Merge branch 'master' into fix2-getConstraintOfIndexedAccess

src/compiler/binder.ts

@@ -303,7 +303,7 @@ namespace ts {
                     // without names can only come from JSDocFunctionTypes.
                     Debug.assert(node.parent.kind === SyntaxKind.JSDocFunctionType);
                     const functionType = <JSDocFunctionType>node.parent;
-                    const index = indexOf(functionType.parameters, node);
+                    const index = functionType.parameters.indexOf(node as ParameterDeclaration);
                     return "arg" + index as __String;
                 case SyntaxKind.JSDocTypedefTag:
                     const name = getNameOfJSDocTypedef(node as JSDocTypedefTag);
@@ -746,7 +746,11 @@ namespace ts {
         }
 
         function isNarrowingTypeofOperands(expr1: Expression, expr2: Expression) {
-            return expr1.kind === SyntaxKind.TypeOfExpression && isNarrowableOperand((<TypeOfExpression>expr1).expression) && expr2.kind === SyntaxKind.StringLiteral;
+            return expr1.kind === SyntaxKind.TypeOfExpression && isNarrowableOperand((<TypeOfExpression>expr1).expression) && (expr2.kind === SyntaxKind.StringLiteral || expr2.kind === SyntaxKind.NoSubstitutionTemplateLiteral);
+        }
+
+        function isNarrowableInOperands(left: Expression, right: Expression) {
+            return (left.kind === SyntaxKind.StringLiteral || left.kind === SyntaxKind.NoSubstitutionTemplateLiteral) && isNarrowingExpression(right);
         }
 
         function isNarrowingBinaryExpression(expr: BinaryExpression) {
@@ -761,6 +765,8 @@ namespace ts {
                         isNarrowingTypeofOperands(expr.right, expr.left) || isNarrowingTypeofOperands(expr.left, expr.right);
                 case SyntaxKind.InstanceOfKeyword:
                     return isNarrowableOperand(expr.left);
+                case SyntaxKind.InKeyword:
+                    return isNarrowableInOperands(expr.left, expr.right);
                 case SyntaxKind.CommaToken:
                     return isNarrowingExpression(expr.right);
             }
@@ -1627,7 +1633,7 @@ namespace ts {
             // to the one we would get for: { <...>(...): T }
             //
             // We do that by making an anonymous type literal symbol, and then setting the function
-            // symbol as its sole member. To the rest of the system, this symbol will be  indistinguishable
+            // symbol as its sole member. To the rest of the system, this symbol will be indistinguishable
             // from an actual type literal symbol you would have gotten had you used the long form.
             const symbol = createSymbol(SymbolFlags.Signature, getDeclarationName(node));
             addDeclarationToSymbol(symbol, node, SymbolFlags.Signature);
@@ -2283,30 +2289,13 @@ namespace ts {
             declareSymbol(file.symbol.exports, file.symbol, <PropertyAccessExpression>node.left, SymbolFlags.Property | SymbolFlags.ExportValue, SymbolFlags.None);
         }
 
