosticsFromFile({ declarationFilePath }, sources: SourceFile[], isBundledEmit: boolean) {
+            emitDeclarations(host, resolver, declarationDiagnostics, declarationFilePath, sources, isBundledEmit);
+        }
     }
 
-    function emitDeclarations(host: EmitHost, resolver: EmitResolver, diagnostics: Diagnostic[], jsFilePath: string, root?: SourceFile): DeclarationEmit {
+    function emitDeclarations(host: EmitHost, resolver: EmitResolver, emitterDiagnostics: DiagnosticCollection, declarationFilePath: string,
+        sourceFiles: SourceFile[], isBundledEmit: boolean): DeclarationEmit {
         const newLine = host.getNewLine();
         const compilerOptions = host.getCompilerOptions();
 
@@ -58,8 +62,9 @@ namespace ts {
         let errorNameNode: DeclarationName;
         const emitJsDocComments = compilerOptions.removeComments ? function (declaration: Node) { } : writeJsDocComments;
         const emit = compilerOptions.stripInternal ? stripInternal : emitNode;
+        let noDeclare: boolean;
 
-        const moduleElementDeclarationEmitInfo: ModuleElementDeclarationEmitInfo[] = [];
+        let moduleElementDeclarationEmitInfo: ModuleElementDeclarationEmitInfo[] = [];
         let asynchronousSubModuleDeclarationEmitInfo: ModuleElementDeclarationEmitInfo[];
 
         // Contains the reference paths that needs to go in the declaration file.
@@ -67,71 +72,78 @@ namespace ts {
         // and we could be collecting these paths from multiple files into single one with --out option
         let referencePathsOutput = "";
 
-        if (root) {
-            // Emitting just a single file, so emit references in this file only
+        // Emit references corresponding to each file
+        const emittedReferencedFiles: SourceFile[] = [];
+        let addedGlobalFileReference = false;
+        let allSourcesModuleElementDeclarationEmitInfo: ModuleElementDeclarationEmitInfo[] = [];
+        forEach(sourceFiles, sourceFile => {
+            // Dont emit for javascript file
+            if (isSourceFileJavaScript(sourceFile)) {
+                return;
+            }
+
+            // Check what references need to be added
             if (!compilerOptions.noResolve) {
-                let addedGlobalFileReference = false;
-                forEach(root.referencedFiles, fileReference => {
-                    const referencedFile = tryResolveScriptReference(host, root, fileReference);
+                forEach(sourceFile.referencedFiles, fileReference => {
+                    const referencedFile = tryResolveScriptReference(host, sourceFile, fileReference);
 
-                    // All the references that are not going to be part of same file
-                    if (referencedFile && ((referencedFile.flags & NodeFlags.DeclarationFile) || // This is a declare file reference
-                        shouldEmitToOwnFile(referencedFile, compilerOptions) || // This is referenced file is emitting its own js file
-                        !addedGlobalFileReference)) { // Or the global out file corresponding to this reference was not added
-
-                        writeReferencePath(referencedFile);
-                        if (!isExternalModuleOrDeclarationFile(referencedFile)) {
+                    // Emit reference in dts, if the file reference was not already emitted
+                    if (referencedFile && !contains(emittedReferencedFiles, referencedFile)) {
+                        // Add a reference to generated dts file,
+                        // global file reference is added only 
+                        //  - if it is not bundled emit (because otherwise it would be self reference)
+                        //  - and it is not already added
+                        if (writeReferencePath(referencedFile, !isBundledEmit && !addedGlobalFileReference)) {
                             addedGlobalFileReference = true;
                         }
+                        emittedReferencedFiles.push(referencedFile);
                     }
                 });
             }
 
-            emitSourceFile(root);
+            if (!isBundledEmit || !isExternalModule(sourceFile)) {
+                noDeclare = false;
+                emitSourceFile(sourceFile);
+            }
+            else if (isExternalModule(sourceFile)) {
+                noDeclare = true;
+                write(`declare module "${getResolvedExternalModuleName(host, sourceFile)}" {`);
+                writeLine();
+                increaseIndent();
+                emitSourceFile(sourceFile);
+                decreaseIndent();
+                write("}");
+                writeLine();
+            }
 
             // create asynchronous output for the importDeclarations
             if (moduleElementDeclarationEmitInfo.length) {
                 const oldWriter = writer;
                 forEach(moduleElementDeclarationEmitInfo, aliasEmitInfo => {
-                    if (aliasEmitInfo.isVisible) {
+                    if (aliasEmitInfo.isVisible && !aliasEmitInfo.asynchronousOutput) {
                         Debug.assert(aliasEmitInfo.node.kind === SyntaxKind.ImportDeclaration);
                         createAndSetNewTextWriterWithSymbolWriter();
-                        Debug.assert(aliasEmitInfo.indent === 0);
+                        Debug.assert(aliasEmitInfo.indent === 0 || (aliasEmitInfo.indent === 1 && isBundledEmit));
+                        for (let i = 0; i < aliasEmitInfo.indent; i++) {
+                            increaseIndent();
+                        }
                         writeImportDeclaration(<ImportDeclaration>aliasEmitInfo.node);
                         aliasEmitInfo.asynchronousOutput = writer.getText();
+                        for (let i = 0; i < aliasEmitInfo.indent; i++) {
+                            decreaseIndent();
+                        }
                     }
                 });
                 setWriter(oldWriter);
+
+                allSourcesModuleElementDeclarationEmitInfo = allSourcesModuleElementDeclarationEmitInfo.concat(moduleElementDeclarationEmitInfo);
+                moduleElementDeclarationEmitInfo = [];
             }
-        }
-        else {
-            // Emit references corresponding to this file
-            const emittedReferencedFiles: SourceFile[] = [];
-            forEach(host.getSourceFiles(), sourceFile => {
-                if (!isExternalModuleOrDeclarationFile(sourceFile)) {
-                    // Check what references need to be added
-                    if (!compilerOptions.noResolve) {
-                        forEach(sourceFile.referencedFiles, fileReference => {
-                            const referencedFile = tryResolveScriptReference(host, sourceFile, fileReference);
-
-                            // If the reference file is a declaration file or an external module, emit that reference
-                            if (referencedFile && (isExternalModuleOrDeclarationFile(referencedFile) &&
-                                !contains(emittedReferencedFiles, referencedFile))) { // If the file reference was not already emitted
-
-                                writeReferencePath(referencedFile);
-                                emittedReferencedFiles.push(referencedFile);
-                            }
-                        });
-                    }
-
-                    emitSourceFile(sourceFile);
-                }
-            });
-        }
+        });
 
         return {
             reportedDeclarationError,
-            moduleElementDeclarationEmitInfo,
+            moduleElementDeclarationEmitInfo: allSourcesModuleElementDeclarationEmitInfo,
             synchronousDeclarationOutput: writer.getText(),
             referencePathsOutput,
         };
@@ -243,14 +255,14 @@ namespace ts {
                 const errorInfo = writer.getSymbolAccessibilityDiagnostic(symbolAccesibilityResult);
                 if (errorInfo) {
                     if (errorInfo.typeName) {
-                        diagnostics.push(createDiagnosticForNode(symbolAccesibilityResult.errorNode || errorInfo.errorNode,
+                        emitterDiagnostics.add(createDiagnosticForNode(symbolAccesibilityResult.errorNode || errorInfo.errorNode,
                             errorInfo.diagnosticMessage,
                             getTextOfNodeFromSourceText(currentText, errorInfo.typeName),
                             symbolAccesibilityResult.errorSymbolName,
                             symbolAccesibilityResult.errorModuleName));
                     }
                     else {
-                        diagnostics.push(createDiagnosticForNode(symbolAccesibilityResult.errorNode || errorInfo.errorNode,
+                        emitterDiagnostics.add(createDiagnosticForNode(symbolAccesibilityResult.errorNode || errorInfo.errorNode,
                             errorInfo.diagnosticMessage,
                             symbolAccesibilityResult.errorSymbolName,
                             symbolAccesibilityResult.errorModuleName));
@@ -265,7 +277,8 @@ namespace ts {
 
         function reportInaccessibleThisError() {
             if (errorNameNode) {
-                diagnostics.push(createDiagnosticForNode(errorNameNode, Diagnostics.The_inferred_type_of_0_references_an_inaccessible_this_type_A_type_annotation_is_necessary,
+                reportedDeclarationError = true;
+                emitterDiagnostics.add(createDiagnosticForNode(errorNameNode, Diagnostics.The_inferred_type_of_0_references_an_inaccessible_this_type_A_type_annotation_is_necessary,
                     declarationNameToString(errorNameNode)));
             }
         }
@@ -343,7 +356,7 @@ namespace ts {
                 case SyntaxKind.BooleanKeyword:
                 case SyntaxKind.SymbolKeyword:
                 case SyntaxKind.VoidKeyword:
-                case SyntaxKind.ThisKeyword:
+                case SyntaxKind.ThisType:
                 case SyntaxKind.StringLiteral:
                     return writeTextOfNode(currentText, type);
                 case SyntaxKind.ExpressionWithTypeArguments:
@@ -607,7 +620,7 @@ namespace ts {
                 if (node.flags & NodeFlags.Default) {
                     write("default ");
                 }
-                else if (node.kind !== SyntaxKind.InterfaceDeclaration) {
+                else if (node.kind !== SyntaxKind.InterfaceDeclaration && !noDeclare) {
                     write("declare ");
                 }
             }
@@ -702,11 +715,25 @@ namespace ts {
                 }
                 write(" from ");
             }
-            writeTextOfNode(currentText, node.moduleSpecifier);
+            emitExternalModuleSpecifier(node.moduleSpecifier);
             write(";");
             writer.writeLine();
         }
 
+        function emitExternalModuleSpecifier(moduleSpecifier: Expression) {
+            if (moduleSpecifier.kind === SyntaxKind.StringLiteral && isBundledEmit) {
+                const moduleName = getExternalModuleNameFromDeclaration(host, resolver, moduleSpecifier.parent as (ImportEqualsDeclaration | ImportDeclaration | ExportDeclaration));
+                if (moduleName) {
+                    write("\"");
+                    write(moduleName);
+                    write("\"");
+                    return;
+                }
+            }
+
+            writeTextOfNode(currentText, moduleSpecifier);
+        }
+
         function emitImportOrExportSpecifier(node: ImportOrExportSpecifier) {
             if (node.propertyName) {
                 writeTextOfNode(currentText, node.propertyName);
@@ -738,7 +765,7 @@ namespace ts {
             }
             if (node.moduleSpecifier) {
                 write(" from ");
-                writeTextOfNode(currentText, node.moduleSpecifier);
+                emitExternalModuleSpecifier(node.moduleSpecifier);
             }
             write(";");
             writer.writeLine();
@@ -1594,34 +1621,58 @@ namespace ts {
             }
         }
 
-        function writeReferencePath(referencedFile: SourceFile) {
-            let declFileName = referencedFile.flags & NodeFlags.DeclarationFile
-                ? referencedFile.fileName // Declaration file, use declaration file name
-                : shouldEmitToOwnFile(referencedFile, compilerOptions)
-                    ? getOwnEmitOutputFilePath(referencedFile, host, ".d.ts") // Own output file so get the .d.ts file
-                    : removeFileExtension(compilerOptions.outFile || compilerOptions.out) + ".d.ts"; // Global out file
+        /**
+         * Adds the reference to referenced file, returns true if global file reference was emitted
+         * @param referencedFile
+         * @param addBundledFileReference Determines if global file reference corresponding to bundled file should be emitted or not
+         */
+        function writeReferencePath(referencedFile: SourceFile, addBundledFileReference: boolean): boolean {
+            let declFileName: string;
+            let addedBundledEmitReference = false;
+            if (isDeclarationFile(referencedFile)) {
+                // Declaration file, use declaration file name
+                declFileName = referencedFile.fileName;
+            }
+            else {
+                // Get the declaration file path
+                forEachExpectedEmitFile(host, getDeclFileName, referencedFile);
+            }
 
-            declFileName = getRelativePathToDirectoryOrUrl(
-                getDirectoryPath(normalizeSlashes(jsFilePath)),
-                declFileName,
-                host.getCurrentDirectory(),
-                host.getCanonicalFileName,
-            /*isAbsolutePathAnUrl*/ false);
+            if (declFileName) {
+                declFileName = getRelativePathToDirectoryOrUrl(
+                    getDirectoryPath(normalizeSlashes(declarationFilePath)),
+                    declFileName,
+                    host.getCurrentDirectory(),
+                    host.getCanonicalFileName,
+                    /*isAbsolutePathAnUrl*/ false);
 
-            referencePathsOutput += "/// <reference path=\"" + declFileName + "\" />" + newLine;
+                referencePathsOutput += "/// <reference path=\"" + declFileName + "\" />" + newLine;
+            }
+            return addedBundledEmitReference;
+
+            function getDeclFileName(emitFileNames: EmitFileNames, sourceFiles: SourceFile[], isBundledEmit: boolean) {
+                // Dont add reference path to this file if it is a bundled emit and caller asked not emit bundled file path
+                if (isBundledEmit && !addBundledFileReference) {
+                    return;
+                }
+
+                Debug.assert(!!emitFileNames.declarationFilePath || isSourceFileJavaScript(referencedFile), "Declaration file is not present only for javascript files");
+                declFileName = emitFileNames.declarationFilePath || emitFileNames.jsFilePath;
+                addedBundledEmitReference = isBundledEmit;
+            }
         }
     }
 
     /* @internal */
-    export function writeDeclarationFile(jsFilePath: string, sourceFile: SourceFile, host: EmitHost, resolver: EmitResolver, diagnostics: Diagnostic[]) {
-        const emitDeclarationResult = emitDeclarations(host, resolver, diagnostics, jsFilePath, sourceFile);
-        // TODO(shkamat): Should we not write any declaration file if any of them can produce error,
-        // or should we just not write this file like we are doing now
-        if (!emitDeclarationResult.reportedDeclarationError) {
+    export function writeDeclarationFile(declarationFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean, host: EmitHost, resolver: EmitResolver, emitterDiagnostics: DiagnosticCollection) {
+        const emitDeclarationResult = emitDeclarations(host, resolver, emitterDiagnostics, declarationFilePath, sourceFiles, isBundledEmit);
+        const emitSkipped = emitDeclarationResult.reportedDeclarationError || host.isEmitBlocked(declarationFilePath);
+        if (!emitSkipped) {
             const declarationOutput = emitDeclarationResult.referencePathsOutput
                 + getDeclarationOutput(emitDeclarationResult.synchronousDeclarationOutput, emitDeclarationResult.moduleElementDeclarationEmitInfo);
-            writeFile(host, diagnostics, removeFileExtension(jsFilePath) + ".d.ts", declarationOutput, host.getCompilerOptions().emitBOM);
+            writeFile(host, emitterDiagnostics, declarationFilePath, declarationOutput, host.getCompilerOptions().emitBOM);
         }
+        return emitSkipped;
 
         function getDeclarationOutput(synchronousDeclarationOutput: string, moduleElementDeclarationEmitInfo: ModuleElementDeclarationEmitInfo[]) {
             let appliedSyncOutputPos = 0;

src/compiler/diagnosticMessages.json

@@ -2060,6 +2060,14 @@
         "category": "Error",
         "code": 5054
     },
+    "Cannot write file '{0}' because it would overwrite input file.": {
+        "category": "Error",
+        "code": 5055
+    },
+    "Cannot write file '{0}' because it would be overwritten by multiple input files.": {
+        "category": "Error",
+        "code": 5056
+    },
 
     "Concatenate and emit output to single file.": {
         "category": "Message",
@@ -2314,7 +2322,6 @@
         "category": "Message",
         "code": 6078
     },
-
     "Specify JSX code generation: 'preserve' or 'react'": {
         "category": "Message",
         "code": 6080
@@ -2323,6 +2330,14 @@
         "category": "Message",
         "code": 6081
     },
+    "Only 'amd' and 'system' modules are supported alongside --{0}.": {
+        "category": "Error",
+        "code": 6082
+    },
+    "Allow javascript files to be compiled.": {
+        "category": "Message",
+        "code": 6083
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",

src/compiler/emitter.ts

@@ -3,8 +3,16 @@
 
 /* @internal */
 namespace ts {
-    export function isExternalModuleOrDeclarationFile(sourceFile: SourceFile) {
-        return isExternalModule(sourceFile) || isDeclarationFile(sourceFile);
+    export function getResolvedExternalModuleName(host: EmitHost, file: SourceFile): string {
+        return file.moduleName || getExternalModuleNameFromPath(host, file.fileName);
+    }
+
+    export function getExternalModuleNameFromDeclaration(host: EmitHost, resolver: EmitResolver, declaration: ImportEqualsDeclaration | ImportDeclaration | ExportDeclaration): string {
+        const file = resolver.getExternalModuleFileFromDeclaration(declaration);
+        if (!file || isDeclarationFile(file)) {
+            return undefined;
+        }
+        return getResolvedExternalModuleName(host, file);
     }
 
     type DependencyGroup = Array<ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration>;
@@ -325,45 +333,19 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 };`;
 
         const compilerOptions = host.getCompilerOptions();
-        const languageVersion = compilerOptions.target || ScriptTarget.ES3;
-        const modulekind = compilerOptions.module ? compilerOptions.module : languageVersion === ScriptTarget.ES6 ? ModuleKind.ES6 : ModuleKind.None;
+        const languageVersion = getEmitScriptTarget(compilerOptions);
+        const modulekind = getEmitModuleKind(compilerOptions);
         const sourceMapDataList: SourceMapData[] = compilerOptions.sourceMap || compilerOptions.inlineSourceMap ? [] : undefined;
-        let diagnostics: Diagnostic[] = [];
+        const emitterDiagnostics = createDiagnosticCollection();
+        let emitSkipped = false;
         const newLine = host.getNewLine();
-        const jsxDesugaring = host.getCompilerOptions().jsx !== JsxEmit.Preserve;
-        const shouldEmitJsx = (s: SourceFile) => (s.languageVariant === LanguageVariant.JSX && !jsxDesugaring);
 
         const emitJavaScript = createFileEmitter();
-
-        if (targetSourceFile === undefined) {
-            forEach(host.getSourceFiles(), sourceFile => {
-                if (shouldEmitToOwnFile(sourceFile, compilerOptions)) {
-                    const jsFilePath = getOwnEmitOutputFilePath(sourceFile, host, shouldEmitJsx(sourceFile) ? ".jsx" : ".js");
-                    emitFile(jsFilePath, sourceFile);
-                }
-            });
-
-            if (compilerOptions.outFile || compilerOptions.out) {
-                emitFile(compilerOptions.outFile || compilerOptions.out);
-            }
-        }
-        else {
-            // targetSourceFile is specified (e.g calling emitter from language service or calling getSemanticDiagnostic from language service)
-            if (shouldEmitToOwnFile(targetSourceFile, compilerOptions)) {
-                const jsFilePath = getOwnEmitOutputFilePath(targetSourceFile, host, shouldEmitJsx(targetSourceFile) ? ".jsx" : ".js");
-                emitFile(jsFilePath, targetSourceFile);
-            }
-            else if (!isDeclarationFile(targetSourceFile) && (compilerOptions.outFile || compilerOptions.out)) {
-                emitFile(compilerOptions.outFile || compilerOptions.out);
-            }
-        }
-
-        // Sort and make the unique list of diagnostics
-        diagnostics = sortAndDeduplicateDiagnostics(diagnostics);
+        forEachExpectedEmitFile(host, emitFile, targetSourceFile);
 
         return {
-            emitSkipped: false,
-            diagnostics,
+            emitSkipped,
+            diagnostics: emitterDiagnostics.getDiagnostics(),
             sourceMaps: sourceMapDataList
         };
 
@@ -414,7 +396,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
              * var loop = function(x) { <code where 'arguments' is replaced witg 'arguments_1'> }
              * var arguments_1 = arguments
              * for (var x;;) loop(x);
-             * otherwise semantics of the code will be different since 'arguments' inside converted loop body 
+             * otherwise semantics of the code will be different since 'arguments' inside converted loop body
              * will refer to function that holds converted loop.
              * This value is set on demand.
              */
@@ -422,10 +404,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
             /*
              * list of non-block scoped variable declarations that appear inside converted loop
-             * such variable declarations should be moved outside the loop body 
+             * such variable declarations should be moved outside the loop body
              * for (let x;;) {
              *     var y = 1;
-             *     ... 
+             *     ...
              * }
              * should be converted to
              * var loop = function(x) {
@@ -472,8 +454,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             }
         }
 
-        function createFileEmitter(): (jsFilePath: string, root?: SourceFile) => void {
-            const writer: EmitTextWriter = createTextWriter(newLine);
+        function createFileEmitter(): (jsFilePath: string, sourceMapFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean) => void {
+            const writer = createTextWriter(newLine);
             const { write, writeTextOfNode, writeLine, increaseIndent, decreaseIndent } = writer;
 
             let currentSourceFile: SourceFile;
@@ -502,7 +484,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             let decorateEmitted: boolean;
             let paramEmitted: boolean;
             let awaiterEmitted: boolean;
-            let tempFlags: TempFlags;
+            let tempFlags: TempFlags = 0;
             let tempVariables: Identifier[];
             let tempParameters: Identifier[];
             let externalImports: (ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration)[];
@@ -545,10 +527,13 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             /** Sourcemap data that will get encoded */
             let sourceMapData: SourceMapData;
 
+            /** Is the file being emitted into its own file */
+            let isOwnFileEmit: boolean;
+
             /** If removeComments is true, no leading-comments needed to be emitted **/
             const emitLeadingCommentsOfPosition = compilerOptions.removeComments ? function (pos: number) { } : emitLeadingCommentsOfPositionWorker;
 
-            const moduleEmitDelegates: Map<(node: SourceFile) => void> = {
+            const moduleEmitDelegates: Map<(node: SourceFile, emitRelativePathAsModuleName?: boolean) => void> = {
                 [ModuleKind.ES6]: emitES6Module,
                 [ModuleKind.AMD]: emitAMDModule,
                 [ModuleKind.System]: emitSystemModule,
@@ -556,20 +541,47 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 [ModuleKind.CommonJS]: emitCommonJSModule,
             };
 
+            const bundleEmitDelegates: Map<(node: SourceFile, emitRelativePathAsModuleName?: boolean) => void> = {
+                [ModuleKind.ES6]() {},
+                [ModuleKind.AMD]: emitAMDModule,
+                [ModuleKind.System]: emitSystemModule,
+                [ModuleKind.UMD]() {},
+                [ModuleKind.CommonJS]() {},
+            };
+
+
             return doEmit;
 
-            function doEmit(jsFilePath: string, root?: SourceFile) {
+            function doEmit(jsFilePath: string, sourceMapFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean) {
+                generatedNameSet = {};
+                nodeToGeneratedName = [];
+                isOwnFileEmit = !isBundledEmit;
+
+                if (compilerOptions.sourceMap || compilerOptions.inlineSourceMap) {
+                    initializeEmitterWithSourceMaps(jsFilePath, sourceMapFilePath, sourceFiles, isBundledEmit);
+                }
+
+                // Emit helpers from all the files
+                if (isBundledEmit && modulekind) {
+                    forEach(sourceFiles, emitEmitHelpers);
+                }
+
+                // Do not call emit directly. It does not set the currentSourceFile.
+                forEach(sourceFiles, emitSourceFile);
+
+                writeLine();
+                writeEmittedFiles(writer.getText(), jsFilePath, /*writeByteOrderMark*/ compilerOptions.emitBOM);
+
                 // reset the state
                 writer.reset();
                 currentSourceFile = undefined;
                 currentText = undefined;
                 currentLineMap = undefined;
                 exportFunctionForFile = undefined;
-                generatedNameSet = {};
-                nodeToGeneratedName = [];
+                generatedNameSet = undefined;
+                nodeToGeneratedName = undefined;
                 computedPropertyNamesToGeneratedNames = undefined;
                 convertedLoopState = undefined;
-
                 extendsEmitted = false;
                 decorateEmitted = false;
                 paramEmitted = false;
@@ -586,25 +598,6 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 isEs6Module = false;
                 renamedDependencies = undefined;
                 isCurrentFileExternalModule = false;
-
-                if (compilerOptions.sourceMap || compilerOptions.inlineSourceMap) {
-                    initializeEmitterWithSourceMaps(jsFilePath, root);
-                }
-
-                if (root) {
-                    // Do not call emit directly. It does not set the currentSourceFile.
-                    emitSourceFile(root);
-                }
-                else {
-                    forEach(host.getSourceFiles(), sourceFile => {
-                        if (!isExternalModuleOrDeclarationFile(sourceFile)) {
-                            emitSourceFile(sourceFile);
-                        }
-                    });
-                }
-
-                writeLine();
-                writeEmittedFiles(writer.getText(), jsFilePath, /*writeByteOrderMark*/ compilerOptions.emitBOM);
             }
 
             function emitSourceFile(sourceFile: SourceFile): void {
@@ -715,7 +708,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 return nodeToGeneratedName[id] || (nodeToGeneratedName[id] = unescapeIdentifier(generateNameForNode(node)));
             }
 
