Merge branch 'master' into emitHelper

src/compiler/binder.ts

@@ -499,8 +499,8 @@ namespace ts {
                 const saveReturnTarget = currentReturnTarget;
                 const saveActiveLabels = activeLabels;
                 const saveHasExplicitReturn = hasExplicitReturn;
-                const isIIFE = containerFlags & ContainerFlags.IsFunctionExpression && !!getImmediatelyInvokedFunctionExpression(node);
-                // An IIFE is considered part of the containing control flow. Return statements behave
+                const isIIFE = containerFlags & ContainerFlags.IsFunctionExpression && !hasModifier(node, ModifierFlags.Async) && !!getImmediatelyInvokedFunctionExpression(node);
+                // A non-async IIFE is considered part of the containing control flow. Return statements behave
                 // similarly to break statements that exit to a label just past the statement body.
                 if (isIIFE) {
                     currentReturnTarget = createBranchLabel();
@@ -560,6 +560,7 @@ namespace ts {
                 skipTransformFlagAggregation = true;
                 bindChildrenWorker(node);
                 skipTransformFlagAggregation = false;
+                subtreeTransformFlags |= node.transformFlags & ~getTransformFlagsSubtreeExclusions(node.kind);
             }
             else {
                 const savedSubtreeTransformFlags = subtreeTransformFlags;
@@ -892,8 +893,13 @@ namespace ts {
 
         function bindDoStatement(node: DoStatement): void {
             const preDoLabel = createLoopLabel();
-            const preConditionLabel = createBranchLabel();
-            const postDoLabel = createBranchLabel();
+            const enclosingLabeledStatement = node.parent.kind === SyntaxKind.LabeledStatement
+                ? lastOrUndefined(activeLabels)
+                : undefined;
+            // if do statement is wrapped in labeled statement then target labels for break/continue with or without
+            // label should be the same
+            const preConditionLabel = enclosingLabeledStatement ? enclosingLabeledStatement.continueTarget : createBranchLabel();
+            const postDoLabel = enclosingLabeledStatement ? enclosingLabeledStatement.breakTarget : createBranchLabel();
             addAntecedent(preDoLabel, currentFlow);
             currentFlow = preDoLabel;
             bindIterativeStatement(node.statement, postDoLabel, preConditionLabel);
@@ -1111,8 +1117,11 @@ namespace ts {
             if (!activeLabel.referenced && !options.allowUnusedLabels) {
                 file.bindDiagnostics.push(createDiagnosticForNode(node.label, Diagnostics.Unused_label));
             }
-            addAntecedent(postStatementLabel, currentFlow);
-            currentFlow = finishFlowLabel(postStatementLabel);
+            if (!node.statement || node.statement.kind !== SyntaxKind.DoStatement) {
+                // do statement sets current flow inside bindDoStatement
+                addAntecedent(postStatementLabel, currentFlow);
+                currentFlow = finishFlowLabel(postStatementLabel);
+            }
         }
 
         function bindDestructuringTargetFlow(node: Expression) {
@@ -1201,9 +1210,9 @@ namespace ts {
             }
             else {
                 forEachChild(node, bind);
-                if (operator === SyntaxKind.EqualsToken && !isAssignmentTarget(node)) {
+                if (isAssignmentOperator(operator) && !isAssignmentTarget(node)) {
                     bindAssignmentTargetFlow(node.left);
-                    if (node.left.kind === SyntaxKind.ElementAccessExpression) {
+                    if (operator === SyntaxKind.EqualsToken && node.left.kind === SyntaxKind.ElementAccessExpression) {
                         const elementAccess = <ElementAccessExpression>node.left;
                         if (isNarrowableOperand(elementAccess.expression)) {
                             currentFlow = createFlowArrayMutation(currentFlow, node);
@@ -1226,9 +1235,11 @@ namespace ts {
             const postExpressionLabel = createBranchLabel();
             bindCondition(node.condition, trueLabel, falseLabel);
             currentFlow = finishFlowLabel(trueLabel);
+            bind(node.questionToken);
             bind(node.whenTrue);
             addAntecedent(postExpressionLabel, currentFlow);
             currentFlow = finishFlowLabel(falseLabel);
+            bind(node.colonToken);
             bind(node.whenFalse);
             addAntecedent(postExpressionLabel, currentFlow);
             currentFlow = finishFlowLabel(postExpressionLabel);
@@ -3089,6 +3100,8 @@ namespace ts {
             case SyntaxKind.InterfaceDeclaration:
             case SyntaxKind.TypeAliasDeclaration:
             case SyntaxKind.ThisType:
+            case SyntaxKind.TypeOperator:
+            case SyntaxKind.IndexedAccessType:
             case SyntaxKind.LiteralType:
                 // Types and signatures are TypeScript syntax, and exclude all other facts.
                 transformFlags = TransformFlags.AssertTypeScript;
@@ -3194,4 +3207,65 @@ namespace ts {
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~excludeFlags;
     }
+
+    /**
+     * Gets the transform flags to exclude when unioning the transform flags of a subtree.
+     *
+     * NOTE: This needs to be kept up-to-date with the exclusions used in `computeTransformFlagsForNode`.
+     *       For performance reasons, `computeTransformFlagsForNode` uses local constant values rather
+     *       than calling this function.
+     */
+    /* @internal */
+    export function getTransformFlagsSubtreeExclusions(kind: SyntaxKind) {
+        if (kind >= SyntaxKind.FirstTypeNode && kind <= SyntaxKind.LastTypeNode) {
+            return TransformFlags.TypeExcludes;
+        }
+
+        switch (kind) {
+            case SyntaxKind.CallExpression:
+            case SyntaxKind.NewExpression:
+            case SyntaxKind.ArrayLiteralExpression:
+                return TransformFlags.ArrayLiteralOrCallOrNewExcludes;
+            case SyntaxKind.ModuleDeclaration:
+                return TransformFlags.ModuleExcludes;
+            case SyntaxKind.Parameter:
+                return TransformFlags.ParameterExcludes;
+            case SyntaxKind.ArrowFunction:
+                return TransformFlags.ArrowFunctionExcludes;
+            case SyntaxKind.FunctionExpression:
+            case SyntaxKind.FunctionDeclaration:
+                return TransformFlags.FunctionExcludes;
+            case SyntaxKind.VariableDeclarationList:
+                return TransformFlags.VariableDeclarationListExcludes;
+            case SyntaxKind.ClassDeclaration:
+            case SyntaxKind.ClassExpression:
+                return TransformFlags.ClassExcludes;
+            case SyntaxKind.Constructor:
+                return TransformFlags.ConstructorExcludes;
+            case SyntaxKind.MethodDeclaration:
+            case SyntaxKind.GetAccessor:
+            case SyntaxKind.SetAccessor:
+                return TransformFlags.MethodOrAccessorExcludes;
+            case SyntaxKind.AnyKeyword:
+            case SyntaxKind.NumberKeyword:
+            case SyntaxKind.NeverKeyword:
+            case SyntaxKind.StringKeyword:
+            case SyntaxKind.BooleanKeyword:
+            case SyntaxKind.SymbolKeyword:
+            case SyntaxKind.VoidKeyword:
+            case SyntaxKind.TypeParameter:
+            case SyntaxKind.PropertySignature:
+            case SyntaxKind.MethodSignature:
+            case SyntaxKind.CallSignature:
+            case SyntaxKind.ConstructSignature:
+            case SyntaxKind.IndexSignature:
+            case SyntaxKind.InterfaceDeclaration:
+            case SyntaxKind.TypeAliasDeclaration:
+                return TransformFlags.TypeExcludes;
+            case SyntaxKind.ObjectLiteralExpression:
+                return TransformFlags.ObjectLiteralExcludes;
+            default:
+                return TransformFlags.NodeExcludes;
+        }
+    }
 }

src/compiler/commandLineParser.ts

@@ -1008,9 +1008,7 @@ namespace ts {
     function convertTypingOptionsFromJsonWorker(jsonOptions: any,
         basePath: string, errors: Diagnostic[], configFileName?: string): TypingOptions {
 
-        const options: TypingOptions = getBaseFileName(configFileName) === "jsconfig.json"
-            ? { enableAutoDiscovery: true, include: [], exclude: [] }
-            : { enableAutoDiscovery: false, include: [], exclude: [] };
+        const options: TypingOptions = { enableAutoDiscovery: getBaseFileName(configFileName) === "jsconfig.json", include: [], exclude: [] };
         convertOptionsFromJson(typingOptionDeclarations, jsonOptions, basePath, options, Diagnostics.Unknown_typing_option_0, errors);
         return options;
     }
@@ -1263,12 +1261,13 @@ namespace ts {
     /**
      * Gets directories in a set of include patterns that should be watched for changes.
      */
-    function getWildcardDirectories(include: string[], exclude: string[], path: string, useCaseSensitiveFileNames: boolean) {
+    function getWildcardDirectories(include: string[], exclude: string[], path: string, useCaseSensitiveFileNames: boolean): Map<WatchDirectoryFlags> {
         // We watch a directory recursively if it contains a wildcard anywhere in a directory segment
         // of the pattern:
         //
         //  /a/b/**/d   - Watch /a/b recursively to catch changes to any d in any subfolder recursively
         //  /a/b/*/d    - Watch /a/b recursively to catch any d in any immediate subfolder, even if a new subfolder is added
+        //  /a/b        - Watch /a/b recursively to catch changes to anything in any recursive subfoler
         //
         // We watch a directory without recursion if it contains a wildcard in the file segment of
         // the pattern:
@@ -1281,15 +1280,14 @@ namespace ts {
         if (include !== undefined) {
             const recursiveKeys: string[] = [];
             for (const file of include) {
-                const name = normalizePath(combinePaths(path, file));
-                if (excludeRegex && excludeRegex.test(name)) {
+                const spec = normalizePath(combinePaths(path, file));
+                if (excludeRegex && excludeRegex.test(spec)) {
                     continue;
                 }
 
-                const match = wildcardDirectoryPattern.exec(name);
+                const match = getWildcardDirectoryFromSpec(spec, useCaseSensitiveFileNames);
                 if (match) {
-                    const key = useCaseSensitiveFileNames ? match[0] : match[0].toLowerCase();
-                    const flags = watchRecursivePattern.test(name) ? WatchDirectoryFlags.Recursive : WatchDirectoryFlags.None;
+                    const { key, flags } = match;
                     const existingFlags = wildcardDirectories[key];
                     if (existingFlags === undefined || existingFlags < flags) {
                         wildcardDirectories[key] = flags;
@@ -1313,6 +1311,20 @@ namespace ts {
         return wildcardDirectories;
     }
 
+    function getWildcardDirectoryFromSpec(spec: string, useCaseSensitiveFileNames: boolean): { key: string, flags: WatchDirectoryFlags } | undefined {
+        const match = wildcardDirectoryPattern.exec(spec);
+        if (match) {
+            return {
+                key: useCaseSensitiveFileNames ? match[0] : match[0].toLowerCase(),
+                flags: watchRecursivePattern.test(spec) ? WatchDirectoryFlags.Recursive : WatchDirectoryFlags.None
+            };
+        }
+        if (isImplicitGlob(spec)) {
+            return { key: spec, flags: WatchDirectoryFlags.Recursive };
+        }
+        return undefined;
+    }
+
     /**
      * Determines whether a literal or wildcard file has already been included that has a higher
      * extension priority.

src/compiler/core.ts

@@ -446,8 +446,8 @@ namespace ts {
     }
 
     export function concatenate<T>(array1: T[], array2: T[]): T[] {
-        if (!array2 || !array2.length) return array1;
-        if (!array1 || !array1.length) return array2;
+        if (!some(array2)) return array1;
+        if (!some(array1)) return array2;
         return [...array1, ...array2];
     }
 
@@ -527,6 +527,27 @@ namespace ts {
         return result || array;
     }
 
+    /**
+     * Gets the relative complement of `arrayA` with respect to `b`, returning the elements that
+     * are not present in `arrayA` but are present in `arrayB`. Assumes both arrays are sorted
+     * based on the provided comparer.
+     */
+    export function relativeComplement<T>(arrayA: T[] | undefined, arrayB: T[] | undefined, comparer: (x: T, y: T) => Comparison = compareValues, offsetA = 0, offsetB = 0): T[] | undefined {
+        if (!arrayB || !arrayA || arrayB.length === 0 || arrayA.length === 0) return arrayB;
+        const result: T[] = [];
+        outer: for (; offsetB < arrayB.length; offsetB++) {
+            inner: for (; offsetA < arrayA.length; offsetA++) {
+                switch (comparer(arrayB[offsetB], arrayA[offsetA])) {
+                    case Comparison.LessThan: break inner;
+                    case Comparison.EqualTo: continue outer;
+                    case Comparison.GreaterThan: continue inner;
+                }
+            }
+            result.push(arrayB[offsetB]);
+        }
+        return result;
+    }
+
     export function sum(array: any[], prop: string): number {
         let result = 0;
         for (const v of array) {
@@ -636,12 +657,12 @@ namespace ts {
      * @param array A sorted array whose first element must be no larger than number
      * @param number The value to be searched for in the array.
      */
-    export function binarySearch<T>(array: T[], value: T, comparer?: (v1: T, v2: T) => number): number {
+    export function binarySearch<T>(array: T[], value: T, comparer?: (v1: T, v2: T) => number, offset?: number): number {
         if (!array || array.length === 0) {
             return -1;
         }
 
-        let low = 0;
+        let low = offset || 0;
         let high = array.length - 1;
         comparer = comparer !== undefined
             ? comparer
@@ -1116,6 +1137,18 @@ namespace ts {
         };
     }
 
+    export function createCompilerDiagnosticFromMessageChain(chain: DiagnosticMessageChain): Diagnostic {
+        return {
+            file: undefined,
+            start: undefined,
+            length: undefined,
+
+            code: chain.code,
+            category: chain.category,
+            messageText: chain.next ? chain : chain.messageText
+        };
+    }
+
     export function chainDiagnosticMessages(details: DiagnosticMessageChain, message: DiagnosticMessage, ...args: any[]): DiagnosticMessageChain;
     export function chainDiagnosticMessages(details: DiagnosticMessageChain, message: DiagnosticMessage): DiagnosticMessageChain {
         let text = getLocaleSpecificMessage(message);
@@ -1322,7 +1355,7 @@ namespace ts {
      */
     export function getDirectoryPath(path: Path): Path;
     export function getDirectoryPath(path: string): string;
-    export function getDirectoryPath(path: string): any {
+    export function getDirectoryPath(path: string): string {
         return path.substr(0, Math.max(getRootLength(path), path.lastIndexOf(directorySeparator)));
     }
 
@@ -1582,6 +1615,10 @@ namespace ts {
         return expectedPos >= 0 && str.indexOf(suffix, expectedPos) === expectedPos;
     }
 
+    export function hasExtension(fileName: string): boolean {
+        return getBaseFileName(fileName).indexOf(".") >= 0;
+    }
+
     export function fileExtensionIs(path: string, extension: string): boolean {
         return path.length > extension.length && endsWith(path, extension);
     }
@@ -1627,73 +1664,21 @@ namespace ts {
 
         let pattern = "";
         let hasWrittenSubpattern = false;
-        spec: for (const spec of specs) {
+        for (const spec of specs) {
             if (!spec) {
                 continue;
             }
 
-            let subpattern = "";
-            let hasRecursiveDirectoryWildcard = false;
-            let hasWrittenComponent = false;
-            const components = getNormalizedPathComponents(spec, basePath);
-            if (usage !== "exclude" && components[components.length - 1] === "**") {
-                continue spec;
-            }
-
-            // getNormalizedPathComponents includes the separator for the root component.
-            // We need to remove to create our regex correctly.
-            components[0] = removeTrailingDirectorySeparator(components[0]);
-
-            let optionalCount = 0;
-            for (let component of components) {
-                if (component === "**") {
-                    if (hasRecursiveDirectoryWildcard) {
-                        continue spec;
-                    }
-
-                    subpattern += doubleAsteriskRegexFragment;
-                    hasRecursiveDirectoryWildcard = true;
-                    hasWrittenComponent = true;
-                }
-                else {
-                    if (usage === "directories") {
-                        subpattern += "(";
-                        optionalCount++;
-                    }
-
-                    if (hasWrittenComponent) {
-                        subpattern += directorySeparator;
-                    }
-
-                    if (usage !== "exclude") {
-                        // The * and ? wildcards should not match directories or files that start with . if they
-                        // appear first in a component. Dotted directories and files can be included explicitly
-                        // like so: **/.*/.*
-                        if (component.charCodeAt(0) === CharacterCodes.asterisk) {
-                            subpattern += "([^./]" + singleAsteriskRegexFragment + ")?";
-                            component = component.substr(1);
-                        }
-                        else if (component.charCodeAt(0) === CharacterCodes.question) {
-                            subpattern += "[^./]";
-                            component = component.substr(1);
-                        }
-                    }
-
-                    subpattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
-                    hasWrittenComponent = true;
-                }
-            }
-
-            while (optionalCount > 0) {
-                subpattern += ")?";
-                optionalCount--;
+            const subPattern = getSubPatternFromSpec(spec, basePath, usage, singleAsteriskRegexFragment, doubleAsteriskRegexFragment, replaceWildcardCharacter);
+            if (subPattern === undefined) {
+                continue;
             }
 
             if (hasWrittenSubpattern) {
                 pattern += "|";
             }
 
-            pattern += "(" + subpattern + ")";
+            pattern += "(" + subPattern + ")";
             hasWrittenSubpattern = true;
         }
 
@@ -1701,7 +1686,83 @@ namespace ts {
             return undefined;
         }
 
-        return "^(" + pattern + (usage === "exclude" ? ")($|/)" : ")$");
+        // If excluding, match "foo/bar/baz...", but if including, only allow "foo".
+        const terminator = usage === "exclude" ? "($|/)" : "$";
+        return `^(${pattern})${terminator}`;
+    }
+
+    /**
+     * An "includes" path "foo" is implicitly a glob "foo/** /*" (without the space) if its last component has no extension,
+     * and does not contain any glob characters itself.
+     */
+    export function isImplicitGlob(lastPathComponent: string): boolean {
+        return !/[.*?]/.test(lastPathComponent);
+    }
+
+    function getSubPatternFromSpec(spec: string, basePath: string, usage: "files" | "directories" | "exclude", singleAsteriskRegexFragment: string, doubleAsteriskRegexFragment: string, replaceWildcardCharacter: (match: string) => string): string | undefined {
+        let subpattern = "";
+        let hasRecursiveDirectoryWildcard = false;
+        let hasWrittenComponent = false;
+        const components = getNormalizedPathComponents(spec, basePath);
+        const lastComponent = lastOrUndefined(components);
+        if (usage !== "exclude" && lastComponent === "**") {
+            return undefined;
+        }
+
+        // getNormalizedPathComponents includes the separator for the root component.
+        // We need to remove to create our regex correctly.
+        components[0] = removeTrailingDirectorySeparator(components[0]);
+
+        if (isImplicitGlob(lastComponent)) {
+            components.push("**", "*");
+        }
+
+        let optionalCount = 0;
+        for (let component of components) {
+            if (component === "**") {
+                if (hasRecursiveDirectoryWildcard) {
+                    return undefined;
+                }
+
+                subpattern += doubleAsteriskRegexFragment;
+                hasRecursiveDirectoryWildcard = true;
+            }
+            else {
+                if (usage === "directories") {
+                    subpattern += "(";
+                    optionalCount++;
+                }
+
+                if (hasWrittenComponent) {
+                    subpattern += directorySeparator;
+                }
+
+                if (usage !== "exclude") {
+                    // The * and ? wildcards should not match directories or files that start with . if they
+                    // appear first in a component. Dotted directories and files can be included explicitly
+                    // like so: **/.*/.*
+                    if (component.charCodeAt(0) === CharacterCodes.asterisk) {
+                        subpattern += "([^./]" + singleAsteriskRegexFragment + ")?";
+                        component = component.substr(1);
+                    }
+                    else if (component.charCodeAt(0) === CharacterCodes.question) {
+                        subpattern += "[^./]";
+                        component = component.substr(1);
+                    }
+                }
+
+                subpattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
+            }
+
+            hasWrittenComponent = true;
+        }
+
+        while (optionalCount > 0) {
+            subpattern += ")?";
+            optionalCount--;
+        }
+
+        return subpattern;
     }
 
     function replaceWildCardCharacterFiles(match: string) {
@@ -1788,6 +1849,7 @@ namespace ts {
     function getBasePaths(path: string, includes: string[], useCaseSensitiveFileNames: boolean) {
         // Storage for our results in the form of literal paths (e.g. the paths as written by the user).
         const basePaths: string[] = [path];
+
         if (includes) {
             // Storage for literal base paths amongst the include patterns.
             const includeBasePaths: string[] = [];
@@ -1795,14 +1857,8 @@ namespace ts {
                 // We also need to check the relative paths by converting them to absolute and normalizing
                 // in case they escape the base path (e.g "..\somedirectory")
                 const absolute: string = isRootedDiskPath(include) ? include : normalizePath(combinePaths(path, include));
-
-                const wildcardOffset = indexOfAnyCharCode(absolute, wildcardCharCodes);
-                const includeBasePath = wildcardOffset < 0
-                    ? removeTrailingDirectorySeparator(getDirectoryPath(absolute))
-                    : absolute.substring(0, absolute.lastIndexOf(directorySeparator, wildcardOffset));
-
                 // Append the literal and canonical candidate base paths.
-                includeBasePaths.push(includeBasePath);
+                includeBasePaths.push(getIncludeBasePath(absolute));
             }
 