-        function isExportsOrModuleExportsOrAlias(node: Node): boolean {
-            return isExportsIdentifier(node) ||
-                isModuleExportsPropertyAccessExpression(node) ||
-                isIdentifier(node) && isNameOfExportsOrModuleExportsAliasDeclaration(node);
-        }
-
-        function isNameOfExportsOrModuleExportsAliasDeclaration(node: Identifier): boolean {
-            const symbol = lookupSymbolForName(node.escapedText);
-            return symbol && symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration) &&
-                symbol.valueDeclaration.initializer && isExportsOrModuleExportsOrAliasOrAssignment(symbol.valueDeclaration.initializer);
-        }
-
-        function isExportsOrModuleExportsOrAliasOrAssignment(node: Node): boolean {
-            return isExportsOrModuleExportsOrAlias(node) ||
-                (isAssignmentExpression(node, /*excludeCompoundAssignements*/ true) && (isExportsOrModuleExportsOrAliasOrAssignment(node.left) || isExportsOrModuleExportsOrAliasOrAssignment(node.right)));
-        }
-
         function bindModuleExportsAssignment(node: BinaryExpression) {
             // A common practice in node modules is to set 'export = module.exports = {}', this ensures that 'exports'
             // is still pointing to 'module.exports'.
             // We do not want to consider this as 'export=' since a module can have only one of these.
             // Similarly we do not want to treat 'module.exports = exports' as an 'export='.
             const assignedExpression = getRightMostAssignedExpression(node.right);
-            if (isEmptyObjectLiteral(assignedExpression) || isExportsOrModuleExportsOrAlias(assignedExpression)) {
+            if (isEmptyObjectLiteral(assignedExpression) || container === file && isExportsOrModuleExportsOrAlias(file, assignedExpression)) {
                 // Mark it as a module in case there are no other exports in the file
                 setCommonJsModuleIndicator(node);
                 return;
@@ -2387,7 +2376,7 @@ namespace ts {
                 if (node.kind === SyntaxKind.BinaryExpression) {
                     leftSideOfAssignment.parent = node;
                 }
-                if (isNameOfExportsOrModuleExportsAliasDeclaration(target)) {
+                if (container === file && isNameOfExportsOrModuleExportsAliasDeclaration(file, target)) {
                     // This can be an alias for the 'exports' or 'module.exports' names, e.g.
                     //    var util = module.exports;
                     //    util.property = function ...
@@ -2400,11 +2389,7 @@ namespace ts {
         }
 
         function lookupSymbolForName(name: __String) {
-            const local = container.locals && container.locals.get(name);
-            if (local) {
-                return local.exportSymbol || local;
-            }
-            return container.symbol && container.symbol.exports && container.symbol.exports.get(name);
+            return lookupSymbolForNameWorker(container, name);
         }
 
         function bindPropertyAssignment(functionName: __String, propertyAccess: PropertyAccessExpression, isPrototypeProperty: boolean) {
@@ -2425,7 +2410,7 @@ namespace ts {
             if (!isPrototypeProperty && (!targetSymbol || !(targetSymbol.flags & SymbolFlags.Namespace)) && isLegalPosition) {
                 Debug.assert(isIdentifier(propertyAccess.expression));
                 const identifier = propertyAccess.expression as Identifier;
-                const flags =  SymbolFlags.Module | SymbolFlags.JSContainer;
+                const flags = SymbolFlags.Module | SymbolFlags.JSContainer;
                 const excludeFlags = SymbolFlags.ValueModuleExcludes & ~SymbolFlags.JSContainer;
                 if (targetSymbol) {
                     addDeclarationToSymbol(symbol, identifier, flags);
@@ -2532,7 +2517,7 @@ namespace ts {
             }
 
             if (isBindingPattern(node.name)) {
-                bindAnonymousDeclaration(node, SymbolFlags.FunctionScopedVariable, "__" + indexOf(node.parent.parameters, node) as __String);
+                bindAnonymousDeclaration(node, SymbolFlags.FunctionScopedVariable, "__" + node.parent.parameters.indexOf(node) as __String);
             }
             else {
                 declareSymbolAndAddToSymbolTable(node, SymbolFlags.FunctionScopedVariable, SymbolFlags.ParameterExcludes);
@@ -2643,6 +2628,33 @@ namespace ts {
         }
     }
 