-            function initializeEmitterWithSourceMaps(jsFilePath: string, root?: SourceFile) {
+            function initializeEmitterWithSourceMaps(jsFilePath: string, sourceMapFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean) {
                 let sourceMapDir: string; // The directory in which sourcemap will be
 
                 // Current source map file and its index in the sources list
@@ -1016,24 +1009,23 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     if (compilerOptions.inlineSourceMap) {
                         // Encode the sourceMap into the sourceMap url
                         const base64SourceMapText = convertToBase64(sourceMapText);
-                        sourceMapUrl = `//# sourceMappingURL=data:application/json;base64,${base64SourceMapText}`;
+                        sourceMapData.jsSourceMappingURL = `data:application/json;base64,${base64SourceMapText}`;
                     }
                     else {
                         // Write source map file
-                        writeFile(host, diagnostics, sourceMapData.sourceMapFilePath, sourceMapText, /*writeByteOrderMark*/ false);
-                        sourceMapUrl = `//# sourceMappingURL=${sourceMapData.jsSourceMappingURL}`;
+                        writeFile(host, emitterDiagnostics, sourceMapData.sourceMapFilePath, sourceMapText, /*writeByteOrderMark*/ false);
                     }
+                    sourceMapUrl = `//# sourceMappingURL=${sourceMapData.jsSourceMappingURL}`;
 
                     // Write sourcemap url to the js file and write the js file
                     writeJavaScriptFile(emitOutput + sourceMapUrl, jsFilePath, writeByteOrderMark);
                 }
 
                 // Initialize source map data
-                const sourceMapJsFile = getBaseFileName(normalizeSlashes(jsFilePath));
                 sourceMapData = {
-                    sourceMapFilePath: jsFilePath + ".map",
-                    jsSourceMappingURL: sourceMapJsFile + ".map",
-                    sourceMapFile: sourceMapJsFile,
+                    sourceMapFilePath: sourceMapFilePath,
+                    jsSourceMappingURL: !compilerOptions.inlineSourceMap ? getBaseFileName(normalizeSlashes(sourceMapFilePath)) : undefined,
+                    sourceMapFile: getBaseFileName(normalizeSlashes(jsFilePath)),
                     sourceMapSourceRoot: compilerOptions.sourceRoot || "",
                     sourceMapSources: [],
                     inputSourceFileNames: [],
@@ -1052,10 +1044,11 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
                 if (compilerOptions.mapRoot) {
                     sourceMapDir = normalizeSlashes(compilerOptions.mapRoot);
-                    if (root) { // emitting single module file
+                    if (!isBundledEmit) { // emitting single module file
+                        Debug.assert(sourceFiles.length === 1);
                         // For modules or multiple emit files the mapRoot will have directory structure like the sources
                         // So if src\a.ts and src\lib\b.ts are compiled together user would be moving the maps into mapRoot\a.js.map and mapRoot\lib\b.js.map
-                        sourceMapDir = getDirectoryPath(getSourceFilePathInNewDir(root, host, sourceMapDir));
+                        sourceMapDir = getDirectoryPath(getSourceFilePathInNewDir(sourceFiles[0], host, sourceMapDir));
                     }
 
                     if (!isRootedDiskPath(sourceMapDir) && !isUrl(sourceMapDir)) {
@@ -1108,7 +1101,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             }
 
             function writeJavaScriptFile(emitOutput: string, jsFilePath: string, writeByteOrderMark: boolean) {
-                writeFile(host, diagnostics, jsFilePath, emitOutput, writeByteOrderMark);
+                writeFile(host, emitterDiagnostics, jsFilePath, emitOutput, writeByteOrderMark);
             }
 
             // Create a temporary variable with a unique unused name.
@@ -1263,7 +1256,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
             function emitCommaList(nodes: Node[]) {
                 if (nodes) {
-                    emitList(nodes, 0, nodes.length, /*multiline*/ false, /*trailingComma*/ false);
+                    emitList(nodes, 0, nodes.length, /*multiLine*/ false, /*trailingComma*/ false);
                 }
             }
 
@@ -1563,13 +1556,13 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 /// these emit into an object literal property name, we don't need to be worried
                 /// about keywords, just non-identifier characters
                 function emitAttributeName(name: Identifier) {
-                    if (/[A-Za-z_]+[\w*]/.test(name.text)) {
-                        write("\"");
+                    if (/^[A-Za-z_]\w*$/.test(name.text)) {
                         emit(name);
-                        write("\"");
                     }
                     else {
+                        write("\"");
                         emit(name);
+                        write("\"");
                     }
                 }
 
@@ -2162,7 +2155,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 }
                 else if (languageVersion >= ScriptTarget.ES6 || !forEach(elements, isSpreadElementExpression)) {
                     write("[");
-                    emitLinePreservingList(node, node.elements, elements.hasTrailingComma, /*spacesBetweenBraces:*/ false);
+                    emitLinePreservingList(node, node.elements, elements.hasTrailingComma, /*spacesBetweenBraces*/ false);
                     write("]");
                 }
                 else {
@@ -2186,7 +2179,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     // then try to preserve the original shape of the object literal.
                     // Otherwise just try to preserve the formatting.
                     if (numElements === properties.length) {
-                        emitLinePreservingList(node, properties, /* allowTrailingComma */ languageVersion >= ScriptTarget.ES5, /* spacesBetweenBraces */ true);
+                        emitLinePreservingList(node, properties, /*allowTrailingComma*/ languageVersion >= ScriptTarget.ES5, /*spacesBetweenBraces*/ true);
                     }
                     else {
                         const multiLine = (node.flags & NodeFlags.MultiLine) !== 0;
@@ -2461,7 +2454,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 //       let obj = { y };
                 //   }
                 // Here we need to emit obj = { y : m.y } regardless of the output target.
-                if (languageVersion < ScriptTarget.ES6 || isNamespaceExportReference(node.name)) {
+                if (modulekind !== ModuleKind.ES6 || isNamespaceExportReference(node.name)) {
                     // Emit identifier as an identifier
                     write(": ");
                     emit(node.name);
@@ -2736,7 +2729,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     write(".bind.apply(");
                     emit(target);
                     write(", [void 0].concat(");
-                    emitListWithSpread(node.arguments, /*needsUniqueCopy*/ false, /*multiline*/ false, /*trailingComma*/ false, /*useConcat*/ false);
+                    emitListWithSpread(node.arguments, /*needsUniqueCopy*/ false, /*multiLine*/ false, /*trailingComma*/ false, /*useConcat*/ false);
                     write(")))");
                     write("()");
                 }
@@ -2953,7 +2946,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
                         synthesizedLHS = <ElementAccessExpression>createSynthesizedNode(SyntaxKind.ElementAccessExpression, /*startsOnNewLine*/ false);
 
-                        const identifier = emitTempVariableAssignment(leftHandSideExpression.expression, /*canDefinedTempVariablesInPlaces*/ false, /*shouldEmitCommaBeforeAssignment*/ false);
+                        const identifier = emitTempVariableAssignment(leftHandSideExpression.expression, /*canDefineTempVariablesInPlace*/ false, /*shouldEmitCommaBeforeAssignment*/ false);
                         synthesizedLHS.expression = identifier;
 
                         if (leftHandSideExpression.argumentExpression.kind !== SyntaxKind.NumericLiteral &&
@@ -2972,7 +2965,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                         write("(");
                         synthesizedLHS = <PropertyAccessExpression>createSynthesizedNode(SyntaxKind.PropertyAccessExpression, /*startsOnNewLine*/ false);
 
-                        const identifier = emitTempVariableAssignment(leftHandSideExpression.expression, /*canDefinedTempVariablesInPlaces*/ false, /*shouldemitCommaBeforeAssignment*/ false);
+                        const identifier = emitTempVariableAssignment(leftHandSideExpression.expression, /*canDefineTempVariablesInPlace*/ false, /*shouldEmitCommaBeforeAssignment*/ false);
                         synthesizedLHS.expression = identifier;
 
                         (<PropertyAccessExpression>synthesizedLHS).dotToken = leftHandSideExpression.dotToken;
@@ -3152,10 +3145,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             function emitDoStatementWorker(node: DoStatement, loop: ConvertedLoop) {
                 write("do");
                 if (loop) {
-                    emitConvertedLoopCall(loop, /* emitAsBlock */ true);
+                    emitConvertedLoopCall(loop, /*emitAsBlock*/ true);
                 }
                 else {
-                    emitNormalLoopBody(node, /* emitAsEmbeddedStatement */ true);
+                    emitNormalLoopBody(node, /*emitAsEmbeddedStatement*/ true);
                 }
                 if (node.statement.kind === SyntaxKind.Block) {
                     write(" ");
@@ -3178,10 +3171,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 write(")");
 
                 if (loop) {
-                    emitConvertedLoopCall(loop, /* emitAsBlock */ true);
+                    emitConvertedLoopCall(loop, /*emitAsBlock*/ true);
                 }
                 else {
-                    emitNormalLoopBody(node, /* emitAsEmbeddedStatement */ true);
+                    emitNormalLoopBody(node, /*emitAsEmbeddedStatement*/ true);
                 }
             }
 
@@ -3197,7 +3190,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 }
 
                 if (convertedLoopState && (getCombinedNodeFlags(decl) & NodeFlags.BlockScoped) === 0) {
-                    // we are inside a converted loop - this can only happen in downlevel scenarios 
+                    // we are inside a converted loop - this can only happen in downlevel scenarios
                     // record names for all variable declarations
                     for (const varDecl of decl.declarations) {
                         hoistVariableDeclarationFromLoop(convertedLoopState, varDecl);
@@ -3503,8 +3496,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     write(`switch(${loopResultVariable}) {`);
                     increaseIndent();
 
-                    emitDispatchEntriesForLabeledJumps(currentLoop.labeledNonLocalBreaks, /* isBreak */ true, loopResultVariable, outerLoop);
-                    emitDispatchEntriesForLabeledJumps(currentLoop.labeledNonLocalContinues, /* isBreak */ false, loopResultVariable, outerLoop);
+                    emitDispatchEntriesForLabeledJumps(currentLoop.labeledNonLocalBreaks, /*isBreak*/ true, loopResultVariable, outerLoop);
+                    emitDispatchEntriesForLabeledJumps(currentLoop.labeledNonLocalContinues, /*isBreak*/ false, loopResultVariable, outerLoop);
 
                     decreaseIndent();
                     writeLine();
@@ -3522,7 +3515,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                         write(`case "${labelMarker}": `);
                         // if there are no outer converted loop or outer label in question is located inside outer converted loop
                         // then emit labeled break\continue
-                        // otherwise propagate pair 'label -> marker' to outer converted loop and emit 'return labelMarker' so outer loop can later decide what to do  
+                        // otherwise propagate pair 'label -> marker' to outer converted loop and emit 'return labelMarker' so outer loop can later decide what to do
                         if (!outerLoop || (outerLoop.labels && outerLoop.labels[labelText])) {
                             if (isBreak) {
                                 write("break ");
@@ -3568,10 +3561,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 write(")");
 
                 if (loop) {
-                    emitConvertedLoopCall(loop, /* emitAsBlock */ true);
+                    emitConvertedLoopCall(loop, /*emitAsBlock*/ true);
                 }
                 else {
-                    emitNormalLoopBody(node, /* emitAsEmbeddedStatement */ true);
+                    emitNormalLoopBody(node, /*emitAsEmbeddedStatement*/ true);
                 }
             }
 
@@ -3609,10 +3602,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 emitToken(SyntaxKind.CloseParenToken, node.expression.end);
 
                 if (loop) {
-                    emitConvertedLoopCall(loop, /* emitAsBlock */ true);
+                    emitConvertedLoopCall(loop, /*emitAsBlock*/ true);
                 }
                 else {
-                    emitNormalLoopBody(node, /* emitAsEmbeddedStatement */ true);
+                    emitNormalLoopBody(node, /*emitAsEmbeddedStatement*/ true);
                 }
             }
 
@@ -3752,10 +3745,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
                 if (loop) {
                     writeLine();
-                    emitConvertedLoopCall(loop, /* emitAsBlock */ false);
+                    emitConvertedLoopCall(loop, /*emitAsBlock*/ false);
                 }
                 else {
-                    emitNormalLoopBody(node, /* emitAsEmbeddedStatement */ false);
+                    emitNormalLoopBody(node, /*emitAsEmbeddedStatement*/ false);
                 }
 
                 writeLine();
@@ -3789,11 +3782,11 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                             let labelMarker: string;
                             if (node.kind === SyntaxKind.BreakStatement) {
                                 labelMarker = `break-${node.label.text}`;
-                                setLabeledJump(convertedLoopState, /* isBreak */ true, node.label.text, labelMarker);
+                                setLabeledJump(convertedLoopState, /*isBreak*/ true, node.label.text, labelMarker);
                             }
                             else {
                                 labelMarker = `continue-${node.label.text}`;
-                                setLabeledJump(convertedLoopState, /* isBreak */ false, node.label.text, labelMarker);
+                                setLabeledJump(convertedLoopState, /*isBreak*/ false, node.label.text, labelMarker);
                             }
                             write(`return "${labelMarker}";`);
                         }
@@ -4215,15 +4208,22 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     return node;
                 }
 
-                function createPropertyAccessForDestructuringProperty(object: Expression, propName: Identifier | LiteralExpression): Expression {
-                    // We create a synthetic copy of the identifier in order to avoid the rewriting that might
-                    // otherwise occur when the identifier is emitted.
-                    const syntheticName = <Identifier | LiteralExpression>createSynthesizedNode(propName.kind);
-                    syntheticName.text = propName.text;
-                    if (syntheticName.kind !== SyntaxKind.Identifier) {
-                        return createElementAccessExpression(object, syntheticName);
+                function createPropertyAccessForDestructuringProperty(object: Expression, propName: PropertyName): Expression {
+                    let index: Expression;
+                    const nameIsComputed = propName.kind === SyntaxKind.ComputedPropertyName;
+                    if (nameIsComputed) {
+                        index = ensureIdentifier((<ComputedPropertyName>propName).expression, /*reuseIdentifierExpressions*/ false);
                     }
-                    return createPropertyAccessExpression(object, syntheticName);
+                    else {
+                        // We create a synthetic copy of the identifier in order to avoid the rewriting that might
+                        // otherwise occur when the identifier is emitted.
+                        index = <Identifier | LiteralExpression>createSynthesizedNode(propName.kind);
+                        (<Identifier | LiteralExpression>index).text = (<Identifier | LiteralExpression>propName).text;
+                    }
+
+                    return !nameIsComputed && index.kind === SyntaxKind.Identifier
+                        ? createPropertyAccessExpression(object, <Identifier>index)
+                        : createElementAccessExpression(object, index);
                 }
 
                 function createSliceCall(value: Expression, sliceIndex: number): CallExpression {
@@ -4967,8 +4967,10 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     increaseIndent();
                     writeLine();
                     emitLeadingComments(node.body);
+                    emitStart(body);
                     write("return ");
                     emit(body);
+                    emitEnd(body);
                     write(";");
                     emitTrailingComments(node.body);
 
@@ -5342,7 +5344,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                         emitEnd(baseTypeElement);
                     }
                 }
-                emitPropertyDeclarations(node, getInitializedProperties(node, /*static:*/ false));
+                emitPropertyDeclarations(node, getInitializedProperties(node, /*isStatic*/ false));
                 if (ctor) {
                     let statements: Node[] = (<Block>ctor.body).statements;
                     if (superCall) {
@@ -5464,7 +5466,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 //
                 // This keeps the expression as an expression, while ensuring that the static parts
                 // of it have been initialized by the time it is used.
-                const staticProperties = getInitializedProperties(node, /*static:*/ true);
+                const staticProperties = getInitializedProperties(node, /*isStatic*/ true);
                 const isClassExpressionWithStaticProperties = staticProperties.length > 0 && node.kind === SyntaxKind.ClassExpression;
                 let tempVariable: Identifier;
 
@@ -5526,7 +5528,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     for (var property of staticProperties) {
                         write(",");
                         writeLine();
-                        emitPropertyDeclaration(node, property, /*receiver:*/ tempVariable, /*isExpression:*/ true);
+                        emitPropertyDeclaration(node, property, /*receiver*/ tempVariable, /*isExpression*/ true);
                     }
                     write(",");
                     writeLine();
@@ -5600,7 +5602,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 writeLine();
                 emitConstructor(node, baseTypeNode);
                 emitMemberFunctionsForES5AndLower(node);
-                emitPropertyDeclarations(node, getInitializedProperties(node, /*static:*/ true));
+                emitPropertyDeclarations(node, getInitializedProperties(node, /*isStatic*/ true));
                 writeLine();
                 emitDecoratorsOfClass(node);
                 writeLine();
@@ -5970,6 +5972,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                         case SyntaxKind.UnionType:
                         case SyntaxKind.IntersectionType:
                         case SyntaxKind.AnyKeyword:
+                        case SyntaxKind.ThisType:
                             break;
 
                         default:
@@ -5988,9 +5991,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 }
 
                 // Clone the type name and parent it to a location outside of the current declaration.
-                const typeName = cloneEntityName(node.typeName);
-                typeName.parent = location;
-
+                const typeName = cloneEntityName(node.typeName, location);
                 const result = resolver.getTypeReferenceSerializationKind(typeName);
                 switch (result) {
                     case TypeReferenceSerializationKind.Unknown:
@@ -7297,7 +7298,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 write("}"); // execute
             }
 
-            function emitSystemModule(node: SourceFile): void {
+            function writeModuleName(node: SourceFile, emitRelativePathAsModuleName?: boolean): void {
+                let moduleName = node.moduleName;
+                if (moduleName || (emitRelativePathAsModuleName && (moduleName = getResolvedExternalModuleName(host, node)))) {
+                    write(`"${moduleName}", `);
+                }
+            }
+
+            function emitSystemModule(node: SourceFile,  emitRelativePathAsModuleName?: boolean): void {
                 collectExternalModuleInfo(node);
                 // System modules has the following shape
                 // System.register(['dep-1', ... 'dep-n'], function(exports) {/* module body function */})
@@ -7312,16 +7320,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 exportFunctionForFile = makeUniqueName("exports");
                 writeLine();
                 write("System.register(");
-                if (node.moduleName) {
-                    write(`"${node.moduleName}", `);
-                }
+                writeModuleName(node, emitRelativePathAsModuleName);
                 write("[");
 
                 const groupIndices: Map<number> = {};
                 const dependencyGroups: DependencyGroup[] = [];
 
                 for (let i = 0; i < externalImports.length; ++i) {
-                    const text = getExternalModuleNameText(externalImports[i]);
+                    let text = getExternalModuleNameText(externalImports[i]);
                     if (hasProperty(groupIndices, text)) {
                         // deduplicate/group entries in dependency list by the dependency name
                         const groupIndex = groupIndices[text];
@@ -7337,6 +7343,12 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                         write(", ");
                     }
 
+                    if (emitRelativePathAsModuleName) {
+                        const name = getExternalModuleNameFromDeclaration(host, resolver, externalImports[i]);
+                        if (name) {
+                            text = `"${name}"`;
+                        }
+                    }
                     write(text);
                 }
                 write(`], function(${exportFunctionForFile}) {`);
@@ -7357,7 +7369,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 importAliasNames: string[];
             }
 
-            function getAMDDependencyNames(node: SourceFile, includeNonAmdDependencies: boolean): AMDDependencyNames {
+            function getAMDDependencyNames(node: SourceFile, includeNonAmdDependencies: boolean, emitRelativePathAsModuleName?: boolean): AMDDependencyNames {
                 // names of modules with corresponding parameter in the factory function
                 const aliasedModuleNames: string[] = [];
                 // names of modules with no corresponding parameters in factory function
@@ -7379,7 +7391,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 
                 for (const importNode of externalImports) {
                     // Find the name of the external module
-                    const externalModuleName = getExternalModuleNameText(importNode);
+                    let externalModuleName = getExternalModuleNameText(importNode);
+
+                    if (emitRelativePathAsModuleName) {
+                        const name = getExternalModuleNameFromDeclaration(host, resolver, importNode);
+                        if (name) {
+                            externalModuleName = `"${name}"`;
+                        }
+                    }
 
                     // Find the name of the module alias, if there is one
                     const importAliasName = getLocalNameForExternalImport(importNode);
@@ -7395,7 +7414,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 return { aliasedModuleNames, unaliasedModuleNames, importAliasNames };
             }
 
-            function emitAMDDependencies(node: SourceFile, includeNonAmdDependencies: boolean) {
+            function emitAMDDependencies(node: SourceFile, includeNonAmdDependencies: boolean, emitRelativePathAsModuleName?: boolean) {
                 // An AMD define function has the following shape:
                 //     define(id?, dependencies?, factory);
                 //
@@ -7408,7 +7427,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 // `import "module"` or `<amd-dependency path= "a.css" />`
                 // we need to add modules without alias names to the end of the dependencies list
 
-                const dependencyNames = getAMDDependencyNames(node, includeNonAmdDependencies);
+                const dependencyNames = getAMDDependencyNames(node, includeNonAmdDependencies, emitRelativePathAsModuleName);
                 emitAMDDependencyList(dependencyNames);
                 write(", ");
                 emitAMDFactoryHeader(dependencyNames);
@@ -7436,16 +7455,14 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 write(") {");
             }
 
-            function emitAMDModule(node: SourceFile) {
+            function emitAMDModule(node: SourceFile, emitRelativePathAsModuleName?: boolean) {
                 emitEmitHelpers(node);
                 collectExternalModuleInfo(node);
 
                 writeLine();
                 write("define(");
-                if (node.moduleName) {
-                    write("\"" + node.moduleName + "\", ");
-                }
-                emitAMDDependencies(node, /*includeNonAmdDependencies*/ true);
+                writeModuleName(node, emitRelativePathAsModuleName);
+                emitAMDDependencies(node, /*includeNonAmdDependencies*/ true, emitRelativePathAsModuleName);
                 increaseIndent();
                 const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true);
                 emitExportStarHelper();
@@ -7694,8 +7711,13 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 emitDetachedCommentsAndUpdateCommentsInfo(node);
 
                 if (isExternalModule(node) || compilerOptions.isolatedModules) {
-                    const emitModule = moduleEmitDelegates[modulekind] || moduleEmitDelegates[ModuleKind.CommonJS];
-                    emitModule(node);
+                    if (isOwnFileEmit || (!isExternalModule(node) && compilerOptions.isolatedModules)) {
+                        const emitModule = moduleEmitDelegates[modulekind] || moduleEmitDelegates[ModuleKind.CommonJS];
+                        emitModule(node);
+                    }
+                    else {
+                        bundleEmitDelegates[modulekind](node, /*emitRelativePathAsModuleName*/true);
+                    }
                 }
                 else {
                     // emit prologue directives prior to __extends
@@ -8035,11 +8057,11 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
              * Emit comments associated with node that will not be emitted into JS file
              */
             function emitCommentsOnNotEmittedNode(node: Node) {
-                emitLeadingCommentsWorker(node, /*isEmittedNode:*/ false);
+                emitLeadingCommentsWorker(node, /*isEmittedNode*/ false);
             }
 
             function emitLeadingComments(node: Node) {
-                return emitLeadingCommentsWorker(node, /*isEmittedNode:*/ true);
+                return emitLeadingCommentsWorker(node, /*isEmittedNode*/ true);
             }
 
             function emitLeadingCommentsWorker(node: Node, isEmittedNode: boolean) {
@@ -8068,7 +8090,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 emitNewLineBeforeLeadingComments(currentLineMap, writer, node, leadingComments);
 
                 // Leading comments are emitted at /*leading comment1 */space/*leading comment*/space
-                emitComments(currentText, currentLineMap, writer, leadingComments, /*trailingSeparator:*/ true, newLine, writeComment);
+                emitComments(currentText, currentLineMap, writer, leadingComments, /*trailingSeparator*/ true, newLine, writeComment);
             }
 
             function emitTrailingComments(node: Node) {
@@ -8141,11 +8163,18 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             }
         }
 