             // Sort the offsets array using either the literal or canonical path representations.
@@ -1810,21 +1866,27 @@ namespace ts {
 
             // Iterate over each include base path and include unique base paths that are not a
             // subpath of an existing base path
-            include: for (let i = 0; i < includeBasePaths.length; i++) {
-                const includeBasePath = includeBasePaths[i];
-                for (let j = 0; j < basePaths.length; j++) {
-                    if (containsPath(basePaths[j], includeBasePath, path, !useCaseSensitiveFileNames)) {
-                        continue include;
-                    }
+            for (const includeBasePath of includeBasePaths) {
+                if (ts.every(basePaths, basePath => !containsPath(basePath, includeBasePath, path, !useCaseSensitiveFileNames))) {
+                    basePaths.push(includeBasePath);
                 }
-
-                basePaths.push(includeBasePath);
             }
         }
 
         return basePaths;
     }
 
+    function getIncludeBasePath(absolute: string): string {
+        const wildcardOffset = indexOfAnyCharCode(absolute, wildcardCharCodes);
+        if (wildcardOffset < 0) {
+            // No "*" or "?" in the path
+            return !hasExtension(absolute)
+                ? absolute
+                : removeTrailingDirectorySeparator(getDirectoryPath(absolute));
+        }
+        return absolute.substring(0, absolute.lastIndexOf(directorySeparator, wildcardOffset));
+    }
+
     export function ensureScriptKind(fileName: string, scriptKind?: ScriptKind): ScriptKind {
         // Using scriptKind as a condition handles both:
         // - 'scriptKind' is unspecified and thus it is `undefined`

src/compiler/declarationEmitter.ts

@@ -413,6 +413,10 @@ namespace ts {
                     return emitIntersectionType(<IntersectionTypeNode>type);
                 case SyntaxKind.ParenthesizedType:
                     return emitParenType(<ParenthesizedTypeNode>type);
+                case SyntaxKind.TypeOperator:
+                    return emitTypeOperator(<TypeOperatorNode>type);
+                case SyntaxKind.IndexedAccessType:
+                    return emitPropertyAccessType(<IndexedAccessTypeNode>type);
                 case SyntaxKind.FunctionType:
                 case SyntaxKind.ConstructorType:
                     return emitSignatureDeclarationWithJsDocComments(<FunctionOrConstructorTypeNode>type);
@@ -506,6 +510,19 @@ namespace ts {
                 write(")");
             }
 
+            function emitTypeOperator(type: TypeOperatorNode) {
+                write(tokenToString(type.operator));
+                write(" ");
+                emitType(type.type);
+            }
+
+            function emitPropertyAccessType(node: IndexedAccessTypeNode) {
+                emitType(node.objectType);
+                write("[");
+                emitType(node.indexType);
+                write("]");
+            }
+
             function emitTypeLiteral(type: TypeLiteralNode) {
                 write("{");
                 if (type.members.length) {

src/compiler/diagnosticMessages.json

@@ -163,7 +163,7 @@
         "category": "Error",
         "code": 1054
     },
-    "Type '{0}' is not a valid async function return type.": {
+    "Type '{0}' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.": {
         "category": "Error",
         "code": 1055
     },
@@ -1071,7 +1071,7 @@
         "category": "Error",
         "code": 2356
     },
-    "The operand of an increment or decrement operator must be a variable, property or indexer.": {
+    "The operand of an increment or decrement operator must be a variable or a property access.": {
         "category": "Error",
         "code": 2357
     },
@@ -1099,7 +1099,7 @@
         "category": "Error",
         "code": 2363
     },
-    "Invalid left-hand side of assignment expression.": {
+    "The left-hand side of an assignment expression must be a variable or a property access.": {
         "category": "Error",
         "code": 2364
     },
@@ -1259,7 +1259,7 @@
         "category": "Error",
         "code": 2405
     },
-    "Invalid left-hand side in 'for...in' statement.": {
+    "The left-hand side of a 'for...in' statement must be a variable or a property access.": {
         "category": "Error",
         "code": 2406
     },
@@ -1411,14 +1411,6 @@
         "category": "Error",
         "code": 2448
     },
-    "The operand of an increment or decrement operator cannot be a constant or a read-only property.": {
-        "category": "Error",
-        "code": 2449
-    },
-    "Left-hand side of assignment expression cannot be a constant or a read-only property.": {
-        "category": "Error",
-        "code": 2450
-    },
     "Cannot redeclare block-scoped variable '{0}'.": {
         "category": "Error",
         "code": 2451
@@ -1551,15 +1543,7 @@
         "category": "Error",
         "code": 2484
     },
-    "The left-hand side of a 'for...of' statement cannot be a constant or a read-only property.": {
-        "category": "Error",
-        "code": 2485
-    },
-    "The left-hand side of a 'for...in' statement cannot be a constant or a read-only property.": {
-        "category": "Error",
-        "code": 2486
-    },
-    "Invalid left-hand side in 'for...of' statement.": {
+    "The left-hand side of a 'for...of' statement must be a variable or a property access.": {
         "category": "Error",
         "code": 2487
     },
@@ -1747,6 +1731,34 @@
         "category": "Error",
         "code": 2535
     },
+    "Type '{0}' is not constrained to 'keyof {1}'.": {
+        "category": "Error",
+        "code": 2536
+    },
+    "Type '{0}' has no matching index signature for type '{1}'.": {
+        "category": "Error",
+        "code": 2537
+    },
+    "Type '{0}' cannot be used as an index type.": {
+        "category": "Error",
+        "code": 2538
+    },
+    "Cannot assign to '{0}' because it is not a variable.": {
+        "category": "Error",
+        "code": 2539
+    },
+    "Cannot assign to '{0}' because it is a constant or a read-only property.": {
+        "category": "Error",
+        "code": 2540
+    },
+    "The target of an assignment must be a variable or a property access.": {
+        "category": "Error",
+        "code": 2541
+    },
+    "Index signature in type '{0}' only permits reading.": {
+        "category": "Error",
+        "code": 2542
+    },
     "JSX element attributes type '{0}' may not be a union type.": {
         "category": "Error",
         "code": 2600
@@ -1839,6 +1851,10 @@
         "category": "Error",
         "code": 2664
     },
+    "Invalid module name in augmentation. Module '{0}' resolves to an untyped module at '{1}', which cannot be augmented.": {
+        "category": "Error",
+        "code": 2665
+    },
     "Exports and export assignments are not permitted in module augmentations.": {
         "category": "Error",
         "code": 2666
@@ -1963,6 +1979,10 @@
         "category": "Error",
         "code": 2696
     },
+    "An async function or method must return a 'Promise'. Make sure you have a declaration for 'Promise' or include 'ES2015' in your `--lib` option.": {
+        "category": "Error",
+        "code": 2697
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
@@ -2869,6 +2889,14 @@
         "category": "Error",
         "code": 6143
     },
+    "Module '{0}' was resolved as locally declared ambient module in file '{1}'.": {
+        "category": "Message",
+        "code": 6144
+    },
+    "Module '{0}' was resolved as ambient module declared in '{1}' since this file was not modified.": {
+        "category": "Message",
+        "code": 6145
+    },
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005
@@ -2905,7 +2933,7 @@
         "category": "Error",
         "code": 7016
     },
-    "Index signature of object type implicitly has an 'any' type.": {
+    "Element implicitly has an 'any' type because type '{0}' has no index signature.": {
         "category": "Error",
         "code": 7017
     },
@@ -3130,5 +3158,9 @@
     "Implement inherited abstract class": {
         "category": "Message",
         "code": 90007
+    },
+    "Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig": {
+        "category": "Error",
+        "code": 90009
     }
 }

src/compiler/emitter.ts

@@ -418,6 +418,10 @@ namespace ts {
                     return emitExpressionWithTypeArguments(<ExpressionWithTypeArguments>node);
                 case SyntaxKind.ThisType:
                     return emitThisType();
+                case SyntaxKind.TypeOperator:
+                    return emitTypeOperator(<TypeOperatorNode>node);
+                case SyntaxKind.IndexedAccessType:
+                    return emitPropertyAccessType(<IndexedAccessTypeNode>node);
                 case SyntaxKind.LiteralType:
                     return emitLiteralType(<LiteralTypeNode>node);
 
@@ -909,6 +913,19 @@ namespace ts {
             write("this");
         }
 
+        function emitTypeOperator(node: TypeOperatorNode) {
+            writeTokenText(node.operator);
+            write(" ");
+            emit(node.type);
+        }
+
+        function emitPropertyAccessType(node: IndexedAccessTypeNode) {
+            emit(node.objectType);
+            write("[");
+            emit(node.indexType);
+            write("]");
+        }
+
         function emitLiteralType(node: LiteralTypeNode) {
             emitExpression(node.literal);
         }

src/compiler/moduleNameResolver.ts

@@ -2,12 +2,15 @@
 /// <reference path="diagnosticInformationMap.generated.ts" />
 
 namespace ts {
-    function trace(host: ModuleResolutionHost, message: DiagnosticMessage, ...args: any[]): void;
-    function trace(host: ModuleResolutionHost): void {
+
+    /* @internal */
+    export function trace(host: ModuleResolutionHost, message: DiagnosticMessage, ...args: any[]): void;
+    export function trace(host: ModuleResolutionHost): void {
         host.trace(formatMessage.apply(undefined, arguments));
     }
 
-    function isTraceEnabled(compilerOptions: CompilerOptions, host: ModuleResolutionHost): boolean {
+    /* @internal */
+    export function isTraceEnabled(compilerOptions: CompilerOptions, host: ModuleResolutionHost): boolean {
         return compilerOptions.traceResolution && host.trace !== undefined;
     }
 

src/compiler/parser.ts

@@ -134,7 +134,11 @@ namespace ts {
             case SyntaxKind.IntersectionType:
                 return visitNodes(cbNodes, (<UnionOrIntersectionTypeNode>node).types);
             case SyntaxKind.ParenthesizedType:
-                return visitNode(cbNode, (<ParenthesizedTypeNode>node).type);
+            case SyntaxKind.TypeOperator:
+                return visitNode(cbNode, (<ParenthesizedTypeNode | TypeOperatorNode>node).type);
+            case SyntaxKind.IndexedAccessType:
+                return visitNode(cbNode, (<IndexedAccessTypeNode>node).objectType) ||
+                    visitNode(cbNode, (<IndexedAccessTypeNode>node).indexType);
             case SyntaxKind.LiteralType:
                 return visitNode(cbNode, (<LiteralTypeNode>node).literal);
             case SyntaxKind.ObjectBindingPattern:
@@ -2519,14 +2523,39 @@ namespace ts {
         function parseArrayTypeOrHigher(): TypeNode {
             let type = parseNonArrayType();
             while (!scanner.hasPrecedingLineBreak() && parseOptional(SyntaxKind.OpenBracketToken)) {
-                parseExpected(SyntaxKind.CloseBracketToken);
-                const node = <ArrayTypeNode>createNode(SyntaxKind.ArrayType, type.pos);
-                node.elementType = type;
-                type = finishNode(node);
+                if (isStartOfType()) {
+                    const node = <IndexedAccessTypeNode>createNode(SyntaxKind.IndexedAccessType, type.pos);
+                    node.objectType = type;
+                    node.indexType = parseType();
+                    parseExpected(SyntaxKind.CloseBracketToken);
+                    type = finishNode(node);
+                }
+                else {
+                    const node = <ArrayTypeNode>createNode(SyntaxKind.ArrayType, type.pos);
+                    node.elementType = type;
+                    parseExpected(SyntaxKind.CloseBracketToken);
+                    type = finishNode(node);
+                }
             }
             return type;
         }
 
+        function parseTypeOperator(operator: SyntaxKind.KeyOfKeyword) {
+            const node = <TypeOperatorNode>createNode(SyntaxKind.TypeOperator);
+            parseExpected(operator);
+            node.operator = operator;
+            node.type = parseTypeOperatorOrHigher();
+            return finishNode(node);
+        }
+
+        function parseTypeOperatorOrHigher(): TypeNode {
+            switch (token()) {
+                case SyntaxKind.KeyOfKeyword:
+                    return parseTypeOperator(SyntaxKind.KeyOfKeyword);
+            }
+            return parseArrayTypeOrHigher();
+        }
+
         function parseUnionOrIntersectionType(kind: SyntaxKind, parseConstituentType: () => TypeNode, operator: SyntaxKind): TypeNode {
             let type = parseConstituentType();
             if (token() === operator) {
@@ -2543,7 +2572,7 @@ namespace ts {
         }
 
         function parseIntersectionTypeOrHigher(): TypeNode {
-            return parseUnionOrIntersectionType(SyntaxKind.IntersectionType, parseArrayTypeOrHigher, SyntaxKind.AmpersandToken);
+            return parseUnionOrIntersectionType(SyntaxKind.IntersectionType, parseTypeOperatorOrHigher, SyntaxKind.AmpersandToken);
         }
 
         function parseUnionTypeOrHigher(): TypeNode {

src/compiler/program.ts

@@ -239,11 +239,11 @@ namespace ts {
                 const { line, character } = getLineAndCharacterOfPosition(diagnostic.file, diagnostic.start);
                 const fileName = diagnostic.file.fileName;
                 const relativeFileName = convertToRelativePath(fileName, host.getCurrentDirectory(), fileName => host.getCanonicalFileName(fileName));
-                output += `${ relativeFileName }(${ line + 1 },${ character + 1 }): `;
+                output += `${relativeFileName}(${line + 1},${character + 1}): `;
             }
 
             const category = DiagnosticCategory[diagnostic.category].toLowerCase();
-            output += `${ category } TS${ diagnostic.code }: ${ flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine()) }${ host.getNewLine() }`;
+            output += `${category} TS${diagnostic.code}: ${flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine())}${host.getNewLine()}`;
         }
         return output;
     }
@@ -420,6 +420,7 @@ namespace ts {
             getTypeCount: () => getDiagnosticsProducingTypeChecker().getTypeCount(),
             getFileProcessingDiagnostics: () => fileProcessingDiagnostics,
             getResolvedTypeReferenceDirectives: () => resolvedTypeReferenceDirectives,
+            isSourceFileFromExternalLibrary,
             dropDiagnosticsProducingTypeChecker
         };
 
@@ -462,6 +463,130 @@ namespace ts {
             return classifiableNames;
         }
 
+        interface OldProgramState {
+            program: Program;
+            file: SourceFile;
+            modifiedFilePaths: Path[];
+        }
+
+        function resolveModuleNamesReusingOldState(moduleNames: string[], containingFile: string, file: SourceFile, oldProgramState?: OldProgramState) {
+            if (!oldProgramState && !file.ambientModuleNames.length) {
+                // if old program state is not supplied and file does not contain locally defined ambient modules
+                // then the best we can do is fallback to the default logic
+                return resolveModuleNamesWorker(moduleNames, containingFile);
+            }
+
+            // at this point we know that either 
+            // - file has local declarations for ambient modules
+            // OR
+            // - old program state is available
+            // OR
+            // - both of items above
+            // With this it is possible that we can tell how some module names from the initial list will be resolved
+            // without doing actual resolution (in particular if some name was resolved to ambient module).
+            // Such names should be excluded from the list of module names that will be provided to `resolveModuleNamesWorker`
+            // since we don't want to resolve them again.
+
+            // this is a list of modules for which we cannot predict resolution so they should be actually resolved
+            let unknownModuleNames: string[];
+            // this is a list of combined results assembles from predicted and resolved results.
+            // Order in this list matches the order in the original list of module names `moduleNames` which is important
+            // so later we can split results to resolutions of modules and resolutions of module augmentations.
+            let result: ResolvedModuleFull[];
+            // a transient placeholder that is used to mark predicted resolution in the result list
+            const predictedToResolveToAmbientModuleMarker: ResolvedModuleFull = <any>{};
+
+            for (let i = 0; i < moduleNames.length; i++) {
+                const moduleName = moduleNames[i];
+                // module name is known to be resolved to ambient module if
+                // - module name is contained in the list of ambient modules that are locally declared in the file
+                // - in the old program module name was resolved to ambient module whose declaration is in non-modified file
+                //   (so the same module declaration will land in the new program)
+                let isKnownToResolveToAmbientModule = false;
+                if (contains(file.ambientModuleNames, moduleName)) {
+                    isKnownToResolveToAmbientModule = true;
+                    if (isTraceEnabled(options, host)) {
+                        trace(host, Diagnostics.Module_0_was_resolved_as_locally_declared_ambient_module_in_file_1, moduleName, containingFile);
+                    }
+                }
+                else {
+                    isKnownToResolveToAmbientModule = checkModuleNameResolvedToAmbientModuleInNonModifiedFile(moduleName, oldProgramState);
+                }
+
+                if (isKnownToResolveToAmbientModule) {
+                    if (!unknownModuleNames) {
+                        // found a first module name for which result can be prediced
+                        // this means that this module name should not be passed to `resolveModuleNamesWorker`.
+                        // We'll use a separate list for module names that are definitely unknown.
+                        result = new Array(moduleNames.length);
+                        // copy all module names that appear before the current one in the list
+                        // since they are known to be unknown
+                        unknownModuleNames = moduleNames.slice(0, i);
+                    }
+                    // mark prediced resolution in the result list
+                    result[i] = predictedToResolveToAmbientModuleMarker;
+                }
+                else if (unknownModuleNames) {
+                    // found unknown module name and we are already using separate list for those - add it to the list
+                    unknownModuleNames.push(moduleName);
+                }
+            }
+
+            if (!unknownModuleNames) {
+                // we've looked throught the list but have not seen any predicted resolution
+                // use default logic
+                return resolveModuleNamesWorker(moduleNames, containingFile);
+            }
+
+            const resolutions = unknownModuleNames.length
+                ? resolveModuleNamesWorker(unknownModuleNames, containingFile)
+                : emptyArray;
+
+            // combine results of resolutions and predicted results
+            let j = 0;
+            for (let i = 0; i < result.length; i++) {
+                if (result[i] == predictedToResolveToAmbientModuleMarker) {
+                    result[i] = undefined;
+                }
+                else {
+                    result[i] = resolutions[j];
+                    j++;
+                }
+            }
+            Debug.assert(j === resolutions.length);
+            return result;
+
+            function checkModuleNameResolvedToAmbientModuleInNonModifiedFile(moduleName: string, oldProgramState?: OldProgramState): boolean {
+                if (!oldProgramState) {
+                    return false;
+                }
+                const resolutionToFile = getResolvedModule(oldProgramState.file, moduleName);
+                if (resolutionToFile) {
+                    // module used to be resolved to file - ignore it
+                    return false;
+                }
+                const ambientModule = oldProgram.getTypeChecker().tryFindAmbientModuleWithoutAugmentations(moduleName);
+                if (!(ambientModule && ambientModule.declarations)) {
+                    return false;
+                }
+
+                // at least one of declarations should come from non-modified source file
+                const firstUnmodifiedFile = forEach(ambientModule.declarations, d => {
+                    const f = getSourceFileOfNode(d);
+                    return !contains(oldProgramState.modifiedFilePaths, f.path) && f;
+                });
+
+                if (!firstUnmodifiedFile) {
+                    return false;
+                }
+
+                if (isTraceEnabled(options, host)) {
+                    trace(host, Diagnostics.Module_0_was_resolved_as_ambient_module_declared_in_1_since_this_file_was_not_modified, moduleName, firstUnmodifiedFile.fileName);
+                }
+                return true;
+            }
+        }
+
         function tryReuseStructureFromOldProgram(): boolean {
             if (!oldProgram) {
                 return false;
@@ -489,7 +614,7 @@ namespace ts {
             // check if program source files has changed in the way that can affect structure of the program
             const newSourceFiles: SourceFile[] = [];
             const filePaths: Path[] = [];
-            const modifiedSourceFiles: SourceFile[] = [];
+            const modifiedSourceFiles: { oldFile: SourceFile, newFile: SourceFile }[] = [];
 
             for (const oldSourceFile of oldProgram.getSourceFiles()) {
                 let newSourceFile = host.getSourceFileByPath
@@ -532,29 +657,8 @@ namespace ts {
                         return false;
                     }
 