+    /* @internal */
+    export function isExportsOrModuleExportsOrAlias(sourceFile: SourceFile, node: Expression): boolean {
+        return isExportsIdentifier(node) ||
+            isModuleExportsPropertyAccessExpression(node) ||
+            isIdentifier(node) && isNameOfExportsOrModuleExportsAliasDeclaration(sourceFile, node);
+    }
+
+    function isNameOfExportsOrModuleExportsAliasDeclaration(sourceFile: SourceFile, node: Identifier): boolean {
+        const symbol = lookupSymbolForNameWorker(sourceFile, node.escapedText);
+        return symbol && symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration) &&
+            symbol.valueDeclaration.initializer && isExportsOrModuleExportsOrAliasOrAssignment(sourceFile, symbol.valueDeclaration.initializer);
+    }
+
+    function isExportsOrModuleExportsOrAliasOrAssignment(sourceFile: SourceFile, node: Expression): boolean {
+        return isExportsOrModuleExportsOrAlias(sourceFile, node) ||
+            (isAssignmentExpression(node, /*excludeCompoundAssignements*/ true) && (
+                isExportsOrModuleExportsOrAliasOrAssignment(sourceFile, node.left) || isExportsOrModuleExportsOrAliasOrAssignment(sourceFile, node.right)));
+    }
+
+    function lookupSymbolForNameWorker(container: Node, name: __String): Symbol | undefined {
+        const local = container.locals && container.locals.get(name);
+        if (local) {
+            return local.exportSymbol || local;
+        }
+        return container.symbol && container.symbol.exports && container.symbol.exports.get(name);
+    }
+
     /**
      * Computes the transform flags for a node, given the transform flags of its subtree
      *

src/compiler/builder.ts

@@ -468,9 +468,9 @@ namespace ts {
             }
 
             function getReferencedByPaths(referencedFilePath: Path) {
-                return mapDefinedIter(references.entries(), ([filePath, referencesInFile]) =>
+                return arrayFrom(mapDefinedIterator(references.entries(), ([filePath, referencesInFile]) =>
                     referencesInFile.has(referencedFilePath) ? filePath as Path : undefined
-                );
+                ));
             }
 
             function getFilesAffectedByUpdatedShape(program: Program, sourceFile: SourceFile): ReadonlyArray<SourceFile> {
@@ -504,7 +504,7 @@ namespace ts {
                 }
 
                 // Return array of values that needs emit
-                return flatMapIter(seenFileNamesMap.values(), value => value);
+                return arrayFrom(mapDefinedIterator(seenFileNamesMap.values(), value => value));
             }
         }
     }

src/compiler/commandLineParser.ts

@@ -144,7 +144,9 @@ namespace ts {
                     "es2017.string": "lib.es2017.string.d.ts",
                     "es2017.intl": "lib.es2017.intl.d.ts",
                     "es2017.typedarrays": "lib.es2017.typedarrays.d.ts",
+                    "esnext.array": "lib.esnext.array.d.ts",
                     "esnext.asynciterable": "lib.esnext.asynciterable.d.ts",
+                    "esnext.promise": "lib.esnext.promise.d.ts",
                 }),
             },
             showInSimplifiedHelpView: true,
@@ -400,6 +402,13 @@ namespace ts {
             category: Diagnostics.Module_Resolution_Options,
             description: Diagnostics.Allow_default_imports_from_modules_with_no_default_export_This_does_not_affect_code_emit_just_typechecking
         },
+        {
+            name: "esModuleInterop",
+            type: "boolean",
+            showInSimplifiedHelpView: true,
+            category: Diagnostics.Module_Resolution_Options,
+            description: Diagnostics.Enables_emit_interoperability_between_CommonJS_and_ES_Modules_via_creation_of_namespace_objects_for_all_imports_Implies_allowSyntheticDefaultImports
+        },
         {
             name: "preserveSymlinks",
             type: "boolean",
@@ -702,7 +711,8 @@ namespace ts {
     export const defaultInitCompilerOptions: CompilerOptions = {
         module: ModuleKind.CommonJS,
         target: ScriptTarget.ES5,
-        strict: true
+        strict: true,
+        esModuleInterop: true
     };
 
     let optionNameMapCache: OptionNameMap;
@@ -1863,7 +1873,7 @@ namespace ts {
         return normalizeNonListOptionValue(option, basePath, value);
     }
 
-    function normalizeNonListOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue  {
+    function normalizeNonListOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue {
         if (option.isFilePath) {
             value = normalizePath(combinePaths(basePath, value));
             if (value === "") {
@@ -1906,21 +1916,6 @@ namespace ts {
      */
     const invalidTrailingRecursionPattern = /(^|\/)\*\*\/?$/;
 