-        function emitFile(jsFilePath: string, sourceFile?: SourceFile) {
-            emitJavaScript(jsFilePath, sourceFile);
+        function emitFile({ jsFilePath, sourceMapFilePath, declarationFilePath}: { jsFilePath: string, sourceMapFilePath: string, declarationFilePath: string },
+            sourceFiles: SourceFile[], isBundledEmit: boolean) {
+            // Make sure not to write js File and source map file if any of them cannot be written
+            if (!host.isEmitBlocked(jsFilePath)) {
+                emitJavaScript(jsFilePath, sourceMapFilePath, sourceFiles, isBundledEmit);
+            }
+            else {
+                emitSkipped = true;
+            }
 
-            if (compilerOptions.declaration) {
-                writeDeclarationFile(jsFilePath, sourceFile, host, resolver, diagnostics);
+            if (declarationFilePath) {
+                emitSkipped = writeDeclarationFile(declarationFilePath, sourceFiles, isBundledEmit, host, resolver, emitterDiagnostics) || emitSkipped;
             }
         }
     }

src/compiler/parser.ts

@@ -1,5 +1,5 @@
-/// <reference path="scanner.ts"/>
 /// <reference path="utilities.ts"/>
+/// <reference path="scanner.ts"/>
 
 namespace ts {
     /* @internal */ export let parseTime = 0;
@@ -534,7 +534,8 @@ namespace ts {
         let parseErrorBeforeNextFinishedNode = false;
 
         export function parseSourceFile(fileName: string, _sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor, setParentNodes?: boolean): SourceFile {
-            initializeState(fileName, _sourceText, languageVersion, _syntaxCursor);
+            const isJavaScriptFile = hasJavaScriptFileExtension(fileName) || _sourceText.lastIndexOf("// @language=javascript", 0) === 0;
+            initializeState(fileName, _sourceText, languageVersion, isJavaScriptFile, _syntaxCursor);
 
             const result = parseSourceFileWorker(fileName, languageVersion, setParentNodes);
 
@@ -543,7 +544,12 @@ namespace ts {
             return result;
         }
 
-        function initializeState(fileName: string, _sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor) {
+        function getLanguageVariant(fileName: string) {
+            // .tsx and .jsx files are treated as jsx language variant.
+            return fileExtensionIs(fileName, ".tsx") || fileExtensionIs(fileName, ".jsx") ?  LanguageVariant.JSX  : LanguageVariant.Standard;
+        }
+
+        function initializeState(fileName: string, _sourceText: string, languageVersion: ScriptTarget, isJavaScriptFile: boolean, _syntaxCursor: IncrementalParser.SyntaxCursor) {
             NodeConstructor = objectAllocator.getNodeConstructor();
             SourceFileConstructor = objectAllocator.getSourceFileConstructor();
 
@@ -556,14 +562,14 @@ namespace ts {
             identifierCount = 0;
             nodeCount = 0;
 
-            contextFlags = isJavaScript(fileName) ? ParserContextFlags.JavaScriptFile : ParserContextFlags.None;
+            contextFlags = isJavaScriptFile ? ParserContextFlags.JavaScriptFile : ParserContextFlags.None;
             parseErrorBeforeNextFinishedNode = false;
 
             // Initialize and prime the scanner before parsing the source elements.
             scanner.setText(sourceText);
             scanner.setOnError(scanError);
             scanner.setScriptTarget(languageVersion);
-            scanner.setLanguageVariant(isTsx(fileName) ? LanguageVariant.JSX : LanguageVariant.Standard);
+            scanner.setLanguageVariant(getLanguageVariant(fileName));
         }
 
         function clearState() {
@@ -582,6 +588,10 @@ namespace ts {
         function parseSourceFileWorker(fileName: string, languageVersion: ScriptTarget, setParentNodes: boolean): SourceFile {
             sourceFile = createSourceFile(fileName, languageVersion);
 
+            if (contextFlags & ParserContextFlags.JavaScriptFile) {
+                sourceFile.parserContextFlags = ParserContextFlags.JavaScriptFile;
+            }
+
             // Prime the scanner.
             token = nextToken();
             processReferenceComments(sourceFile);
@@ -604,7 +614,7 @@ namespace ts {
             // If this is a javascript file, proactively see if we can get JSDoc comments for
             // relevant nodes in the file.  We'll use these to provide typing informaion if they're
             // available.
-            if (isJavaScript(fileName)) {
+            if (isSourceFileJavaScript(sourceFile)) {
                 addJSDocComments();
             }
 
@@ -677,7 +687,7 @@ namespace ts {
             sourceFile.languageVersion = languageVersion;
             sourceFile.fileName = normalizePath(fileName);
             sourceFile.flags = fileExtensionIs(sourceFile.fileName, ".d.ts") ? NodeFlags.DeclarationFile : 0;
-            sourceFile.languageVariant = isTsx(sourceFile.fileName) ? LanguageVariant.JSX : LanguageVariant.Standard;
+            sourceFile.languageVariant = getLanguageVariant(sourceFile.fileName);
 
             return sourceFile;
         }
@@ -717,10 +727,10 @@ namespace ts {
             const contextFlagsToClear = context & contextFlags;
             if (contextFlagsToClear) {
                 // clear the requested context flags
-                setContextFlag(false, contextFlagsToClear);
+                setContextFlag(/*val*/ false, contextFlagsToClear);
                 const result = func();
                 // restore the context flags we just cleared
-                setContextFlag(true, contextFlagsToClear);
+                setContextFlag(/*val*/ true, contextFlagsToClear);
                 return result;
             }
 
@@ -738,10 +748,10 @@ namespace ts {
             const contextFlagsToSet = context & ~contextFlags;
             if (contextFlagsToSet) {
                 // set the requested context flags
-                setContextFlag(true, contextFlagsToSet);
+                setContextFlag(/*val*/ true, contextFlagsToSet);
                 const result = func();
                 // reset the context flags we just set
-                setContextFlag(false, contextFlagsToSet);
+                setContextFlag(/*val*/ false, contextFlagsToSet);
                 return result;
             }
 
@@ -1082,7 +1092,7 @@ namespace ts {
                 token === SyntaxKind.NumericLiteral;
         }
 
-        function parsePropertyNameWorker(allowComputedPropertyNames: boolean): DeclarationName {
+        function parsePropertyNameWorker(allowComputedPropertyNames: boolean): PropertyName {
             if (token === SyntaxKind.StringLiteral || token === SyntaxKind.NumericLiteral) {
                 return parseLiteralNode(/*internName*/ true);
             }
@@ -1092,12 +1102,12 @@ namespace ts {
             return parseIdentifierName();
         }
 
-        function parsePropertyName(): DeclarationName {
-            return parsePropertyNameWorker(/*allowComputedPropertyNames:*/ true);
+        function parsePropertyName(): PropertyName {
+            return parsePropertyNameWorker(/*allowComputedPropertyNames*/ true);
         }
 
         function parseSimplePropertyName(): Identifier | LiteralExpression {
-            return <Identifier | LiteralExpression>parsePropertyNameWorker(/*allowComputedPropertyNames:*/ false);
+            return <Identifier | LiteralExpression>parsePropertyNameWorker(/*allowComputedPropertyNames*/ false);
         }
 
         function isSimplePropertyName() {
@@ -1152,7 +1162,7 @@ namespace ts {
         }
 
         function parseAnyContextualModifier(): boolean {
-            return isModifier(token) && tryParse(nextTokenCanFollowModifier);
+            return isModifierKind(token) && tryParse(nextTokenCanFollowModifier);
         }
 
         function canFollowModifier(): boolean {
@@ -1202,7 +1212,7 @@ namespace ts {
                 case ParsingContext.ObjectLiteralMembers:
                     return token === SyntaxKind.OpenBracketToken || token === SyntaxKind.AsteriskToken || isLiteralPropertyName();
                 case ParsingContext.ObjectBindingElements:
-                    return isLiteralPropertyName();
+                    return token === SyntaxKind.OpenBracketToken || isLiteralPropertyName();
                 case ParsingContext.HeritageClauseElement:
                     // If we see { } then only consume it as an expression if it is followed by , or {
                     // That way we won't consume the body of a class in its heritage clause.
@@ -1380,7 +1390,7 @@ namespace ts {
         function isInSomeParsingContext(): boolean {
             for (let kind = 0; kind < ParsingContext.Count; kind++) {
                 if (parsingContext & (1 << kind)) {
-                    if (isListElement(kind, /* inErrorRecovery */ true) || isListTerminator(kind)) {
+                    if (isListElement(kind, /*inErrorRecovery*/ true) || isListTerminator(kind)) {
                         return true;
                     }
                 }
@@ -1397,7 +1407,7 @@ namespace ts {
             result.pos = getNodePos();
 
             while (!isListTerminator(kind)) {
-                if (isListElement(kind, /* inErrorRecovery */ false)) {
+                if (isListElement(kind, /*inErrorRecovery*/ false)) {
                     const element = parseListElement(kind, parseElement);
                     result.push(element);
 
@@ -1746,7 +1756,7 @@ namespace ts {
 
             let commaStart = -1; // Meaning the previous token was not a comma
             while (true) {
-                if (isListElement(kind, /* inErrorRecovery */ false)) {
+                if (isListElement(kind, /*inErrorRecovery*/ false)) {
                     result.push(parseListElement(kind, parseElement));
                     commaStart = scanner.getTokenPos();
                     if (parseOptional(SyntaxKind.CommaToken)) {
@@ -1854,7 +1864,7 @@ namespace ts {
                     // Report that we need an identifier.  However, report it right after the dot,
                     // and not on the next token.  This is because the next token might actually
                     // be an identifier and the error would be quite confusing.
-                    return <Identifier>createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentToken*/ true, Diagnostics.Identifier_expected);
+                    return <Identifier>createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentPosition*/ true, Diagnostics.Identifier_expected);
                 }
             }
 
@@ -1951,6 +1961,12 @@ namespace ts {
             return finishNode(node);
         }
 
+        function parseThisTypeNode(): TypeNode {
+            const node = <TypeNode>createNode(SyntaxKind.ThisType);
+            nextToken();
+            return finishNode(node);
+        }
+
         function parseTypeQuery(): TypeQueryNode {
             const node = <TypeQueryNode>createNode(SyntaxKind.TypeQuery);
             parseExpected(SyntaxKind.TypeOfKeyword);
@@ -1992,16 +2008,14 @@ namespace ts {
 
         function parseParameterType(): TypeNode {
             if (parseOptional(SyntaxKind.ColonToken)) {
-                return token === SyntaxKind.StringLiteral
-                    ? <StringLiteral>parseLiteralNode(/*internName*/ true)
-                    : parseType();
+                return parseType();
             }
 
             return undefined;
         }
 
         function isStartOfParameter(): boolean {
-            return token === SyntaxKind.DotDotDotToken || isIdentifierOrPattern() || isModifier(token) || token === SyntaxKind.AtToken;
+            return token === SyntaxKind.DotDotDotToken || isIdentifierOrPattern() || isModifierKind(token) || token === SyntaxKind.AtToken;
         }
 
         function setModifiers(node: Node, modifiers: ModifiersArray) {
@@ -2022,7 +2036,7 @@ namespace ts {
 
             node.name = parseIdentifierOrPattern();
 
-            if (getFullWidth(node.name) === 0 && node.flags === 0 && isModifier(token)) {
+            if (getFullWidth(node.name) === 0 && node.flags === 0 && isModifierKind(token)) {
                 // in cases like
                 // 'use strict'
                 // function foo(static)
@@ -2129,8 +2143,8 @@ namespace ts {
             parseSemicolon();
         }
 
-        function parseSignatureMember(kind: SyntaxKind): SignatureDeclaration {
-            const node = <SignatureDeclaration>createNode(kind);
+        function parseSignatureMember(kind: SyntaxKind): CallSignatureDeclaration | ConstructSignatureDeclaration {
+            const node = <CallSignatureDeclaration | ConstructSignatureDeclaration>createNode(kind);
             if (kind === SyntaxKind.ConstructSignature) {
                 parseExpected(SyntaxKind.NewKeyword);
             }
@@ -2169,7 +2183,7 @@ namespace ts {
                 return true;
             }
 
-            if (isModifier(token)) {
+            if (isModifierKind(token)) {
                 nextToken();
                 if (isIdentifier()) {
                     return true;
@@ -2212,13 +2226,13 @@ namespace ts {
             return finishNode(node);
         }
 
-        function parsePropertyOrMethodSignature(): Declaration {
+        function parsePropertyOrMethodSignature(): PropertySignature | MethodSignature {
             const fullStart = scanner.getStartPos();
             const name = parsePropertyName();
             const questionToken = parseOptionalToken(SyntaxKind.QuestionToken);
 
             if (token === SyntaxKind.OpenParenToken || token === SyntaxKind.LessThanToken) {
-                const method = <MethodDeclaration>createNode(SyntaxKind.MethodSignature, fullStart);
+                const method = <MethodSignature>createNode(SyntaxKind.MethodSignature, fullStart);
                 method.name = name;
                 method.questionToken = questionToken;
 
@@ -2229,7 +2243,7 @@ namespace ts {
                 return finishNode(method);
             }
             else {
-                const property = <PropertyDeclaration>createNode(SyntaxKind.PropertySignature, fullStart);
+                const property = <PropertySignature>createNode(SyntaxKind.PropertySignature, fullStart);
                 property.name = name;
                 property.questionToken = questionToken;
                 property.type = parseTypeAnnotation();
@@ -2245,7 +2259,7 @@ namespace ts {
                 case SyntaxKind.OpenBracketToken: // Both for indexers and computed properties
                     return true;
                 default:
-                    if (isModifier(token)) {
+                    if (isModifierKind(token)) {
                         const result = lookAhead(isStartOfIndexSignatureDeclaration);
                         if (result) {
                             return result;
@@ -2257,7 +2271,7 @@ namespace ts {
         }
 
         function isStartOfIndexSignatureDeclaration() {
-            while (isModifier(token)) {
+            while (isModifierKind(token)) {
                 nextToken();
             }
 
@@ -2273,7 +2287,7 @@ namespace ts {
                 canParseSemicolon();
         }
 
-        function parseTypeMember(): Declaration {
+        function parseTypeMember(): TypeElement {
             switch (token) {
                 case SyntaxKind.OpenParenToken:
                 case SyntaxKind.LessThanToken:
@@ -2298,7 +2312,7 @@ namespace ts {
                     // when incrementally parsing as the parser will produce the Index declaration
                     // if it has the same text regardless of whether it is inside a class or an
                     // object type.
-                    if (isModifier(token)) {
+                    if (isModifierKind(token)) {
                         const result = tryParse(parseIndexSignatureWithModifiers);
                         if (result) {
                             return result;
@@ -2331,14 +2345,14 @@ namespace ts {
             return finishNode(node);
         }
 
-        function parseObjectTypeMembers(): NodeArray<Declaration> {
-            let members: NodeArray<Declaration>;
+        function parseObjectTypeMembers(): NodeArray<TypeElement> {
+            let members: NodeArray<TypeElement>;
             if (parseExpected(SyntaxKind.OpenBraceToken)) {
                 members = parseList(ParsingContext.TypeMembers, parseTypeMember);
                 parseExpected(SyntaxKind.CloseBraceToken);
             }
             else {
-                members = createMissingList<Declaration>();
+                members = createMissingList<TypeElement>();
             }
 
             return members;
@@ -2382,9 +2396,12 @@ namespace ts {
                     // If these are followed by a dot, then parse these out as a dotted type reference instead.
                     const node = tryParse(parseKeywordAndNoDot);
                     return node || parseTypeReferenceOrTypePredicate();
+                case SyntaxKind.StringLiteral:
+                    return <StringLiteral>parseLiteralNode(/*internName*/ true);
                 case SyntaxKind.VoidKeyword:
-                case SyntaxKind.ThisKeyword:
                     return parseTokenNode<TypeNode>();
+                case SyntaxKind.ThisKeyword:
+                    return parseThisTypeNode();
                 case SyntaxKind.TypeOfKeyword:
                     return parseTypeQuery();
                 case SyntaxKind.OpenBraceToken:
@@ -2412,6 +2429,7 @@ namespace ts {
                 case SyntaxKind.OpenBracketToken:
                 case SyntaxKind.LessThanToken:
                 case SyntaxKind.NewKeyword:
+                case SyntaxKind.StringLiteral:
                     return true;
                 case SyntaxKind.OpenParenToken:
                     // Only consider '(' the start of a type if followed by ')', '...', an identifier, a modifier,
@@ -2477,11 +2495,11 @@ namespace ts {
                 // ( ...
                 return true;
             }
-            if (isIdentifier() || isModifier(token)) {
+            if (isIdentifier() || isModifierKind(token)) {
                 nextToken();
                 if (token === SyntaxKind.ColonToken || token === SyntaxKind.CommaToken ||
                     token === SyntaxKind.QuestionToken || token === SyntaxKind.EqualsToken ||
-                    isIdentifier() || isModifier(token)) {
+                    isIdentifier() || isModifierKind(token)) {
                     // ( id :
                     // ( id ,
                     // ( id ?
@@ -2603,7 +2621,7 @@ namespace ts {
             // clear the decorator context when parsing Expression, as it should be unambiguous when parsing a decorator
             const saveDecoratorContext = inDecoratorContext();
             if (saveDecoratorContext) {
-                setDecoratorContext(false);
+                setDecoratorContext(/*val*/ false);
             }
 
             let expr = parseAssignmentExpressionOrHigher();
@@ -2613,7 +2631,7 @@ namespace ts {
             }
 
             if (saveDecoratorContext) {
-                setDecoratorContext(true);
+                setDecoratorContext(/*val*/ true);
             }
             return expr;
         }
@@ -2767,7 +2785,7 @@ namespace ts {
             node.parameters.pos = parameter.pos;
             node.parameters.end = parameter.end;
 
-            node.equalsGreaterThanToken = parseExpectedToken(SyntaxKind.EqualsGreaterThanToken, false, Diagnostics._0_expected, "=>");
+            node.equalsGreaterThanToken = parseExpectedToken(SyntaxKind.EqualsGreaterThanToken, /*reportAtCurrentPosition*/ false, Diagnostics._0_expected, "=>");
             node.body = parseArrowFunctionExpressionBody(/*isAsync*/ false);
 
             return finishNode(node);
@@ -2888,7 +2906,7 @@ namespace ts {
                 }
 
                 // This *could* be a parenthesized arrow function.
-                // Return Unknown to const the caller know.
+                // Return Unknown to let the caller know.
                 return Tristate.Unknown;
             }
             else {
@@ -2987,7 +3005,7 @@ namespace ts {
                 // user meant to supply a block. For example, if the user wrote:
                 //
                 //  a =>
-                //      const v = 0;
+                //      let v = 0;
                 //  }
                 //
                 // they may be missing an open brace.  Check to see if that's the case so we can
@@ -3214,7 +3232,7 @@ namespace ts {
 
         /**
          * Parse ES7 unary expression and await expression
-         * 
+         *
          * ES7 UnaryExpression:
          *      1) SimpleUnaryExpression[?yield]
          *      2) IncrementExpression[?yield] ** UnaryExpression[?yield]
@@ -3567,7 +3585,7 @@ namespace ts {
                     parseExpected(SyntaxKind.GreaterThanToken);
                 }
                 else {
-                    parseExpected(SyntaxKind.GreaterThanToken, /*diagnostic*/ undefined, /*advance*/ false);
+                    parseExpected(SyntaxKind.GreaterThanToken, /*diagnostic*/ undefined, /*shouldAdvance*/ false);
                     scanJsxText();
                 }
                 node = <JsxSelfClosingElement>createNode(SyntaxKind.JsxSelfClosingElement, fullStart);
@@ -3603,7 +3621,7 @@ namespace ts {
                 parseExpected(SyntaxKind.CloseBraceToken);
             }
             else {
-                parseExpected(SyntaxKind.CloseBraceToken, /*message*/ undefined, /*advance*/ false);
+                parseExpected(SyntaxKind.CloseBraceToken, /*message*/ undefined, /*shouldAdvance*/ false);
                 scanJsxText();
             }
 
@@ -3648,7 +3666,7 @@ namespace ts {
                 parseExpected(SyntaxKind.GreaterThanToken);
             }
             else {
-                parseExpected(SyntaxKind.GreaterThanToken, /*diagnostic*/ undefined, /*advance*/ false);
+                parseExpected(SyntaxKind.GreaterThanToken, /*diagnostic*/ undefined, /*shouldAdvance*/ false);
                 scanJsxText();
             }
             return finishNode(node);
@@ -3967,7 +3985,7 @@ namespace ts {
             //      function BindingIdentifier[opt](FormalParameters){ FunctionBody }
             const saveDecoratorContext = inDecoratorContext();
             if (saveDecoratorContext) {
-                setDecoratorContext(false);
+                setDecoratorContext(/*val*/ false);
             }
 
             const node = <FunctionExpression>createNode(SyntaxKind.FunctionExpression);
@@ -3987,7 +4005,7 @@ namespace ts {
             node.body = parseFunctionBlock(/*allowYield*/ isGenerator, /*allowAwait*/ isAsync, /*ignoreMissingOpenBrace*/ false);
 
             if (saveDecoratorContext) {
-                setDecoratorContext(true);
+                setDecoratorContext(/*val*/ true);
             }
 
             return finishNode(node);
@@ -4033,13 +4051,13 @@ namespace ts {
             // arrow function. The body of the function is not in [Decorator] context.
             const saveDecoratorContext = inDecoratorContext();
             if (saveDecoratorContext) {
-                setDecoratorContext(false);
+                setDecoratorContext(/*val*/ false);
             }
 
             const block = parseBlock(ignoreMissingOpenBrace, diagnosticMessage);
 
             if (saveDecoratorContext) {
-                setDecoratorContext(true);
+                setDecoratorContext(/*val*/ true);
             }
 
             setYieldContext(savedYieldContext);
@@ -4581,7 +4599,6 @@ namespace ts {
 
         function parseObjectBindingElement(): BindingElement {
             const node = <BindingElement>createNode(SyntaxKind.BindingElement);
-            // TODO(andersh): Handle computed properties
             const tokenIsIdentifier = isIdentifier();
             const propertyName = parsePropertyName();
             if (tokenIsIdentifier && token !== SyntaxKind.ColonToken) {
@@ -4589,7 +4606,7 @@ namespace ts {
             }
             else {
                 parseExpected(SyntaxKind.ColonToken);
-                node.propertyName = <Identifier>propertyName;
+                node.propertyName = propertyName;
                 node.name = parseIdentifierOrPattern();
             }
             node.initializer = parseBindingElementInitializer(/*inParameter*/ false);
@@ -4715,7 +4732,7 @@ namespace ts {
             return finishNode(node);
         }
 
-        function parseMethodDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: ModifiersArray, asteriskToken: Node, name: DeclarationName, questionToken: Node, diagnosticMessage?: DiagnosticMessage): MethodDeclaration {
+        function parseMethodDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: ModifiersArray, asteriskToken: Node, name: PropertyName, questionToken: Node, diagnosticMessage?: DiagnosticMessage): MethodDeclaration {
             const method = <MethodDeclaration>createNode(SyntaxKind.MethodDeclaration, fullStart);
             method.decorators = decorators;
             setModifiers(method, modifiers);
@@ -4729,7 +4746,7 @@ namespace ts {
             return finishNode(method);
         }
 
-        function parsePropertyDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: ModifiersArray, name: DeclarationName, questionToken: Node): ClassElement {
+        function parsePropertyDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: ModifiersArray, name: PropertyName, questionToken: Node): ClassElement {
             const property = <PropertyDeclaration>createNode(SyntaxKind.PropertyDeclaration, fullStart);
             property.decorators = decorators;
             setModifiers(property, modifiers);
@@ -4803,7 +4820,7 @@ namespace ts {
             }
 
             // Eat up all modifiers, but hold on to the last one in case it is actually an identifier.
-            while (isModifier(token)) {
+            while (isModifierKind(token)) {
                 idToken = token;
                 // If the idToken is a class modifier (protected, private, public, and static), it is
                 // certain that we are starting to parse class member. This allows better error recovery
@@ -5013,8 +5030,8 @@ namespace ts {
             // implements is a future reserved word so
             // 'class implements' might mean either
             // - class expression with omitted name, 'implements' starts heritage clause
-            // - class with name 'implements' 
-            // 'isImplementsClause' helps to disambiguate between these two cases 
+            // - class with name 'implements'
+            // 'isImplementsClause' helps to disambiguate between these two cases
             return isIdentifier() && !isImplementsClause()
                 ? parseIdentifier()
                 : undefined;
@@ -5518,7 +5535,7 @@ namespace ts {
             }
 
             export function parseJSDocTypeExpressionForTests(content: string, start: number, length: number) {
-                initializeState("file.js", content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined);
+                initializeState("file.js", content, ScriptTarget.Latest, /*isJavaScriptFile*/ true, /*_syntaxCursor:*/ undefined);
                 const jsDocTypeExpression = parseJSDocTypeExpression(start, length);
                 const diagnostics = parseDiagnostics;
                 clearState();
@@ -5629,6 +5646,7 @@ namespace ts {
                         return parseTokenNode<JSDocType>();
                 }
 