-                    const newSourceFilePath = getNormalizedAbsolutePath(newSourceFile.fileName, currentDirectory);
-                    if (resolveModuleNamesWorker) {
-                        const moduleNames = map(concatenate(newSourceFile.imports, newSourceFile.moduleAugmentations), getTextOfLiteral);
-                        const resolutions = resolveModuleNamesWorker(moduleNames, newSourceFilePath);
-                        // ensure that module resolution results are still correct
-                        const resolutionsChanged = hasChangesInResolutions(moduleNames, resolutions, oldSourceFile.resolvedModules, moduleResolutionIsEqualTo);
-                        if (resolutionsChanged) {
-                            return false;
-                        }
-                    }
-                    if (resolveTypeReferenceDirectiveNamesWorker) {
-                        const typesReferenceDirectives = map(newSourceFile.typeReferenceDirectives, x => x.fileName);
-                        const resolutions = resolveTypeReferenceDirectiveNamesWorker(typesReferenceDirectives, newSourceFilePath);
-                        // ensure that types resolutions are still correct
-                        const resolutionsChanged = hasChangesInResolutions(typesReferenceDirectives, resolutions, oldSourceFile.resolvedTypeReferenceDirectiveNames, typeDirectiveIsEqualTo);
-                        if (resolutionsChanged) {
-                            return false;
-                        }
-                    }
-                    // pass the cache of module/types resolutions from the old source file
-                    newSourceFile.resolvedModules = oldSourceFile.resolvedModules;
-                    newSourceFile.resolvedTypeReferenceDirectiveNames = oldSourceFile.resolvedTypeReferenceDirectiveNames;
-                    modifiedSourceFiles.push(newSourceFile);
+                    // tentatively approve the file
+                    modifiedSourceFiles.push({ oldFile: oldSourceFile, newFile: newSourceFile });
                 }
                 else {
                     // file has no changes - use it as is
@@ -565,6 +669,33 @@ namespace ts {
                 newSourceFiles.push(newSourceFile);
             }
 
+            const modifiedFilePaths = modifiedSourceFiles.map(f => f.newFile.path);
+            // try to verify results of module resolution 
+            for (const { oldFile: oldSourceFile, newFile: newSourceFile } of modifiedSourceFiles) {
+                const newSourceFilePath = getNormalizedAbsolutePath(newSourceFile.fileName, currentDirectory);
+                if (resolveModuleNamesWorker) {
+                    const moduleNames = map(concatenate(newSourceFile.imports, newSourceFile.moduleAugmentations), getTextOfLiteral);
+                    const resolutions = resolveModuleNamesReusingOldState(moduleNames, newSourceFilePath, newSourceFile, { file: oldSourceFile, program: oldProgram, modifiedFilePaths });
+                    // ensure that module resolution results are still correct
+                    const resolutionsChanged = hasChangesInResolutions(moduleNames, resolutions, oldSourceFile.resolvedModules, moduleResolutionIsEqualTo);
+                    if (resolutionsChanged) {
+                        return false;
+                    }
+                }
+                if (resolveTypeReferenceDirectiveNamesWorker) {
+                    const typesReferenceDirectives = map(newSourceFile.typeReferenceDirectives, x => x.fileName);
+                    const resolutions = resolveTypeReferenceDirectiveNamesWorker(typesReferenceDirectives, newSourceFilePath);
+                    // ensure that types resolutions are still correct
+                    const resolutionsChanged = hasChangesInResolutions(typesReferenceDirectives, resolutions, oldSourceFile.resolvedTypeReferenceDirectiveNames, typeDirectiveIsEqualTo);
+                    if (resolutionsChanged) {
+                        return false;
+                    }
+                }
+                // pass the cache of module/types resolutions from the old source file
+                newSourceFile.resolvedModules = oldSourceFile.resolvedModules;
+                newSourceFile.resolvedTypeReferenceDirectiveNames = oldSourceFile.resolvedTypeReferenceDirectiveNames;
+            }
+
             // update fileName -> file mapping
             for (let i = 0, len = newSourceFiles.length; i < len; i++) {
                 filesByName.set(filePaths[i], newSourceFiles[i]);
@@ -574,7 +705,7 @@ namespace ts {
             fileProcessingDiagnostics = oldProgram.getFileProcessingDiagnostics();
 
             for (const modifiedFile of modifiedSourceFiles) {
-                fileProcessingDiagnostics.reattachFileDiagnostics(modifiedFile);
+                fileProcessingDiagnostics.reattachFileDiagnostics(modifiedFile.newFile);
             }
             resolvedTypeReferenceDirectives = oldProgram.getResolvedTypeReferenceDirectives();
             oldProgram.structureIsReused = true;
@@ -592,13 +723,17 @@ namespace ts {
                 getSourceFile: program.getSourceFile,
                 getSourceFileByPath: program.getSourceFileByPath,
                 getSourceFiles: program.getSourceFiles,
-                isSourceFileFromExternalLibrary: (file: SourceFile) => !!sourceFilesFoundSearchingNodeModules[file.path],
+                isSourceFileFromExternalLibrary,
                 writeFile: writeFileCallback || (
                     (fileName, data, writeByteOrderMark, onError, sourceFiles) => host.writeFile(fileName, data, writeByteOrderMark, onError, sourceFiles)),
                 isEmitBlocked,
             };
         }
 
+        function isSourceFileFromExternalLibrary(file: SourceFile): boolean {
+            return sourceFilesFoundSearchingNodeModules[file.path];
+        }
+
         function getDiagnosticsProducingTypeChecker() {
             return diagnosticsProducingTypeChecker || (diagnosticsProducingTypeChecker = createTypeChecker(program, /*produceDiagnostics:*/ true));
         }
@@ -719,6 +854,14 @@ namespace ts {
         }
 
         function getSyntacticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
+            // For JavaScript files, we report semantic errors for using TypeScript-only
+            // constructs from within a JavaScript file as syntactic errors.
+            if (isSourceFileJavaScript(sourceFile)) {
+                if (!sourceFile.additionalSyntacticDiagnostics) {
+                    sourceFile.additionalSyntacticDiagnostics = getJavaScriptSyntacticDiagnosticsForFile(sourceFile);
+                }
+                return concatenate(sourceFile.additionalSyntacticDiagnostics, sourceFile.parseDiagnostics);
+            }
             return sourceFile.parseDiagnostics;
         }
 
@@ -751,12 +894,10 @@ namespace ts {
 
                 Debug.assert(!!sourceFile.bindDiagnostics);
                 const bindDiagnostics = sourceFile.bindDiagnostics;
-                // 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.
-                const checkDiagnostics = isSourceFileJavaScript(sourceFile) ?
-                    getJavaScriptSemanticDiagnosticsForFile(sourceFile) :
-                    typeChecker.getDiagnostics(sourceFile, cancellationToken);
+                // For JavaScript files, we don't want to report semantic errors.
+                // Instead, we'll report errors for using TypeScript-only constructs from within a
+                // JavaScript file when we get syntactic diagnostics for the file.
+                const checkDiagnostics = isSourceFileJavaScript(sourceFile) ? [] : typeChecker.getDiagnostics(sourceFile, cancellationToken);
                 const fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 const programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
 
@@ -764,7 +905,7 @@ namespace ts {
             });
         }
 
-        function getJavaScriptSemanticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
+        function getJavaScriptSyntacticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
             return runWithCancellationToken(() => {
                 const diagnostics: Diagnostic[] = [];
                 walk(sourceFile);
@@ -965,10 +1106,6 @@ namespace ts {
             return sortAndDeduplicateDiagnostics(allDiagnostics);
         }
 
-        function hasExtension(fileName: string): boolean {
-            return getBaseFileName(fileName).indexOf(".") >= 0;
-        }
-
         function processRootFile(fileName: string, isDefaultLib: boolean) {
             processSourceFile(normalizePath(fileName), isDefaultLib);
         }
@@ -992,9 +1129,11 @@ namespace ts {
 
             const isJavaScriptFile = isSourceFileJavaScript(file);
             const isExternalModuleFile = isExternalModule(file);
+            const isDtsFile = isDeclarationFile(file);
 
             let imports: LiteralExpression[];
             let moduleAugmentations: LiteralExpression[];
+            let ambientModules: string[];
 
             // If we are importing helpers, we need to add a synthetic reference to resolve the
             // helpers library.
@@ -1016,6 +1155,7 @@ namespace ts {
 
             file.imports = imports || emptyArray;
             file.moduleAugmentations = moduleAugmentations || emptyArray;
+            file.ambientModuleNames = ambientModules || emptyArray;
 
             return;
 
@@ -1051,6 +1191,10 @@ namespace ts {
                                 (moduleAugmentations || (moduleAugmentations = [])).push(moduleName);
                             }
                             else if (!inAmbientModule) {
+                                if (isDtsFile) {
+                                    // for global .d.ts files record name of ambient module
+                                    (ambientModules || (ambientModules = [])).push(moduleName.text);
+                                }
                                 // 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.
@@ -1296,7 +1440,7 @@ namespace ts {
             if (file.imports.length || file.moduleAugmentations.length) {
                 file.resolvedModules = createMap<ResolvedModuleFull>();
                 const moduleNames = map(concatenate(file.imports, file.moduleAugmentations), getTextOfLiteral);
-                const resolutions = resolveModuleNamesWorker(moduleNames, getNormalizedAbsolutePath(file.fileName, currentDirectory));
+                const resolutions = resolveModuleNamesReusingOldState(moduleNames, getNormalizedAbsolutePath(file.fileName, currentDirectory), file);
                 Debug.assert(resolutions.length === moduleNames.length);
                 for (let i = 0; i < moduleNames.length; i++) {
                     const resolution = resolutions[i];
@@ -1546,13 +1690,24 @@ namespace ts {
                     const emitFilePath = toPath(emitFileName, currentDirectory, getCanonicalFileName);
                     // Report error if the output overwrites input file
                     if (filesByName.contains(emitFilePath)) {
-                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file);
+                        if (options.noEmitOverwritenFiles && !options.out && !options.outDir && !options.outFile) {
+                            blockEmittingOfFile(emitFileName);
+                        }
+                        else {
+                            let chain: DiagnosticMessageChain;
+                            if (!options.configFilePath) {
+                                // The program is from either an inferred project or an external project
+                                chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Adding_a_tsconfig_json_file_will_help_organize_projects_that_contain_both_TypeScript_and_JavaScript_files_Learn_more_at_https_Colon_Slash_Slashaka_ms_Slashtsconfig);
+                            }
+                            chain = chainDiagnosticMessages(chain, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file, emitFileName);
+                            blockEmittingOfFile(emitFileName, createCompilerDiagnosticFromMessageChain(chain));
+                        }
                     }
 
                     // Report error if multiple files write into same file
                     if (emitFilesSeen.contains(emitFilePath)) {
                         // Already seen the same emit file - report error
-                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files);
+                        blockEmittingOfFile(emitFileName, createCompilerDiagnostic(Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files, emitFileName));
                     }
                     else {
                         emitFilesSeen.set(emitFilePath, true);
@@ -1561,9 +1716,11 @@ namespace ts {
             }
         }
 
-        function createEmitBlockingDiagnostics(emitFileName: string, message: DiagnosticMessage) {
+        function blockEmittingOfFile(emitFileName: string, diag?: Diagnostic) {
             hasEmitBlockingDiagnostics.set(toPath(emitFileName, currentDirectory, getCanonicalFileName), true);
-            programDiagnostics.add(createCompilerDiagnostic(message, emitFileName));
+            if (diag) {
+                programDiagnostics.add(diag);
+            }
         }
     }
 

src/compiler/scanner.ts

@@ -90,6 +90,7 @@ namespace ts {
         "instanceof": SyntaxKind.InstanceOfKeyword,
         "interface": SyntaxKind.InterfaceKeyword,
         "is": SyntaxKind.IsKeyword,
+        "keyof": SyntaxKind.KeyOfKeyword,
         "let": SyntaxKind.LetKeyword,
         "module": SyntaxKind.ModuleKeyword,
         "namespace": SyntaxKind.NamespaceKeyword,

src/compiler/sys.ts

@@ -17,7 +17,11 @@ namespace ts {
         readFile(path: string, encoding?: string): string;
         getFileSize?(path: string): number;
         writeFile(path: string, data: string, writeByteOrderMark?: boolean): void;
-        watchFile?(path: string, callback: FileWatcherCallback): FileWatcher;
+        /**
+         * @pollingInterval - this parameter is used in polling-based watchers and ignored in watchers that 
+         * use native OS file watching
+         */
+        watchFile?(path: string, callback: FileWatcherCallback, pollingInterval?: number): FileWatcher;
         watchDirectory?(path: string, callback: DirectoryWatcherCallback, recursive?: boolean): FileWatcher;
         resolvePath(path: string): string;
         fileExists(path: string): boolean;
@@ -439,6 +443,7 @@ namespace ts {
                 return filter<string>(_fs.readdirSync(path), dir => fileSystemEntryExists(combinePaths(path, dir), FileSystemEntryKind.Directory));
             }
 
+            const noOpFileWatcher: FileWatcher = { close: noop };
             const nodeSystem: System = {
                 args: process.argv.slice(2),
                 newLine: _os.EOL,
@@ -448,7 +453,7 @@ namespace ts {
                 },
                 readFile,
                 writeFile,
-                watchFile: (fileName, callback) => {
+                watchFile: (fileName, callback, pollingInterval) => {
                     if (useNonPollingWatchers) {
                         const watchedFile = watchedFileSet.addFile(fileName, callback);
                         return {
@@ -456,7 +461,7 @@ namespace ts {
                         };
                     }
                     else {
-                        _fs.watchFile(fileName, { persistent: true, interval: 250 }, fileChanged);
+                        _fs.watchFile(fileName, { persistent: true, interval: pollingInterval || 250 }, fileChanged);
                         return {
                             close: () => _fs.unwatchFile(fileName, fileChanged)
                         };
@@ -475,7 +480,7 @@ namespace ts {
                     // (ref: https://github.com/nodejs/node/pull/2649 and https://github.com/Microsoft/TypeScript/issues/4643)
                     let options: any;
                     if (!directoryExists(directoryName)) {
-                        return;
+                        return noOpFileWatcher;
                     }
 
                     if (isNode4OrLater() && (process.platform === "win32" || process.platform === "darwin")) {

src/compiler/transformers/ts.ts

@@ -328,6 +328,8 @@ namespace ts {
                 case SyntaxKind.IntersectionType:
                 case SyntaxKind.ParenthesizedType:
                 case SyntaxKind.ThisType:
+                case SyntaxKind.TypeOperator:
+                case SyntaxKind.IndexedAccessType:
                 case SyntaxKind.LiteralType:
                     // TypeScript type nodes are elided.
 
@@ -1744,6 +1746,8 @@ namespace ts {
                     }
                     // Fallthrough
                 case SyntaxKind.TypeQuery:
+                case SyntaxKind.TypeOperator:
+                case SyntaxKind.IndexedAccessType:
                 case SyntaxKind.TypeLiteral:
                 case SyntaxKind.AnyKeyword:
                 case SyntaxKind.ThisType:

src/compiler/types.ts

@@ -168,6 +168,7 @@ namespace ts {
         DeclareKeyword,
         GetKeyword,
         IsKeyword,
+        KeyOfKeyword,
         ModuleKeyword,
         NamespaceKeyword,
         NeverKeyword,
@@ -216,6 +217,8 @@ namespace ts {
         IntersectionType,
         ParenthesizedType,
         ThisType,
+        TypeOperator,
+        IndexedAccessType,
         LiteralType,
         // Binding patterns
         ObjectBindingPattern,
@@ -883,6 +886,18 @@ namespace ts {
         type: TypeNode;
     }
 
+    export interface TypeOperatorNode extends TypeNode {
+        kind: SyntaxKind.TypeOperator;
+        operator: SyntaxKind.KeyOfKeyword;
+        type: TypeNode;
+    }
+
+    export interface IndexedAccessTypeNode extends TypeNode {
+        kind: SyntaxKind.IndexedAccessType;
+        objectType: TypeNode;
+        indexType: TypeNode;
+    }
+
     export interface LiteralTypeNode extends TypeNode {
         kind: SyntaxKind.LiteralType;
         literal: Expression;
@@ -954,10 +969,6 @@ namespace ts {
         operator: PostfixUnaryOperator;
     }
 
-    export interface PostfixExpression extends UnaryExpression {
-        _postfixExpressionBrand: any;
-    }
-
     export interface LeftHandSideExpression extends IncrementExpression {
         _leftHandSideExpressionBrand: any;
     }
@@ -2089,6 +2100,9 @@ namespace ts {
         // as well as code diagnostics).
         /* @internal */ parseDiagnostics: Diagnostic[];
 
+        // Stores additional file level diagnostics reported by the program
+        /* @internal */ additionalSyntacticDiagnostics?: Diagnostic[];
+
         // File level diagnostics reported by the binder.
         /* @internal */ bindDiagnostics: Diagnostic[];
 
@@ -2104,6 +2118,7 @@ namespace ts {
         /* @internal */ imports: LiteralExpression[];
         /* @internal */ moduleAugmentations: LiteralExpression[];
         /* @internal */ patternAmbientModules?: PatternAmbientModule[];
+        /* @internal */ ambientModuleNames: string[];
     }
 
     export interface ScriptReferenceHost {
@@ -2191,6 +2206,7 @@ namespace ts {
 
         /* @internal */ getFileProcessingDiagnostics(): DiagnosticCollection;
         /* @internal */ getResolvedTypeReferenceDirectives(): Map<ResolvedTypeReferenceDirective>;
+        /* @internal */ isSourceFileFromExternalLibrary(file: SourceFile): boolean;
         // For testing purposes only.
         /* @internal */ structureIsReused?: boolean;
     }
@@ -2296,6 +2312,8 @@ namespace ts {
         isOptionalParameter(node: ParameterDeclaration): boolean;
         getAmbientModules(): Symbol[];
 
+        /* @internal */ tryFindAmbientModuleWithoutAugmentations(moduleName: string): Symbol;
+
         // Should not be called directly.  Should only be accessed through the Program instance.
         /* @internal */ getDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): Diagnostic[];
         /* @internal */ getGlobalDiagnostics(): Diagnostic[];
@@ -2678,14 +2696,16 @@ namespace ts {
         Object                  = 1 << 15,  // Object type
         Union                   = 1 << 16,  // Union (T | U)
         Intersection            = 1 << 17,  // Intersection (T & U)
+        Index                   = 1 << 18,  // keyof T
+        IndexedAccess           = 1 << 19,  // T[K]
         /* @internal */
-        FreshLiteral            = 1 << 18,  // Fresh literal type
+        FreshLiteral            = 1 << 20,  // Fresh literal type
         /* @internal */
-        ContainsWideningType    = 1 << 19,  // Type is or contains undefined or null widening type
+        ContainsWideningType    = 1 << 21,  // Type is or contains undefined or null widening type
         /* @internal */
-        ContainsObjectLiteral   = 1 << 20,  // Type is or contains object literal type
+        ContainsObjectLiteral   = 1 << 22,  // Type is or contains object literal type
         /* @internal */
-        ContainsAnyFunctionType = 1 << 21,  // Type is or contains object literal type
+        ContainsAnyFunctionType = 1 << 23,  // Type is or contains object literal type
 
         /* @internal */
         Nullable = Undefined | Null,
@@ -2704,11 +2724,11 @@ namespace ts {
         EnumLike = Enum | EnumLiteral,
         UnionOrIntersection = Union | Intersection,
         StructuredType = Object | Union | Intersection,
-        StructuredOrTypeParameter = StructuredType | TypeParameter,
+        StructuredOrTypeParameter = StructuredType | TypeParameter | Index,
 
         // 'Narrowable' types are types where narrowing actually narrows.
         // This *should* be every type other than null, undefined, void, and never
-        Narrowable = Any | StructuredType | TypeParameter | StringLike | NumberLike | BooleanLike | ESSymbol,
+        Narrowable = Any | StructuredType | TypeParameter | Index | IndexedAccess | StringLike | NumberLike | BooleanLike | ESSymbol,
         NotUnionOrUnit = Any | ESSymbol | Object,
         /* @internal */
         RequiresWidening = ContainsWideningType | ContainsObjectLiteral,
@@ -2871,9 +2891,22 @@ namespace ts {
         /* @internal */
         resolvedApparentType: Type;
         /* @internal */
+        resolvedIndexType: IndexType;
+        /* @internal */
+        resolvedIndexedAccessTypes: IndexedAccessType[];
+        /* @internal */
         isThisType?: boolean;
     }
 
+    export interface IndexType extends Type {
+        type: TypeParameter;
+    }
+
+    export interface IndexedAccessType extends Type {
+        objectType: Type;
+        indexType: TypeParameter;
+    }
+
     export const enum SignatureKind {
         Call,
         Construct,
@@ -2905,6 +2938,8 @@ namespace ts {
         isolatedSignatureType?: ObjectType; // A manufactured type that just contains the signature for purposes of signature comparison
         /* @internal */
         typePredicate?: TypePredicate;
+        /* @internal */
+        instantiations?: Map<Signature>;    // Generic signature instantiation cache
     }
 
     export const enum IndexKind {
@@ -2922,7 +2957,6 @@ namespace ts {
     export interface TypeMapper {
         (t: TypeParameter): Type;
         mappedTypes?: Type[];       // Types mapped by this mapper
-        targetTypes?: Type[];       // Types substituted for mapped types
         instantiations?: Type[];    // Cache of instantiations created using this type mapper.
         context?: InferenceContext; // The inference context this mapper was created from.
                                     // Only inference mappers have this set (in createInferenceMapper).
@@ -3040,6 +3074,7 @@ namespace ts {
         moduleResolution?: ModuleResolutionKind;
         newLine?: NewLineKind;
         noEmit?: boolean;
+        /*@internal*/noEmitOverwritenFiles?: boolean;
         noEmitHelpers?: boolean;
         noEmitOnError?: boolean;
         noErrorTruncation?: boolean;
@@ -3156,6 +3191,7 @@ namespace ts {
         Pretty,
     }
 