-    /**
-     * Tests for a path with multiple recursive directory wildcards.
-     * Matches **\** and **\a\**, but not **\a**b.
-     *
-     * NOTE: used \ in place of / above to avoid issues with multiline comments.
-     *
-     * Breakdown:
-     *  (^|\/)      # matches either the beginning of the string or a directory separator.
-     *  \*\*\/      # matches a recursive directory wildcard "**" followed by a directory separator.
-     *  (.*\/)?     # optionally matches any number of characters followed by a directory separator.
-     *  \*\*        # matches a recursive directory wildcard "**"
-     *  ($|\/)      # matches either the end of the string or a directory separator.
-     */
-    const invalidMultipleRecursionPatterns = /(^|\/)\*\*\/(.*\/)?\*\*($|\/)/;
-
     /**
      * Tests for a path where .. appears after a recursive directory wildcard.
      * Matches **\..\*, **\a\..\*, and **\.., but not ..\**\*
@@ -2115,9 +2110,6 @@ namespace ts {
         if (!allowTrailingRecursion && invalidTrailingRecursionPattern.test(spec)) {
             return Diagnostics.File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0;
         }
-        else if (invalidMultipleRecursionPatterns.test(spec)) {
-            return Diagnostics.File_specification_cannot_contain_multiple_recursive_directory_wildcards_Asterisk_Asterisk_Colon_0;
-        }
         else if (invalidDotDotAfterRecursiveWildcardPattern.test(spec)) {
             return Diagnostics.File_specification_cannot_contain_a_parent_directory_that_appears_after_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0;
         }

src/compiler/core.ts

@@ -191,6 +191,19 @@ namespace ts {
         return undefined;
     }
 
+    export function firstDefinedIterator<T, U>(iter: Iterator<T>, callback: (element: T) => U | undefined): U | undefined {
+        while (true) {
+            const { value, done } = iter.next();
+            if (done) {
+                return undefined;
+            }
+            const result = callback(value);
+            if (result !== undefined) {
+                return result;
+            }
+        }
+    }
+
     /**
      * Iterates through the parent chain of a node and performs the callback on each parent until the callback
      * returns a truthy value, then returns that value.
@@ -215,13 +228,27 @@ namespace ts {
 
     export function zipWith<T, U, V>(arrayA: ReadonlyArray<T>, arrayB: ReadonlyArray<U>, callback: (a: T, b: U, index: number) => V): V[] {
         const result: V[] = [];
-        Debug.assert(arrayA.length === arrayB.length);
+        Debug.assertEqual(arrayA.length, arrayB.length);
         for (let i = 0; i < arrayA.length; i++) {
             result.push(callback(arrayA[i], arrayB[i], i));
         }
         return result;
     }
 
+    export function zipToIterator<T, U>(arrayA: ReadonlyArray<T>, arrayB: ReadonlyArray<U>): Iterator<[T, U]> {
+        Debug.assertEqual(arrayA.length, arrayB.length);
+        let i = 0;
+        return {
+            next() {
+                if (i === arrayA.length) {
+                    return { value: undefined as never, done: true };
+                }
+                i++;
+                return { value: [arrayA[i - 1], arrayB[i - 1]], done: false };
+            }
+        };
+    }
+
     export function zipToMap<T>(keys: ReadonlyArray<string>, values: ReadonlyArray<T>): Map<T> {
         Debug.assert(keys.length === values.length);
         const map = createMap<T>();
@@ -261,6 +288,8 @@ namespace ts {
         return undefined;
     }
 
+    export function findLast<T, U extends T>(array: ReadonlyArray<T>, predicate: (element: T, index: number) => element is U): U | undefined;
+    export function findLast<T>(array: ReadonlyArray<T>, predicate: (element: T, index: number) => boolean): T | undefined;
     export function findLast<T>(array: ReadonlyArray<T>, predicate: (element: T, index: number) => boolean): T | undefined {
         for (let i = array.length - 1; i >= 0; i--) {
             const value = array[i];
@@ -306,17 +335,6 @@ namespace ts {
         return false;
     }
 