+                // TODO (drosen): Parse string literal types in JSDoc as well.
                 return parseJSDocTypeReference();
             }
 
@@ -5838,7 +5856,7 @@ namespace ts {
             }
 
             export function parseIsolatedJSDocComment(content: string, start: number, length: number) {
-                initializeState("file.js", content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined);
+                initializeState("file.js", content, ScriptTarget.Latest, /*isJavaScriptFile*/ true, /*_syntaxCursor:*/ undefined);
                 const jsDocComment = parseJSDocComment(/*parent:*/ undefined, start, length);
                 const diagnostics = parseDiagnostics;
                 clearState();
@@ -6156,7 +6174,7 @@ namespace ts {
             if (sourceFile.statements.length === 0) {
                 // If we don't have any statements in the current source file, then there's no real
                 // way to incrementally parse.  So just do a full parse instead.
-                return Parser.parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion, /*syntaxCursor*/ undefined, /*setNodeParents*/ true);
+                return Parser.parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion, /*syntaxCursor*/ undefined, /*setParentNodes*/ true);
             }
 
             // Make sure we're not trying to incrementally update a source file more than once.  Once
@@ -6220,7 +6238,7 @@ namespace ts {
             // inconsistent tree.  Setting the parents on the new tree should be very fast.  We
             // will immediately bail out of walking any subtrees when we can see that their parents
             // are already correct.
-            const result = Parser.parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion, syntaxCursor, /* setParentNode */ true);
+            const result = Parser.parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion, syntaxCursor, /*setParentNodes*/ true);
 
             return result;
         }

src/compiler/program.ts

@@ -14,10 +14,10 @@ namespace ts {
 
     export const version = "1.8.0";
 
-    export function findConfigFile(searchPath: string): string {
+    export function findConfigFile(searchPath: string, fileExists: (fileName: string) => boolean): string {
         let fileName = "tsconfig.json";
         while (true) {
-            if (sys.fileExists(fileName)) {
+            if (fileExists(fileName)) {
                 return fileName;
             }
             const parentPath = getDirectoryPath(searchPath);
@@ -42,24 +42,24 @@ namespace ts {
             : compilerOptions.module === ModuleKind.CommonJS ? ModuleResolutionKind.NodeJs : ModuleResolutionKind.Classic;
 
         switch (moduleResolution) {
-            case ModuleResolutionKind.NodeJs: return nodeModuleNameResolver(moduleName, containingFile, host);
+            case ModuleResolutionKind.NodeJs: return nodeModuleNameResolver(moduleName, containingFile, compilerOptions, host);
             case ModuleResolutionKind.Classic: return classicNameResolver(moduleName, containingFile, compilerOptions, host);
         }
     }
 
-    export function nodeModuleNameResolver(moduleName: string, containingFile: string, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
+    export function nodeModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
         const containingDirectory = getDirectoryPath(containingFile);
-
+        const supportedExtensions = getSupportedExtensions(compilerOptions);
         if (getRootLength(moduleName) !== 0 || nameStartsWithDotSlashOrDotDotSlash(moduleName)) {
             const failedLookupLocations: string[] = [];
             const candidate = normalizePath(combinePaths(containingDirectory, moduleName));
-            let resolvedFileName = loadNodeModuleFromFile(candidate, failedLookupLocations, host);
+            let resolvedFileName = loadNodeModuleFromFile(supportedExtensions, candidate, failedLookupLocations, host);
 
             if (resolvedFileName) {
                 return { resolvedModule: { resolvedFileName }, failedLookupLocations };
             }
 
-            resolvedFileName = loadNodeModuleFromDirectory(candidate, failedLookupLocations, host);
+            resolvedFileName = loadNodeModuleFromDirectory(supportedExtensions, candidate, failedLookupLocations, host);
             return resolvedFileName
                 ? { resolvedModule: { resolvedFileName }, failedLookupLocations }
                 : { resolvedModule: undefined, failedLookupLocations };
@@ -69,8 +69,8 @@ namespace ts {
         }
     }
 
-    function loadNodeModuleFromFile(candidate: string, failedLookupLocation: string[], host: ModuleResolutionHost): string {
-        return forEach(moduleFileExtensions, tryLoad);
+    function loadNodeModuleFromFile(extensions: string[], candidate: string, failedLookupLocation: string[], host: ModuleResolutionHost): string {
+        return forEach(extensions, tryLoad);
 
         function tryLoad(ext: string): string {
             const fileName = fileExtensionIs(candidate, ext) ? candidate : candidate + ext;
@@ -84,7 +84,7 @@ namespace ts {
         }
     }
 
-    function loadNodeModuleFromDirectory(candidate: string, failedLookupLocation: string[], host: ModuleResolutionHost): string {
+    function loadNodeModuleFromDirectory(extensions: string[], candidate: string, failedLookupLocation: string[], host: ModuleResolutionHost): string {
         const packageJsonPath = combinePaths(candidate, "package.json");
         if (host.fileExists(packageJsonPath)) {
 
@@ -100,7 +100,7 @@ namespace ts {
             }
 
             if (jsonContent.typings) {
-                const result = loadNodeModuleFromFile(normalizePath(combinePaths(candidate, jsonContent.typings)), failedLookupLocation, host);
+                const result = loadNodeModuleFromFile(extensions, normalizePath(combinePaths(candidate, jsonContent.typings)), failedLookupLocation, host);
                 if (result) {
                     return result;
                 }
@@ -111,7 +111,7 @@ namespace ts {
             failedLookupLocation.push(packageJsonPath);
         }
 
-        return loadNodeModuleFromFile(combinePaths(candidate, "index"), failedLookupLocation, host);
+        return loadNodeModuleFromFile(extensions, combinePaths(candidate, "index"), failedLookupLocation, host);
     }
 
     function loadModuleFromNodeModules(moduleName: string, directory: string, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
@@ -122,12 +122,13 @@ namespace ts {
             if (baseName !== "node_modules") {
                 const nodeModulesFolder = combinePaths(directory, "node_modules");
                 const candidate = normalizePath(combinePaths(nodeModulesFolder, moduleName));
-                let result = loadNodeModuleFromFile(candidate, failedLookupLocations, host);
+                // Load only typescript files irrespective of allowJs option if loading from node modules
+                let result = loadNodeModuleFromFile(supportedTypeScriptExtensions, candidate, failedLookupLocations, host);
                 if (result) {
                     return { resolvedModule: { resolvedFileName: result, isExternalLibraryImport: true }, failedLookupLocations };
                 }
 
-                result = loadNodeModuleFromDirectory(candidate, failedLookupLocations, host);
+                result = loadNodeModuleFromDirectory(supportedTypeScriptExtensions, candidate, failedLookupLocations, host);
                 if (result) {
                     return { resolvedModule: { resolvedFileName: result, isExternalLibraryImport: true }, failedLookupLocations };
                 }
@@ -162,6 +163,7 @@ namespace ts {
         const failedLookupLocations: string[] = [];
 
         let referencedSourceFile: string;
+        const supportedExtensions = getSupportedExtensions(compilerOptions);
         while (true) {
             searchName = normalizePath(combinePaths(searchPath, moduleName));
             referencedSourceFile = forEach(supportedExtensions, extension => {
@@ -284,13 +286,13 @@ namespace ts {
     }
 
     export function getPreEmitDiagnostics(program: Program, sourceFile?: SourceFile, cancellationToken?: CancellationToken): Diagnostic[] {
-        const diagnostics = program.getOptionsDiagnostics(cancellationToken).concat(
+        let diagnostics = program.getOptionsDiagnostics(cancellationToken).concat(
                           program.getSyntacticDiagnostics(sourceFile, cancellationToken),
                           program.getGlobalDiagnostics(cancellationToken),
                           program.getSemanticDiagnostics(sourceFile, cancellationToken));
 
         if (program.getCompilerOptions().declaration) {
-            diagnostics.concat(program.getDeclarationDiagnostics(sourceFile, cancellationToken));
+            diagnostics = diagnostics.concat(program.getDeclarationDiagnostics(sourceFile, cancellationToken));
         }
 
         return sortAndDeduplicateDiagnostics(diagnostics);
@@ -334,10 +336,13 @@ namespace ts {
         let classifiableNames: Map<string>;
 
         let skipDefaultLib = options.noLib;
+        const supportedExtensions = getSupportedExtensions(options);
 
         const start = new Date().getTime();
 
         host = host || createCompilerHost(options);
+        // Map storing if there is emit blocking diagnostics for given input
+        const hasEmitBlockingDiagnostics = createFileMap<boolean>(getCanonicalFileName);
 
         const currentDirectory = host.getCurrentDirectory();
         const resolveModuleNamesWorker = host.resolveModuleNames
@@ -357,29 +362,26 @@ namespace ts {
                 (oldOptions.noResolve !== options.noResolve) ||
                 (oldOptions.target !== options.target) ||
                 (oldOptions.noLib !== options.noLib) ||
-                (oldOptions.jsx !== options.jsx)) {
+                (oldOptions.jsx !== options.jsx) ||
+                (oldOptions.allowJs !== options.allowJs)) {
                 oldProgram = undefined;
             }
         }
 
         if (!tryReuseStructureFromOldProgram()) {
-            forEach(rootNames, name => processRootFile(name, false));
+            forEach(rootNames, name => processRootFile(name, /*isDefaultLib*/ false));
             // Do not process the default library if:
             //  - The '--noLib' flag is used.
             //  - A 'no-default-lib' reference comment is encountered in
             //      processing the root files.
             if (!skipDefaultLib) {
-                processRootFile(host.getDefaultLibFileName(options), true);
+                processRootFile(host.getDefaultLibFileName(options), /*isDefaultLib*/ true);
             }
         }
 
-        verifyCompilerOptions();
-
         // unconditionally set oldProgram to undefined to prevent it from being captured in closure
         oldProgram = undefined;
 
-        programTime += new Date().getTime() - start;
-
         program = {
             getRootFileNames: () => rootNames,
             getSourceFile,
@@ -402,6 +404,11 @@ namespace ts {
             getTypeCount: () => getDiagnosticsProducingTypeChecker().getTypeCount(),
             getFileProcessingDiagnostics: () => fileProcessingDiagnostics
         };
+
+        verifyCompilerOptions();
+
+        programTime += new Date().getTime() - start;
+
         return program;
 
         function getClassifiableNames() {
@@ -523,6 +530,7 @@ namespace ts {
                 getSourceFiles: program.getSourceFiles,
                 writeFile: writeFileCallback || (
                     (fileName, data, writeByteOrderMark, onError) => host.writeFile(fileName, data, writeByteOrderMark, onError)),
+                isEmitBlocked,
             };
         }
 
@@ -538,6 +546,10 @@ namespace ts {
             return runWithCancellationToken(() => emitWorker(this, sourceFile, writeFileCallback, cancellationToken));
         }
 
+        function isEmitBlocked(emitFileName: string): boolean {
+            return hasEmitBlockingDiagnostics.contains(toPath(emitFileName, currentDirectory, getCanonicalFileName));
+        }
+
         function emitWorker(program: Program, sourceFile: SourceFile, writeFileCallback: WriteFileCallback, cancellationToken: CancellationToken): EmitResult {
             // If the noEmitOnError flag is set, then check if we have any errors so far.  If so,
             // immediately bail out.  Note that we pass 'undefined' for 'sourceFile' so that we
@@ -630,6 +642,13 @@ namespace ts {
         }
 
         function getSemanticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+            // For JavaScript files, we don't want to report the normal typescript semantic errors.
+            // Instead, we just report errors for using TypeScript-only constructs from within a
+            // JavaScript file.
+            if (isSourceFileJavaScript(sourceFile)) {
+                return getJavaScriptSemanticDiagnosticsForFile(sourceFile, cancellationToken);
+            }
+
             return runWithCancellationToken(() => {
                 const typeChecker = getDiagnosticsProducingTypeChecker();
 
@@ -643,6 +662,165 @@ namespace ts {
             });
         }
 
+        function getJavaScriptSemanticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+            return runWithCancellationToken(() => {
+                const diagnostics: Diagnostic[] = [];
+                walk(sourceFile);
+
+                return diagnostics;
+
+                function walk(node: Node): boolean {
+                    if (!node) {
+                        return false;
+                    }
+
+                    switch (node.kind) {
+                        case SyntaxKind.ImportEqualsDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.import_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.ExportAssignment:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.export_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.ClassDeclaration:
+                            let classDeclaration = <ClassDeclaration>node;
+                            if (checkModifiers(classDeclaration.modifiers) ||
+                                checkTypeParameters(classDeclaration.typeParameters)) {
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.HeritageClause:
+                            let heritageClause = <HeritageClause>node;
+                            if (heritageClause.token === SyntaxKind.ImplementsKeyword) {
+                                diagnostics.push(createDiagnosticForNode(node, Diagnostics.implements_clauses_can_only_be_used_in_a_ts_file));
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.InterfaceDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.interface_declarations_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.ModuleDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.module_declarations_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.TypeAliasDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.type_aliases_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.MethodDeclaration:
+                        case SyntaxKind.MethodSignature:
+                        case SyntaxKind.Constructor:
+                        case SyntaxKind.GetAccessor:
+                        case SyntaxKind.SetAccessor:
+                        case SyntaxKind.FunctionExpression:
+                        case SyntaxKind.FunctionDeclaration:
+                        case SyntaxKind.ArrowFunction:
+                        case SyntaxKind.FunctionDeclaration:
+                            const functionDeclaration = <FunctionLikeDeclaration>node;
+                            if (checkModifiers(functionDeclaration.modifiers) ||
+                                checkTypeParameters(functionDeclaration.typeParameters) ||
+                                checkTypeAnnotation(functionDeclaration.type)) {
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.VariableStatement:
+                            const variableStatement = <VariableStatement>node;
+                            if (checkModifiers(variableStatement.modifiers)) {
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.VariableDeclaration:
+                            const variableDeclaration = <VariableDeclaration>node;
+                            if (checkTypeAnnotation(variableDeclaration.type)) {
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.CallExpression:
+                        case SyntaxKind.NewExpression:
+                            const expression = <CallExpression>node;
+                            if (expression.typeArguments && expression.typeArguments.length > 0) {
+                                const start = expression.typeArguments.pos;
+                                diagnostics.push(createFileDiagnostic(sourceFile, start, expression.typeArguments.end - start,
+                                    Diagnostics.type_arguments_can_only_be_used_in_a_ts_file));
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.Parameter:
+                            const parameter = <ParameterDeclaration>node;
+                            if (parameter.modifiers) {
+                                const start = parameter.modifiers.pos;
+                                diagnostics.push(createFileDiagnostic(sourceFile, start, parameter.modifiers.end - start,
+                                    Diagnostics.parameter_modifiers_can_only_be_used_in_a_ts_file));
+                                return true;
+                            }
+                            if (parameter.questionToken) {
+                                diagnostics.push(createDiagnosticForNode(parameter.questionToken, Diagnostics._0_can_only_be_used_in_a_ts_file, "?"));
+                                return true;
+                            }
+                            if (parameter.type) {
+                                diagnostics.push(createDiagnosticForNode(parameter.type, Diagnostics.types_can_only_be_used_in_a_ts_file));
+                                return true;
+                            }
+                            break;
+                        case SyntaxKind.PropertyDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.property_declarations_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.EnumDeclaration:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.enum_declarations_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.TypeAssertionExpression:
+                            let typeAssertionExpression = <TypeAssertion>node;
+                            diagnostics.push(createDiagnosticForNode(typeAssertionExpression.type, Diagnostics.type_assertion_expressions_can_only_be_used_in_a_ts_file));
+                            return true;
+                        case SyntaxKind.Decorator:
+                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.decorators_can_only_be_used_in_a_ts_file));
+                            return true;
+                    }
+
+                    return forEachChild(node, walk);
+                }
+
+                function checkTypeParameters(typeParameters: NodeArray<TypeParameterDeclaration>): boolean {
+                    if (typeParameters) {
+                        const start = typeParameters.pos;
+                        diagnostics.push(createFileDiagnostic(sourceFile, start, typeParameters.end - start, Diagnostics.type_parameter_declarations_can_only_be_used_in_a_ts_file));
+                        return true;
+                    }
+                    return false;
+                }
+
+                function checkTypeAnnotation(type: TypeNode): boolean {
+                    if (type) {
+                        diagnostics.push(createDiagnosticForNode(type, Diagnostics.types_can_only_be_used_in_a_ts_file));
+                        return true;
+                    }
+
+                    return false;
+                }
+
+                function checkModifiers(modifiers: ModifiersArray): boolean {
+                    if (modifiers) {
+                        for (const modifier of modifiers) {
+                            switch (modifier.kind) {
+                                case SyntaxKind.PublicKeyword:
+                                case SyntaxKind.PrivateKeyword:
+                                case SyntaxKind.ProtectedKeyword:
+                                case SyntaxKind.DeclareKeyword:
+                                    diagnostics.push(createDiagnosticForNode(modifier, Diagnostics._0_can_only_be_used_in_a_ts_file, tokenToString(modifier.kind)));
+                                    return true;
+
+                                // These are all legal modifiers.
+                                case SyntaxKind.StaticKeyword:
+                                case SyntaxKind.ExportKeyword:
+                                case SyntaxKind.ConstKeyword:
+                                case SyntaxKind.DefaultKeyword:
+                                case SyntaxKind.AbstractKeyword:
+                            }
+                        }
+                    }
+
+                    return false;
+                }
+            });
+        }
+
         function getDeclarationDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
             return runWithCancellationToken(() => {
                 if (!isDeclarationFile(sourceFile)) {
@@ -688,45 +866,60 @@ namespace ts {
                 return;
             }
 
+            const isJavaScriptFile = isSourceFileJavaScript(file);
+
             let imports: LiteralExpression[];
             for (const node of file.statements) {
-                collect(node, /* allowRelativeModuleNames */ true);
+                collect(node, /*allowRelativeModuleNames*/ true, /*collectOnlyRequireCalls*/ false);
             }
 
             file.imports = imports || emptyArray;
 
-            function collect(node: Node, allowRelativeModuleNames: boolean): void {
-                switch (node.kind) {
-                    case SyntaxKind.ImportDeclaration:
-                    case SyntaxKind.ImportEqualsDeclaration:
-                    case SyntaxKind.ExportDeclaration:
-                        let moduleNameExpr = getExternalModuleName(node);
-                        if (!moduleNameExpr || moduleNameExpr.kind !== SyntaxKind.StringLiteral) {
-                            break;
-                        }
-                        if (!(<LiteralExpression>moduleNameExpr).text) {
-                            break;
-                        }
+            return;
 
-                        if (allowRelativeModuleNames || !isExternalModuleNameRelative((<LiteralExpression>moduleNameExpr).text)) {
-                            (imports || (imports = [])).push(<LiteralExpression>moduleNameExpr);
-                        }
-                        break;
-                    case SyntaxKind.ModuleDeclaration:
-                        if ((<ModuleDeclaration>node).name.kind === SyntaxKind.StringLiteral && (node.flags & NodeFlags.Ambient || isDeclarationFile(file))) {
-                            // TypeScript 1.0 spec (April 2014): 12.1.6
-                            // An AmbientExternalModuleDeclaration declares an external module. 
-                            // This type of declaration is permitted only in the global module.
-                            // The StringLiteral must specify a top - level external module name.
-                            // Relative external module names are not permitted
-                            forEachChild((<ModuleDeclaration>node).body, node => {
+            function collect(node: Node, allowRelativeModuleNames: boolean, collectOnlyRequireCalls: boolean): void {
+                if (!collectOnlyRequireCalls) {
+                    switch (node.kind) {
+                        case SyntaxKind.ImportDeclaration:
+                        case SyntaxKind.ImportEqualsDeclaration:
+                        case SyntaxKind.ExportDeclaration:
+                            let moduleNameExpr = getExternalModuleName(node);
+                            if (!moduleNameExpr || moduleNameExpr.kind !== SyntaxKind.StringLiteral) {
+                                break;
+                            }
+                            if (!(<LiteralExpression>moduleNameExpr).text) {
+                                break;
+                            }
+
+                            if (allowRelativeModuleNames || !isExternalModuleNameRelative((<LiteralExpression>moduleNameExpr).text)) {
+                                (imports || (imports = [])).push(<LiteralExpression>moduleNameExpr);
+                            }
+                            break;
+                        case SyntaxKind.ModuleDeclaration:
+                            if ((<ModuleDeclaration>node).name.kind === SyntaxKind.StringLiteral && (node.flags & NodeFlags.Ambient || isDeclarationFile(file))) {
                                 // TypeScript 1.0 spec (April 2014): 12.1.6
-                                // An ExternalImportDeclaration in anAmbientExternalModuleDeclaration may reference other external modules 
-                                // only through top - level external module names. Relative external module names are not permitted.
-                                collect(node, /* allowRelativeModuleNames */ false);
-                            });
-                        }
-                        break;
+                                // An AmbientExternalModuleDeclaration declares an external module. 
+                                // This type of declaration is permitted only in the global module.
+                                // The StringLiteral must specify a top - level external module name.
+                                // Relative external module names are not permitted
+                                forEachChild((<ModuleDeclaration>node).body, node => {
+                                    // TypeScript 1.0 spec (April 2014): 12.1.6
+                                    // An ExternalImportDeclaration in anAmbientExternalModuleDeclaration may reference other external modules 
+                                    // only through top - level external module names. Relative external module names are not permitted.
+                                    collect(node, /*allowRelativeModuleNames*/ false, collectOnlyRequireCalls);
+                                });
+                            }
+                            break;
+                    }
+                }
+
+                if (isJavaScriptFile) {
+                    if (isRequireCall(node)) {
+                        (imports || (imports = [])).push(<StringLiteral>(<CallExpression>node).arguments[0]);
+                    }
+                    else {
+                        forEachChild(node, node => collect(node, allowRelativeModuleNames, /*collectOnlyRequireCalls*/ true));
+                    }
                 }
             }
         }
@@ -784,12 +977,12 @@ namespace ts {
         }
 
         // Get source file from normalized fileName
-        function findSourceFile(fileName: string, normalizedAbsolutePath: Path, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number): SourceFile {
-            if (filesByName.contains(normalizedAbsolutePath)) {
-                const file = filesByName.get(normalizedAbsolutePath);
+        function findSourceFile(fileName: string, path: Path, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number): SourceFile {
+            if (filesByName.contains(path)) {
+                const file = filesByName.get(path);
                 // try to check if we've already seen this file but with a different casing in path
                 // NOTE: this only makes sense for case-insensitive file systems
-                if (file && options.forceConsistentCasingInFileNames && getNormalizedAbsolutePath(file.fileName, currentDirectory) !== normalizedAbsolutePath) {
+                if (file && options.forceConsistentCasingInFileNames && getNormalizedAbsolutePath(file.fileName, currentDirectory) !== getNormalizedAbsolutePath(fileName, currentDirectory)) {
                     reportFileNamesDifferOnlyInCasingError(fileName, file.fileName, refFile, refPos, refEnd);
                 }
 
@@ -807,18 +1000,18 @@ namespace ts {
                 }
             });
 
-            filesByName.set(normalizedAbsolutePath, file);
+            filesByName.set(path, file);
             if (file) {
-                file.path = normalizedAbsolutePath;
+                file.path = path;
 
                 if (host.useCaseSensitiveFileNames()) {
                     // for case-sensitive file systems check if we've already seen some file with similar filename ignoring case
-                    const existingFile = filesByNameIgnoreCase.get(normalizedAbsolutePath);
+                    const existingFile = filesByNameIgnoreCase.get(path);
                     if (existingFile) {
                         reportFileNamesDifferOnlyInCasingError(fileName, existingFile.fileName, refFile, refPos, refEnd);
                     }
                     else {
-                        filesByNameIgnoreCase.set(normalizedAbsolutePath, file);
+                        filesByNameIgnoreCase.set(path, file);
                     }
                 }
 