+    /** Either a parsed command line or a parsed tsconfig.json */
     export interface ParsedCommandLine {
         options: CompilerOptions;
         typingOptions?: TypingOptions;

src/compiler/utilities.ts

@@ -388,8 +388,8 @@ namespace ts {
     }
 
     /** Given a symbol for a module, checks that it is either an untyped import or a shorthand ambient module. */
-    export function isUntypedModuleSymbol(moduleSymbol: Symbol): boolean {
-        return !moduleSymbol.valueDeclaration || isShorthandAmbientModule(moduleSymbol.valueDeclaration);
+    export function isShorthandAmbientModuleSymbol(moduleSymbol: Symbol): boolean {
+        return isShorthandAmbientModule(moduleSymbol.valueDeclaration);
     }
 
     function isShorthandAmbientModule(node: Node): boolean {
@@ -470,6 +470,17 @@ namespace ts {
         return getFullWidth(name) === 0 ? "(Missing)" : getTextOfNode(name);
     }
 
+    export function entityNameToString(name: EntityNameOrEntityNameExpression): string {
+        switch (name.kind) {
+            case SyntaxKind.Identifier:
+                return getFullWidth(name) === 0 ? unescapeIdentifier((<Identifier>name).text) : getTextOfNode(name);
+            case SyntaxKind.QualifiedName:
+                return entityNameToString((<QualifiedName>name).left) + "." + entityNameToString((<QualifiedName>name).right);
+            case SyntaxKind.PropertyAccessExpression:
+                return entityNameToString((<PropertyAccessEntityNameExpression>name).expression) + "." + entityNameToString((<PropertyAccessEntityNameExpression>name).name);
+        }
+    }
+
     export function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): Diagnostic {
         const sourceFile = getSourceFileOfNode(node);
         const span = getErrorSpanForNode(sourceFile, node);
@@ -1028,17 +1039,19 @@ namespace ts {
     }
 
     export function getEntityNameFromTypeNode(node: TypeNode): EntityNameOrEntityNameExpression {
-        if (node) {
-            switch (node.kind) {
-                case SyntaxKind.TypeReference:
-                    return (<TypeReferenceNode>node).typeName;
-                case SyntaxKind.ExpressionWithTypeArguments:
-                    Debug.assert(isEntityNameExpression((<ExpressionWithTypeArguments>node).expression));
-                    return <EntityNameExpression>(<ExpressionWithTypeArguments>node).expression;
-                case SyntaxKind.Identifier:
-                case SyntaxKind.QualifiedName:
-                    return (<EntityName><Node>node);
-            }
+        switch (node.kind) {
+            case SyntaxKind.TypeReference:
+            case SyntaxKind.JSDocTypeReference:
+                return (<TypeReferenceNode>node).typeName;
+
+            case SyntaxKind.ExpressionWithTypeArguments:
+                return isEntityNameExpression((<ExpressionWithTypeArguments>node).expression)
+                    ? <EntityNameExpression>(<ExpressionWithTypeArguments>node).expression
+                    : undefined;
+
+            case SyntaxKind.Identifier:
+            case SyntaxKind.QualifiedName:
+                return (<EntityName><Node>node);
         }
 
         return undefined;
@@ -1592,29 +1605,51 @@ namespace ts {
         return node && node.dotDotDotToken !== undefined;
     }
 
+    export const enum AssignmentKind {
+        None, Definite, Compound
+    }
+
+    export function getAssignmentTargetKind(node: Node): AssignmentKind {
+        let parent = node.parent;
+        while (true) {
+            switch (parent.kind) {
+                case SyntaxKind.BinaryExpression:
+                    const binaryOperator = (<BinaryExpression>parent).operatorToken.kind;
+                    return isAssignmentOperator(binaryOperator) && (<BinaryExpression>parent).left === node ?
+                        binaryOperator === SyntaxKind.EqualsToken ? AssignmentKind.Definite : AssignmentKind.Compound :
+                        AssignmentKind.None;
+                case SyntaxKind.PrefixUnaryExpression:
+                case SyntaxKind.PostfixUnaryExpression:
+                    const unaryOperator = (<PrefixUnaryExpression | PostfixUnaryExpression>parent).operator;
+                    return unaryOperator === SyntaxKind.PlusPlusToken || unaryOperator === SyntaxKind.MinusMinusToken ? AssignmentKind.Compound : AssignmentKind.None;
+                case SyntaxKind.ForInStatement:
+                case SyntaxKind.ForOfStatement:
+                    return (<ForInStatement | ForOfStatement>parent).initializer === node ? AssignmentKind.Definite : AssignmentKind.None;
+                case SyntaxKind.ParenthesizedExpression:
+                case SyntaxKind.ArrayLiteralExpression:
+                case SyntaxKind.SpreadElementExpression:
+                    node = parent;
+                    break;
+                case SyntaxKind.ShorthandPropertyAssignment:
+                    if ((<ShorthandPropertyAssignment>parent).name !== node) {
+                        return AssignmentKind.None;
+                    }
+                    // Fall through
+                case SyntaxKind.PropertyAssignment:
+                    node = parent.parent;
+                    break;
+                default:
+                    return AssignmentKind.None;
+            }
+            parent = node.parent;
+        }
+    }
+
     // A node is an assignment target if it is on the left hand side of an '=' token, if it is parented by a property
     // assignment in an object literal that is an assignment target, or if it is parented by an array literal that is
     // an assignment target. Examples include 'a = xxx', '{ p: a } = xxx', '[{ p: a}] = xxx'.
     export function isAssignmentTarget(node: Node): boolean {
-        while (node.parent.kind === SyntaxKind.ParenthesizedExpression) {
-            node = node.parent;
-        }
-        while (true) {
-            const parent = node.parent;
-            if (parent.kind === SyntaxKind.ArrayLiteralExpression || parent.kind === SyntaxKind.SpreadElementExpression) {
-                node = parent;
-                continue;
-            }
-            if (parent.kind === SyntaxKind.PropertyAssignment || parent.kind === SyntaxKind.ShorthandPropertyAssignment) {
-                node = parent.parent;
-                continue;
-            }
-            return parent.kind === SyntaxKind.BinaryExpression &&
-                isAssignmentOperator((<BinaryExpression>parent).operatorToken.kind) &&
-                (<BinaryExpression>parent).left === node ||
-                (parent.kind === SyntaxKind.ForInStatement || parent.kind === SyntaxKind.ForOfStatement) &&
-                (<ForInStatement | ForOfStatement>parent).initializer === node;
-        }
+        return getAssignmentTargetKind(node) !== AssignmentKind.None;
     }
 
     export function isNodeDescendantOf(node: Node, ancestor: Node): boolean {

src/compiler/visitor.ts

@@ -553,6 +553,7 @@ namespace ts {
             return undefined;
         }
 
+        aggregateTransformFlags(node);
         const visited = visitor(node);
         if (visited === node) {
             return node;
@@ -621,6 +622,7 @@ namespace ts {
         // Visit each original node.
         for (let i = 0; i < count; i++) {
             const node = nodes[i + start];
+            aggregateTransformFlags(node);
             const visited = node !== undefined ? visitor(node) : undefined;
             if (updated !== undefined || visited === undefined || visited !== node) {
                 if (updated === undefined) {
@@ -1315,66 +1317,6 @@ namespace ts {
         return transformFlags | aggregateTransformFlagsForNode(child);
     }
 
-    /**
-     * Gets the transform flags to exclude when unioning the transform flags of a subtree.
-     *
-     * NOTE: This needs to be kept up-to-date with the exclusions used in `computeTransformFlagsForNode`.
-     *       For performance reasons, `computeTransformFlagsForNode` uses local constant values rather
-     *       than calling this function.
-     */
-    function getTransformFlagsSubtreeExclusions(kind: SyntaxKind) {
-        if (kind >= SyntaxKind.FirstTypeNode && kind <= SyntaxKind.LastTypeNode) {
-            return TransformFlags.TypeExcludes;
-        }
-
-        switch (kind) {
-            case SyntaxKind.CallExpression:
-            case SyntaxKind.NewExpression:
-            case SyntaxKind.ArrayLiteralExpression:
-                return TransformFlags.ArrayLiteralOrCallOrNewExcludes;
-            case SyntaxKind.ModuleDeclaration:
-                return TransformFlags.ModuleExcludes;
-            case SyntaxKind.Parameter:
-                return TransformFlags.ParameterExcludes;
-            case SyntaxKind.ArrowFunction:
-                return TransformFlags.ArrowFunctionExcludes;
-            case SyntaxKind.FunctionExpression:
-            case SyntaxKind.FunctionDeclaration:
-                return TransformFlags.FunctionExcludes;
-            case SyntaxKind.VariableDeclarationList:
-                return TransformFlags.VariableDeclarationListExcludes;
-            case SyntaxKind.ClassDeclaration:
-            case SyntaxKind.ClassExpression:
-                return TransformFlags.ClassExcludes;
-            case SyntaxKind.Constructor:
-                return TransformFlags.ConstructorExcludes;
-            case SyntaxKind.MethodDeclaration:
-            case SyntaxKind.GetAccessor:
-            case SyntaxKind.SetAccessor:
-                return TransformFlags.MethodOrAccessorExcludes;
-            case SyntaxKind.AnyKeyword:
-            case SyntaxKind.NumberKeyword:
-            case SyntaxKind.NeverKeyword:
-            case SyntaxKind.StringKeyword:
-            case SyntaxKind.BooleanKeyword:
-            case SyntaxKind.SymbolKeyword:
-            case SyntaxKind.VoidKeyword:
-            case SyntaxKind.TypeParameter:
-            case SyntaxKind.PropertySignature:
-            case SyntaxKind.MethodSignature:
-            case SyntaxKind.CallSignature:
-            case SyntaxKind.ConstructSignature:
-            case SyntaxKind.IndexSignature:
-            case SyntaxKind.InterfaceDeclaration:
-            case SyntaxKind.TypeAliasDeclaration:
-                return TransformFlags.TypeExcludes;
-            case SyntaxKind.ObjectLiteralExpression:
-                return TransformFlags.ObjectLiteralExcludes;
-            default:
-                return TransformFlags.NodeExcludes;
-        }
-    }
-
     export namespace Debug {
         export const failNotOptional = shouldAssert(AssertionLevel.Normal)
             ? (message?: string) => assert(false, message || "Node not optional.")

src/harness/fourslash.ts

@@ -1026,7 +1026,7 @@ namespace FourSlash {
                 ts.displayPartsToString(help.suffixDisplayParts), expected);
         }
 
-        public verifyCurrentParameterIsletiable(isVariable: boolean) {
+        public verifyCurrentParameterIsVariable(isVariable: boolean) {
             const signature = this.getActiveSignatureHelpItem();
             assert.isOk(signature);
             assert.equal(isVariable, signature.isVariadic);
@@ -1053,6 +1053,10 @@ namespace FourSlash {
             assert.equal(this.getActiveSignatureHelpItem().parameters.length, expectedCount);
         }
 
+        public verifyCurrentSignatureHelpIsVariadic(expected: boolean) {
+            assert.equal(this.getActiveSignatureHelpItem().isVariadic, expected);
+        }
+
         public verifyCurrentSignatureHelpDocComment(docComment: string) {
             const actualDocComment = this.getActiveSignatureHelpItem().documentation;
             assert.equal(ts.displayPartsToString(actualDocComment), docComment, this.assertionMessageAtLastKnownMarker("current signature help doc comment"));
@@ -1253,7 +1257,18 @@ namespace FourSlash {
                             resultString += "Diagnostics:" + Harness.IO.newLine();
                             const diagnostics = ts.getPreEmitDiagnostics(this.languageService.getProgram());
                             for (const diagnostic of diagnostics) {
-                                resultString += "  " + diagnostic.messageText + Harness.IO.newLine();
+                                if (typeof diagnostic.messageText !== "string") {
+                                    let chainedMessage = <ts.DiagnosticMessageChain>diagnostic.messageText;
+                                    let indentation = " ";
+                                    while (chainedMessage) {
+                                        resultString += indentation + chainedMessage.messageText + Harness.IO.newLine();
+                                        chainedMessage = chainedMessage.next;
+                                        indentation = indentation + " ";
+                                    }
+                                }
+                                else {
+                                    resultString += "  " + diagnostic.messageText + Harness.IO.newLine();
+                                }
                             }
                         }
 
@@ -3220,6 +3235,10 @@ namespace FourSlashInterface {
             this.state.verifySignatureHelpCount(expected);
         }
 
+        public signatureHelpCurrentArgumentListIsVariadic(expected: boolean) {
+            this.state.verifyCurrentSignatureHelpIsVariadic(expected);
+        }
+
         public signatureHelpArgumentCountIs(expected: number) {
             this.state.verifySignatureHelpArgumentCount(expected);
         }

src/harness/harness.ts

@@ -1029,7 +1029,7 @@ namespace Harness {
                 },
                 realpath: realPathMap && ((f: string) => {
                     const path = ts.toPath(f, currentDirectory, getCanonicalFileName);
-                    return realPathMap.contains(path) ? realPathMap.get(path) : path;
+                    return realPathMap.get(path) || path;
                 }),
                 directoryExists: dir => {
                     let path = ts.toPath(dir, currentDirectory, getCanonicalFileName);
@@ -1037,13 +1037,7 @@ namespace Harness {
                     if (path[path.length - 1] === "/") {
                         path = <ts.Path>path.substr(0, path.length - 1);
                     }
-                    let exists = false;
-                    fileMap.forEachValue(key => {
-                        if (key.indexOf(path) === 0 && key[path.length] === "/") {
-                            exists = true;
-                        }
-                    });
-                    return exists;
+                    return mapHasFileInDirectory(path, fileMap) || mapHasFileInDirectory(path, realPathMap);
                 },
                 getDirectories: d => {
                     const path = ts.toPath(d, currentDirectory, getCanonicalFileName);
@@ -1064,6 +1058,19 @@ namespace Harness {
             };
         }
 
+        function mapHasFileInDirectory(directoryPath: ts.Path, map: ts.FileMap<any>): boolean {
+            if (!map) {
+                return false;
+            }
+            let exists = false;
+            map.forEachValue(fileName => {
+                if (!exists && ts.startsWith(fileName, directoryPath) && fileName[directoryPath.length] === "/") {
+                    exists = true;
+                }
+            });
+            return exists;
+        }
+
         interface HarnessOptions {
             useCaseSensitiveFileNames?: boolean;
             includeBuiltFile?: string;

src/harness/harnessLanguageService.ts

@@ -720,6 +720,10 @@ namespace Harness.LanguageService {
         clearImmediate(timeoutId: any): void {
             clearImmediate(timeoutId);
         }
+
+        createHash(s: string) {
+            return s;
+        }
     }
 
     export class ServerLanguageServiceAdapter implements LanguageServiceAdapter {

src/harness/unittests/cachingInServerLSHost.ts

@@ -22,33 +22,17 @@ namespace ts {
             newLine: "\r\n",
             useCaseSensitiveFileNames: false,
             write: noop,
-            readFile: (path: string): string => {
-                return path in fileMap ? fileMap[path].content : undefined;
-            },
-            writeFile: (_path: string, _data: string, _writeByteOrderMark?: boolean) => {
-                return ts.notImplemented();
-            },
-            resolvePath: (_path: string): string => {
-                return ts.notImplemented();
-            },
-            fileExists: (path: string): boolean => {
-                return path in fileMap;
-            },
-            directoryExists: (path: string): boolean => {
-                return existingDirectories[path] || false;
-            },
+            readFile: path => path in fileMap ? fileMap[path].content : undefined,
+            writeFile: notImplemented,
+            resolvePath: notImplemented,
+            fileExists: path => path in fileMap,
+            directoryExists: path => existingDirectories[path] || false,
             createDirectory: noop,
-            getExecutingFilePath: (): string => {
-                return "";
-            },
-            getCurrentDirectory: (): string => {
-                return "";
-            },
+            getExecutingFilePath: () => "",
+            getCurrentDirectory: () => "",
             getDirectories: () => [],
             getEnvironmentVariable: () => "",
-            readDirectory: (_path: string, _extension?: string[], _exclude?: string[], _include?: string[]): string[] => {
-                return ts.notImplemented();
-            },
+            readDirectory: notImplemented,
             exit: noop,
             watchFile: () => ({
                 close: noop
@@ -58,8 +42,9 @@ namespace ts {
             }),
             setTimeout,
             clearTimeout,
-            setImmediate,
-            clearImmediate
+            setImmediate: typeof setImmediate !== "undefined" ? setImmediate : action => setTimeout(action, 0),
+            clearImmediate: typeof clearImmediate !== "undefined" ? clearImmediate : clearTimeout,
+            createHash: s => s
         };
     }
 

src/harness/unittests/incrementalParser.ts

@@ -44,10 +44,10 @@ namespace ts {
 
     // NOTE: 'reusedElements' is the expected count of elements reused from the old tree to the new
     // tree.  It may change as we tweak the parser.  If the count increases then that should always
-    // be a good thing.  If it decreases, that's not great (less reusability), but that may be 
-    // unavoidable.  If it does decrease an investigation should be done to make sure that things 
+    // be a good thing.  If it decreases, that's not great (less reusability), but that may be
+    // unavoidable.  If it does decrease an investigation should be done to make sure that things
     // are still ok and we're still appropriately reusing most of the tree.
-    function compareTrees(oldText: IScriptSnapshot, newText: IScriptSnapshot, textChangeRange: TextChangeRange, expectedReusedElements: number, oldTree?: SourceFile): SourceFile {
+    function compareTrees(oldText: IScriptSnapshot, newText: IScriptSnapshot, textChangeRange: TextChangeRange, expectedReusedElements: number, oldTree?: SourceFile) {
         oldTree = oldTree || createTree(oldText, /*version:*/ ".");
         Utils.assertInvariants(oldTree, /*parent:*/ undefined);
 
@@ -76,7 +76,7 @@ namespace ts {
             assert.equal(actualReusedCount, expectedReusedElements, actualReusedCount + " !== " + expectedReusedElements);
         }
 
-        return incrementalNewTree;
+        return { oldTree, newTree, incrementalNewTree };
     }
 
     function reusedElements(oldNode: SourceFile, newNode: SourceFile): number {
@@ -103,7 +103,7 @@ namespace ts {
         for (let i = 0; i < repeat; i++) {
             const oldText = ScriptSnapshot.fromString(source);
             const newTextAndChange = withDelete(oldText, index, 1);
-            const newTree = compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, -1, oldTree);
+            const newTree = compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, -1, oldTree).incrementalNewTree;
 
             source = newTextAndChange.text.getText(0, newTextAndChange.text.getLength());
             oldTree = newTree;
@@ -116,7 +116,7 @@ namespace ts {
         for (let i = 0; i < repeat; i++) {
             const oldText = ScriptSnapshot.fromString(source);
             const newTextAndChange = withInsert(oldText, index + i, toInsert.charAt(i));
-            const newTree = compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, -1, oldTree);
+            const newTree = compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, -1, oldTree).incrementalNewTree;
 
             source = newTextAndChange.text.getText(0, newTextAndChange.text.getLength());
             oldTree = newTree;
@@ -639,7 +639,7 @@ module m3 { }\
         });
 
         it("Unterminated comment after keyword converted to identifier", () => {
-            // 'public' as a keyword should be incrementally unusable (because it has an 
+            // 'public' as a keyword should be incrementally unusable (because it has an
             // unterminated comment).  When we convert it to an identifier, that shouldn't
             // change anything, and we should still get the same errors.
             const source = "return; a.public /*";
@@ -796,6 +796,16 @@ module m3 { }\
             compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 4);
         });
 
+        it("Reuse transformFlags of subtree during bind", () => {
+            const source = `class Greeter { constructor(element: HTMLElement) { } }`;
+            const oldText = ScriptSnapshot.fromString(source);
+            const newTextAndChange = withChange(oldText, 15, 0, "\n");
+            const { oldTree, incrementalNewTree } = compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, -1);
+            bindSourceFile(oldTree, {});
+            bindSourceFile(incrementalNewTree, {});
+            assert.equal(oldTree.transformFlags, incrementalNewTree.transformFlags);
+        });
+
         // Simulated typing tests.
 
         it("Type extends clause 1", () => {

src/harness/unittests/matchFiles.ts

@@ -91,6 +91,12 @@ namespace ts {
 
     const defaultExcludes = ["node_modules", "bower_components", "jspm_packages"];
 
+    function assertParsed(actual: ts.ParsedCommandLine, expected: ts.ParsedCommandLine): void {
+        assert.deepEqual(actual.fileNames, expected.fileNames);
+        assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
+        assert.deepEqual(actual.errors, expected.errors);
+    }
+
     describe("matchFiles", () => {
         describe("with literal file list", () => {
             it("without exclusions", () => {
@@ -110,9 +116,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("missing files are still present", () => {
                 const json = {
@@ -131,9 +135,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("are not removed due to excludes", () => {
                 const json = {
@@ -155,9 +157,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
         });
 
@@ -179,9 +179,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with non .ts file extensions are excluded", () => {
                 const json = {
@@ -200,9 +198,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with missing files are excluded", () => {
                 const json = {
@@ -221,9 +217,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with literal excludes", () => {
                 const json = {
@@ -244,9 +238,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with wildcard excludes", () => {
                 const json = {
@@ -274,9 +266,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with recursive excludes", () => {
                 const json = {
@@ -303,9 +293,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with case sensitive exclude", () => {
                 const json = {
@@ -325,9 +313,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseSensitiveHost, caseSensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and no exclusions", () => {
                 const json = {
@@ -349,9 +335,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and exclusions", () => {
                 const json = {
@@ -378,9 +362,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and empty exclude", () => {
                 const json = {
@@ -406,9 +388,7 @@ namespace ts {
                     wildcardDirectories: {},
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
         });
 