-    export function indexOf<T>(array: ReadonlyArray<T>, value: T): number {
-        if (array) {
-            for (let i = 0; i < array.length; i++) {
-                if (array[i] === value) {
-                    return i;
-                }
-            }
-        }
-        return -1;
-    }
-
     export function indexOfAnyCharCode(text: string, charCodes: ReadonlyArray<number>, start?: number): number {
         for (let i = start || 0; i < text.length; i++) {
             if (contains(charCodes, text.charCodeAt(i))) {
@@ -394,12 +412,14 @@ namespace ts {
         return result;
     }
 
+
     export function mapIterator<T, U>(iter: Iterator<T>, mapFn: (x: T) => U): Iterator<U> {
-        return { next };
-        function next(): { value: U, done: false } | { value: never, done: true } {
-            const iterRes = iter.next();
-            return iterRes.done ? iterRes : { value: mapFn(iterRes.value), done: false };
-        }
+        return {
+            next() {
+                const iterRes = iter.next();
+                return iterRes.done ? iterRes : { value: mapFn(iterRes.value), done: false };
+            }
+        };
     }
 
     // Maps from T to T and avoids allocation if all elements map to themselves
@@ -474,22 +494,32 @@ namespace ts {
         return result;
     }
 
-    export function flatMapIter<T, U>(iter: Iterator<T>, mapfn: (x: T) => U | U[] | undefined): U[] {
-        const result: U[] = [];
-        while (true) {
-            const { value, done } = iter.next();
-            if (done) break;
-            const res = mapfn(value);
-            if (res) {
-                if (isArray(res)) {
-                    result.push(...res);
+    export function flatMapIterator<T, U>(iter: Iterator<T>, mapfn: (x: T) => U[] | Iterator<U> | undefined): Iterator<U> {
+        const first = iter.next();
+        if (first.done) {
+            return emptyIterator;
+        }
+        let currentIter = getIterator(first.value);
+        return {
+            next() {
+                while (true) {
+                    const currentRes = currentIter.next();
+                    if (!currentRes.done) {
+                        return currentRes;
+                    }
+                    const iterRes = iter.next();
+                    if (iterRes.done) {
+                        return iterRes;
+                    }
+                    currentIter = getIterator(iterRes.value);
                 }
-                else {
-                    result.push(res);
-                }
-            }
+            },
+        };
+
+        function getIterator(x: T): Iterator<U> {
+            const res = mapfn(x);
+            return res === undefined ? emptyIterator : isArray(res) ? arrayIterator(res) : res;
         }
-        return result;
     }
 
     /**
@@ -523,12 +553,23 @@ namespace ts {
         return result || array;
     }
 
+    export function mapAllOrFail<T, U>(array: ReadonlyArray<T>, mapFn: (x: T, i: number) => U | undefined): U[] | undefined {
+        const result: U[] = [];
+        for (let i = 0; i < array.length; i++) {
+            const mapped = mapFn(array[i], i);
+            if (mapped === undefined) {
+                return undefined;
+            }
+            result.push(mapped);
+        }
+        return result;
+    }
+
     export function mapDefined<T, U>(array: ReadonlyArray<T> | undefined, mapFn: (x: T, i: number) => U | undefined): U[] {
         const result: U[] = [];
         if (array) {
             for (let i = 0; i < array.length; i++) {
-                const item = array[i];
-                const mapped = mapFn(item, i);
+                const mapped = mapFn(array[i], i);
                 if (mapped !== undefined) {
                     result.push(mapped);
                 }
@@ -537,17 +578,34 @@ namespace ts {
         return result;
     }
 