@@ -833,7 +1026,6 @@ namespace ts {
                 processImportedModules(file, basePath);
 
                 if (isDefaultLib) {
-                    file.isDefaultLib = true;
                     files.unshift(file);
                 }
                 else {
@@ -847,7 +1039,7 @@ namespace ts {
         function processReferencedFiles(file: SourceFile, basePath: string) {
             forEach(file.referencedFiles, ref => {
                 const referencedFileName = resolveTripleslashReference(ref.fileName, file.fileName);
-                processSourceFile(referencedFileName, /* isDefaultLib */ false, file, ref.pos, ref.end);
+                processSourceFile(referencedFileName, /*isDefaultLib*/ false, file, ref.pos, ref.end);
             });
         }
 
@@ -865,7 +1057,7 @@ namespace ts {
                     const resolution = resolutions[i];
                     setResolvedModule(file, moduleNames[i], resolution);
                     if (resolution && !options.noResolve) {
-                        const importedFile = findSourceFile(resolution.resolvedFileName, toPath(resolution.resolvedFileName, currentDirectory, getCanonicalFileName), /* isDefaultLib */ false, file, skipTrivia(file.text, file.imports[i].pos), file.imports[i].end);
+                        const importedFile = findSourceFile(resolution.resolvedFileName, toPath(resolution.resolvedFileName, currentDirectory, getCanonicalFileName), /*isDefaultLib*/ false, file, skipTrivia(file.text, file.imports[i].pos), file.imports[i].end);
 
                         if (importedFile && resolution.isExternalLibraryImport) {
                             if (!isExternalModule(importedFile)) {
@@ -889,7 +1081,7 @@ namespace ts {
 
         function computeCommonSourceDirectory(sourceFiles: SourceFile[]): string {
             let commonPathComponents: string[];
-            forEach(files, sourceFile => {
+            const failed = forEach(files, sourceFile => {
                 // Each file contributes into common source file path
                 if (isDeclarationFile(sourceFile)) {
                     return;
@@ -905,10 +1097,10 @@ namespace ts {
                 }
 
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (commonPathComponents[i] !== sourcePathComponents[i]) {
+                    if (getCanonicalFileName(commonPathComponents[i]) !== getCanonicalFileName(sourcePathComponents[i])) {
                         if (i === 0) {
-                            programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Cannot_find_the_common_subdirectory_path_for_the_input_files));
-                            return;
+                            // Failed to find any common path component
+                            return true;
                         }
 
                         // New common path found that is 0 -> i-1
@@ -923,6 +1115,15 @@ namespace ts {
                 }
             });
 
+            // A common path can not be found when paths span multiple drives on windows, for example
+            if (failed) {
+                return "";
+            }
+
+            if (!commonPathComponents) { // Can happen when all input files are .d.ts files
+                return currentDirectory;
+            }
+
             return getNormalizedPathFromPathComponents(commonPathComponents);
         }
 
@@ -971,16 +1172,15 @@ namespace ts {
                 if (options.mapRoot) {
                     programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "mapRoot", "inlineSourceMap"));
                 }
-                if (options.sourceRoot) {
-                    programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "sourceRoot", "inlineSourceMap"));
-                }
             }
 
-
             if (options.inlineSources) {
                 if (!options.sourceMap && !options.inlineSourceMap) {
                     programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_inlineSources_can_only_be_used_when_either_option_inlineSourceMap_or_option_sourceMap_is_provided));
                 }
+                if (options.sourceRoot) {
+                    programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "sourceRoot", "inlineSources"));
+                }
             }
 
             if (options.out && options.outFile) {
@@ -992,10 +1192,9 @@ namespace ts {
                 if (options.mapRoot) {
                     programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "mapRoot", "sourceMap"));
                 }
-                if (options.sourceRoot) {
+                if (options.sourceRoot && !options.inlineSourceMap) {
                     programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "sourceRoot", "sourceMap"));
                 }
-                return;
             }
 
             const languageVersion = options.target || ScriptTarget.ES3;
@@ -1024,12 +1223,16 @@ namespace ts {
                 programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Cannot_compile_modules_into_es2015_when_targeting_ES5_or_lower));
             }
 
+            // Cannot specify module gen that isn't amd or system with --out
+            if (outFile && options.module && !(options.module === ModuleKind.AMD || options.module === ModuleKind.System)) {
+                programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Only_amd_and_system_modules_are_supported_alongside_0, options.out ? "out" : "outFile"));
+            }
+
             // there has to be common source directory if user specified --outdir || --sourceRoot
             // if user specified --mapRoot, there needs to be common source directory if there would be multiple files being emitted
             if (options.outDir || // there is --outDir specified
                 options.sourceRoot || // there is --sourceRoot specified
-                (options.mapRoot &&  // there is --mapRoot specified and there would be multiple js files generated
-                    (!outFile || firstExternalModuleSourceFile !== undefined))) {
+                options.mapRoot) { // there is --mapRoot specified
 
                 if (options.rootDir && checkSourceFilesBelongToPath(files, options.rootDir)) {
                     // If a rootDir is specified and is valid use it as the commonSourceDirectory
@@ -1038,6 +1241,10 @@ namespace ts {
                 else {
                     // Compute the commonSourceDirectory from the input files
                     commonSourceDirectory = computeCommonSourceDirectory(files);
+                    // If we failed to find a good common directory, but outDir is specified and at least one of our files is on a windows drive/URL/other resource, add a failure
+                    if (options.outDir && commonSourceDirectory === "" && forEach(files, file => getRootLength(file.fileName) > 1)) {
+                            programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Cannot_find_the_common_subdirectory_path_for_the_input_files));
+                    }
                 }
 
                 if (commonSourceDirectory && commonSourceDirectory[commonSourceDirectory.length - 1] !== directorySeparator) {
@@ -1065,11 +1272,49 @@ namespace ts {
                     programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "noEmit", "declaration"));
                 }
             }
+            else if (options.allowJs && options.declaration) {
+                programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_with_option_1, "allowJs", "declaration"));
+            }
 
             if (options.emitDecoratorMetadata &&
                 !options.experimentalDecorators) {
                 programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "emitDecoratorMetadata", "experimentalDecorators"));
             }
+
+            // If the emit is enabled make sure that every output file is unique and not overwriting any of the input files
+            if (!options.noEmit) {
+                const emitHost = getEmitHost();
+                const emitFilesSeen = createFileMap<boolean>(!host.useCaseSensitiveFileNames() ? key => key.toLocaleLowerCase() : undefined);
+                forEachExpectedEmitFile(emitHost, (emitFileNames, sourceFiles, isBundledEmit) => {
+                    verifyEmitFilePath(emitFileNames.jsFilePath, emitFilesSeen);
+                    verifyEmitFilePath(emitFileNames.declarationFilePath, emitFilesSeen);
+                });
+            }
+
+            // Verify that all the emit files are unique and don't overwrite input files
+            function verifyEmitFilePath(emitFileName: string, emitFilesSeen: FileMap<boolean>) {
+                if (emitFileName) {
+                    const emitFilePath = toPath(emitFileName, currentDirectory, getCanonicalFileName);
+                    // Report error if the output overwrites input file
+                    if (filesByName.contains(emitFilePath)) {
+                        createEmitBlockingDiagnostics(emitFileName, emitFilePath, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file);
+                    }
+
+                    // Report error if multiple files write into same file
+                    if (emitFilesSeen.contains(emitFilePath)) {
+                        // Already seen the same emit file - report error
+                        createEmitBlockingDiagnostics(emitFileName, emitFilePath, Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files);
+                    }
+                    else {
+                        emitFilesSeen.set(emitFilePath, true);
+                    }
+                }
+            }
+        }
+
+        function createEmitBlockingDiagnostics(emitFileName: string, emitFilePath: Path, message: DiagnosticMessage) {
+            hasEmitBlockingDiagnostics.set(toPath(emitFileName, currentDirectory, getCanonicalFileName), true);
+            programDiagnostics.add(createCompilerDiagnostic(message, emitFileName));
         }
     }
 }

src/compiler/scanner.ts

@@ -1634,11 +1634,11 @@ namespace ts {
         }
 
         function lookAhead<T>(callback: () => T): T {
-            return speculationHelper(callback, /*isLookahead:*/ true);
+            return speculationHelper(callback, /*isLookahead*/ true);
         }
 
         function tryScan<T>(callback: () => T): T {
-            return speculationHelper(callback, /*isLookahead:*/ false);
+            return speculationHelper(callback, /*isLookahead*/ false);
         }
 
         function setText(newText: string, start: number, length: number) {

src/compiler/tsc.ts

@@ -280,7 +280,7 @@ namespace ts {
         }
 
         if (commandLine.options.version) {
-            reportDiagnostic(createCompilerDiagnostic(Diagnostics.Version_0, ts.version), /* compilerHost */ undefined);
+            printVersion();
             return sys.exit(ExitStatus.Success);
         }
 
@@ -303,7 +303,7 @@ namespace ts {
         }
         else if (commandLine.fileNames.length === 0 && isJSONSupported()) {
             const searchPath = normalizePath(sys.getCurrentDirectory());
-            configFileName = findConfigFile(searchPath);
+            configFileName = findConfigFile(searchPath, sys.fileExists);
         }
 
         if (commandLine.fileNames.length === 0 && !configFileName) {
@@ -346,10 +346,21 @@ namespace ts {
                     return;
                 }
             }
+            if (!cachedConfigFileText) {
+                const error = createCompilerDiagnostic(Diagnostics.File_0_not_found, configFileName);
+                reportDiagnostics([error], /* compilerHost */ undefined);
+                sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
+                return;
+            }
 
             const result = parseConfigFileTextToJson(configFileName, cachedConfigFileText);
             const configObject = result.config;
-            const configParseResult = parseJsonConfigFileContent(configObject, sys, getDirectoryPath(configFileName));
+            if (!configObject) {
+                reportDiagnostics([result.error], /* compilerHost */ undefined);
+                sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
+                return;
+            }
+            const configParseResult = parseJsonConfigFileContent(configObject, sys, getDirectoryPath(configFileName), commandLine.options);
             if (configParseResult.errors.length > 0) {
                 reportDiagnostics(configParseResult.errors, /* compilerHost */ undefined);
                 sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
@@ -365,7 +376,7 @@ namespace ts {
                 if (configFileName) {
                     const configParseResult = parseConfigFile();
                     rootFileNames = configParseResult.fileNames;
-                    compilerOptions = extend(commandLine.options, configParseResult.options);
+                    compilerOptions = configParseResult.options;
                 }
                 else {
                     rootFileNames = commandLine.fileNames;
@@ -458,7 +469,7 @@ namespace ts {
         }
 
         function watchedDirectoryChanged(fileName: string) {
-            if (fileName && !ts.isSupportedSourceFileName(fileName)) {
+            if (fileName && !ts.isSupportedSourceFileName(fileName, commandLine.options)) {
                 return;
             }
 

src/compiler/utilities.ts

@@ -1,4 +1,3 @@
-/// <reference path="binder.ts" />
 /// <reference path="sys.ts" />
 
 /* @internal */
@@ -39,6 +38,8 @@ namespace ts {
         getCanonicalFileName(fileName: string): string;
         getNewLine(): string;
 
+        isEmitBlocked(emitFileName: string): boolean;
+
         writeFile: WriteFileCallback;
     }
 
@@ -362,6 +363,10 @@ namespace ts {
         return file.externalModuleIndicator !== undefined;
     }
 
+    export function isExternalOrCommonJsModule(file: SourceFile): boolean {
+        return (file.externalModuleIndicator || file.commonJsModuleIndicator) !== undefined;
+    }
+
     export function isDeclarationFile(file: SourceFile): boolean {
         return (file.flags & NodeFlags.DeclarationFile) !== 0;
     }
@@ -1056,6 +1061,57 @@ namespace ts {
         return node.kind === SyntaxKind.ImportEqualsDeclaration && (<ImportEqualsDeclaration>node).moduleReference.kind !== SyntaxKind.ExternalModuleReference;
     }
 
+    export function isSourceFileJavaScript(file: SourceFile): boolean {
+        return isInJavaScriptFile(file);
+    }
+
+    export function isInJavaScriptFile(node: Node): boolean {
+        return node && !!(node.parserContextFlags & ParserContextFlags.JavaScriptFile);
+    }
+
+    /**
+     * Returns true if the node is a CallExpression to the identifier 'require' with
+     * exactly one string literal argument.
+     * This function does not test if the node is in a JavaScript file or not.
+    */
+    export function isRequireCall(expression: Node): expression is CallExpression {
+        // of the form 'require("name")'
+        return expression.kind === SyntaxKind.CallExpression &&
+                (<CallExpression>expression).expression.kind === SyntaxKind.Identifier &&
+                (<Identifier>(<CallExpression>expression).expression).text === "require" &&
+                (<CallExpression>expression).arguments.length === 1 &&
+                (<CallExpression>expression).arguments[0].kind === SyntaxKind.StringLiteral;
+    }
+
+    /**
+     * Returns true if the node is an assignment to a property on the identifier 'exports'.
+     * This function does not test if the node is in a JavaScript file or not.
+    */
+    export function isExportsPropertyAssignment(expression: Node): boolean {
+        // of the form 'exports.name = expr' where 'name' and 'expr' are arbitrary
+        return isInJavaScriptFile(expression) &&
+            (expression.kind === SyntaxKind.BinaryExpression) &&
+            ((<BinaryExpression>expression).operatorToken.kind === SyntaxKind.EqualsToken) &&
+            ((<BinaryExpression>expression).left.kind === SyntaxKind.PropertyAccessExpression) &&
+            ((<PropertyAccessExpression>(<BinaryExpression>expression).left).expression.kind === SyntaxKind.Identifier) &&
+            ((<Identifier>((<PropertyAccessExpression>(<BinaryExpression>expression).left).expression)).text === "exports");
+    }
+
+    /**
+     * Returns true if the node is an assignment to the property access expression 'module.exports'.
+     * This function does not test if the node is in a JavaScript file or not.
+    */
+    export function isModuleExportsAssignment(expression: Node): boolean {
+        // of the form 'module.exports = expr' where 'expr' is arbitrary
+        return isInJavaScriptFile(expression) &&
+            (expression.kind === SyntaxKind.BinaryExpression) &&
+            ((<BinaryExpression>expression).operatorToken.kind === SyntaxKind.EqualsToken) &&
+            ((<BinaryExpression>expression).left.kind === SyntaxKind.PropertyAccessExpression) &&
+            ((<PropertyAccessExpression>(<BinaryExpression>expression).left).expression.kind === SyntaxKind.Identifier) &&
+            ((<Identifier>((<PropertyAccessExpression>(<BinaryExpression>expression).left).expression)).text === "module") &&
+            ((<PropertyAccessExpression>(<BinaryExpression>expression).left).name.text === "exports");
+    }
+
     export function getExternalModuleName(node: Node): Expression {
         if (node.kind === SyntaxKind.ImportDeclaration) {
             return (<ImportDeclaration>node).moduleSpecifier;
@@ -1273,7 +1329,7 @@ namespace ts {
     }
 
     // True if the given identifier, string literal, or number literal is the name of a declaration node
-    export function isDeclarationName(name: Node): boolean {
+    export function isDeclarationName(name: Node): name is Identifier | StringLiteral | LiteralExpression {
         if (name.kind !== SyntaxKind.Identifier && name.kind !== SyntaxKind.StringLiteral && name.kind !== SyntaxKind.NumericLiteral) {
             return false;
         }
@@ -1435,6 +1491,10 @@ namespace ts {
         return isFunctionLike(node) && (node.flags & NodeFlags.Async) !== 0 && !isAccessor(node);
     }
 
+    export function isStringOrNumericLiteral(kind: SyntaxKind): boolean {
+        return kind === SyntaxKind.StringLiteral || kind === SyntaxKind.NumericLiteral;
+    }
+
     /**
      * A declaration has a dynamic name if both of the following are true:
      *   1. The declaration has a computed property name
@@ -1443,9 +1503,13 @@ namespace ts {
      *      Symbol.
      */
     export function hasDynamicName(declaration: Declaration): boolean {
-        return declaration.name &&
-            declaration.name.kind === SyntaxKind.ComputedPropertyName &&
-            !isWellKnownSymbolSyntactically((<ComputedPropertyName>declaration.name).expression);
+        return declaration.name && isDynamicName(declaration.name);
+    }
+
+    export function isDynamicName(name: DeclarationName): boolean {
+        return name.kind === SyntaxKind.ComputedPropertyName &&
+            !isStringOrNumericLiteral((<ComputedPropertyName>name).expression.kind) &&
+            !isWellKnownSymbolSyntactically((<ComputedPropertyName>name).expression);
     }
 
     /**
@@ -1483,7 +1547,7 @@ namespace ts {
         return node.kind === SyntaxKind.Identifier && (<Identifier>node).text === "Symbol";
     }
 
-    export function isModifier(token: SyntaxKind): boolean {
+    export function isModifierKind(token: SyntaxKind): boolean {
         switch (token) {
             case SyntaxKind.AbstractKeyword:
             case SyntaxKind.AsyncKeyword:
@@ -1516,20 +1580,60 @@ namespace ts {
         return isFunctionLike(n) || n.kind === SyntaxKind.ModuleDeclaration || n.kind === SyntaxKind.SourceFile;
     }
 
-    export function cloneEntityName(node: EntityName): EntityName {
-        if (node.kind === SyntaxKind.Identifier) {
-            const clone = <Identifier>createSynthesizedNode(SyntaxKind.Identifier);
-            clone.text = (<Identifier>node).text;
-            return clone;
+    /**
+     * Creates a shallow, memberwise clone of a node. The "kind", "pos", "end", "flags", and "parent"
+     * properties are excluded by default, and can be provided via the "location", "flags", and
+     * "parent" parameters.
+     * @param node The node to clone.
+     * @param location An optional TextRange to use to supply the new position.
+     * @param flags The NodeFlags to use for the cloned node.
+     * @param parent The parent for the new node.
+     */
+    export function cloneNode<T extends Node>(node: T, location?: TextRange, flags?: NodeFlags, parent?: Node): T {
+        // We don't use "clone" from core.ts here, as we need to preserve the prototype chain of
+        // the original node. We also need to exclude specific properties and only include own-
+        // properties (to skip members already defined on the shared prototype).
+        const clone = location !== undefined
+            ? <T>createNode(node.kind, location.pos, location.end)
+            : <T>createSynthesizedNode(node.kind);
+
+        for (const key in node) {
+            if (clone.hasOwnProperty(key) || !node.hasOwnProperty(key)) {
+                continue;
+            }
+
+            (<any>clone)[key] = (<any>node)[key];
         }
-        else {
-            const clone = <QualifiedName>createSynthesizedNode(SyntaxKind.QualifiedName);
-            clone.left = cloneEntityName((<QualifiedName>node).left);
-            clone.left.parent = clone;
-            clone.right = <Identifier>cloneEntityName((<QualifiedName>node).right);
-            clone.right.parent = clone;
-            return clone;
+
+        if (flags !== undefined) {
+            clone.flags = flags;
         }
+
+        if (parent !== undefined) {
+            clone.parent = parent;
+        }
+
+        return clone;
+    }
+
+    /**
+     * Creates a deep clone of an EntityName, with new parent pointers.
+     * @param node The EntityName to clone.
+     * @param parent The parent for the cloned node.
+     */
+    export function cloneEntityName(node: EntityName, parent?: Node): EntityName {
+        const clone = cloneNode(node, node, node.flags, parent);
+        if (isQualifiedName(clone)) {
+            const { left, right } = clone;
+            clone.left = cloneEntityName(left, clone);
+            clone.right = cloneNode(right, right, right.flags, parent);
+        }
+
+        return clone;
+    }
+
+    export function isQualifiedName(node: Node): node is QualifiedName {
+        return node.kind === SyntaxKind.QualifiedName;
     }
 
     export function nodeIsSynthesized(node: Node): boolean {
@@ -1660,6 +1764,7 @@ namespace ts {
         "\u0085": "\\u0085"  // nextLine
     };
 
+
     /**
      * Based heavily on the abstract 'Quote'/'QuoteJSONString' operation from ECMA-262 (24.3.2.2),
      * but augmented for a few select characters (e.g. lineSeparator, paragraphSeparator, nextLine)
@@ -1800,6 +1905,15 @@ namespace ts {
         };
     }
 
+    /**
+     * Resolves a local path to a path which is absolute to the base of the emit
+     */
+    export function getExternalModuleNameFromPath(host: EmitHost, fileName: string): string {
+        const dir = host.getCurrentDirectory();
+        const relativePath = getRelativePathToDirectoryOrUrl(dir, fileName, dir, f => host.getCanonicalFileName(f), /*isAbsolutePathAnUrl*/ false);
+        return removeFileExtension(relativePath);
+    }
+
     export function getOwnEmitOutputFilePath(sourceFile: SourceFile, host: EmitHost, extension: string) {
         const compilerOptions = host.getCompilerOptions();
         let emitOutputFilePathWithoutExtension: string;
@@ -1813,15 +1927,85 @@ namespace ts {
         return emitOutputFilePathWithoutExtension + extension;
     }
 
+    export function getEmitScriptTarget(compilerOptions: CompilerOptions) {
+        return compilerOptions.target || ScriptTarget.ES3;
+    }
+
+    export function getEmitModuleKind(compilerOptions: CompilerOptions) {
+        return compilerOptions.module ?
+            compilerOptions.module :
+            getEmitScriptTarget(compilerOptions) === ScriptTarget.ES6 ? ModuleKind.ES6 : ModuleKind.None;
+    }
+
+    export interface EmitFileNames {
+        jsFilePath: string;
+        sourceMapFilePath: string;
+        declarationFilePath: string;
+    }
+
+    export function forEachExpectedEmitFile(host: EmitHost,
+        action: (emitFileNames: EmitFileNames, sourceFiles: SourceFile[], isBundledEmit: boolean) => void,
+        targetSourceFile?: SourceFile) {
+        const options = host.getCompilerOptions();
+        // Emit on each source file
+        if (options.outFile || options.out) {
+            onBundledEmit(host);
+        }
+        else {
+            const sourceFiles = targetSourceFile === undefined ? host.getSourceFiles() : [targetSourceFile];
+            for (const sourceFile of sourceFiles) {
+                if (!isDeclarationFile(sourceFile)) {
+                    onSingleFileEmit(host, sourceFile);
+                }
+            }
+        }
+
+        function onSingleFileEmit(host: EmitHost, sourceFile: SourceFile) {
+            const jsFilePath = getOwnEmitOutputFilePath(sourceFile, host,
+                sourceFile.languageVariant === LanguageVariant.JSX && options.jsx === JsxEmit.Preserve ? ".jsx" : ".js");
+            const emitFileNames: EmitFileNames = {
+                jsFilePath,
+                sourceMapFilePath: getSourceMapFilePath(jsFilePath, options),
+                declarationFilePath: !isSourceFileJavaScript(sourceFile) ? getDeclarationEmitFilePath(jsFilePath, options) : undefined
+            };
+            action(emitFileNames, [sourceFile], /*isBundledEmit*/false);
+        }
+
+        function onBundledEmit(host: EmitHost) {
+            // Can emit only sources that are not declaration file and are either non module code or module with --module or --target es6 specified
+            const bundledSources = filter(host.getSourceFiles(),
+                sourceFile => !isDeclarationFile(sourceFile) && // Not a declaration file
+                    (!isExternalModule(sourceFile) || // non module file
+                        (getEmitModuleKind(options) && isExternalModule(sourceFile)))); // module that can emit - note falsy value from getEmitModuleKind means the module kind that shouldn't be emitted
+            if (bundledSources.length) {
+                const jsFilePath = options.outFile || options.out;
+                const emitFileNames: EmitFileNames = {
+                    jsFilePath,
+                    sourceMapFilePath: getSourceMapFilePath(jsFilePath, options),
+                    declarationFilePath: getDeclarationEmitFilePath(jsFilePath, options)
+                };
+                action(emitFileNames, bundledSources, /*isBundledEmit*/true);
+            }
+        }
+
+        function getSourceMapFilePath(jsFilePath: string, options: CompilerOptions) {
+            return options.sourceMap ? jsFilePath + ".map" : undefined;
+        }
+
+        function getDeclarationEmitFilePath(jsFilePath: string, options: CompilerOptions) {
+            return options.declaration ? removeFileExtension(jsFilePath) + ".d.ts" : undefined;
+        }
+    }
+
     export function getSourceFilePathInNewDir(sourceFile: SourceFile, host: EmitHost, newDirPath: string) {
         let sourceFilePath = getNormalizedAbsolutePath(sourceFile.fileName, host.getCurrentDirectory());
         sourceFilePath = sourceFilePath.replace(host.getCommonSourceDirectory(), "");
         return combinePaths(newDirPath, sourceFilePath);
     }
 