@@ -432,9 +412,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("`*` matches only ts files", () => {
                 const json = {
@@ -455,9 +433,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("`?` matches only a single character", () => {
                 const json = {
@@ -477,9 +453,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with recursive directory", () => {
                 const json = {
@@ -501,9 +475,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with multiple recursive directories", () => {
                 const json = {
@@ -527,9 +499,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("case sensitive", () => {
                 const json = {
@@ -548,9 +518,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseSensitiveHost, caseSensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with missing files are excluded", () => {
                 const json = {
@@ -570,9 +538,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("always include literal files", () => {
                 const json = {
@@ -597,9 +563,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("exclude folders", () => {
                 const json = {
@@ -624,9 +588,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and no exclusions", () => {
                 const json = {
@@ -645,9 +607,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and exclusions", () => {
                 const json = {
@@ -671,9 +631,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with common package folders and empty exclude", () => {
                 const json = {
@@ -696,9 +654,7 @@ namespace ts {
                     },
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("exclude .js files when allowJs=false", () => {
                 const json = {
@@ -723,9 +679,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("include .js files when allowJs=true", () => {
                 const json = {
@@ -750,9 +704,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("include explicitly listed .min.js files when allowJs=true", () => {
                 const json = {
@@ -777,9 +729,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("include paths outside of the project", () => {
                 const json = {
@@ -803,9 +753,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("include paths outside of the project using relative paths", () => {
                 const json = {
@@ -828,9 +776,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("exclude paths outside of the project using relative paths", () => {
                 const json = {
@@ -851,9 +797,7 @@ namespace ts {
                     wildcardDirectories: {}
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("include files with .. in their name", () => {
                 const json = {
@@ -873,9 +817,7 @@ namespace ts {
                     wildcardDirectories: {}
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("exclude files with .. in their name", () => {
                 const json = {
@@ -897,9 +839,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with jsx=none, allowJs=false", () => {
                 const json = {
@@ -922,9 +862,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveMixedExtensionHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with jsx=preserve, allowJs=false", () => {
                 const json = {
@@ -949,9 +887,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveMixedExtensionHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with jsx=none, allowJs=true", () => {
                 const json = {
@@ -976,9 +912,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveMixedExtensionHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("with jsx=preserve, allowJs=true", () => {
                 const json = {
@@ -1005,9 +939,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveMixedExtensionHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             it("exclude .min.js files using wildcards", () => {
                 const json = {
@@ -1034,9 +966,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             describe("with trailing recursive directory", () => {
                 it("in includes", () => {
@@ -1056,9 +986,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
                 it("in excludes", () => {
                     const json = {
@@ -1079,9 +1007,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
             });
             describe("with multiple recursive directory patterns", () => {
@@ -1102,9 +1028,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
                 it("in excludes", () => {
                     const json = {
@@ -1131,9 +1055,7 @@ namespace ts {
                         }
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
             });
 
@@ -1155,9 +1077,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
 
                 it("in includes after a subdirectory", () => {
@@ -1177,9 +1097,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
 
                 it("in excludes immediately after", () => {
@@ -1207,9 +1125,7 @@ namespace ts {
                         }
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
 
                 it("in excludes after a subdirectory", () => {
@@ -1237,9 +1153,25 @@ namespace ts {
                         }
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
+                });
+            });
+
+            describe("with implicit globbification", () => {
+                it("Expands 'z' to 'z/**/*'", () => {
+                    const json = {
+                        include: ["z"]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [ "a.ts", "aba.ts", "abz.ts", "b.ts", "bba.ts", "bbz.ts" ].map(x => `c:/dev/z/${x}`),
+                        wildcardDirectories: {
+                            "c:/dev/z": ts.WatchDirectoryFlags.Recursive
+                        }
+                    };
+                    const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveHost, caseInsensitiveBasePath);
+                    assertParsed(actual, expected);
                 });
             });
         });
@@ -1264,9 +1196,7 @@ namespace ts {
                     }
                 };
                 const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveDottedFoldersHost, caseInsensitiveBasePath);
-                assert.deepEqual(actual.fileNames, expected.fileNames);
-                assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                assert.deepEqual(actual.errors, expected.errors);
+                assertParsed(actual, expected);
             });
             describe("that are explicitly included", () => {
                 it("without wildcards", () => {
@@ -1286,9 +1216,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveDottedFoldersHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
                 it("with recursive wildcards that match directories", () => {
                     const json = {
@@ -1310,9 +1238,7 @@ namespace ts {
                         }
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveDottedFoldersHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
                 it("with recursive wildcards that match nothing", () => {
                     const json = {
@@ -1334,9 +1260,7 @@ namespace ts {
                         }
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveDottedFoldersHost, caseInsensitiveBasePath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
                 it("with wildcard excludes that implicitly exclude dotted files", () => {
                     const json = {
@@ -1357,9 +1281,7 @@ namespace ts {
                         wildcardDirectories: {}
                     };
                     const actual = ts.parseJsonConfigFileContent(json, caseInsensitiveDottedFoldersHost, caseInsensitiveBasePath, undefined, caseInsensitiveTsconfigPath);
-                    assert.deepEqual(actual.fileNames, expected.fileNames);
-                    assert.deepEqual(actual.wildcardDirectories, expected.wildcardDirectories);
-                    assert.deepEqual(actual.errors, expected.errors);
+                    assertParsed(actual, expected);
                 });
             });
         });

src/harness/unittests/moduleResolution.ts

@@ -1065,5 +1065,69 @@ import b = require("./moduleB");
             assert.equal(diagnostics2.length, 1, "expected one diagnostic");
             assert.equal(diagnostics1[0].messageText, diagnostics2[0].messageText, "expected one diagnostic");
         });
+
+        it ("Modules in the same .d.ts file are preferred to external files", () => {
+            const f = {
+                name: "/a/b/c/c/app.d.ts",
+                content: `
+                declare module "fs" {
+                    export interface Stat { id: number }
+                }
+                declare module "fs-client" {
+                    import { Stat } from "fs";
+                    export function foo(): Stat;
+                }`
+            };
+            const file = createSourceFile(f.name, f.content, ScriptTarget.ES2015);
+            const compilerHost: CompilerHost = {
+                fileExists : fileName => fileName === file.fileName,
+                getSourceFile: fileName => fileName === file.fileName ? file : undefined,
+                getDefaultLibFileName: () => "lib.d.ts",
+                writeFile: notImplemented,
+                getCurrentDirectory: () => "/",
+                getDirectories: () => [],
+                getCanonicalFileName: f => f.toLowerCase(),
+                getNewLine: () => "\r\n",
+                useCaseSensitiveFileNames: () => false,
+                readFile: fileName => fileName === file.fileName ? file.text : undefined,
+                resolveModuleNames() {
+                    assert(false, "resolveModuleNames should not be called");
+                    return undefined;
+                }
+            };
+            createProgram([f.name], {}, compilerHost);
+        });
+
+        it ("Modules in .ts file are not checked in the same file", () => {
+            const f = {
+                name: "/a/b/c/c/app.ts",
+                content: `
+                declare module "fs" {
+                    export interface Stat { id: number }
+                }
+                declare module "fs-client" {
+                    import { Stat } from "fs";
+                    export function foo(): Stat;
+                }`
+            };
+            const file = createSourceFile(f.name, f.content, ScriptTarget.ES2015);
+            const compilerHost: CompilerHost = {
+                fileExists : fileName => fileName === file.fileName,
+                getSourceFile: fileName => fileName === file.fileName ? file : undefined,
+                getDefaultLibFileName: () => "lib.d.ts",
+                writeFile: notImplemented,
+                getCurrentDirectory: () => "/",
+                getDirectories: () => [],
+                getCanonicalFileName: f => f.toLowerCase(),
+                getNewLine: () => "\r\n",
+                useCaseSensitiveFileNames: () => false,
+                readFile: fileName => fileName === file.fileName ? file.text : undefined,
+                resolveModuleNames(moduleNames: string[], _containingFile: string) {
+                    assert.deepEqual(moduleNames, ["fs"]);
+                    return [undefined];
+                }
+            };
+            createProgram([f.name], {}, compilerHost);
+        });
     });
 }

src/harness/unittests/reuseProgramStructure.ts

@@ -22,6 +22,11 @@ namespace ts {
 
     interface ProgramWithSourceTexts extends Program {
         sourceTexts?: NamedSourceText[];
+        host: TestCompilerHost;
+    }
+
+    interface TestCompilerHost extends CompilerHost {
+        getTrace(): string[];
     }
 
     class SourceText implements IScriptSnapshot {
@@ -101,10 +106,21 @@ namespace ts {
         return file;
     }
 
-    function createTestCompilerHost(texts: NamedSourceText[], target: ScriptTarget): CompilerHost {
-        const files = arrayToMap(texts, t => t.name, t => createSourceFileWithText(t.name, t.text, target));
+    function createTestCompilerHost(texts: NamedSourceText[], target: ScriptTarget, oldProgram?: ProgramWithSourceTexts): TestCompilerHost {
+        const files = arrayToMap(texts, t => t.name, t => {
+            if (oldProgram) {
+                const oldFile = <SourceFileWithText>oldProgram.getSourceFile(t.name);
+                if (oldFile && oldFile.sourceText.getVersion() === t.text.getVersion()) {
+                    return oldFile;
+                }
+            }
+            return createSourceFileWithText(t.name, t.text, target);
+        });
+        const trace: string[] = [];
 
         return {
+            trace: s => trace.push(s),
+            getTrace: () => trace,
             getSourceFile(fileName): SourceFile {
                 return files[fileName];
             },
@@ -130,23 +146,25 @@ namespace ts {
             fileExists: fileName => fileName in files,
             readFile: fileName => {
                 return fileName in files ? files[fileName].text : undefined;
-            }
+            },
         };
     }
 
-    function newProgram(texts: NamedSourceText[], rootNames: string[], options: CompilerOptions): Program {
+    function newProgram(texts: NamedSourceText[], rootNames: string[], options: CompilerOptions): ProgramWithSourceTexts {
         const host = createTestCompilerHost(texts, options.target);
         const program = <ProgramWithSourceTexts>createProgram(rootNames, options, host);
         program.sourceTexts = texts;
+        program.host = host;
         return program;
     }
 
-    function updateProgram(oldProgram: Program, rootNames: string[], options: CompilerOptions, updater: (files: NamedSourceText[]) => void) {
+    function updateProgram(oldProgram: ProgramWithSourceTexts, rootNames: string[], options: CompilerOptions, updater: (files: NamedSourceText[]) => void) {
         const texts: NamedSourceText[] = (<ProgramWithSourceTexts>oldProgram).sourceTexts.slice(0);
         updater(texts);
-        const host = createTestCompilerHost(texts, options.target);
+        const host = createTestCompilerHost(texts, options.target, oldProgram);
         const program = <ProgramWithSourceTexts>createProgram(rootNames, options, host, oldProgram);
         program.sourceTexts = texts;
+        program.host = host;
         return program;
     }
 
@@ -355,6 +373,112 @@ namespace ts {
             assert.isTrue(!program_3.structureIsReused);
             checkResolvedTypeDirectivesCache(program_1, "/a.ts", createMap({ "typedefs": { resolvedFileName: "/types/typedefs/index.d.ts", primary: true } }));
         });
+
+        it("can reuse ambient module declarations from non-modified files", () => {
+            const files = [
+                { name: "/a/b/app.ts", text: SourceText.New("", "import * as fs from 'fs'", "") },
+                { name: "/a/b/node.d.ts", text: SourceText.New("", "", "declare module 'fs' {}") }
+            ];
+            const options = { target: ScriptTarget.ES2015, traceResolution: true };
+            const program = newProgram(files, files.map(f => f.name), options);
+            assert.deepEqual(program.host.getTrace(),
+                [
+                    "======== Resolving module 'fs' from '/a/b/app.ts'. ========",
+                    "Module resolution kind is not specified, using 'Classic'.",
+                    "File '/a/b/fs.ts' does not exist.",
+                    "File '/a/b/fs.tsx' does not exist.",
+                    "File '/a/b/fs.d.ts' does not exist.",
+                    "File '/a/fs.ts' does not exist.",
+                    "File '/a/fs.tsx' does not exist.",
+                    "File '/a/fs.d.ts' does not exist.",
+                    "File '/fs.ts' does not exist.",
+                    "File '/fs.tsx' does not exist.",
+                    "File '/fs.d.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/a/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/node_modules/@types/fs.ts' does not exist.",
+                    "File '/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/a/b/fs.js' does not exist.",
+                    "File '/a/b/fs.jsx' does not exist.",
+                    "File '/a/fs.js' does not exist.",
+                    "File '/a/fs.jsx' does not exist.",
+                    "File '/fs.js' does not exist.",
+                    "File '/fs.jsx' does not exist.",
+                    "======== Module name 'fs' was not resolved. ========",
+                ], "should look for 'fs'");
+
+            const program_2 = updateProgram(program, program.getRootFileNames(), options, f => {
+                f[0].text = f[0].text.updateProgram("var x = 1;");
+            });
+            assert.deepEqual(program_2.host.getTrace(), [
+                "Module 'fs' was resolved as ambient module declared in '/a/b/node.d.ts' since this file was not modified."
+            ], "should reuse 'fs' since node.d.ts was not changed");
+
+            const program_3 = updateProgram(program_2, program_2.getRootFileNames(), options, f => {
+                f[0].text = f[0].text.updateProgram("var y = 1;");
+                f[1].text = f[1].text.updateProgram("declare var process: any");
+            });
+            assert.deepEqual(program_3.host.getTrace(),
+                [
+                    "======== Resolving module 'fs' from '/a/b/app.ts'. ========",
+                    "Module resolution kind is not specified, using 'Classic'.",
+                    "File '/a/b/fs.ts' does not exist.",
+                    "File '/a/b/fs.tsx' does not exist.",
+                    "File '/a/b/fs.d.ts' does not exist.",
+                    "File '/a/fs.ts' does not exist.",
+                    "File '/a/fs.tsx' does not exist.",
+                    "File '/a/fs.d.ts' does not exist.",
+                    "File '/fs.ts' does not exist.",
+                    "File '/fs.tsx' does not exist.",
+                    "File '/fs.d.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/a/b/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/a/b/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/a/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/a/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/node_modules/@types/fs.ts' does not exist.",
+                    "File '/node_modules/@types/fs.tsx' does not exist.",
+                    "File '/node_modules/@types/fs.d.ts' does not exist.",
+                    "File '/node_modules/@types/fs/package.json' does not exist.",
+                    "File '/node_modules/@types/fs/index.ts' does not exist.",
+                    "File '/node_modules/@types/fs/index.tsx' does not exist.",
+                    "File '/node_modules/@types/fs/index.d.ts' does not exist.",
+                    "File '/a/b/fs.js' does not exist.",
+                    "File '/a/b/fs.jsx' does not exist.",
+                    "File '/a/fs.js' does not exist.",
+                    "File '/a/fs.jsx' does not exist.",
+                    "File '/fs.js' does not exist.",
+                    "File '/fs.jsx' does not exist.",
+                    "======== Module name 'fs' was not resolved. ========",
+                ], "should look for 'fs' again since node.d.ts was changed");
+
+        });
     });
 
     describe("host is optional", () => {

src/harness/unittests/session.ts

@@ -24,7 +24,8 @@ namespace ts.server {
         setTimeout() { return 0; },
         clearTimeout: noop,
         setImmediate: () => 0,
-        clearImmediate: noop
+        clearImmediate: noop,
+        createHash: s => s
     };
     const nullCancellationToken: HostCancellationToken = { isCancellationRequested: () => false };
     const mockLogger: Logger = {
@@ -150,7 +151,8 @@ namespace ts.server {
                         target: ScriptTarget.ES5,
                         jsx: JsxEmit.React,
                         newLine: NewLineKind.LineFeed,
-                        moduleResolution: ModuleResolutionKind.NodeJs
+                        moduleResolution: ModuleResolutionKind.NodeJs,
+                        allowNonTsExtensions: true // injected by tsserver
                     });
             });
         });

src/harness/unittests/tsserverProjectSystem.ts

@@ -18,7 +18,6 @@ namespace ts.projectSystem {
     };
 
     export interface PostExecAction {
-        readonly requestKind: TI.RequestKind;
         readonly success: boolean;
         readonly callback: TI.RequestCompletedAction;
     }
@@ -47,9 +46,14 @@ namespace ts.projectSystem {
 
     export class TestTypingsInstaller extends TI.TypingsInstaller implements server.ITypingsInstaller {
         protected projectService: server.ProjectService;
-        constructor(readonly globalTypingsCacheLocation: string, throttleLimit: number, readonly installTypingHost: server.ServerHost, log?: TI.Log) {
-            super(globalTypingsCacheLocation, safeList.path, throttleLimit, log);
-            this.init();
+        constructor(
+            readonly globalTypingsCacheLocation: string,
+            throttleLimit: number,
+            installTypingHost: server.ServerHost,
+            readonly typesRegistry = createMap<void>(),
+            telemetryEnabled?: boolean,
+            log?: TI.Log) {
+            super(installTypingHost, globalTypingsCacheLocation, safeList.path, throttleLimit, telemetryEnabled, log);
         }
 
         safeFileList = safeList.path;
@@ -63,9 +67,8 @@ namespace ts.projectSystem {
             }
         }
 
-        checkPendingCommands(expected: TI.RequestKind[]) {
-            assert.equal(this.postExecActions.length, expected.length, `Expected ${expected.length} post install actions`);
-            this.postExecActions.forEach((act, i) => assert.equal(act.requestKind, expected[i], "Unexpected post install action"));
+        checkPendingCommands(expectedCount: number) {
+            assert.equal(this.postExecActions.length, expectedCount, `Expected ${expectedCount} post install actions`);
         }
 
         onProjectClosed() {
@@ -79,15 +82,8 @@ namespace ts.projectSystem {
             return this.installTypingHost;
         }
 
-        executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
-            switch (requestKind) {
-                case TI.NpmViewRequest:
-                case TI.NpmInstallRequest:
-                    break;
-                default:
-                    assert.isTrue(false, `request ${requestKind} is not supported`);
-            }
-            this.addPostExecAction(requestKind, "success", cb);
+        installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+            this.addPostExecAction("success", cb);
         }
 
         sendResponse(response: server.SetTypings | server.InvalidateCachedTypings) {
@@ -99,12 +95,11 @@ namespace ts.projectSystem {
             this.install(request);
         }
 
-        addPostExecAction(requestKind: TI.RequestKind, stdout: string | string[], cb: TI.RequestCompletedAction) {
+        addPostExecAction(stdout: string | string[], cb: TI.RequestCompletedAction) {
             const out = typeof stdout === "string" ? stdout : createNpmPackageJsonString(stdout);
             const action: PostExecAction = {
                 success: !!out,
-                callback: cb,
-                requestKind
+                callback: cb
             };
             this.postExecActions.push(action);
         }
@@ -439,6 +434,10 @@ namespace ts.projectSystem {
             };
         }
 
+        createHash(s: string): string {
+            return s;
+        }
+
         triggerDirectoryWatcherCallback(directoryName: string, fileName: string): void {
             const path = this.toPath(directoryName);
             const callbacks = this.watchedDirectories[path];
@@ -1969,6 +1968,33 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ configuredProjects: 1 });
             checkProjectActualFiles(projectService.configuredProjects[0], [libES5.path, libES2015Promise.path, app.path]);
         });
+
+        it("should handle non-existing directories in config file", () => {
+            const f = {
+                path: "/a/src/app.ts",
+                content: "let x = 1;"
+            };
+            const config = {
+                path: "/a/tsconfig.json",
+                content: JSON.stringify({
+                    compilerOptions: {},
+                    include: [
+                        "src/**/*",
+                        "notexistingfolder/*"
+                    ]
+                })
+            };
+            const host = createServerHost([f, config]);
+            const projectService = createProjectService(host);
+            projectService.openClientFile(f.path);
+            projectService.checkNumberOfProjects({ configuredProjects: 1 });
+
+            projectService.closeClientFile(f.path);
+            projectService.checkNumberOfProjects({ configuredProjects: 0 });
+
+            projectService.openClientFile(f.path);
+            projectService.checkNumberOfProjects({ configuredProjects: 1 });
+        });
     });
 
     describe("prefer typings to js", () => {
@@ -2227,6 +2253,27 @@ namespace ts.projectSystem {
             assert.equal(diags.length, 0);
         });
 
+        it("should property handle missing config files", () => {
+            const f1 = {
+                path: "/a/b/app.ts",
+                content: "let x = 1"
+            };
+            const config = {
+                path: "/a/b/tsconfig.json",
+                content: "{}"
+            };
+            const projectName = "project1";
+            const host = createServerHost([f1]);
+            const projectService = createProjectService(host);
+            projectService.openExternalProject({ rootFiles: toExternalFiles([f1.path, config.path]), options: {}, projectFileName: projectName });
+
+            // should have one external project since config file is missing
+            projectService.checkNumberOfProjects({ externalProjects: 1 });
+
+            host.reloadFS([f1, config]);
+            projectService.openExternalProject({ rootFiles: toExternalFiles([f1.path, config.path]), options: {}, projectFileName: projectName });
+            projectService.checkNumberOfProjects({ configuredProjects: 1 });
+        });
     });
 
     describe("add the missing module file for inferred project", () => {
@@ -2471,4 +2518,62 @@ namespace ts.projectSystem {
 