-    export function writeFile(host: EmitHost, diagnostics: Diagnostic[], fileName: string, data: string, writeByteOrderMark: boolean) {
+    export function writeFile(host: EmitHost, diagnostics: DiagnosticCollection, fileName: string, data: string, writeByteOrderMark: boolean) {
         host.writeFile(fileName, data, writeByteOrderMark, hostErrorMessage => {
-            diagnostics.push(createCompilerDiagnostic(Diagnostics.Could_not_write_file_0_Colon_1, fileName, hostErrorMessage));
+            diagnostics.add(createCompilerDiagnostic(Diagnostics.Could_not_write_file_0_Colon_1, fileName, hostErrorMessage));
         });
     }
 
@@ -1845,18 +2029,6 @@ namespace ts {
         return accessor && accessor.parameters.length > 0 && accessor.parameters[0].type;
     }
 
-    export function shouldEmitToOwnFile(sourceFile: SourceFile, compilerOptions: CompilerOptions): boolean {
-        if (!isDeclarationFile(sourceFile)) {
-            if ((isExternalModule(sourceFile) || !(compilerOptions.outFile || compilerOptions.out))) {
-                // 1. in-browser single file compilation scenario
-                // 2. non .js file
-                return compilerOptions.isolatedModules || !fileExtensionIs(sourceFile.fileName, ".js");
-            }
-            return false;
-        }
-        return false;
-    }
-
     export function getAllAccessorDeclarations(declarations: NodeArray<Declaration>, accessor: AccessorDeclaration) {
         let firstAccessor: AccessorDeclaration;
         let secondAccessor: AccessorDeclaration;
@@ -2200,12 +2372,8 @@ namespace ts {
         return symbol && symbol.valueDeclaration && (symbol.valueDeclaration.flags & NodeFlags.Default) ? symbol.valueDeclaration.localSymbol : undefined;
     }
 
-    export function isJavaScript(fileName: string) {
-        return fileExtensionIs(fileName, ".js");
-    }
-
-    export function isTsx(fileName: string) {
-        return fileExtensionIs(fileName, ".tsx");
+    export function hasJavaScriptFileExtension(fileName: string) {
+        return forEach(supportedJavascriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
 
     /**

src/harness/compilerRunner.ts

@@ -40,89 +40,79 @@ class CompilerBaselineRunner extends RunnerBase {
         this.basePath += "/" + this.testSuiteName;
     }
 
+    private makeUnitName(name: string, root: string) {
+        return ts.isRootedDiskPath(name) ? name : ts.combinePaths(root, name);
+    };
+
     public checkTestCodeOutput(fileName: string) {
         describe("compiler tests for " + fileName, () => {
             // Mocha holds onto the closure environment of the describe callback even after the test is done.
             // Everything declared here should be cleared out in the "after" callback.
             let justName: string;
-            let content: string;
-            let testCaseContent: { settings: Harness.TestCaseParser.CompilerSettings; testUnitData: Harness.TestCaseParser.TestUnitData[]; };
-
-            let units: Harness.TestCaseParser.TestUnitData[];
-            let tcSettings: Harness.TestCaseParser.CompilerSettings;
 
             let lastUnit: Harness.TestCaseParser.TestUnitData;
-            let rootDir: string;
+            let harnessSettings: Harness.TestCaseParser.CompilerSettings;
+            let hasNonDtsFiles: boolean;
 
             let result: Harness.Compiler.CompilerResult;
-            let program: ts.Program;
             let options: ts.CompilerOptions;
             // equivalent to the files that will be passed on the command line
-            let toBeCompiled: { unitName: string; content: string }[];
+            let toBeCompiled: Harness.Compiler.TestFile[];
             // equivalent to other files on the file system not directly passed to the compiler (ie things that are referenced by other files)
-            let otherFiles: { unitName: string; content: string }[];
-            let harnessCompiler: Harness.Compiler.HarnessCompiler;
+            let otherFiles: Harness.Compiler.TestFile[];
 
             before(() => {
                 justName = fileName.replace(/^.*[\\\/]/, ""); // strips the fileName from the path.
-                content = Harness.IO.readFile(fileName);
-                testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
-                units = testCaseContent.testUnitData;
-                tcSettings = testCaseContent.settings;
+                const content = Harness.IO.readFile(fileName);
+                const testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
+                const units = testCaseContent.testUnitData;
+                harnessSettings = testCaseContent.settings;
                 lastUnit = units[units.length - 1];
-                rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
-                harnessCompiler = Harness.Compiler.getCompiler();
+                hasNonDtsFiles = ts.forEach(units, unit => !ts.fileExtensionIs(unit.name, ".d.ts"));
+                const rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
                 // We need to assemble the list of input files for the compiler and other related files on the 'filesystem' (ie in a multi-file test)
                 // If the last file in a test uses require or a triple slash reference we'll assume all other files will be brought in via references,
                 // otherwise, assume all files are just meant to be in the same compilation session without explicit references to one another.
                 toBeCompiled = [];
                 otherFiles = [];
                 if (/require\(/.test(lastUnit.content) || /reference\spath/.test(lastUnit.content)) {
-                    toBeCompiled.push({ unitName: rootDir + lastUnit.name, content: lastUnit.content });
+                    toBeCompiled.push({ unitName: this.makeUnitName(lastUnit.name, rootDir), content: lastUnit.content });
                     units.forEach(unit => {
                         if (unit.name !== lastUnit.name) {
-                            otherFiles.push({ unitName: rootDir + unit.name, content: unit.content });
+                            otherFiles.push({ unitName: this.makeUnitName(unit.name, rootDir), content: unit.content });
                         }
                     });
                 }
                 else {
                     toBeCompiled = units.map(unit => {
-                        return { unitName: rootDir + unit.name, content: unit.content };
+                        return { unitName: this.makeUnitName(unit.name, rootDir), content: unit.content };
                     });
                 }
 
-                options = harnessCompiler.compileFiles(toBeCompiled, otherFiles, function (compileResult, _program) {
-                    result = compileResult;
-                    // The program will be used by typeWriter
-                    program = _program;
-                }, function (settings) {
-                        harnessCompiler.setCompilerSettings(tcSettings);
-                    });
+                const output = Harness.Compiler.compileFiles(
+                    toBeCompiled, otherFiles, harnessSettings, /* options */ undefined, /* currentDirectory */ undefined);
+
+                options = output.options;
+                result = output.result;
             });
 
             after(() => {
                 // Mocha holds onto the closure environment of the describe callback even after the test is done.
                 // Therefore we have to clean out large objects after the test is done.
                 justName = undefined;
-                content = undefined;
-                testCaseContent = undefined;
-                units = undefined;
-                tcSettings = undefined;
                 lastUnit = undefined;
-                rootDir = undefined;
+                hasNonDtsFiles = undefined;
                 result = undefined;
-                program = undefined;
                 options = undefined;
                 toBeCompiled = undefined;
                 otherFiles = undefined;
-                harnessCompiler = undefined;
             });
 
             function getByteOrderMarkText(file: Harness.Compiler.GeneratedFile): string {
                 return file.writeByteOrderMark ? "\u00EF\u00BB\u00BF" : "";
             }
 
-            function getErrorBaseline(toBeCompiled: { unitName: string; content: string }[], otherFiles: { unitName: string; content: string }[], result: Harness.Compiler.CompilerResult) {
+            function getErrorBaseline(toBeCompiled: Harness.Compiler.TestFile[], otherFiles: Harness.Compiler.TestFile[], result: Harness.Compiler.CompilerResult) {
                 return Harness.Compiler.getErrorBaseline(toBeCompiled.concat(otherFiles), result.errors);
             }
 
@@ -151,7 +141,7 @@ class CompilerBaselineRunner extends RunnerBase {
             });
 
             it("Correct JS output for " + fileName, () => {
-                if (!ts.fileExtensionIs(lastUnit.name, ".d.ts") && this.emit) {
+                if (hasNonDtsFiles && this.emit) {
                     if (result.files.length === 0 && result.errors.length === 0) {
                         throw new Error("Expected at least one js file to be emitted or at least one error to be created.");
                     }
@@ -184,9 +174,9 @@ class CompilerBaselineRunner extends RunnerBase {
                             }
                         }
 
-                        const declFileCompilationResult = harnessCompiler.compileDeclarationFiles(toBeCompiled, otherFiles, result, function (settings) {
-                            harnessCompiler.setCompilerSettings(tcSettings);
-                        }, options);
+                        const declFileCompilationResult =
+                            Harness.Compiler.compileDeclarationFiles(
+                                toBeCompiled, otherFiles, result, harnessSettings, options, /*currentDirectory*/ undefined);
 
                         if (declFileCompilationResult && declFileCompilationResult.declResult.errors.length) {
                             jsCode += "\r\n\r\n//// [DtsFileErrors]\r\n";
@@ -257,10 +247,11 @@ class CompilerBaselineRunner extends RunnerBase {
                     // These types are equivalent, but depend on what order the compiler observed
                     // certain parts of the program.
 
+                    const program = result.program;
                     const allFiles = toBeCompiled.concat(otherFiles).filter(file => !!program.getSourceFile(file.unitName));
 
-                    const fullWalker = new TypeWriterWalker(program, /*fullTypeCheck:*/ true);
-                    const pullWalker = new TypeWriterWalker(program, /*fullTypeCheck:*/ false);
+                    const fullWalker = new TypeWriterWalker(program, /*fullTypeCheck*/ true);
+                    const pullWalker = new TypeWriterWalker(program, /*fullTypeCheck*/ false);
 
                     const fullResults: ts.Map<TypeWriterResult[]> = {};
                     const pullResults: ts.Map<TypeWriterResult[]> = {};
@@ -274,14 +265,14 @@ class CompilerBaselineRunner extends RunnerBase {
                     // The second gives symbols for all identifiers.
                     let e1: Error, e2: Error;
                     try {
-                        checkBaseLines(/*isSymbolBaseLine:*/ false);
+                        checkBaseLines(/*isSymbolBaseLine*/ false);
                     }
                     catch (e) {
                         e1 = e;
                     }
 
                     try {
-                        checkBaseLines(/*isSymbolBaseLine:*/ true);
+                        checkBaseLines(/*isSymbolBaseLine*/ true);
                     }
                     catch (e) {
                         e2 = e;
@@ -367,7 +358,6 @@ class CompilerBaselineRunner extends RunnerBase {
     public initializeTests() {
         describe(this.testSuiteName + " tests", () => {
             describe("Setup compiler for compiler baselines", () => {
-                const harnessCompiler = Harness.Compiler.getCompiler();
                 this.parseOptions();
             });
 

src/harness/fourslashRunner.ts

@@ -58,56 +58,6 @@ class FourSlashRunner extends RunnerBase {
                     }
                 });
             });
-
-            describe("Generate Tao XML", () => {
-                const invalidReasons: any = {};
-                FourSlash.xmlData.forEach(xml => {
-                    if (xml.invalidReason !== null) {
-                        invalidReasons[xml.invalidReason] = (invalidReasons[xml.invalidReason] || 0) + 1;
-                    }
-                });
-                const invalidReport: { reason: string; count: number }[] = [];
-                for (const reason in invalidReasons) {
-                    if (invalidReasons.hasOwnProperty(reason)) {
-                        invalidReport.push({ reason: reason, count: invalidReasons[reason] });
-                    }
-                }
-                invalidReport.sort((lhs, rhs) => lhs.count > rhs.count ? -1 : lhs.count === rhs.count ? 0 : 1);
-
-                const lines: string[] = [];
-                lines.push("<!-- Blocked Test Report");
-                invalidReport.forEach((reasonAndCount) => {
-                    lines.push(reasonAndCount.count + " tests blocked by " + reasonAndCount.reason);
-                });
-                lines.push("-->");
-                lines.push("<TaoTest xmlns=\"http://microsoft.com/schemas/VSLanguages/TAO\">");
-                lines.push("    <InitTest>");
-                lines.push("        <StartTarget />");
-                lines.push("    </InitTest>");
-                lines.push("    <ScenarioList>");
-                FourSlash.xmlData.forEach(xml => {
-                    if (xml.invalidReason !== null) {
-                        lines.push("<!-- Skipped " + xml.originalName + ", reason: " + xml.invalidReason + " -->");
-                    }
-                    else {
-                        lines.push("        <Scenario Name=\"" + xml.originalName + "\">");
-                        xml.actions.forEach(action => {
-                            lines.push("            " + action);
-                        });
-                        lines.push("        </Scenario>");
-                    }
-                });
-                lines.push("    </ScenarioList>");
-                lines.push("    <CleanupScenario>");
-                lines.push("        <CloseAllDocuments />");
-                lines.push("        <CleanupCreatedFiles />");
-                lines.push("    </CleanupScenario>");
-                lines.push("    <CleanupTest>");
-                lines.push("        <CloseTarget />");
-                lines.push("    </CleanupTest>");
-                lines.push("</TaoTest>");
-                Harness.IO.writeFile("built/local/fourslash.xml", lines.join("\r\n"));
-            });
         });
     }
 }

src/harness/harness.ts

@@ -176,7 +176,9 @@ namespace Utils {
             ts.forEachChild(node, child => { childNodesAndArrays.push(child); }, array => { childNodesAndArrays.push(array); });
 
             for (const childName in node) {
-                if (childName === "parent" || childName === "nextContainer" || childName === "modifiers" || childName === "externalModuleIndicator") {
+                if (childName === "parent" || childName === "nextContainer" || childName === "modifiers" || childName === "externalModuleIndicator" ||
+                    // for now ignore jsdoc comments
+                    childName === "jsDocComment") {
                     continue;
                 }
                 const child = (<any>node)[childName];
@@ -628,7 +630,7 @@ namespace Harness {
                 function getResolvedPathFromServer(path: string) {
                     const xhr = new XMLHttpRequest();
                     try {
-                        xhr.open("GET", path + "?resolve", false);
+                        xhr.open("GET", path + "?resolve", /*async*/ false);
                         xhr.send();
                     }
                     catch (e) {
@@ -647,7 +649,7 @@ namespace Harness {
                 export function getFileFromServerSync(url: string): XHRResponse {
                     const xhr = new XMLHttpRequest();
                     try {
-                        xhr.open("GET", url, false);
+                        xhr.open("GET", url, /*async*/ false);
                         xhr.send();
                     }
                     catch (e) {
@@ -662,7 +664,7 @@ namespace Harness {
                     const xhr = new XMLHttpRequest();
                     try {
                         const actionMsg = "?action=" + action;
-                        xhr.open("POST", url + actionMsg, false);
+                        xhr.open("POST", url + actionMsg, /*async*/ false);
                         xhr.setRequestHeader("Access-Control-Allow-Origin", "*");
                         xhr.send(contents);
                     }
@@ -767,26 +769,9 @@ namespace Harness {
 }
 
 namespace Harness {
-    let tcServicesFileName = "typescriptServices.js";
-
-    export let libFolder: string;
-    switch (Utils.getExecutionEnvironment()) {
-        case Utils.ExecutionEnvironment.CScript:
-            libFolder = "built/local/";
-            tcServicesFileName = "built/local/typescriptServices.js";
-            break;
-        case Utils.ExecutionEnvironment.Node:
-            libFolder = "built/local/";
-            tcServicesFileName = "built/local/typescriptServices.js";
-            break;
-        case Utils.ExecutionEnvironment.Browser:
-            libFolder = "built/local/";
-            tcServicesFileName = "built/local/typescriptServices.js";
-            break;
-        default:
-            throw new Error("Unknown context");
-    }
-    export let tcServicesFile = IO.readFile(tcServicesFileName);
+    export const libFolder = "built/local/";
+    const tcServicesFileName = ts.combinePaths(libFolder, "typescriptServices.js");
+    export const tcServicesFile = IO.readFile(tcServicesFileName);
 
     export interface SourceMapEmitterCallback {
         (emittedFile: string, emittedLine: number, emittedColumn: number, sourceFile: string, sourceLine: number, sourceColumn: number, sourceName: string): void;
@@ -827,57 +812,14 @@ namespace Harness {
             }
         }
 
-        export interface IEmitterIOHost {
-            writeFile(path: string, contents: string, writeByteOrderMark: boolean): void;
-            resolvePath(path: string): string;
-        }
-
-        /** Mimics having multiple files, later concatenated to a single file. */
-        export class EmitterIOHost implements IEmitterIOHost {
-            private fileCollection: any = {};
-
-            /** create file gets the whole path to create, so this works as expected with the --out parameter */
-            public writeFile(s: string, contents: string, writeByteOrderMark: boolean): void {
-                let writer: ITextWriter;
-                if (this.fileCollection[s]) {
-                    writer = <ITextWriter>this.fileCollection[s];
-                }
-                else {
-                    writer = new Harness.Compiler.WriterAggregator();
-                    this.fileCollection[s] = writer;
-                }
-
-                writer.Write(contents);
-                writer.Close();
-            }
-
-            public resolvePath(s: string) { return s; }
-
-            public reset() { this.fileCollection = {}; }
-
-            public toArray(): { fileName: string; file: WriterAggregator; }[] {
-                const result: { fileName: string; file: WriterAggregator; }[] = [];
-                for (const p in this.fileCollection) {
-                    if (this.fileCollection.hasOwnProperty(p)) {
-                        const current = <Harness.Compiler.WriterAggregator>this.fileCollection[p];
-                        if (current.lines.length > 0) {
-                            if (p.indexOf(".d.ts") !== -1) { current.lines.unshift(["////[", Path.getFileName(p), "]"].join("")); }
-                            result.push({ fileName: p, file: this.fileCollection[p] });
-                        }
-                    }
-                }
-                return result;
-            }
-        }
-
         export function createSourceFileAndAssertInvariants(
             fileName: string,
             sourceText: string,
             languageVersion: ts.ScriptTarget) {
-            // We'll only assert inletiants outside of light mode. 
+            // We'll only assert invariants outside of light mode. 
             const shouldAssertInvariants = !Harness.lightMode;
 
-            // Only set the parent nodes if we're asserting inletiants.  We don't need them otherwise.
+            // Only set the parent nodes if we're asserting invariants.  We don't need them otherwise.
             const result = ts.createSourceFile(fileName, sourceText, languageVersion, /*setParentNodes:*/ shouldAssertInvariants);
 
             if (shouldAssertInvariants) {
@@ -890,12 +832,12 @@ namespace Harness {
         const carriageReturnLineFeed = "\r\n";
         const lineFeed = "\n";
 
-        export let defaultLibFileName = "lib.d.ts";
-        export let defaultLibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + "lib.core.d.ts"), /*languageVersion*/ ts.ScriptTarget.Latest);
-        export let defaultES6LibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + "lib.core.es6.d.ts"), /*languageVersion*/ ts.ScriptTarget.Latest);
+        export const defaultLibFileName = "lib.d.ts";
+        export const defaultLibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + "lib.core.d.ts"), /*languageVersion*/ ts.ScriptTarget.Latest);
+        export const defaultES6LibSourceFile = createSourceFileAndAssertInvariants(defaultLibFileName, IO.readFile(libFolder + "lib.core.es6.d.ts"), /*languageVersion*/ ts.ScriptTarget.Latest);
 
         // Cache these between executions so we don't have to re-parse them for every test
-        export let fourslashFileName = "fourslash.ts";
+        export const fourslashFileName = "fourslash.ts";
         export let fourslashSourceFile: ts.SourceFile;
 
         export function getCanonicalFileName(fileName: string): string {
@@ -903,41 +845,32 @@ namespace Harness {
         }
 
         export function createCompilerHost(
-            inputFiles: { unitName: string; content: string; }[],
+            inputFiles: TestFile[],
             writeFile: (fn: string, contents: string, writeByteOrderMark: boolean) => void,
             scriptTarget: ts.ScriptTarget,
             useCaseSensitiveFileNames: boolean,
             // the currentDirectory is needed for rwcRunner to passed in specified current directory to compiler host
-            currentDirectory?: string,
+            currentDirectory: string,
             newLineKind?: ts.NewLineKind): ts.CompilerHost {
 
             // Local get canonical file name function, that depends on passed in parameter for useCaseSensitiveFileNames
-            function getCanonicalFileName(fileName: string): string {
-                return useCaseSensitiveFileNames ? fileName : fileName.toLowerCase();
-            }
+            const getCanonicalFileName = ts.createGetCanonicalFileName(useCaseSensitiveFileNames);
 
-            const filemap: { [fileName: string]: ts.SourceFile; } = {};
-            const getCurrentDirectory = currentDirectory === undefined ? Harness.IO.getCurrentDirectory : () => currentDirectory;
-
-            // Register input files
-            function register(file: { unitName: string; content: string; }) {
+            const fileMap: ts.FileMap<ts.SourceFile> = ts.createFileMap<ts.SourceFile>();
+            for (const file of inputFiles) {
                 if (file.content !== undefined) {
                     const fileName = ts.normalizePath(file.unitName);
                     const sourceFile = createSourceFileAndAssertInvariants(fileName, file.content, scriptTarget);
-                    filemap[getCanonicalFileName(fileName)] = sourceFile;
-                    filemap[getCanonicalFileName(ts.getNormalizedAbsolutePath(fileName, getCurrentDirectory()))] = sourceFile;
+                    const path = ts.toPath(file.unitName, currentDirectory, getCanonicalFileName);
+                    fileMap.set(path, sourceFile);
                 }
-            };
-            inputFiles.forEach(register);
+            }
 
             function getSourceFile(fn: string, languageVersion: ts.ScriptTarget) {
                 fn = ts.normalizePath(fn);
-                if (Object.prototype.hasOwnProperty.call(filemap, getCanonicalFileName(fn))) {
-                    return filemap[getCanonicalFileName(fn)];
-                }
-                else if (currentDirectory) {
-                    const canonicalAbsolutePath = getCanonicalFileName(ts.getNormalizedAbsolutePath(fn, currentDirectory));
-                    return Object.prototype.hasOwnProperty.call(filemap, getCanonicalFileName(canonicalAbsolutePath)) ? filemap[canonicalAbsolutePath] : undefined;
+                const path = ts.toPath(fn, currentDirectory, getCanonicalFileName);
+                if (fileMap.contains(path)) {
+                    return fileMap.get(path);
                 }
                 else if (fn === fourslashFileName) {
                     const tsFn = "tests/cases/fourslash/" + fourslashFileName;
@@ -959,7 +892,7 @@ namespace Harness {
                         Harness.IO.newLine();
 
             return {
-                getCurrentDirectory,
+                getCurrentDirectory: () => currentDirectory,
                 getSourceFile,
                 getDefaultLibFileName: options => defaultLibFileName,
                 writeFile,
@@ -1034,177 +967,138 @@ namespace Harness {
             }
         }
 
-        export class HarnessCompiler {
-            private inputFiles: { unitName: string; content: string }[] = [];
-            private compileOptions: ts.CompilerOptions;
-            private settings: Harness.TestCaseParser.CompilerSettings = {};
+        export interface TestFile {
+            unitName: string;
+            content: string;
+        }
 
-            private lastErrors: ts.Diagnostic[];
+        export interface CompilationOutput {
+            result: CompilerResult;
+            options: ts.CompilerOptions & HarnessOptions;
+        }
 
-            public reset() {
-                this.inputFiles = [];
-                this.settings = {};
-                this.lastErrors = [];
+        export function compileFiles(
+            inputFiles: TestFile[],
+            otherFiles: TestFile[],
+            harnessSettings: TestCaseParser.CompilerSettings,
+            compilerOptions: ts.CompilerOptions,
+            // Current directory is needed for rwcRunner to be able to use currentDirectory defined in json file
+            currentDirectory: string): CompilationOutput {
+
+            const options: ts.CompilerOptions & HarnessOptions = compilerOptions ? ts.clone(compilerOptions) : { noResolve: false };
+            options.target = options.target || ts.ScriptTarget.ES3;
+            options.module = options.module || ts.ModuleKind.None;
+            options.newLine = options.newLine || ts.NewLineKind.CarriageReturnLineFeed;
+            options.noErrorTruncation = true;
+            options.skipDefaultLibCheck = true;
+
+            currentDirectory = currentDirectory || Harness.IO.getCurrentDirectory();
+
+            // Parse settings
+            let useCaseSensitiveFileNames = Harness.IO.useCaseSensitiveFileNames();
+            if (harnessSettings) {
+                setCompilerOptionsFromHarnessSetting(harnessSettings, options);
+            }
+            if (options.useCaseSensitiveFileNames !== undefined) {
+                useCaseSensitiveFileNames = options.useCaseSensitiveFileNames;
             }
 
-            public reportCompilationErrors() {
-                return this.lastErrors;
+            const programFiles: TestFile[] = inputFiles.slice();
+            // Files from built\local that are requested by test "@includeBuiltFiles" to be in the context.
+            // Treat them as library files, so include them in build, but not in baselines.
+            if (options.includeBuiltFile) {
+                const builtFileName = ts.combinePaths(libFolder, options.includeBuiltFile);
+                const builtFile: TestFile = {
+                    unitName: builtFileName,
+                    content: normalizeLineEndings(IO.readFile(builtFileName), Harness.IO.newLine()),
+                };
+                programFiles.push(builtFile);
             }
 
-            public setCompilerSettings(tcSettings: Harness.TestCaseParser.CompilerSettings) {
-                this.settings = tcSettings;
+            const fileOutputs: GeneratedFile[] = [];
+
+            const programFileNames = programFiles.map(file => file.unitName);
+
+            const compilerHost = createCompilerHost(
+                programFiles.concat(otherFiles),
+                (fileName, code, writeByteOrderMark) => fileOutputs.push({ fileName, code, writeByteOrderMark }),
+                options.target,
+                useCaseSensitiveFileNames,
+                currentDirectory,
+                options.newLine);
+            const program = ts.createProgram(programFileNames, options, compilerHost);
+
+            const emitResult = program.emit();
+
+            const errors = ts.getPreEmitDiagnostics(program);
+
+            const result = new CompilerResult(fileOutputs, errors, program, Harness.IO.getCurrentDirectory(), emitResult.sourceMaps);
+            return { result, options };
+        }
+
+        export function compileDeclarationFiles(inputFiles: TestFile[],
+            otherFiles: TestFile[],
+            result: CompilerResult,
+            harnessSettings: TestCaseParser.CompilerSettings & HarnessOptions,
+            options: ts.CompilerOptions,
+            // Current directory is needed for rwcRunner to be able to use currentDirectory defined in json file
+            currentDirectory: string) {
+            if (options.declaration && result.errors.length === 0 && result.declFilesCode.length !== result.files.length) {
+                throw new Error("There were no errors and declFiles generated did not match number of js files generated");
             }
 
-            public addInputFiles(files: { unitName: string; content: string }[]) {
-                files.forEach(file => this.addInputFile(file));
+            const declInputFiles: TestFile[] = [];
+            const declOtherFiles: TestFile[] = [];
+
+            // if the .d.ts is non-empty, confirm it compiles correctly as well
+            if (options.declaration && result.errors.length === 0 && result.declFilesCode.length > 0) {
+                ts.forEach(inputFiles, file => addDtsFile(file, declInputFiles));
+                ts.forEach(otherFiles, file => addDtsFile(file, declOtherFiles));
+                const output = compileFiles(declInputFiles, declOtherFiles, harnessSettings, options, currentDirectory);
+                return { declInputFiles, declOtherFiles, declResult: output.result };
             }
 
-            public addInputFile(file: { unitName: string; content: string }) {
-                this.inputFiles.push(file);
-            }
-
-            public setCompilerOptions(options?: ts.CompilerOptions) {
-                this.compileOptions = options || { noResolve: false };
-            }
-
-            public emitAll(ioHost?: IEmitterIOHost) {
-                this.compileFiles(this.inputFiles,
-                    /*otherFiles*/ [],
-                    /*onComplete*/ result => {
-                        result.files.forEach(writeFile);
-                        result.declFilesCode.forEach(writeFile);
-                        result.sourceMaps.forEach(writeFile);
-                    },
-                    /*settingsCallback*/ () => { },
-                    this.compileOptions);
-
-                function writeFile(file: GeneratedFile) {
-                    ioHost.writeFile(file.fileName, file.code, false);
+            function addDtsFile(file: TestFile, dtsFiles: TestFile[]) {
+                if (isDTS(file.unitName)) {
+                    dtsFiles.push(file);
                 }
-            }
-
-            public compileFiles(inputFiles: { unitName: string; content: string }[],
-                otherFiles: { unitName: string; content: string }[],
-                onComplete: (result: CompilerResult, program: ts.Program) => void,
-                settingsCallback?: (settings: ts.CompilerOptions) => void,
-                options?: ts.CompilerOptions & HarnessOptions,
-                // Current directory is needed for rwcRunner to be able to use currentDirectory defined in json file
-                currentDirectory?: string) {
-
-                options = options || { noResolve: false };
-                options.target = options.target || ts.ScriptTarget.ES3;
-                options.module = options.module || ts.ModuleKind.None;
-                options.newLine = options.newLine || ts.NewLineKind.CarriageReturnLineFeed;
-                options.noErrorTruncation = true;
-                options.skipDefaultLibCheck = true;
-
-                if (settingsCallback) {
-                    settingsCallback(null);
-                }
-
-                const newLine = "\r\n";
-
-                // Parse settings
-                setCompilerOptionsFromHarnessSetting(this.settings, options);
-
-                // Files from built\local that are requested by test "@includeBuiltFiles" to be in the context.
-                // Treat them as library files, so include them in build, but not in baselines.
-                const includeBuiltFiles: { unitName: string; content: string }[] = [];
-                if (options.includeBuiltFile) {
-                    const builtFileName = libFolder + options.includeBuiltFile;
-                    includeBuiltFiles.push({ unitName: builtFileName, content: normalizeLineEndings(IO.readFile(builtFileName), newLine) });
-                }
-
-                const useCaseSensitiveFileNames = options.useCaseSensitiveFileNames !== undefined ? options.useCaseSensitiveFileNames : Harness.IO.useCaseSensitiveFileNames();
-
-                const fileOutputs: GeneratedFile[] = [];
-
-                const programFiles = inputFiles.concat(includeBuiltFiles).map(file => file.unitName);
-
-                const compilerHost = createCompilerHost(
-                    inputFiles.concat(includeBuiltFiles).concat(otherFiles),
-                    (fn, contents, writeByteOrderMark) => fileOutputs.push({ fileName: fn, code: contents, writeByteOrderMark: writeByteOrderMark }),
-                    options.target, useCaseSensitiveFileNames, currentDirectory, options.newLine);
-                const program = ts.createProgram(programFiles, options, compilerHost);
-
-                const emitResult = program.emit();
-
-                const errors = ts.getPreEmitDiagnostics(program).concat(emitResult.diagnostics);
-                this.lastErrors = errors;
-
-                const result = new CompilerResult(fileOutputs, errors, program, Harness.IO.getCurrentDirectory(), emitResult.sourceMaps);
-                onComplete(result, program);
-
-                return options;
-            }
-
-            public compileDeclarationFiles(inputFiles: { unitName: string; content: string; }[],
-                otherFiles: { unitName: string; content: string; }[],
-                result: CompilerResult,
-                settingsCallback?: (settings: ts.CompilerOptions) => void,
-                options?: ts.CompilerOptions,
-                // Current directory is needed for rwcRunner to be able to use currentDirectory defined in json file
-                currentDirectory?: string) {
-                if (options.declaration && result.errors.length === 0 && result.declFilesCode.length !== result.files.length) {
-                    throw new Error("There were no errors and declFiles generated did not match number of js files generated");
-                }
-
-                const declInputFiles: { unitName: string; content: string }[] = [];
-                const declOtherFiles: { unitName: string; content: string }[] = [];
-                let declResult: Harness.Compiler.CompilerResult;
-
-                // if the .d.ts is non-empty, confirm it compiles correctly as well
-                if (options.declaration && result.errors.length === 0 && result.declFilesCode.length > 0) {
-                    ts.forEach(inputFiles, file => addDtsFile(file, declInputFiles));
-                    ts.forEach(otherFiles, file => addDtsFile(file, declOtherFiles));
-                    this.compileFiles(declInputFiles, declOtherFiles, function (compileResult) { declResult = compileResult; },
-                        settingsCallback, options, currentDirectory);
-
-                    return { declInputFiles, declOtherFiles, declResult };
-                }
-
-                function addDtsFile(file: { unitName: string; content: string }, dtsFiles: { unitName: string; content: string }[]) {
-                    if (isDTS(file.unitName)) {
-                        dtsFiles.push(file);
-                    }
-                    else if (isTS(file.unitName)) {
-                        const declFile = findResultCodeFile(file.unitName);
-                        if (!findUnit(declFile.fileName, declInputFiles) && !findUnit(declFile.fileName, declOtherFiles)) {
-                            dtsFiles.push({ unitName: declFile.fileName, content: declFile.code });
-                        }
-                    }
-
-                    function findResultCodeFile(fileName: string) {
-                        const sourceFile = result.program.getSourceFile(fileName);
-                        assert(sourceFile, "Program has no source file with name '" + fileName + "'");
-                        // Is this file going to be emitted separately
-                        let sourceFileName: string;
-                        const outFile = options.outFile || options.out;
-                        if (ts.isExternalModule(sourceFile) || !outFile) {
-                            if (options.outDir) {
-                                let sourceFilePath = ts.getNormalizedAbsolutePath(sourceFile.fileName, result.currentDirectoryForProgram);
-                                sourceFilePath = sourceFilePath.replace(result.program.getCommonSourceDirectory(), "");
-                                sourceFileName = ts.combinePaths(options.outDir, sourceFilePath);
-                            }
-                            else {
-                                sourceFileName = sourceFile.fileName;
-                            }
-                        }
-                        else {
-                            // Goes to single --out file
-                            sourceFileName = outFile;
-                        }
-
-                        const dTsFileName = ts.removeFileExtension(sourceFileName) + ".d.ts";
-
-                        return ts.forEach(result.declFilesCode, declFile => declFile.fileName === dTsFileName ? declFile : undefined);
-                    }
-
-                    function findUnit(fileName: string, units: { unitName: string; content: string; }[]) {
-                        return ts.forEach(units, unit => unit.unitName === fileName ? unit : undefined);
+                else if (isTS(file.unitName)) {
+                    const declFile = findResultCodeFile(file.unitName);
+                    if (declFile && !findUnit(declFile.fileName, declInputFiles) && !findUnit(declFile.fileName, declOtherFiles)) {
+                        dtsFiles.push({ unitName: declFile.fileName, content: declFile.code });
                     }
                 }
             }
+
+            function findResultCodeFile(fileName: string) {
+                const sourceFile = result.program.getSourceFile(fileName);
+                assert(sourceFile, "Program has no source file with name '" + fileName + "'");
+                // Is this file going to be emitted separately
+                let sourceFileName: string;
+                const outFile = options.outFile || options.out;
+                if (!outFile) {
+                    if (options.outDir) {
+                        let sourceFilePath = ts.getNormalizedAbsolutePath(sourceFile.fileName, result.currentDirectoryForProgram);
+                        sourceFilePath = sourceFilePath.replace(result.program.getCommonSourceDirectory(), "");
+                        sourceFileName = ts.combinePaths(options.outDir, sourceFilePath);
+                    }
+                    else {
+                        sourceFileName = sourceFile.fileName;
+                    }
+                }
+                else {
+                    // Goes to single --out file
+                    sourceFileName = outFile;
+                }
+
+                const dTsFileName = ts.removeFileExtension(sourceFileName) + ".d.ts";
+
+                return ts.forEach(result.declFilesCode, declFile => declFile.fileName === dTsFileName ? declFile : undefined);
+            }
+
+            function findUnit(fileName: string, units: TestFile[]) {
+                return ts.forEach(units, unit => unit.unitName === fileName ? unit : undefined);
+            }
         }
 
         function normalizeLineEndings(text: string, lineEnding: string): string {
@@ -1230,7 +1124,7 @@ namespace Harness {
             return errorOutput;
         }
 
-        export function getErrorBaseline(inputFiles: { unitName: string; content: string }[], diagnostics: ts.Diagnostic[]) {
+        export function getErrorBaseline(inputFiles: TestFile[], diagnostics: ts.Diagnostic[]) {
             diagnostics.sort(ts.compareDiagnostics);
             const outputLines: string[] = [];
             // Count up all errors that were found in files other than lib.d.ts so we don't miss any
@@ -1371,16 +1265,6 @@ namespace Harness {
             }
         }
 
-        /** The harness' compiler instance used when tests are actually run. Reseting or changing settings of this compiler instance must be done within a test case (i.e., describe/it) */
-        let harnessCompiler: HarnessCompiler;
-
-        /** Returns the singleton harness compiler instance for generating and running tests.
-            If required a fresh compiler instance will be created, otherwise the existing singleton will be re-used.
-        */
-        export function getCompiler() {
-            return harnessCompiler = harnessCompiler || new HarnessCompiler();
-        }
-
         // This does not need to exist strictly speaking, but many tests will need to be updated if it's removed
         export function compileString(code: string, unitName: string, callback: (result: CompilerResult) => void) {
             // NEWTODO: Re-implement 'compileString'
@@ -1431,7 +1315,7 @@ namespace Harness {
             constructor(fileResults: GeneratedFile[], errors: ts.Diagnostic[], public program: ts.Program,
                 public currentDirectoryForProgram: string, private sourceMapData: ts.SourceMapData[]) {
 
-                fileResults.forEach(emittedFile => {
+                for (const emittedFile of fileResults) {
                     if (isDTS(emittedFile.fileName)) {
                         // .d.ts file, add to declFiles emit
                         this.declFilesCode.push(emittedFile);
@@ -1446,7 +1330,7 @@ namespace Harness {
                     else {
                         throw new Error("Unrecognized file extension for file " + emittedFile.fileName);
                     }
-                });
+                }
 
                 this.errors = errors;
             }
@@ -1555,7 +1439,7 @@ namespace Harness {
             }
 
             // normalize the fileName for the single file case
-            currentFileName = testUnitData.length > 0 ? currentFileName : Path.getFileName(fileName);
+            currentFileName = testUnitData.length > 0 || currentFileName ? currentFileName : Path.getFileName(fileName);
 
             // EOF, push whatever remains
             const newTestFile2 = {
@@ -1674,7 +1558,7 @@ namespace Harness {
             const encoded_actual =  Utils.encodeString(actual);
             if (expected != encoded_actual) {
                 // Overwrite & issue error
-                const errMsg = "The baseline file " + relativeFileName + " has changed";
+                const errMsg = "The baseline file " + relativeFileName + " has changed.";
                 throw new Error(errMsg);
             }
         }
@@ -1711,12 +1595,9 @@ namespace Harness {
         return filePath.indexOf(Harness.libFolder) === 0;
     }
 
-    export function getDefaultLibraryFile(io: Harness.IO): { unitName: string, content: string } {
+    export function getDefaultLibraryFile(io: Harness.IO): Harness.Compiler.TestFile {
         const libFile = Harness.userSpecifiedRoot + Harness.libFolder + "lib.d.ts";
-        return {
-            unitName: libFile,
-            content: io.readFile(libFile)
-        };
+        return { unitName: libFile, content: io.readFile(libFile) };
     }
 
     if (Error) (<any>Error).stackTraceLimit = 1;

src/harness/harnessLanguageService.ts

@@ -7,7 +7,7 @@ namespace Harness.LanguageService {
     export class ScriptInfo {
         public version: number = 1;
         public editRanges: { length: number; textChangeRange: ts.TextChangeRange; }[] = [];
-        public lineMap: number[] = undefined;
+        private lineMap: number[] = undefined;
 
         constructor(public fileName: string, public content: string) {
             this.setContent(content);
@@ -15,7 +15,11 @@ namespace Harness.LanguageService {
 
         private setContent(content: string): void {
             this.content = content;
-            this.lineMap = ts.computeLineStarts(content);
+            this.lineMap = undefined;
+        }
+
+        public getLineMap(): number[] {
+            return this.lineMap || (this.lineMap = ts.computeLineStarts(this.content));
         }
 
         public updateContent(content: string): void {
@@ -153,7 +157,7 @@ namespace Harness.LanguageService {
             throw new Error("No script with name '" + fileName + "'");
         }
 
-        public openFile(fileName: string): void {
+        public openFile(fileName: string, content?: string): void {
         }
 
         /**
@@ -164,7 +168,7 @@ namespace Harness.LanguageService {
             const script: ScriptInfo = this.fileNameToScript[fileName];
             assert.isNotNull(script);
 
-            return ts.computeLineAndCharacterOfPosition(script.lineMap, position);
+            return ts.computeLineAndCharacterOfPosition(script.getLineMap(), position);
         }
     }
 
@@ -197,7 +201,7 @@ namespace Harness.LanguageService {
         getHost() { return this.host; }
         getLanguageService(): ts.LanguageService { return ts.createLanguageService(this.host); }
         getClassifier(): ts.Classifier { return ts.createClassifier(); }
-        getPreProcessedFileInfo(fileName: string, fileContents: string): ts.PreProcessedFileInfo { return ts.preProcessFile(fileContents); }
+        getPreProcessedFileInfo(fileName: string, fileContents: string): ts.PreProcessedFileInfo { return ts.preProcessFile(fileContents, /* readImportFiles */ true, ts.hasJavaScriptFileExtension(fileName)); }
     }
 
     /// Shim adapter
@@ -493,9 +497,9 @@ namespace Harness.LanguageService {
             this.client = client;
         }
 
-        openFile(fileName: string): void {
-            super.openFile(fileName);
-            this.client.openFile(fileName);
+        openFile(fileName: string, content?: string): void {
+            super.openFile(fileName, content);
+            this.client.openFile(fileName, content);
         }
 
         editScript(fileName: string, start: number, end: number, newText: string) {

src/harness/loggedIO.ts

@@ -174,7 +174,7 @@ namespace Playback {
                     return true;
                 }
                 else {
-                    return findResultByFields(replayLog.fileExists, { path }, false);
+                    return findResultByFields(replayLog.fileExists, { path }, /*defaultValue*/ false);
                 }
             })
         );

src/harness/projectsRunner.ts

@@ -7,19 +7,11 @@ interface ProjectRunnerTestCase {
     scenario: string;
     projectRoot: string; // project where it lives - this also is the current directory when compiling
     inputFiles: string[]; // list of input files to be given to program
-    out?: string; // --out
-    outDir?: string; // --outDir
-    sourceMap?: boolean; // --map
-    mapRoot?: string; // --mapRoot
     resolveMapRoot?: boolean; // should we resolve this map root and give compiler the absolute disk path as map root?
-    sourceRoot?: string; // --sourceRoot
     resolveSourceRoot?: boolean; // should we resolve this source root and give compiler the absolute disk path as map root?
-    declaration?: boolean; // --d
     baselineCheck?: boolean; // Verify the baselines of output files, if this is false, we will write to output to the disk but there is no verification of baselines
     runTest?: boolean; // Run the resulting test
     bug?: string; // If there is any bug associated with this test case
-    noResolve?: boolean;
-    rootDir?: string; // --rootDir
 }
 
 interface ProjectRunnerTestCaseResolutionInfo extends ProjectRunnerTestCase {
@@ -34,14 +26,14 @@ interface BatchCompileProjectTestCaseEmittedFile extends Harness.Compiler.Genera
 
 interface CompileProjectFilesResult {
     moduleKind: ts.ModuleKind;
-    program: ts.Program;
+    program?: ts.Program;
+    compilerOptions?: ts.CompilerOptions;
     errors: ts.Diagnostic[];
-    sourceMapData: ts.SourceMapData[];
+    sourceMapData?: ts.SourceMapData[];
 }
 
 interface BatchCompileProjectTestCaseResult extends CompileProjectFilesResult {
-    outputFiles: BatchCompileProjectTestCaseEmittedFile[];
-    nonSubfolderDiskFiles: number;
+    outputFiles?: BatchCompileProjectTestCaseEmittedFile[];
 }
 
 class ProjectRunner extends RunnerBase {
@@ -59,7 +51,7 @@ class ProjectRunner extends RunnerBase {
     }
 
     private runProjectTestCase(testCaseFileName: string) {
-        let testCase: ProjectRunnerTestCase;
+        let testCase: ProjectRunnerTestCase & ts.CompilerOptions;
 
         let testFileText: string = null;
         try {
@@ -70,7 +62,7 @@ class ProjectRunner extends RunnerBase {
         }
 
         try {
-            testCase = <ProjectRunnerTestCase>JSON.parse(testFileText);
+            testCase = <ProjectRunnerTestCase & ts.CompilerOptions>JSON.parse(testFileText);
         }
         catch (e) {
             assert(false, "Testcase: " + testCaseFileName + " does not contain valid json format: " + e.message);
@@ -128,9 +120,10 @@ class ProjectRunner extends RunnerBase {
 
         function compileProjectFiles(moduleKind: ts.ModuleKind, getInputFiles: () => string[],
             getSourceFileTextImpl: (fileName: string) => string,
-            writeFile: (fileName: string, data: string, writeByteOrderMark: boolean) => void): CompileProjectFilesResult {
+            writeFile: (fileName: string, data: string, writeByteOrderMark: boolean) => void,
+            compilerOptions: ts.CompilerOptions): CompileProjectFilesResult {
 
-            const program = ts.createProgram(getInputFiles(), createCompilerOptions(), createCompilerHost());
+            const program = ts.createProgram(getInputFiles(), compilerOptions, createCompilerHost());
             let errors = ts.getPreEmitDiagnostics(program);
 
             const emitResult = program.emit();
@@ -155,21 +148,6 @@ class ProjectRunner extends RunnerBase {
                 sourceMapData
             };
 
-            function createCompilerOptions(): ts.CompilerOptions {
-                return {
-                    declaration: !!testCase.declaration,
-                    sourceMap: !!testCase.sourceMap,
-                    outFile: testCase.out,
-                    outDir: testCase.outDir,
-                    mapRoot: testCase.resolveMapRoot && testCase.mapRoot ? Harness.IO.resolvePath(testCase.mapRoot) : testCase.mapRoot,
-                    sourceRoot: testCase.resolveSourceRoot && testCase.sourceRoot ? Harness.IO.resolvePath(testCase.sourceRoot) : testCase.sourceRoot,
-                    module: moduleKind,
-                    moduleResolution: ts.ModuleResolutionKind.Classic, // currently all tests use classic module resolution kind, this will change in the future 
-                    noResolve: testCase.noResolve,
-                    rootDir: testCase.rootDir
-                };
-            }
-
             function getSourceFileText(fileName: string): string {
                 const text = getSourceFileTextImpl(fileName);
                 return text !== undefined ? text : getSourceFileTextImpl(ts.getNormalizedAbsolutePath(fileName, getCurrentDirectory()));
@@ -209,23 +187,105 @@ class ProjectRunner extends RunnerBase {
             let nonSubfolderDiskFiles = 0;
 
             const outputFiles: BatchCompileProjectTestCaseEmittedFile[] = [];
+            let inputFiles = testCase.inputFiles;
+            let compilerOptions = createCompilerOptions();
 
-            const projectCompilerResult = compileProjectFiles(moduleKind, () => testCase.inputFiles, getSourceFileText, writeFile);
+            let configFileName: string;
+            if (compilerOptions.project) {
+                // Parse project
+                configFileName = ts.normalizePath(ts.combinePaths(compilerOptions.project, "tsconfig.json"));
+                assert(!inputFiles || inputFiles.length === 0, "cannot specify input files and project option together");
+            }
+            else if (!inputFiles || inputFiles.length === 0) {
+                configFileName = ts.findConfigFile("", fileExists);
+            }
+
+            if (configFileName) {
+                const result = ts.readConfigFile(configFileName, getSourceFileText);
+                if (result.error) {
+                    return {
+                        moduleKind,
+                        errors: [result.error]
+                    };
+                }
+
+                const configObject = result.config;
+                const configParseResult = ts.parseJsonConfigFileContent(configObject, { readDirectory }, ts.getDirectoryPath(configFileName), compilerOptions);
+                if (configParseResult.errors.length > 0) {
+                    return {
+                        moduleKind,
+                        errors: configParseResult.errors
+                    };
+                }
+                inputFiles = configParseResult.fileNames;
+                compilerOptions = configParseResult.options;
+            }
+
+            const projectCompilerResult = compileProjectFiles(moduleKind, () => inputFiles, getSourceFileText, writeFile, compilerOptions);
             return {
                 moduleKind,
                 program: projectCompilerResult.program,
+                compilerOptions,
                 sourceMapData: projectCompilerResult.sourceMapData,
                 outputFiles,
                 errors: projectCompilerResult.errors,
-                nonSubfolderDiskFiles,
             };
 