         });
     });
+
+    describe("Inferred projects", () => {
+        it("should support files without extensions", () => {
+            const f = {
+                path: "/a/compile",
+                content: "let x = 1"
+            };
+            const host = createServerHost([f]);
+            const session = createSession(host);
+            session.executeCommand(<server.protocol.SetCompilerOptionsForInferredProjectsRequest>{
+                seq: 1,
+                type: "request",
+                command: "compilerOptionsForInferredProjects",
+                arguments: {
+                    options: {
+                        allowJs: true
+                    }
+                }
+            });
+            session.executeCommand(<server.protocol.OpenRequest>{
+                seq: 2,
+                type: "request",
+                command: "open",
+                arguments: {
+                    file: f.path,
+                    fileContent: f.content,
+                    scriptKindName: "JS"
+                }
+            });
+            const projectService = session.getProjectService();
+            checkNumberOfProjects(projectService, { inferredProjects: 1 });
+            checkProjectActualFiles(projectService.inferredProjects[0], [f.path]);
+        });
+    });
+
+    describe("No overwrite emit error", () => {
+        it("for inferred project", () => {
+            const f1 = {
+                path: "/a/b/f1.js",
+                content: "function test1() { }"
+            };
+            const host = createServerHost([f1, libFile]);
+            const session = createSession(host);
+            openFilesForSession([f1], session);
+
+            const projectService = session.getProjectService();
+            checkNumberOfProjects(projectService, { inferredProjects: 1 });
+            const projectName = projectService.inferredProjects[0].getProjectName();
+
+            const diags = session.executeCommand(<server.protocol.CompilerOptionsDiagnosticsRequest>{
+                type: "request",
+                command: server.CommandNames.CompilerOptionsDiagnosticsFull,
+                seq: 2,
+                arguments: { projectFileName: projectName }
+            }).response;
+            assert.isTrue(diags.length === 0);
+        });
+    });
 }

src/harness/unittests/typingsInstaller.ts

@@ -8,44 +8,44 @@ namespace ts.projectSystem {
     interface InstallerParams {
         globalTypingsCacheLocation?: string;
         throttleLimit?: number;
+        typesRegistry?: Map<void>;
+    }
+
+    function createTypesRegistry(...list: string[]): Map<void> {
+        const map = createMap<void>();
+        for (const l of list) {
+            map[l] = undefined;
+        }
+        return map;
     }
 
     class Installer extends TestTypingsInstaller {
-        constructor(host: server.ServerHost, p?: InstallerParams, log?: TI.Log) {
+        constructor(host: server.ServerHost, p?: InstallerParams, telemetryEnabled?: boolean, log?: TI.Log) {
             super(
                 (p && p.globalTypingsCacheLocation) || "/a/data",
                 (p && p.throttleLimit) || 5,
                 host,
+                (p && p.typesRegistry),
+                telemetryEnabled,
                 log);
         }
 
-        installAll(expectedView: typeof TI.NpmViewRequest[], expectedInstall: typeof TI.NpmInstallRequest[]) {
-            this.checkPendingCommands(expectedView);
-            this.executePendingCommands();
-            this.checkPendingCommands(expectedInstall);
+        installAll(expectedCount: number) {
+            this.checkPendingCommands(expectedCount);
             this.executePendingCommands();
         }
     }
 
-    describe("typingsInstaller", () => {
-        function executeCommand(self: Installer, host: TestServerHost, installedTypings: string[], typingFiles: FileOrFolder[], requestKind: TI.RequestKind, cb: TI.RequestCompletedAction): void {
-            switch (requestKind) {
-                case TI.NpmInstallRequest:
-                    self.addPostExecAction(requestKind, installedTypings, success => {
-                        for (const file of typingFiles) {
-                            host.createFileOrFolder(file, /*createParentDirectory*/ true);
-                        }
-                        cb(success);
-                    });
-                    break;
-                case TI.NpmViewRequest:
-                    self.addPostExecAction(requestKind, installedTypings, cb);
-                    break;
-                default:
-                    assert.isTrue(false, `unexpected request kind ${requestKind}`);
-                    break;
+    function executeCommand(self: Installer, host: TestServerHost, installedTypings: string[], typingFiles: FileOrFolder[], cb: TI.RequestCompletedAction): void {
+        self.addPostExecAction(installedTypings, success => {
+            for (const file of typingFiles) {
+                host.createFileOrFolder(file, /*createParentDirectory*/ true);
             }
-        }
+            cb(success);
+        });
+    }
+
+    describe("typingsInstaller", () => {
         it("configured projects (typings installed) 1", () => {
             const file1 = {
                 path: "/a/b/app.js",
@@ -79,12 +79,12 @@ namespace ts.projectSystem {
             const host = createServerHost([file1, tsconfig, packageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/jquery"];
                     const typingFiles = [jquery];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -95,7 +95,7 @@ namespace ts.projectSystem {
             const p = projectService.configuredProjects[0];
             checkProjectActualFiles(p, [file1.path]);
 
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { configuredProjects: 1 });
             checkProjectActualFiles(p, [file1.path, jquery.path]);
@@ -123,12 +123,12 @@ namespace ts.projectSystem {
             const host = createServerHost([file1, packageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/jquery"];
                     const typingFiles = [jquery];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -139,7 +139,7 @@ namespace ts.projectSystem {
             const p = projectService.inferredProjects[0];
             checkProjectActualFiles(p, [file1.path]);
 
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { inferredProjects: 1 });
             checkProjectActualFiles(p, [file1.path, jquery.path]);
@@ -167,7 +167,7 @@ namespace ts.projectSystem {
                 options: {},
                 rootFiles: [toExternalFile(file1.path)]
             });
-            installer.checkPendingCommands([]);
+            installer.checkPendingCommands(/*expectedCount*/ 0);
             // by default auto discovery will kick in if project contain only .js/.d.ts files
             // in this case project contain only ts files - no auto discovery
             projectService.checkNumberOfProjects({ externalProjects: 1 });
@@ -181,7 +181,7 @@ namespace ts.projectSystem {
             const host = createServerHost([file1]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery") });
                 }
                 enqueueInstallTypingsRequest() {
                     assert(false, "auto discovery should not be enabled");
@@ -196,7 +196,7 @@ namespace ts.projectSystem {
                 rootFiles: [toExternalFile(file1.path)],
                 typingOptions: { include: ["jquery"] }
             });
-            installer.checkPendingCommands([]);
+            installer.checkPendingCommands(/*expectedCount*/ 0);
             // by default auto discovery will kick in if project contain only .js/.d.ts files
             // in this case project contain only ts files - no auto discovery even if typing options is set
             projectService.checkNumberOfProjects({ externalProjects: 1 });
@@ -215,16 +215,16 @@ namespace ts.projectSystem {
             let enqueueIsCalled = false;
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery") });
                 }
                 enqueueInstallTypingsRequest(project: server.Project, typingOptions: TypingOptions, unresolvedImports: server.SortedReadonlyArray<string>) {
                     enqueueIsCalled = true;
                     super.enqueueInstallTypingsRequest(project, typingOptions, unresolvedImports);
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
-                    const installedTypings = ["@types/jquery"];
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings = ["@types/node"];
                     const typingFiles = [jquery];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -234,11 +234,11 @@ namespace ts.projectSystem {
                 projectFileName,
                 options: {},
                 rootFiles: [toExternalFile(file1.path)],
-                typingOptions: { enableAutoDiscovery: true, include: ["node"] }
+                typingOptions: { enableAutoDiscovery: true, include: ["jquery"] }
             });
 
             assert.isTrue(enqueueIsCalled, "expected enqueueIsCalled to be true");
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
 
             // autoDiscovery is set in typing options - use it even if project contains only .ts files
             projectService.checkNumberOfProjects({ externalProjects: 1 });
@@ -273,12 +273,12 @@ namespace ts.projectSystem {
             const host = createServerHost([file1, file2, file3]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("lodash", "react") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
                     const installedTypings = ["@types/lodash", "@types/react"];
                     const typingFiles = [lodash, react];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -295,7 +295,7 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path]);
 
-            installer.installAll([TI.NpmViewRequest, TI.NpmViewRequest], [TI.NpmInstallRequest], );
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path, lodash.path, react.path]);
@@ -317,16 +317,16 @@ namespace ts.projectSystem {
             let enqueueIsCalled = false;
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery") });
                 }
                 enqueueInstallTypingsRequest(project: server.Project, typingOptions: TypingOptions, unresolvedImports: server.SortedReadonlyArray<string>) {
                     enqueueIsCalled = true;
                     super.enqueueInstallTypingsRequest(project, typingOptions, unresolvedImports);
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
                     const installedTypings: string[] = [];
                     const typingFiles: FileOrFolder[] = [];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -343,7 +343,7 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path]);
 
-            installer.checkPendingCommands([]);
+            installer.checkPendingCommands(/*expectedCount*/ 0);
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path]);
@@ -396,12 +396,12 @@ namespace ts.projectSystem {
             const host = createServerHost([file1, file2, file3, packageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host);
+                    super(host, { typesRegistry: createTypesRegistry("jquery", "commander", "moment", "express") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
                     const installedTypings = ["@types/commander", "@types/express", "@types/jquery", "@types/moment"];
                     const typingFiles = [commander, express, jquery, moment];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -418,10 +418,7 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path]);
 
-            installer.installAll(
-                [TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest],
-                [TI.NpmInstallRequest]
-            );
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path, commander.path, express.path, jquery.path, moment.path]);
@@ -475,11 +472,11 @@ namespace ts.projectSystem {
             const host = createServerHost([lodashJs, commanderJs, file3, packageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { throttleLimit: 3 });
+                    super(host, { throttleLimit: 3, typesRegistry: createTypesRegistry("commander", "express", "jquery", "moment", "lodash") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
                     const installedTypings = ["@types/commander", "@types/express", "@types/jquery", "@types/moment", "@types/lodash"];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -495,18 +492,7 @@ namespace ts.projectSystem {
             const p = projectService.externalProjects[0];
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [lodashJs.path, commanderJs.path, file3.path]);
-            // expected 3 view requests in the queue
-            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
-            assert.equal(installer.pendingRunRequests.length, 2, "expected 2 pending requests");
-
-            // push view requests
-            installer.executePendingCommands();
-            // expected 2 remaining view requests in the queue
-            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest]);
-            // push view requests
-            installer.executePendingCommands();
-            // expected one install request
-            installer.checkPendingCommands([TI.NpmInstallRequest]);
+            installer.checkPendingCommands(/*expectedCount*/ 1);
             installer.executePendingCommands();
             // expected all typings file to exist
             for (const f of typingFiles) {
@@ -565,22 +551,17 @@ namespace ts.projectSystem {
             const host = createServerHost([lodashJs, commanderJs, file3]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { throttleLimit: 3 });
+                    super(host, { throttleLimit: 1, typesRegistry: createTypesRegistry("commander", "jquery", "lodash", "cordova", "gulp", "grunt") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
-                    if (requestKind === TI.NpmInstallRequest) {
-                        let typingFiles: (FileOrFolder & { typings: string })[] = [];
-                        if (args.indexOf("@types/commander") >= 0) {
-                            typingFiles = [commander, jquery, lodash, cordova];
-                        }
-                        else {
-                            typingFiles = [grunt, gulp];
-                        }
-                        executeCommand(this, host, typingFiles.map(f => f.typings), typingFiles, requestKind, cb);
+                installWorker(_requestId: number, args: string[], _cwd: string, cb: TI.RequestCompletedAction): void {
+                    let typingFiles: (FileOrFolder & { typings: string })[] = [];
+                    if (args.indexOf("@types/commander") >= 0) {
+                        typingFiles = [commander, jquery, lodash, cordova];
                     }
                     else {
-                        executeCommand(this, host, [], [], requestKind, cb);
+                        typingFiles = [grunt, gulp];
                     }
+                    executeCommand(this, host, typingFiles.map(f => f.typings), typingFiles, cb);
                 }
             })();
 
@@ -594,8 +575,8 @@ namespace ts.projectSystem {
                 typingOptions: { include: ["jquery", "cordova"] }
             });
 
-            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
-            assert.equal(installer.pendingRunRequests.length, 1, "expect one throttled request");
+            installer.checkPendingCommands(/*expectedCount*/ 1);
+            assert.equal(installer.pendingRunRequests.length, 0, "expect no throttled requests");
 
             // Create project #2 with 2 typings
             const projectFileName2 = "/a/app/test2.csproj";
@@ -605,7 +586,7 @@ namespace ts.projectSystem {
                 rootFiles: [toExternalFile(file3.path)],
                 typingOptions: { include: ["grunt", "gulp"] }
             });
-            assert.equal(installer.pendingRunRequests.length, 3, "expect three throttled request");
+            assert.equal(installer.pendingRunRequests.length, 1, "expect one throttled request");
 
             const p1 = projectService.externalProjects[0];
             const p2 = projectService.externalProjects[1];
@@ -613,18 +594,14 @@ namespace ts.projectSystem {
             checkProjectActualFiles(p1, [lodashJs.path, commanderJs.path, file3.path]);
             checkProjectActualFiles(p2, [file3.path]);
 
-
             installer.executePendingCommands();
-            // expected one view request from the first project and two - from the second one
-            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
+
+            // expected one install request from the second project
+            installer.checkPendingCommands(/*expectedCount*/ 1);
             assert.equal(installer.pendingRunRequests.length, 0, "expected no throttled requests");
 
             installer.executePendingCommands();
 
-            // should be two install requests from both projects
-            installer.checkPendingCommands([TI.NpmInstallRequest, TI.NpmInstallRequest]);
-            installer.executePendingCommands();
-
             checkProjectActualFiles(p1, [lodashJs.path, commanderJs.path, file3.path, commander.path, jquery.path, lodash.path, cordova.path]);
             checkProjectActualFiles(p2, [file3.path, grunt.path, gulp.path]);
         });
@@ -653,12 +630,12 @@ namespace ts.projectSystem {
             const host = createServerHost([app, jsconfig, jquery, jqueryPackage]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: "/tmp" });
+                    super(host, { globalTypingsCacheLocation: "/tmp", typesRegistry: createTypesRegistry("jquery") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/jquery"];
                     const typingFiles = [jqueryDTS];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -669,7 +646,7 @@ namespace ts.projectSystem {
             const p = projectService.configuredProjects[0];
             checkProjectActualFiles(p, [app.path]);
 
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { configuredProjects: 1 });
             checkProjectActualFiles(p, [app.path, jqueryDTS.path]);
@@ -699,12 +676,12 @@ namespace ts.projectSystem {
             const host = createServerHost([app, jsconfig, bowerJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: "/tmp" });
+                    super(host, { globalTypingsCacheLocation: "/tmp", typesRegistry: createTypesRegistry("jquery") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/jquery"];
                     const typingFiles = [jqueryDTS];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
 
@@ -715,7 +692,7 @@ namespace ts.projectSystem {
             const p = projectService.configuredProjects[0];
             checkProjectActualFiles(p, [app.path]);
 
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
 
             checkNumberOfProjects(projectService, { configuredProjects: 1 });
             checkProjectActualFiles(p, [app.path, jqueryDTS.path]);
@@ -742,23 +719,23 @@ namespace ts.projectSystem {
             const host = createServerHost([f, brokenPackageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: cachePath });
+                    super(host, { globalTypingsCacheLocation: cachePath, typesRegistry: createTypesRegistry("commander") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/commander"];
                     const typingFiles = [commander];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
             const service = createProjectService(host, { typingsInstaller: installer });
             service.openClientFile(f.path);
 
-            installer.checkPendingCommands([]);
+            installer.checkPendingCommands(/*expectedCount*/ 0);
 
             host.reloadFS([f, fixedPackageJson]);
             host.triggerFileWatcherCallback(fixedPackageJson.path, /*removed*/ false);
-            // expected one view and one install request
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            // expected install request
+            installer.installAll(/*expectedCount*/ 1);
 
             service.checkNumberOfProjects({ inferredProjects: 1 });
             checkProjectActualFiles(service.inferredProjects[0], [f.path, commander.path]);
@@ -783,12 +760,12 @@ namespace ts.projectSystem {
             const host = createServerHost([file]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: cachePath });
+                    super(host, { globalTypingsCacheLocation: cachePath, typesRegistry: createTypesRegistry("node", "commander") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
                     const installedTypings = ["@types/node", "@types/commander"];
                     const typingFiles = [node, commander];
-                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
                 }
             })();
             const service = createProjectService(host, { typingsInstaller: installer });
@@ -797,7 +774,7 @@ namespace ts.projectSystem {
             service.checkNumberOfProjects({ inferredProjects: 1 });
             checkProjectActualFiles(service.inferredProjects[0], [file.path]);
 
-            installer.installAll([TI.NpmViewRequest, TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/1);
 
             assert.isTrue(host.fileExists(node.path), "typings for 'node' should be created");
             assert.isTrue(host.fileExists(commander.path), "typings for 'commander' should be created");
@@ -822,14 +799,10 @@ namespace ts.projectSystem {
             const host = createServerHost([f1]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: "/tmp" });
+                    super(host, { globalTypingsCacheLocation: "/tmp", typesRegistry: createTypesRegistry("foo") });
                 }
-                executeRequest(requestKind: TI.RequestKind, _requestId: number, args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
-                    if (requestKind === TI.NpmViewRequest) {
-                        // args should have only non-scoped packages - scoped packages are not yet supported
-                        assert.deepEqual(args, ["foo"]);
-                    }
-                    executeCommand(this, host, ["foo"], [], requestKind, cb);
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                    executeCommand(this, host, ["foo"], [], cb);
                 }
             })();
             const projectService = createProjectService(host, { typingsInstaller: installer });
@@ -844,7 +817,7 @@ namespace ts.projectSystem {
                 ["foo", "foo", "foo", "@bar/router", "@bar/common", "@bar/common"]
             );
 
-            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+            installer.installAll(/*expectedCount*/ 1);
         });
 
         it("cached unresolved typings are not recomputed if program structure did not change", () => {
@@ -934,16 +907,16 @@ namespace ts.projectSystem {
             const host = createServerHost([f1, packageJson]);
             const installer = new (class extends Installer {
                 constructor() {
-                    super(host, { globalTypingsCacheLocation: "/tmp" }, { isEnabled: () => true, writeLine: msg => messages.push(msg) });
+                    super(host, { globalTypingsCacheLocation: "/tmp" }, /*telemetryEnabled*/ false, { isEnabled: () => true, writeLine: msg => messages.push(msg) });
                 }
-                executeRequest() {
+                installWorker(_requestId: number, _args: string[], _cwd: string, _cb: server.typingsInstaller.RequestCompletedAction) {
                     assert(false, "runCommand should not be invoked");
                 }
             })();
             const projectService = createProjectService(host, { typingsInstaller: installer });
             projectService.openClientFile(f1.path);
 