+            function createCompilerOptions() {
+                // Set the special options that depend on other testcase options
+                const compilerOptions: ts.CompilerOptions = {
+                    mapRoot: testCase.resolveMapRoot && testCase.mapRoot ? Harness.IO.resolvePath(testCase.mapRoot) : testCase.mapRoot,
+                    sourceRoot: testCase.resolveSourceRoot && testCase.sourceRoot ? Harness.IO.resolvePath(testCase.sourceRoot) : testCase.sourceRoot,
+                    module: moduleKind,
+                    moduleResolution: ts.ModuleResolutionKind.Classic, // currently all tests use classic module resolution kind, this will change in the future 
+                };
+                // Set the values specified using json
+                const optionNameMap: ts.Map<ts.CommandLineOption> = {};
+                ts.forEach(ts.optionDeclarations, option => {
+                    optionNameMap[option.name] = option;
+                });
+                for (const name in testCase) {
+                    if (name !== "mapRoot" && name !== "sourceRoot" && ts.hasProperty(optionNameMap, name)) {
+                        const option = optionNameMap[name];
+                        const optType = option.type;
+                        let value = <any>testCase[name];
+                        if (typeof optType !== "string") {
+                            const key = value.toLowerCase();
+                            if (ts.hasProperty(optType, key)) {
+                                value = optType[key];
+                            }
+                        }
+                        compilerOptions[option.name] = value;
+                    }
+                }
+
+                return compilerOptions;
+            }
+
+            function getFileNameInTheProjectTest(fileName: string): string {
+                return ts.isRootedDiskPath(fileName)
+                    ? fileName
+                    : ts.normalizeSlashes(testCase.projectRoot) + "/" + ts.normalizeSlashes(fileName);
+            }
+
+            function readDirectory(rootDir: string, extension: string, exclude: string[]): string[] {
+                const harnessReadDirectoryResult = Harness.IO.readDirectory(getFileNameInTheProjectTest(rootDir), extension, exclude);
+                const result: string[] = [];
+                for (let i = 0; i < harnessReadDirectoryResult.length; i++) {
+                    result[i] = ts.getRelativePathToDirectoryOrUrl(testCase.projectRoot, harnessReadDirectoryResult[i],
+                        getCurrentDirectory(), Harness.Compiler.getCanonicalFileName, /*isAbsolutePathAnUrl*/ false);
+                }
+                return result;
+            }
+
+            function fileExists(fileName: string): boolean {
+                return Harness.IO.fileExists(getFileNameInTheProjectTest(fileName));
+            }
+
             function getSourceFileText(fileName: string): string {
                 let text: string = undefined;
                 try {
-                    text = Harness.IO.readFile(ts.isRootedDiskPath(fileName)
-                        ? fileName
-                        : ts.normalizeSlashes(testCase.projectRoot) + "/" + ts.normalizeSlashes(fileName));
+                    text = Harness.IO.readFile(getFileNameInTheProjectTest(fileName));
                 }
                 catch (e) {
                     // text doesn't get defined.
@@ -288,13 +348,16 @@ class ProjectRunner extends RunnerBase {
 
         function compileCompileDTsFiles(compilerResult: BatchCompileProjectTestCaseResult) {
             const allInputFiles: { emittedFileName: string; code: string; }[] = [];
+            if (!compilerResult.program) {
+                return;
+            }
             const compilerOptions = compilerResult.program.getCompilerOptions();
 
             ts.forEach(compilerResult.program.getSourceFiles(), sourceFile => {
-                if (Harness.Compiler.isDTS(sourceFile.fileName)) {
+                if (ts.isDeclarationFile(sourceFile)) {
                     allInputFiles.unshift({ emittedFileName: sourceFile.fileName, code: sourceFile.text });
                 }
-                else if (ts.shouldEmitToOwnFile(sourceFile, compilerResult.program.getCompilerOptions())) {
+                else if (!(compilerOptions.outFile || compilerOptions.out)) {
                     let emitOutputFilePathWithoutExtension: string = undefined;
                     if (compilerOptions.outDir) {
                         let sourceFilePath = ts.getNormalizedAbsolutePath(sourceFile.fileName, compilerResult.program.getCurrentDirectory());
@@ -306,7 +369,10 @@ class ProjectRunner extends RunnerBase {
                     }
 
                     const outputDtsFileName = emitOutputFilePathWithoutExtension + ".d.ts";
-                    allInputFiles.unshift(findOutpuDtsFile(outputDtsFileName));
+                    const file = findOutpuDtsFile(outputDtsFileName);
+                    if (file) {
+                        allInputFiles.unshift(file);
+                    }
                 }
                 else {
                     const outputDtsFileName = ts.removeFileExtension(compilerOptions.outFile || compilerOptions.out) + ".d.ts";
@@ -317,7 +383,8 @@ class ProjectRunner extends RunnerBase {
                 }
             });
 
-            return compileProjectFiles(compilerResult.moduleKind, getInputFiles, getSourceFileText, writeFile);
+            // Dont allow config files since we are compiling existing source options
+            return compileProjectFiles(compilerResult.moduleKind, getInputFiles, getSourceFileText, writeFile, compilerResult.compilerOptions);
 
             function findOutpuDtsFile(fileName: string) {
                 return ts.forEach(compilerResult.outputFiles, outputFile => outputFile.emittedFileName === fileName ? outputFile : undefined);
@@ -343,11 +410,16 @@ class ProjectRunner extends RunnerBase {
         }
 
         function getErrorsBaseline(compilerResult: CompileProjectFilesResult) {
-            const inputFiles = ts.map(ts.filter(compilerResult.program.getSourceFiles(),
+            const inputFiles = compilerResult.program ? ts.map(ts.filter(compilerResult.program.getSourceFiles(),
                 sourceFile => sourceFile.fileName !== "lib.d.ts"),
                 sourceFile => {
-                    return { unitName: sourceFile.fileName, content: sourceFile.text };
-                });
+                    return {
+                        unitName: ts.isRootedDiskPath(sourceFile.fileName) ?
+                            RunnerBase.removeFullPaths(sourceFile.fileName) :
+                            sourceFile.fileName,
+                        content: sourceFile.text
+                    };
+                }) : [];
 
             return Harness.Compiler.getErrorBaseline(inputFiles, compilerResult.errors);
         }
@@ -360,34 +432,17 @@ class ProjectRunner extends RunnerBase {
                     let compilerResult: BatchCompileProjectTestCaseResult;
 
                     function getCompilerResolutionInfo() {
-                        const resolutionInfo: ProjectRunnerTestCaseResolutionInfo = {
-                            scenario: testCase.scenario,
-                            projectRoot: testCase.projectRoot,
-                            inputFiles: testCase.inputFiles,
-                            out: testCase.out,
-                            outDir: testCase.outDir,
-                            sourceMap: testCase.sourceMap,
-                            mapRoot: testCase.mapRoot,
-                            resolveMapRoot: testCase.resolveMapRoot,
-                            sourceRoot: testCase.sourceRoot,
-                            resolveSourceRoot: testCase.resolveSourceRoot,
-                            declaration: testCase.declaration,
-                            baselineCheck: testCase.baselineCheck,
-                            runTest: testCase.runTest,
-                            bug: testCase.bug,
-                            rootDir: testCase.rootDir,
-                            resolvedInputFiles: ts.map(compilerResult.program.getSourceFiles(), inputFile => {
-                                return ts.convertToRelativePath(inputFile.fileName, getCurrentDirectory(), path => Harness.Compiler.getCanonicalFileName(path));
-                            }),
-                            emittedFiles: ts.map(compilerResult.outputFiles, outputFile => {
-                                return ts.convertToRelativePath(outputFile.emittedFileName, getCurrentDirectory(), path => Harness.Compiler.getCanonicalFileName(path));
-                            })
-                        };
-
+                        const resolutionInfo: ProjectRunnerTestCaseResolutionInfo & ts.CompilerOptions = JSON.parse(JSON.stringify(testCase));
+                        resolutionInfo.resolvedInputFiles = ts.map(compilerResult.program.getSourceFiles(), inputFile => {
+                            return ts.convertToRelativePath(inputFile.fileName, getCurrentDirectory(), path => Harness.Compiler.getCanonicalFileName(path));
+                        });
+                        resolutionInfo.emittedFiles = ts.map(compilerResult.outputFiles, outputFile => {
+                            return ts.convertToRelativePath(outputFile.emittedFileName, getCurrentDirectory(), path => Harness.Compiler.getCanonicalFileName(path));
+                        });
                         return resolutionInfo;
                     }
 
-                    it(name + ": " + moduleNameToString(moduleKind) , () => {
+                    it(name + ": " + moduleNameToString(moduleKind), () => {
                         // Compile using node
                         compilerResult = batchCompilerProjectTestCase(moduleKind);
                     });
@@ -439,7 +494,7 @@ class ProjectRunner extends RunnerBase {
                     it("Errors in generated Dts files for (" + moduleNameToString(moduleKind) + "): " + testCaseFileName, () => {
                         if (!compilerResult.errors.length && testCase.declaration) {
                             const dTsCompileResult = compileCompileDTsFiles(compilerResult);
-                            if (dTsCompileResult.errors.length) {
+                            if (dTsCompileResult && dTsCompileResult.errors.length) {
                                 Harness.Baseline.runBaseline("Errors in generated Dts files for (" + moduleNameToString(compilerResult.moduleKind) + "): " + testCaseFileName, getBaselineFolder(compilerResult.moduleKind) + testCaseJustName + ".dts.errors.txt", () => {
                                     return getErrorsBaseline(dTsCompileResult);
                                 });

src/harness/rwcRunner.ts

@@ -27,8 +27,8 @@ namespace RWC {
 
     export function runRWCTest(jsonPath: string) {
         describe("Testing a RWC project: " + jsonPath, () => {
-            let inputFiles: { unitName: string; content: string; }[] = [];
-            let otherFiles: { unitName: string; content: string; }[] = [];
+            let inputFiles: Harness.Compiler.TestFile[] = [];
+            let otherFiles: Harness.Compiler.TestFile[] = [];
             let compilerResult: Harness.Compiler.CompilerResult;
             let compilerOptions: ts.CompilerOptions;
             let baselineOpts: Harness.Baseline.BaselineOptions = {
@@ -55,7 +55,6 @@ namespace RWC {
             });
 
             it("can compile", () => {
-                const harnessCompiler = Harness.Compiler.getCompiler();
                 let opts: ts.ParsedCommandLine;
 
                 const ioLog: IOLog = JSON.parse(Harness.IO.readFile(jsonPath));
@@ -71,8 +70,6 @@ namespace RWC {
                 });
 
                 runWithIOLog(ioLog, oldIO => {
-                    harnessCompiler.reset();
-
                     let fileNames = opts.fileNames;
 
                     const tsconfigFile = ts.forEach(ioLog.filesRead, f => isTsConfigFile(f) ? f : undefined);
@@ -128,17 +125,21 @@ namespace RWC {
                     opts.options.noLib = true;
 
                     // Emit the results
-                    compilerOptions = harnessCompiler.compileFiles(
+                    compilerOptions = null;
+                    const output = Harness.Compiler.compileFiles(
                         inputFiles,
                         otherFiles,
-                        newCompilerResults => { compilerResult = newCompilerResults; },
-                        /*settingsCallback*/ undefined, opts.options,
+                        /* harnessOptions */ undefined,
+                        opts.options,
                         // Since each RWC json file specifies its current directory in its json file, we need
                         // to pass this information in explicitly instead of acquiring it from the process.
                         currentDirectory);
+
+                    compilerOptions = output.options;
+                    compilerResult = output.result;
                 });
 
-                function getHarnessCompilerInputUnit(fileName: string) {
+                function getHarnessCompilerInputUnit(fileName: string): Harness.Compiler.TestFile {
                     const unitName = ts.normalizeSlashes(Harness.IO.resolvePath(fileName));
                     let content: string = null;
                     try {
@@ -201,8 +202,9 @@ namespace RWC {
             it("has the expected errors in generated declaration files", () => {
                 if (compilerOptions.declaration && !compilerResult.errors.length) {
                     Harness.Baseline.runBaseline("has the expected errors in generated declaration files", baseName + ".dts.errors.txt", () => {
-                        const declFileCompilationResult = Harness.Compiler.getCompiler().compileDeclarationFiles(inputFiles, otherFiles, compilerResult,
-                            /*settingscallback*/ undefined, compilerOptions, currentDirectory);
+                        const declFileCompilationResult = Harness.Compiler.compileDeclarationFiles(
+                            inputFiles, otherFiles, compilerResult, /*harnessSettings*/ undefined, compilerOptions, currentDirectory);
+
                         if (declFileCompilationResult.declResult.errors.length === 0) {
                             return null;
                         }

src/harness/sourceMapRecorder.ts

@@ -190,7 +190,7 @@ namespace Harness.SourceMapRecoder {
                 return { error: errorDecodeOfEncodedMapping, sourceMapSpan: decodeOfEncodedMapping };
             }
 
-            createErrorIfCondition(true, "No encoded entry found");
+            createErrorIfCondition(/*condition*/ true, "No encoded entry found");
         }
 
         export function hasCompletedDecoding() {

src/harness/test262Runner.ts

@@ -5,9 +5,9 @@
 class Test262BaselineRunner extends RunnerBase {
     private static basePath = "internal/cases/test262";
     private static helpersFilePath = "tests/cases/test262-harness/helpers.d.ts";
-    private static helperFile = {
+    private static helperFile: Harness.Compiler.TestFile = {
         unitName: Test262BaselineRunner.helpersFilePath,
-        content: Harness.IO.readFile(Test262BaselineRunner.helpersFilePath)
+        content: Harness.IO.readFile(Test262BaselineRunner.helpersFilePath),
     };
     private static testFileExtensionRegex = /\.js$/;
     private static options: ts.CompilerOptions = {
@@ -31,8 +31,7 @@ class Test262BaselineRunner extends RunnerBase {
             let testState: {
                 filename: string;
                 compilerResult: Harness.Compiler.CompilerResult;
-                inputFiles: { unitName: string; content: string }[];
-                program: ts.Program;
+                inputFiles: Harness.Compiler.TestFile[];
             };
 
             before(() => {
@@ -40,8 +39,9 @@ class Test262BaselineRunner extends RunnerBase {
                 const testFilename = ts.removeFileExtension(filePath).replace(/\//g, "_") + ".test";
                 const testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, testFilename);
 
-                const inputFiles = testCaseContent.testUnitData.map(unit => {
-                    return { unitName: Test262BaselineRunner.getTestFilePath(unit.name), content: unit.content };
+                const inputFiles: Harness.Compiler.TestFile[] = testCaseContent.testUnitData.map(unit => {
+                    const unitName = Test262BaselineRunner.getTestFilePath(unit.name);
+                    return { unitName, content: unit.content };
                 });
 
                 // Emit the results
@@ -49,13 +49,16 @@ class Test262BaselineRunner extends RunnerBase {
                     filename: testFilename,
                     inputFiles: inputFiles,
                     compilerResult: undefined,
-                    program: undefined,
                 };
 
-                Harness.Compiler.getCompiler().compileFiles([Test262BaselineRunner.helperFile].concat(inputFiles), /*otherFiles*/ [], (compilerResult, program) => {
-                    testState.compilerResult = compilerResult;
-                    testState.program = program;
-                }, /*settingsCallback*/ undefined, Test262BaselineRunner.options);
+                const output = Harness.Compiler.compileFiles(
+                    [Test262BaselineRunner.helperFile].concat(inputFiles),
+                    /*otherFiles*/ [],
+                    /* harnessOptions */ undefined,
+                    Test262BaselineRunner.options,
+                    /* currentDirectory */ undefined
+                    );
+                testState.compilerResult = output.result;
             });
 
             after(() => {
@@ -80,14 +83,14 @@ class Test262BaselineRunner extends RunnerBase {
                 }, false, Test262BaselineRunner.baselineOptions);
             });
 
-            it("satisfies inletiants", () => {
-                const sourceFile = testState.program.getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));
+            it("satisfies invariants", () => {
+                const sourceFile = testState.compilerResult.program.getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));
                 Utils.assertInvariants(sourceFile, /*parent:*/ undefined);
             });
 
             it("has the expected AST", () => {
                 Harness.Baseline.runBaseline("has the expected AST", testState.filename + ".AST.txt", () => {
-                    const sourceFile = testState.program.getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));
+                    const sourceFile = testState.compilerResult.program.getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));
                     return Utils.sourceFileToJSON(sourceFile);
                 }, false, Test262BaselineRunner.baselineOptions);
             });

src/server/client.ts

@@ -120,8 +120,8 @@ namespace ts.server {
             return response;
         }
 
-        openFile(fileName: string): void {
-            var args: protocol.FileRequestArgs = { file: fileName };
+        openFile(fileName: string, content?: string): void {
+            var args: protocol.OpenRequestArgs = { file: fileName, fileContent: content };
             this.processRequest(CommandNames.Open, args);
         }
 

src/server/editorServices.ts

@@ -371,6 +371,10 @@ namespace ts.server {
         openRefCount = 0;
 
         constructor(public projectService: ProjectService, public projectOptions?: ProjectOptions) {
+            if (projectOptions && projectOptions.files) {
+                // If files are listed explicitly, allow all extensions
+                projectOptions.compilerOptions.allowNonTsExtensions = true;
+            }
             this.compilerService = new CompilerService(this, projectOptions && projectOptions.compilerOptions);
         }
 
@@ -384,7 +388,7 @@ namespace ts.server {
         }
 
         openReferencedFile(filename: string) {
-            return this.projectService.openFile(filename, false);
+            return this.projectService.openFile(filename, /*openedByClient*/ false);
         }
 
         getRootFiles() {
@@ -461,6 +465,7 @@ namespace ts.server {
         setProjectOptions(projectOptions: ProjectOptions) {
             this.projectOptions = projectOptions;
             if (projectOptions.compilerOptions) {
+                projectOptions.compilerOptions.allowNonTsExtensions = true;
                 this.compilerService.setCompilerOptions(projectOptions.compilerOptions);
             }
         }
@@ -559,7 +564,7 @@ namespace ts.server {
             // If a change was made inside "folder/file", node will trigger the callback twice:
             // one with the fileName being "folder/file", and the other one with "folder".
             // We don't respond to the second one.
-            if (fileName && !ts.isSupportedSourceFileName(fileName)) {
+            if (fileName && !ts.isSupportedSourceFileName(fileName, project.projectOptions ? project.projectOptions.compilerOptions : undefined)) {
                 return;
             }
 
@@ -1001,14 +1006,15 @@ namespace ts.server {
 
         /**
          * @param filename is absolute pathname
+         * @param fileContent is a known version of the file content that is more up to date than the one on disk
          */
-        openFile(fileName: string, openedByClient: boolean) {
+        openFile(fileName: string, openedByClient: boolean, fileContent?: string) {
             fileName = ts.normalizePath(fileName);
             let info = ts.lookUp(this.filenameToScriptInfo, fileName);
             if (!info) {
                 let content: string;
                 if (this.host.fileExists(fileName)) {
-                    content = this.host.readFile(fileName);
+                    content = fileContent || this.host.readFile(fileName);
                 }
                 if (!content) {
                     if (openedByClient) {
@@ -1025,6 +1031,9 @@ namespace ts.server {
                 }
             }
             if (info) {
+                if (fileContent) {
+                    info.svc.reload(fileContent);
+                }
                 if (openedByClient) {
                     info.isOpen = true;
                 }
@@ -1055,10 +1064,11 @@ namespace ts.server {
         /**
          * Open file whose contents is managed by the client
          * @param filename is absolute pathname
+         * @param fileContent is a known version of the file content that is more up to date than the one on disk
          */
-        openClientFile(fileName: string) {
+        openClientFile(fileName: string, fileContent?: string) {
             this.openOrUpdateConfiguredProjectForFile(fileName);
-            const info = this.openFile(fileName, true);
+            const info = this.openFile(fileName, /*openedByClient*/ true, fileContent);
             this.addOpenFile(info);
             this.printProjects();
             return info;
@@ -1267,7 +1277,7 @@ namespace ts.server {
                     for (const fileName of fileNamesToAdd) {
                         let info = this.getScriptInfo(fileName);
                         if (!info) {
-                            info = this.openFile(fileName, false);
+                            info = this.openFile(fileName, /*openedByClient*/ false);
                         }
                         else {
                             // if the root file was opened by client, it would belong to either 
@@ -1316,7 +1326,9 @@ namespace ts.server {
                 this.setCompilerOptions(opt);
             }
             else {
-                this.setCompilerOptions(ts.getDefaultCompilerOptions());
+                const defaultOpts = ts.getDefaultCompilerOptions();
+                defaultOpts.allowNonTsExtensions = true;
+                this.setCompilerOptions(defaultOpts);
             }
             this.languageService = ts.createLanguageService(this.host, this.documentRegistry);
             this.classifier = ts.createClassifier();

src/server/protocol.d.ts

@@ -513,6 +513,11 @@ declare namespace ts.server.protocol {
       *  Information found in an "open" request.
       */
     export interface OpenRequestArgs extends FileRequestArgs {
+        /**
+         * Used when a version of the file content is known to be more up to date than the one on disk. 
+         * Then the known content will be used upon opening instead of the disk copy   
+         */
+        fileContent?: string;
     }
 
     /**

src/server/session.ts

@@ -532,9 +532,13 @@ namespace ts.server {
             };
         }
 
-        private openClientFile(fileName: string) {
+        /**
+         * @param fileName is the name of the file to be opened
+         * @param fileContent is a version of the file content that is known to be more up to date than the one on disk
+         */
+        private openClientFile(fileName: string, fileContent?: string) {
             const file = ts.normalizePath(fileName);
-            this.projectService.openClientFile(file);
+            this.projectService.openClientFile(file, fileContent);
         }
 
         private getQuickInfo(line: number, offset: number, fileName: string): protocol.QuickInfoResponseBody {
@@ -897,7 +901,7 @@ namespace ts.server {
         }
 
         getDiagnosticsForProject(delay: number, fileName: string) {
-            const { configFileName, fileNames } = this.getProjectInfo(fileName, true);
+            const { configFileName, fileNames } = this.getProjectInfo(fileName, /*needFileNameList*/ true);
             // No need to analyze lib.d.ts
             let fileNamesInProject = fileNames.filter((value, index, array) => value.indexOf("lib.d.ts") < 0);
 
@@ -968,7 +972,7 @@ namespace ts.server {
             },
             [CommandNames.Open]: (request: protocol.Request) => {
                 const openArgs = <protocol.OpenRequestArgs>request.arguments;
-                this.openClientFile(openArgs.file);
+                this.openClientFile(openArgs.file, openArgs.fileContent);
                 return {responseRequired: false};
             },
             [CommandNames.Quickinfo]: (request: protocol.Request) => {

src/services/formatting/tokenRange.ts

@@ -14,7 +14,7 @@ namespace ts.formatting {
             constructor(from: SyntaxKind, to: SyntaxKind, except: SyntaxKind[]) {
                 this.tokens = [];
                 for (let token = from; token <= to; token++) {
-                    if (except.indexOf(token) < 0) {
+                    if (ts.indexOf(except, token) < 0) {
                         this.tokens.push(token);
                     }
                 }
@@ -123,4 +123,4 @@ namespace ts.formatting {
             static TypeNames = TokenRange.FromTokens([SyntaxKind.Identifier, SyntaxKind.NumberKeyword, SyntaxKind.StringKeyword, SyntaxKind.BooleanKeyword, SyntaxKind.SymbolKeyword, SyntaxKind.VoidKeyword, SyntaxKind.AnyKeyword]);
         }
     }
-}
+}

src/services/navigationBar.ts

@@ -2,7 +2,7 @@
 
 /* @internal */
 namespace ts.NavigationBar {
-    export function getNavigationBarItems(sourceFile: SourceFile): ts.NavigationBarItem[]  {
+    export function getNavigationBarItems(sourceFile: SourceFile, compilerOptions: CompilerOptions): ts.NavigationBarItem[]  {
         // If the source file has any child items, then it included in the tree
         // and takes lexical ownership of all other top-level items.
         let hasGlobalNode = false;

src/services/shims.ts

@@ -956,7 +956,8 @@ namespace ts {
             return this.forwardJSONCall(
                 "getPreProcessedFileInfo('" + fileName + "')",
                 () => {
-                    var result = preProcessFile(sourceTextSnapshot.getText(0, sourceTextSnapshot.getLength()));
+                    // for now treat files as JavaScript 
+                    var result = preProcessFile(sourceTextSnapshot.getText(0, sourceTextSnapshot.getLength()), /* readImportFiles */ true, /* detectJavaScriptImports */ true);
                     var convertResult = {
                         referencedFiles: <IFileReference[]>[],
                         importedFiles: <IFileReference[]>[],

src/services/signatureHelp.ts

@@ -204,7 +204,7 @@ namespace ts.SignatureHelp {
         if (!candidates.length) {
             // We didn't have any sig help items produced by the TS compiler.  If this is a JS 
             // file, then see if we can figure out anything better.
-            if (isJavaScript(sourceFile.fileName)) {
+            if (isSourceFileJavaScript(sourceFile)) {
                 return createJavaScriptSignatureHelpItems(argumentInfo);
             }