-            installer.checkPendingCommands([]);
+            installer.checkPendingCommands(/*expectedCount*/ 0);
             assert.isTrue(messages.indexOf("Package name '; say ‘Hello from TypeScript!’ #' contains non URI safe characters") > 0, "should find package with invalid name");
         });
     });
@@ -978,4 +951,50 @@ namespace ts.projectSystem {
             assert.deepEqual(result.newTypingNames, ["bar"]);
         });
     });
+
+    describe("telemetry events", () => {
+        it ("should be received", () => {
+            const f1 = {
+                path: "/a/app.js",
+                content: ""
+            };
+            const package = {
+                path: "/a/package.json",
+                content: JSON.stringify({ dependencies: { "commander": "1.0.0" } })
+            };
+            const cachePath = "/a/cache/";
+            const commander = {
+                path: cachePath + "node_modules/@types/commander/index.d.ts",
+                content: "export let x: number"
+            };
+            const host = createServerHost([f1, package]);
+            let seenTelemetryEvent = false;
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host, { globalTypingsCacheLocation: cachePath, typesRegistry: createTypesRegistry("commander") }, /*telemetryEnabled*/ true);
+                }
+                installWorker(_requestId: number, _args: string[], _cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                    const installedTypings = ["@types/commander"];
+                    const typingFiles = [commander];
+                    executeCommand(this, host, installedTypings, typingFiles, cb);
+                }
+                sendResponse(response: server.SetTypings | server.InvalidateCachedTypings | server.TypingsInstallEvent) {
+                    if (response.kind === server.EventInstall) {
+                        assert.deepEqual(response.packagesToInstall, ["@types/commander"]);
+                        seenTelemetryEvent = true;
+                        return;
+                    }
+                    super.sendResponse(response);
+                }
+            })();
+            const projectService = createProjectService(host, { typingsInstaller: installer });
+            projectService.openClientFile(f1.path);
+
+            installer.installAll(/*expectedCount*/ 1);
+
+            assert.isTrue(seenTelemetryEvent);
+            checkNumberOfProjects(projectService, { inferredProjects: 1 });
+            checkProjectActualFiles(projectService.inferredProjects[0], [f1.path, commander.path]);
+        });
+    });
 }

src/lib/dom.generated.d.ts

@@ -1679,6 +1679,7 @@ interface CSSStyleDeclaration {
     writingMode: string | null;
     zIndex: string | null;
     zoom: string | null;
+    resize: string | null;
     getPropertyPriority(propertyName: string): string;
     getPropertyValue(propertyName: string): string;
     item(index: number): string;
@@ -1748,6 +1749,7 @@ declare var CanvasGradient: {
 }
 
 interface CanvasPattern {
+    setTransform(matrix: SVGMatrix): void;
 }
 
 declare var CanvasPattern: {
@@ -2173,7 +2175,7 @@ interface DataTransfer {
     effectAllowed: string;
     readonly files: FileList;
     readonly items: DataTransferItemList;
-    readonly types: DOMStringList;
+    readonly types: string[];
     clearData(format?: string): boolean;
     getData(format: string): string;
     setData(format: string, data: string): boolean;
@@ -8602,7 +8604,7 @@ interface MouseEvent extends UIEvent {
     readonly x: number;
     readonly y: number;
     getModifierState(keyArg: string): boolean;
-    initMouseEvent(typeArg: string, canBubbleArg: boolean, cancelableArg: boolean, viewArg: Window, detailArg: number, screenXArg: number, screenYArg: number, clientXArg: number, clientYArg: number, ctrlKeyArg: boolean, altKeyArg: boolean, shiftKeyArg: boolean, metaKeyArg: boolean, buttonArg: number, relatedTargetArg: EventTarget): void;
+    initMouseEvent(typeArg: string, canBubbleArg: boolean, cancelableArg: boolean, viewArg: Window, detailArg: number, screenXArg: number, screenYArg: number, clientXArg: number, clientYArg: number, ctrlKeyArg: boolean, altKeyArg: boolean, shiftKeyArg: boolean, metaKeyArg: boolean, buttonArg: number, relatedTargetArg: EventTarget | null): void;
 }
 
 declare var MouseEvent: {
@@ -8715,6 +8717,7 @@ interface Navigator extends Object, NavigatorID, NavigatorOnLine, NavigatorConte
     readonly plugins: PluginArray;
     readonly pointerEnabled: boolean;
     readonly webdriver: boolean;
+    readonly hardwareConcurrency: number;
     getGamepads(): Gamepad[];
     javaEnabled(): boolean;
     msLaunchUri(uri: string, successCallback?: MSLaunchUriCallback, noHandlerCallback?: MSLaunchUriCallback): void;
@@ -8732,18 +8735,18 @@ interface Node extends EventTarget {
     readonly attributes: NamedNodeMap;
     readonly baseURI: string | null;
     readonly childNodes: NodeList;
-    readonly firstChild: Node;
-    readonly lastChild: Node;
+    readonly firstChild: Node | null;
+    readonly lastChild: Node | null;
     readonly localName: string | null;
     readonly namespaceURI: string | null;
-    readonly nextSibling: Node;
+    readonly nextSibling: Node | null;
     readonly nodeName: string;
     readonly nodeType: number;
     nodeValue: string | null;
     readonly ownerDocument: Document;
-    readonly parentElement: HTMLElement;
-    readonly parentNode: Node;
-    readonly previousSibling: Node;
+    readonly parentElement: HTMLElement | null;
+    readonly parentNode: Node | null;
+    readonly previousSibling: Node | null;
     textContent: string | null;
     appendChild(newChild: Node): Node;
     cloneNode(deep?: boolean): Node;
@@ -12853,7 +12856,7 @@ interface Window extends EventTarget, WindowTimers, WindowSessionStorage, Window
     readonly devicePixelRatio: number;
     readonly doNotTrack: string;
     readonly document: Document;
-    event: Event;
+    event: Event | undefined;
     readonly external: External;
     readonly frameElement: Element;
     readonly frames: Window;
@@ -13155,6 +13158,7 @@ interface XMLHttpRequest extends EventTarget, XMLHttpRequestEventTarget {
     readonly upload: XMLHttpRequestUpload;
     withCredentials: boolean;
     msCaching?: string;
+    readonly responseURL: string;
     abort(): void;
     getAllResponseHeaders(): string;
     getResponseHeader(header: string): string | null;
@@ -14301,7 +14305,7 @@ declare var defaultStatus: string;
 declare var devicePixelRatio: number;
 declare var doNotTrack: string;
 declare var document: Document;
-declare var event: Event;
+declare var event: Event | undefined;
 declare var external: External;
 declare var frameElement: Element;
 declare var frames: Window;

src/lib/webworker.generated.d.ts

@@ -740,6 +740,7 @@ interface XMLHttpRequest extends EventTarget, XMLHttpRequestEventTarget {
     readonly upload: XMLHttpRequestUpload;
     withCredentials: boolean;
     msCaching?: string;
+    readonly responseURL: string;
     abort(): void;
     getAllResponseHeaders(): string;
     getResponseHeader(header: string): string | null;
@@ -902,6 +903,7 @@ declare var WorkerLocation: {
 }
 
 interface WorkerNavigator extends Object, NavigatorID, NavigatorOnLine {
+    readonly hardwareConcurrency: number;
     addEventListener(type: string, listener: EventListenerOrEventListenerObject, useCapture?: boolean): void;
 }
 

src/server/builder.ts

@@ -5,15 +5,6 @@
 
 namespace ts.server {
 
-    interface Hash {
-        update(data: any, input_encoding?: string): Hash;
-        digest(encoding: string): any;
-    }
-
-    const crypto: {
-        createHash(algorithm: string): Hash
-    } = require("crypto");
-
     export function shouldEmitFile(scriptInfo: ScriptInfo) {
         return !scriptInfo.hasMixedContent;
     }
@@ -49,9 +40,7 @@ namespace ts.server {
         }
 
         private computeHash(text: string): string {
-            return crypto.createHash("md5")
-                .update(text)
-                .digest("base64");
+            return this.project.projectService.host.createHash(text);
         }
 
         private getSourceFile(): SourceFile {

src/server/editorServices.ts

@@ -250,6 +250,8 @@ namespace ts.server {
             readonly typingsInstaller: ITypingsInstaller = nullTypingsInstaller,
             private readonly eventHandler?: ProjectServiceEventHandler) {
 
+            Debug.assert(!!host.createHash, "'ServerHost.createHash' is required for ProjectService");
+
             this.toCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames);
             this.directoryWatchers = new DirectoryWatchers(this);
             this.throttledOperations = new ThrottledOperations(host);
@@ -286,10 +288,10 @@ namespace ts.server {
                 return;
             }
             switch (response.kind) {
-                case "set":
+                case ActionSet:
                     this.typingsCache.updateTypingsForProject(response.projectName, response.compilerOptions, response.typingOptions, response.unresolvedImports, response.typings);
                     break;
-                case "invalidate":
+                case ActionInvalidate:
                     this.typingsCache.deleteTypingsForProject(response.projectName);
                     break;
             }
@@ -298,6 +300,9 @@ namespace ts.server {
 
         setCompilerOptionsForInferredProjects(projectCompilerOptions: protocol.ExternalProjectCompilerOptions): void {
             this.compilerOptionsForInferredProjects = convertCompilerOptions(projectCompilerOptions);
+            // always set 'allowNonTsExtensions' for inferred projects since user cannot configure it from the outside
+            // previously we did not expose a way for user to change these settings and this option was enabled by default
+            this.compilerOptionsForInferredProjects.allowNonTsExtensions = true;
             this.compileOnSaveForInferredProjects = projectCompilerOptions.compileOnSave;
             for (const proj of this.inferredProjects) {
                 proj.setCompilerOptions(this.compilerOptionsForInferredProjects);
@@ -1285,7 +1290,9 @@ namespace ts.server {
             for (const file of proj.rootFiles) {
                 const normalized = toNormalizedPath(file.fileName);
                 if (getBaseFileName(normalized) === "tsconfig.json") {
-                    (tsConfigFiles || (tsConfigFiles = [])).push(normalized);
+                    if (this.host.fileExists(normalized)) {
+                        (tsConfigFiles || (tsConfigFiles = [])).push(normalized);
+                    }
                 }
                 else {
                     rootFiles.push(file);

src/server/lsHost.ts

@@ -13,6 +13,7 @@ namespace ts.server {
 
         private readonly resolveModuleName: typeof resolveModuleName;
         readonly trace: (s: string) => void;
+        readonly realpath?: (path: string) => string;
 
         constructor(private readonly host: ServerHost, private readonly project: Project, private readonly cancellationToken: HostCancellationToken) {
             this.getCanonicalFileName = ts.createGetCanonicalFileName(this.host.useCaseSensitiveFileNames);
@@ -39,6 +40,10 @@ namespace ts.server {
                 }
                 return primaryResult;
             };
+
+            if (this.host.realpath) {
+                this.realpath = path => this.host.realpath(path);
+            }
         }
 
         public startRecordingFilesWithChangedResolutions() {

src/server/project.ts

@@ -161,6 +161,10 @@ namespace ts.server {
                 this.compilerOptions.allowNonTsExtensions = true;
             }
 
+            if (this.projectKind === ProjectKind.Inferred) {
+                this.compilerOptions.noEmitOverwritenFiles = true;
+            }
+
             if (languageServiceEnabled) {
                 this.enableLanguageService();
             }
@@ -297,7 +301,7 @@ namespace ts.server {
             return this.getLanguageService().getEmitOutput(info.fileName, emitOnlyDtsFiles);
         }
 
-        getFileNames() {
+        getFileNames(excludeFilesFromExternalLibraries?: boolean) {
             if (!this.program) {
                 return [];
             }
@@ -313,8 +317,14 @@ namespace ts.server {
                 }
                 return rootFiles;
             }
-            const sourceFiles = this.program.getSourceFiles();
-            return sourceFiles.map(sourceFile => asNormalizedPath(sourceFile.fileName));
+            const result: NormalizedPath[] = [];
+            for (const f of this.program.getSourceFiles()) {
+                if (excludeFilesFromExternalLibraries && this.program.isSourceFileFromExternalLibrary(f)) {
+                    continue;
+                }
+                result.push(asNormalizedPath(f.fileName));
+            }
+            return result;
         }
 
         getAllEmittableFiles() {

src/server/protocol.ts

@@ -2057,6 +2057,32 @@ namespace ts.server.protocol {
         childItems?: NavigationTree[];
     }
 
+    export type TelemetryEventName = "telemetry";
+
+    export interface TelemetryEvent extends Event {
+        event: TelemetryEventName;
+        body: TelemetryEventBody;
+    }
+
+    export interface TelemetryEventBody {
+        telemetryEventName: string;
+        payload: any;
+    }
+
+    export type TypingsInstalledTelemetryEventName = "typingsInstalled";
+
+    export interface TypingsInstalledTelemetryEventBody extends TelemetryEventBody {
+        telemetryEventName: TypingsInstalledTelemetryEventName;
+        payload: TypingsInstalledTelemetryEventPayload;
+    }
+
+    export interface TypingsInstalledTelemetryEventPayload {
+        /**
+         * Comma separated list of installed typing packages
+         */
+        installedPackages: string;
+    }
+
     export interface NavBarResponse extends Response {
         body?: NavigationBarItem[];
     }

src/server/server.ts

@@ -1,4 +1,5 @@
 /// <reference types="node" />
+/// <reference path="shared.ts" />
 /// <reference path="session.ts" />
 // used in fs.writeSync
 /* tslint:disable:no-null-keyword */
@@ -196,8 +197,10 @@ namespace ts.server {
         private socket: NodeSocket;
         private projectService: ProjectService;
         private throttledOperations: ThrottledOperations;
+        private telemetrySender: EventSender;
 
         constructor(
+            private readonly telemetryEnabled: boolean,
             private readonly logger: server.Logger,
             host: ServerHost,
             eventPort: number,
@@ -226,15 +229,22 @@ namespace ts.server {
             this.socket.write(formatMessage({ seq, type: "event", event, body }, this.logger, Buffer.byteLength, this.newLine), "utf8");
         }
 
+        setTelemetrySender(telemetrySender: EventSender) {
+            this.telemetrySender = telemetrySender;
+        }
+
         attach(projectService: ProjectService) {
             this.projectService = projectService;
             if (this.logger.hasLevel(LogLevel.requestTime)) {
                 this.logger.info("Binding...");
             }
 
-            const args: string[] = ["--globalTypingsCacheLocation", this.globalTypingsCacheLocation];
+            const args: string[] = [Arguments.GlobalCacheLocation, this.globalTypingsCacheLocation];
+            if (this.telemetryEnabled) {
+                args.push(Arguments.EnableTelemetry);
+            }
             if (this.logger.loggingEnabled() && this.logger.getLogFileName()) {
-                args.push("--logFile", combinePaths(getDirectoryPath(normalizeSlashes(this.logger.getLogFileName())), `ti-${process.pid}.log`));
+                args.push(Arguments.LogFile, combinePaths(getDirectoryPath(normalizeSlashes(this.logger.getLogFileName())), `ti-${process.pid}.log`));
             }
             const execArgv: string[] = [];
             {
@@ -280,12 +290,25 @@ namespace ts.server {
             });
         }
 
-        private handleMessage(response: SetTypings | InvalidateCachedTypings) {
+        private handleMessage(response: SetTypings | InvalidateCachedTypings | TypingsInstallEvent) {
             if (this.logger.hasLevel(LogLevel.verbose)) {
                 this.logger.info(`Received response: ${JSON.stringify(response)}`);
             }
+            if (response.kind === EventInstall) {
+                if (this.telemetrySender) {
+                    const body: protocol.TypingsInstalledTelemetryEventBody = {
+                        telemetryEventName: "typingsInstalled",
+                        payload: {
+                            installedPackages: response.packagesToInstall.join(",")
+                        }
+                    };
+                    const eventName: protocol.TelemetryEventName = "telemetry";
+                    this.telemetrySender.event(body, eventName);
+                }
+                return;
+            }
             this.projectService.updateTypingsForProject(response);
-            if (response.kind == "set" && this.socket) {
+            if (response.kind == ActionSet && this.socket) {
                 this.sendEvent(0, "setTypings", response);
             }
         }
@@ -300,18 +323,25 @@ namespace ts.server {
             useSingleInferredProject: boolean,
             disableAutomaticTypingAcquisition: boolean,
             globalTypingsCacheLocation: string,
+            telemetryEnabled: boolean,
             logger: server.Logger) {
-            super(
-                host,
-                cancellationToken,
-                useSingleInferredProject,
-                disableAutomaticTypingAcquisition
-                    ? nullTypingsInstaller
-                    : new NodeTypingsInstaller(logger, host, installerEventPort, globalTypingsCacheLocation, host.newLine),
-                Buffer.byteLength,
-                process.hrtime,
-                logger,
-                canUseEvents);
+                const typingsInstaller = disableAutomaticTypingAcquisition
+                    ? undefined
+                    : new NodeTypingsInstaller(telemetryEnabled, logger, host, installerEventPort, globalTypingsCacheLocation, host.newLine);
+
+                super(
+                    host,
+                    cancellationToken,
+                    useSingleInferredProject,
+                    typingsInstaller || nullTypingsInstaller,
+                    Buffer.byteLength,
+                    process.hrtime,
+                    logger,
+                    canUseEvents);
+
+                if (telemetryEnabled && typingsInstaller) {
+                    typingsInstaller.setTelemetrySender(this);
+                }
         }
 
         exit() {
@@ -538,17 +568,17 @@ namespace ts.server {
 
     let eventPort: number;
     {
-        const index = sys.args.indexOf("--eventPort");
-        if (index >= 0 && index < sys.args.length - 1) {
-            const v = parseInt(sys.args[index + 1]);
-            if (!isNaN(v)) {
-                eventPort = v;
-            }
+        const str = findArgument("--eventPort");
+        const v = str && parseInt(str);
+        if (!isNaN(v)) {
+            eventPort = v;
         }
     }
 
-    const useSingleInferredProject = sys.args.indexOf("--useSingleInferredProject") >= 0;
-    const disableAutomaticTypingAcquisition = sys.args.indexOf("--disableAutomaticTypingAcquisition") >= 0;
+    const useSingleInferredProject = hasArgument("--useSingleInferredProject");
+    const disableAutomaticTypingAcquisition = hasArgument("--disableAutomaticTypingAcquisition");
+    const telemetryEnabled = hasArgument(Arguments.EnableTelemetry);
+
     const ioSession = new IOSession(
         sys,
         cancellationToken,
@@ -557,6 +587,7 @@ namespace ts.server {
         useSingleInferredProject,
         disableAutomaticTypingAcquisition,
         getGlobalTypingsCacheLocation(),
+        telemetryEnabled,
         logger);
     process.on("uncaughtException", function (err: Error) {
         ioSession.logError(err, "unknown");

src/server/session.ts

@@ -73,6 +73,10 @@ namespace ts.server {
         project: Project;
     }
 
+    export interface EventSender {
+        event(payload: any, eventName: string): void;
+    }
+
     function allEditsBeforePos(edits: ts.TextChange[], pos: number) {
         for (const edit of edits) {
             if (textSpanEnd(edit.span) >= pos) {
@@ -165,7 +169,7 @@ namespace ts.server {
         return `Content-Length: ${1 + len}\r\n\r\n${json}${newLine}`;
     }
 
-    export class Session {
+    export class Session implements EventSender {
         private readonly gcTimer: GcTimer;
         protected projectService: ProjectService;
         private errorTimer: any; /*NodeJS.Timer | number*/

src/server/shared.ts

@@ -0,0 +1,24 @@
+/// <reference path="types.d.ts" />
+
+namespace ts.server {
+    export const ActionSet: ActionSet = "action::set";
+    export const ActionInvalidate: ActionInvalidate = "action::invalidate";
+    export const EventInstall: EventInstall = "event::install";
+
+    export namespace Arguments {
+        export const GlobalCacheLocation = "--globalTypingsCacheLocation";
+        export const LogFile = "--logFile";
+        export const EnableTelemetry = "--enableTelemetry";
+    }
+
+    export function hasArgument(argumentName: string) {
+        return sys.args.indexOf(argumentName) >= 0;
+    }
+
+    export function findArgument(argumentName: string) {
+        const index = sys.args.indexOf(argumentName);
+        return index >= 0 && index < sys.args.length - 1
+            ? sys.args[index + 1]
+            : undefined;
+    }
+}

src/server/tsconfig.json

@@ -18,6 +18,7 @@
     "files": [
         "../services/shims.ts",
         "../services/utilities.ts",
+        "shared.ts",
         "utilities.ts",
         "scriptVersionCache.ts",
         "scriptInfo.ts",

src/server/tsconfig.library.json

@@ -15,6 +15,7 @@
     "files": [
         "../services/shims.ts",
         "../services/utilities.ts",
+        "shared.ts",
         "utilities.ts",
         "scriptVersionCache.ts",
         "scriptInfo.ts",

src/server/types.d.ts

@@ -41,28 +41,38 @@ declare namespace ts.server {
         readonly kind: "closeProject";
     }
 
-    export type SetRequest = "set";
-    export type InvalidateRequest = "invalidate";
+    export type ActionSet = "action::set";
+    export type ActionInvalidate = "action::invalidate";
+    export type EventInstall = "event::install";
+
     export interface TypingInstallerResponse {
-        readonly projectName: string;
-        readonly kind: SetRequest | InvalidateRequest;
+        readonly kind: ActionSet | ActionInvalidate | EventInstall;
     }
 
-    export interface SetTypings extends TypingInstallerResponse {
+    export interface ProjectResponse extends TypingInstallerResponse {
+        readonly projectName: string;
+    }
+
+    export interface SetTypings extends ProjectResponse {
         readonly typingOptions: ts.TypingOptions;
         readonly compilerOptions: ts.CompilerOptions;
         readonly typings: string[];
         readonly unresolvedImports: SortedReadonlyArray<string>;
-        readonly kind: SetRequest;
+        readonly kind: ActionSet;
     }
 
-    export interface InvalidateCachedTypings extends TypingInstallerResponse {
-        readonly kind: InvalidateRequest;
+    export interface InvalidateCachedTypings extends ProjectResponse {
+        readonly kind: ActionInvalidate;
+    }
+
+    export interface TypingsInstallEvent extends TypingInstallerResponse {
+        readonly packagesToInstall: ReadonlyArray<string>;
+        readonly kind: EventInstall;
     }
 
     export interface InstallTypingHost extends JsTyping.TypingResolutionHost {
         writeFile(path: string, content: string): void;
         createDirectory(path: string): void;
-        watchFile?(path: string, callback: FileWatcherCallback): FileWatcher;
+        watchFile?(path: string, callback: FileWatcherCallback, pollingInterval?: number): FileWatcher;
     }
 }

src/server/typingsInstaller/nodeTypingsInstaller.ts

@@ -33,42 +33,81 @@ namespace ts.server.typingsInstaller {
         }
     }
 
-    type HttpGet = {
-        (url: string, callback: (response: HttpResponse) => void): NodeJS.EventEmitter;
-    };
-
-    interface HttpResponse extends NodeJS.ReadableStream {
-        statusCode: number;
-        statusMessage: string;
-        destroy(): void;
+    interface TypesRegistryFile {
+        entries: MapLike<void>;
     }
 
+    function loadTypesRegistryFile(typesRegistryFilePath: string, host: InstallTypingHost, log: Log): Map<void> {
+        if (!host.fileExists(typesRegistryFilePath)) {
+            if (log.isEnabled()) {
+                log.writeLine(`Types registry file '${typesRegistryFilePath}' does not exist`);
+            }
+            return createMap<void>();
+        }
+        try {
+            const content = <TypesRegistryFile>JSON.parse(host.readFile(typesRegistryFilePath));
+            return createMap<void>(content.entries);
+        }
+        catch (e) {
+            if (log.isEnabled()) {
+                log.writeLine(`Error when loading types registry file '${typesRegistryFilePath}': ${(<Error>e).message}, ${(<Error>e).stack}`);
+            }
+            return createMap<void>();
+        }
+    }
+
+    const TypesRegistryPackageName = "types-registry";
+    function getTypesRegistryFileLocation(globalTypingsCacheLocation: string): string {
+        return combinePaths(normalizeSlashes(globalTypingsCacheLocation), `node_modules/${TypesRegistryPackageName}/index.json`);
+    }
+
+
     type Exec = {
         (command: string, options: { cwd: string }, callback?: (error: Error, stdout: string, stderr: string) => void): any
     };
 
+    type ExecSync = {
+        (command: string, options: { cwd: string, stdio: "ignore" }): any
+    };
+
     export class NodeTypingsInstaller extends TypingsInstaller {
         private readonly exec: Exec;
-        private readonly httpGet: HttpGet;
         private readonly npmPath: string;
-        readonly installTypingHost: InstallTypingHost = sys;
+        readonly typesRegistry: Map<void>;
 
-        constructor(globalTypingsCacheLocation: string, throttleLimit: number, log: Log) {
+        constructor(globalTypingsCacheLocation: string, throttleLimit: number, telemetryEnabled: boolean, log: Log) {
             super(
+                sys,
                 globalTypingsCacheLocation,
                 toPath("typingSafeList.json", __dirname, createGetCanonicalFileName(sys.useCaseSensitiveFileNames)),
                 throttleLimit,
+                telemetryEnabled,
                 log);
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Process id: ${process.pid}`);
             }
             this.npmPath = getNPMLocation(process.argv[0]);
-            this.exec = require("child_process").exec;
-            this.httpGet = require("http").get;
+            let execSync: ExecSync;
+            ({ exec: this.exec, execSync } = require("child_process"));
+
+            this.ensurePackageDirectoryExists(globalTypingsCacheLocation);
+
+            try {
+                if (this.log.isEnabled()) {
+                    this.log.writeLine(`Updating ${TypesRegistryPackageName} npm package...`);
+                }
+                execSync(`${this.npmPath} install ${TypesRegistryPackageName}`, { cwd: globalTypingsCacheLocation, stdio: "ignore" });
+            }
+            catch (e) {
+                if (this.log.isEnabled()) {
+                    this.log.writeLine(`Error updating ${TypesRegistryPackageName} package: ${(<Error>e).message}`);
+                }
+            }
+
+            this.typesRegistry = loadTypesRegistryFile(getTypesRegistryFileLocation(globalTypingsCacheLocation), this.installTypingHost, this.log);
         }
 
-        init() {
-            super.init();
+        listen() {
             process.on("message", (req: DiscoverTypings | CloseProject) => {
                 switch (req.kind) {
                     case "discover":
@@ -90,66 +129,26 @@ namespace ts.server.typingsInstaller {
             }
         }
 
-        protected executeRequest(requestKind: RequestKind, requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void {
+        protected installWorker(requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void {
             if (this.log.isEnabled()) {
-                this.log.writeLine(`#${requestId} executing ${requestKind}, arguments'${JSON.stringify(args)}'.`);
-            }
-            switch (requestKind) {
-                case NpmViewRequest: {
-                        // const command = `${self.npmPath} view @types/${typing} --silent name`;
-                        // use http request to global npm registry instead of running npm view
-                        Debug.assert(args.length === 1);
-                        const url = `http://registry.npmjs.org/@types%2f${args[0]}`;
-                        const start = Date.now();
-                        this.httpGet(url, response => {
-                            let ok = false;
-                            if (this.log.isEnabled()) {
-                                this.log.writeLine(`${requestKind} #${requestId} request to ${url}:: status code ${response.statusCode}, status message '${response.statusMessage}', took ${Date.now() - start} ms`);
-                            }
-                            switch (response.statusCode) {
-                                case 200: // OK
-                                case 301: // redirect - Moved - treat package as present
-                                case 302: // redirect - Found - treat package as present
-                                    ok = true;
-                                    break;
-                            }
-                            response.destroy();
-                            onRequestCompleted(ok);
-                        }).on("error", (err: Error) => {
-                            if (this.log.isEnabled()) {
-                                this.log.writeLine(`${requestKind} #${requestId} query to npm registry failed with error ${err.message}, stack ${err.stack}`);
-                            }
-                            onRequestCompleted(/*success*/ false);
-                        });
-                    }
-                    break;
-                case NpmInstallRequest: {
-                        const command = `${this.npmPath} install ${args.join(" ")} --save-dev`;
-                        const start = Date.now();
-                        this.exec(command, { cwd }, (_err, stdout, stderr) => {
-                            if (this.log.isEnabled()) {
-                                this.log.writeLine(`${requestKind} #${requestId} took: ${Date.now() - start} ms${sys.newLine}stdout: ${stdout}${sys.newLine}stderr: ${stderr}`);
-                            }
-                            // treat any output on stdout as success
-                            onRequestCompleted(!!stdout);
-                        });
-                    }
-                    break;
-                default:
-                    Debug.assert(false, `Unknown request kind ${requestKind}`);
+                this.log.writeLine(`#${requestId} with arguments'${JSON.stringify(args)}'.`);
             }
+            const command = `${this.npmPath} install ${args.join(" ")} --save-dev`;
+            const start = Date.now();
+            this.exec(command, { cwd }, (_err, stdout, stderr) => {
+                if (this.log.isEnabled()) {
+                    this.log.writeLine(`npm install #${requestId} took: ${Date.now() - start} ms${sys.newLine}stdout: ${stdout}${sys.newLine}stderr: ${stderr}`);
+                }
+                // treat any output on stdout as success
+                onRequestCompleted(!!stdout);
+            });
         }
     }
 
-    function findArgument(argumentName: string) {
-        const index = sys.args.indexOf(argumentName);
-        return index >= 0 && index < sys.args.length - 1
-            ? sys.args[index + 1]
-            : undefined;
-    }
+    const logFilePath = findArgument(server.Arguments.LogFile);
+    const globalTypingsCacheLocation = findArgument(server.Arguments.GlobalCacheLocation);
+    const telemetryEnabled = hasArgument(server.Arguments.EnableTelemetry);
 
-    const logFilePath = findArgument("--logFile");
-    const globalTypingsCacheLocation = findArgument("--globalTypingsCacheLocation");
     const log = new FileLog(logFilePath);
     if (log.isEnabled()) {
         process.on("uncaughtException", (e: Error) => {
@@ -162,6 +161,6 @@ namespace ts.server.typingsInstaller {
         }
         process.exit(0);
     });
-    const installer = new NodeTypingsInstaller(globalTypingsCacheLocation, /*throttleLimit*/5, log);
-    installer.init();
+    const installer = new NodeTypingsInstaller(globalTypingsCacheLocation, /*throttleLimit*/5, telemetryEnabled, log);
+    installer.listen();
 }

src/server/typingsInstaller/tsconfig.json

@@ -17,6 +17,7 @@
     },
     "files": [
         "../types.d.ts",
+        "../shared.ts",
         "typingsInstaller.ts",
         "nodeTypingsInstaller.ts"
     ]

src/server/typingsInstaller/typingsInstaller.ts

@@ -2,6 +2,7 @@
 /// <reference path="../../compiler/moduleNameResolver.ts" />
 /// <reference path="../../services/jsTyping.ts"/>
 /// <reference path="../types.d.ts"/>
+/// <reference path="../shared.ts"/>
 
 namespace ts.server.typingsInstaller {
     interface NpmConfig {
@@ -63,14 +64,8 @@ namespace ts.server.typingsInstaller {
         return PackageNameValidationResult.Ok;
     }
 
-    export const NpmViewRequest: "npm view" = "npm view";
-    export const NpmInstallRequest: "npm install" = "npm install";
-
-    export type RequestKind = typeof NpmViewRequest | typeof NpmInstallRequest;
-
     export type RequestCompletedAction = (success: boolean) => void;
     type PendingRequest = {
-        requestKind: RequestKind;
         requestId: number;
         args: string[];
         cwd: string;
@@ -87,19 +82,18 @@ namespace ts.server.typingsInstaller {
         private installRunCount = 1;
         private inFlightRequestCount = 0;
 
-        abstract readonly installTypingHost: InstallTypingHost;
+        abstract readonly typesRegistry: Map<void>;
 
         constructor(
+            readonly installTypingHost: InstallTypingHost,
             readonly globalCachePath: string,
             readonly safeListPath: Path,
             readonly throttleLimit: number,
+            readonly telemetryEnabled: boolean,
             protected readonly log = nullLog) {
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Global cache location '${globalCachePath}', safe file path '${safeListPath}'`);
             }
-        }
-
-        init() {
             this.processCacheLocation(this.globalCachePath);
         }
 
@@ -224,7 +218,7 @@ namespace ts.server.typingsInstaller {
             this.knownCachesSet[cacheLocation] = true;
         }
 
-        private filterTypings(typingsToInstall: string[]) {
+        private filterAndMapToScopedName(typingsToInstall: string[]) {
             if (typingsToInstall.length === 0) {
                 return typingsToInstall;
             }
@@ -235,7 +229,14 @@ namespace ts.server.typingsInstaller {
                 }
                 const validationResult = validatePackageName(typing);
                 if (validationResult === PackageNameValidationResult.Ok) {
-                    result.push(typing);
+                    if (typing in this.typesRegistry) {
+                        result.push(`@types/${typing}`);
+                    }
+                    else {
+                        if (this.log.isEnabled()) {
+                            this.log.writeLine(`Entry for package '${typing}' does not exist in local types registry - skipping...`);
+                        }
+                    }
                 }
                 else {
                     // add typing name to missing set so we won't process it again
@@ -267,19 +268,8 @@ namespace ts.server.typingsInstaller {
             return result;
         }
 
-        private installTypings(req: DiscoverTypings, cachePath: string, currentlyCachedTypings: string[], typingsToInstall: string[]) {
-            if (this.log.isEnabled()) {
-                this.log.writeLine(`Installing typings ${JSON.stringify(typingsToInstall)}`);
-            }
-            typingsToInstall = this.filterTypings(typingsToInstall);
-            if (typingsToInstall.length === 0) {
-                if (this.log.isEnabled()) {
-                    this.log.writeLine(`All typings are known to be missing or invalid - no need to go any further`);
-                }
-                return;
-            }
-
-            const npmConfigPath = combinePaths(cachePath, "package.json");
+        protected ensurePackageDirectoryExists(directory: string) {
+            const npmConfigPath = combinePaths(directory, "package.json");
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Npm config file: ${npmConfigPath}`);
             }
@@ -287,23 +277,50 @@ namespace ts.server.typingsInstaller {
                 if (this.log.isEnabled()) {
                     this.log.writeLine(`Npm config file: '${npmConfigPath}' is missing, creating new one...`);
                 }
-                this.ensureDirectoryExists(cachePath, this.installTypingHost);
+                this.ensureDirectoryExists(directory, this.installTypingHost);
                 this.installTypingHost.writeFile(npmConfigPath, "{}");
             }
+        }
+
+        private installTypings(req: DiscoverTypings, cachePath: string, currentlyCachedTypings: string[], typingsToInstall: string[]) {
+            if (this.log.isEnabled()) {
+                this.log.writeLine(`Installing typings ${JSON.stringify(typingsToInstall)}`);
+            }
+            const scopedTypings = this.filterAndMapToScopedName(typingsToInstall);
+            if (scopedTypings.length === 0) {
+                if (this.log.isEnabled()) {
+                    this.log.writeLine(`All typings are known to be missing or invalid - no need to go any further`);
+                }
+                return;
+            }
+
+            this.ensurePackageDirectoryExists(cachePath);
+
+            const requestId = this.installRunCount;
+            this.installRunCount++;
+
+            this.installTypingsAsync(requestId, scopedTypings, cachePath, ok => {
+                if (this.telemetryEnabled) {
+                    this.sendResponse(<TypingsInstallEvent>{
+                        kind: EventInstall,
+                        packagesToInstall: scopedTypings
+                    });
+                }
+
+                if (!ok) {
+                    return;
+                }
 
-            this.runInstall(cachePath, typingsToInstall, installedTypings => {
                 // TODO: watch project directory
                 if (this.log.isEnabled()) {
-                    this.log.writeLine(`Requested to install typings ${JSON.stringify(typingsToInstall)}, installed typings ${JSON.stringify(installedTypings)}`);
+                    this.log.writeLine(`Requested to install typings ${JSON.stringify(scopedTypings)}, installed typings ${JSON.stringify(scopedTypings)}`);
                 }
-                const installedPackages: Map<true> = createMap<true>();
                 const installedTypingFiles: string[] = [];
-                for (const t of installedTypings) {
+                for (const t of scopedTypings) {
                     const packageName = getBaseFileName(t);
                     if (!packageName) {
                         continue;
                     }
-                    installedPackages[packageName] = true;
                     const typingFile = typingToFileName(cachePath, packageName, this.installTypingHost);
                     if (!typingFile) {
                         continue;
@@ -316,53 +333,11 @@ namespace ts.server.typingsInstaller {
                 if (this.log.isEnabled()) {
                     this.log.writeLine(`Installed typing files ${JSON.stringify(installedTypingFiles)}`);
                 }
-                for (const toInstall of typingsToInstall) {
-                    if (!installedPackages[toInstall]) {
-                        if (this.log.isEnabled()) {
-                            this.log.writeLine(`New missing typing package '${toInstall}'`);
-                        }
-                        this.missingTypingsSet[toInstall] = true;
-                    }
-                }
 
                 this.sendResponse(this.createSetTypings(req, currentlyCachedTypings.concat(installedTypingFiles)));
             });
         }
 
-        private runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void {
-            const requestId = this.installRunCount;
-
-            this.installRunCount++;
-            let execInstallCmdCount = 0;
-            const filteredTypings: string[] = [];
-            for (const typing of typingsToInstall) {
-                filterExistingTypings(this, typing);
-            }
-
-            function filterExistingTypings(self: TypingsInstaller, typing: string) {
-                self.execAsync(NpmViewRequest, requestId, [typing], cachePath, ok => {
-                    if (ok) {
-                        filteredTypings.push(typing);
-                    }
-                    execInstallCmdCount++;
-                    if (execInstallCmdCount === typingsToInstall.length) {
-                        installFilteredTypings(self, filteredTypings);
-                    }
-                });
-            }
-
-            function installFilteredTypings(self: TypingsInstaller, filteredTypings: string[]) {
-                if (filteredTypings.length === 0) {
-                    postInstallAction([]);
-                    return;
-                }
-                const scopedTypings = filteredTypings.map(t => "@types/" + t);
-                self.execAsync(NpmInstallRequest, requestId, scopedTypings, cachePath, ok => {
-                    postInstallAction(ok ? scopedTypings : []);
-                });
-            }
-        }
-
         private ensureDirectoryExists(directory: string, host: InstallTypingHost): void {
             const directoryName = getDirectoryPath(directory);
             if (!host.directoryExists(directoryName)) {
@@ -389,10 +364,10 @@ namespace ts.server.typingsInstaller {
                         this.log.writeLine(`Got FS notification for ${f}, handler is already invoked '${isInvoked}'`);
                     }
                     if (!isInvoked) {
-                        this.sendResponse({ projectName: projectName, kind: "invalidate" });
+                        this.sendResponse({ projectName: projectName, kind: server.ActionInvalidate });
                         isInvoked = true;
                     }
-                });
+                }, /*pollingInterval*/ 2000);
                 watchers.push(w);
             }
             this.projectWatchers[projectName] = watchers;
@@ -405,12 +380,12 @@ namespace ts.server.typingsInstaller {
                 compilerOptions: request.compilerOptions,
                 typings,
                 unresolvedImports: request.unresolvedImports,
-                kind: "set"
+                kind: server.ActionSet
             };
         }
 
-        private execAsync(requestKind: RequestKind, requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void {
-            this.pendingRunRequests.unshift({ requestKind, requestId, args, cwd, onRequestCompleted });
+        private installTypingsAsync(requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void {
+            this.pendingRunRequests.unshift({ requestId, args, cwd, onRequestCompleted });
             this.executeWithThrottling();
         }
 
@@ -418,7 +393,7 @@ namespace ts.server.typingsInstaller {
             while (this.inFlightRequestCount < this.throttleLimit && this.pendingRunRequests.length) {
                 this.inFlightRequestCount++;
                 const request = this.pendingRunRequests.pop();
-                this.executeRequest(request.requestKind, request.requestId, request.args, request.cwd, ok => {
+                this.installWorker(request.requestId, request.args, request.cwd, ok => {
                     this.inFlightRequestCount--;
                     request.onRequestCompleted(ok);
                     this.executeWithThrottling();
@@ -426,7 +401,7 @@ namespace ts.server.typingsInstaller {
             }
         }
 
-        protected abstract executeRequest(requestKind: RequestKind, requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void;
-        protected abstract sendResponse(response: SetTypings | InvalidateCachedTypings): void;
+        protected abstract installWorker(requestId: number, args: string[], cwd: string, onRequestCompleted: RequestCompletedAction): void;
+        protected abstract sendResponse(response: SetTypings | InvalidateCachedTypings | TypingsInstallEvent): void;
     }
 }

src/server/utilities.ts

@@ -1,4 +1,5 @@
 /// <reference path="types.d.ts" />
+/// <reference path="shared.ts" />
 
 namespace ts.server {
     export enum LogLevel {
@@ -10,6 +11,7 @@ namespace ts.server {
 
     export const emptyArray: ReadonlyArray<any> = [];
 
+
     export interface Logger {
         close(): void;
         hasLevel(level: LogLevel): boolean;
@@ -48,7 +50,7 @@ namespace ts.server {
     export function createInstallTypingsRequest(project: Project, typingOptions: TypingOptions, unresolvedImports: SortedReadonlyArray<string>, cachePath?: string): DiscoverTypings {
         return {
             projectName: project.getProjectName(),
-            fileNames: project.getFileNames(),
+            fileNames: project.getFileNames(/*excludeFilesFromExternalLibraries*/ true),
             compilerOptions: project.getCompilerOptions(),
             typingOptions,
             unresolvedImports,

src/services/jsTyping.ts

@@ -88,7 +88,7 @@ namespace ts.JsTyping {
         exclude = typingOptions.exclude || [];
 
         const possibleSearchDirs = map(fileNames, getDirectoryPath);
-        if (projectRootPath !== undefined) {
+        if (projectRootPath) {
             possibleSearchDirs.push(projectRootPath);
         }
         searchDirs = deduplicate(possibleSearchDirs);

src/services/services.ts

@@ -48,7 +48,6 @@ namespace ts {
         public jsDocComments: JSDoc[];
         public original: Node;
         public transformFlags: TransformFlags;
-        public excludeTransformFlags: TransformFlags;
         private _children: Node[];
 
         constructor(kind: SyntaxKind, pos: number, end: number) {
@@ -56,7 +55,6 @@ namespace ts {
             this.end = end;
             this.flags = NodeFlags.None;
             this.transformFlags = undefined;
-            this.excludeTransformFlags = undefined;
             this.parent = undefined;
             this.kind = kind;
         }
@@ -472,6 +470,7 @@ namespace ts {
         public imports: LiteralExpression[];
         public moduleAugmentations: LiteralExpression[];
         private namedDeclarations: Map<Declaration[]>;
+        public ambientModuleNames: string[];
 
         constructor(kind: SyntaxKind, pos: number, end: number) {
             super(kind, pos, end);

src/services/signatureHelp.ts

@@ -557,7 +557,9 @@ namespace ts.SignatureHelp {
                 addRange(prefixDisplayParts, callTargetDisplayParts);
             }
 
+            let isVariadic: boolean;
             if (isTypeParameterList) {
+                isVariadic = false; // type parameter lists are not variadic
                 prefixDisplayParts.push(punctuationPart(SyntaxKind.LessThanToken));
                 const typeParameters = candidateSignature.typeParameters;
                 signatureHelpParameters = typeParameters && typeParameters.length > 0 ? map(typeParameters, createSignatureHelpParameterForTypeParameter) : emptyArray;
@@ -567,6 +569,7 @@ namespace ts.SignatureHelp {
                 addRange(suffixDisplayParts, parameterParts);
             }
             else {
+                isVariadic = candidateSignature.hasRestParameter;
                 const typeParameterParts = mapToDisplayParts(writer =>
                     typeChecker.getSymbolDisplayBuilder().buildDisplayForTypeParametersAndDelimiters(candidateSignature.typeParameters, writer, invocation));
                 addRange(prefixDisplayParts, typeParameterParts);
@@ -582,7 +585,7 @@ namespace ts.SignatureHelp {
             addRange(suffixDisplayParts, returnTypeParts);
 
             return {
-                isVariadic: candidateSignature.hasRestParameter,
+                isVariadic,
                 prefixDisplayParts,
                 suffixDisplayParts,
                 separatorDisplayParts: [punctuationPart(SyntaxKind.CommaToken), spacePart()],