-    export function mapDefinedIter<T, U>(iter: Iterator<T>, mapFn: (x: T) => U | undefined): U[] {
-        const result: U[] = [];
-        while (true) {
-            const { value, done } = iter.next();
-            if (done) break;
-            const res = mapFn(value);
-            if (res !== undefined) {
-                result.push(res);
+    export function mapDefinedIterator<T, U>(iter: Iterator<T>, mapFn: (x: T) => U | undefined): Iterator<U> {
+        return {
+            next() {
+                while (true) {
+                    const res = iter.next();
+                    if (res.done) {
+                        return res;
+                    }
+                    const value = mapFn(res.value);
+                    if (value !== undefined) {
+                        return { value, done: false };
+                    }
+                }
             }
-        }
-        return result;
+        };
+    }
+
+    export const emptyIterator: Iterator<never> = { next: () => ({ value: undefined as never, done: true }) };
+
+    export function singleIterator<T>(value: T): Iterator<T> {
+        let done = false;
+        return {
+            next() {
+                const wasDone = done;
+                done = true;
+                return wasDone ? { value: undefined as never, done: true } : { value, done: false };
+            }
+        };
     }
 
     /**
@@ -1345,7 +1403,6 @@ namespace ts {
             this.set(key, values = [value]);
         }
         return values;
-
     }
     function multiMapRemove<T>(this: MultiMap<T>, key: string, value: T) {
         const values = this.get(key);
@@ -1360,12 +1417,12 @@ namespace ts {
     /**
      * Tests whether a value is an array.
      */
-    export function isArray(value: any): value is ReadonlyArray<any> {
+    export function isArray(value: any): value is ReadonlyArray<{}> {
         return Array.isArray ? Array.isArray(value) : value instanceof Array;
     }
 
-    export function toArray<T>(value: T | ReadonlyArray<T>): ReadonlyArray<T>;
     export function toArray<T>(value: T | T[]): T[];
+    export function toArray<T>(value: T | ReadonlyArray<T>): ReadonlyArray<T>;
     export function toArray<T>(value: T | T[]): T[] {
         return isArray(value) ? value : [value];
     }
@@ -1939,11 +1996,6 @@ namespace ts {
         return /^\.\.?($|[\\/])/.test(path);
     }
 
-    /** @deprecated Use `!isExternalModuleNameRelative(moduleName)` instead. */
-    export function moduleHasNonRelativeName(moduleName: string): boolean {
-        return !isExternalModuleNameRelative(moduleName);
-    }
-
     export function getEmitScriptTarget(compilerOptions: CompilerOptions) {
         return compilerOptions.target || ScriptTarget.ES3;
     }
@@ -1966,7 +2018,9 @@ namespace ts {
         const moduleKind = getEmitModuleKind(compilerOptions);
         return compilerOptions.allowSyntheticDefaultImports !== undefined
             ? compilerOptions.allowSyntheticDefaultImports
-            : moduleKind === ModuleKind.System;
+            : compilerOptions.esModuleInterop
+                ? moduleKind !== ModuleKind.None && moduleKind < ModuleKind.ES2015
+                : moduleKind === ModuleKind.System;
     }
 
     export type StrictOptionName = "noImplicitAny" | "noImplicitThis" | "strictNullChecks" | "strictFunctionTypes" | "strictPropertyInitialization" | "alwaysStrict";
@@ -2030,7 +2084,7 @@ namespace ts {
 
     function getNormalizedPathComponentsOfUrl(url: string) {
         // Get root length of http://www.website.com/folder1/folder2/
-        // In this example the root is:  http://www.website.com/
+        // In this example the root is: http://www.website.com/
         // normalized path components should be ["http://www.website.com/", "folder1", "folder2"]
 
         const urlLength = url.length;
@@ -2063,7 +2117,7 @@ namespace ts {
         }
         else {
             // Can't find the host assume the rest of the string as component
-            // but make sure we append "/"  to it as root is not joined using "/"
+            // but make sure we append "/" to it as root is not joined using "/"
             // eg. if url passed in was http://website.com we want to use root as [http://website.com/]
             // so that other path manipulations will be correct and it can be merged with relative paths correctly
             return [url + directorySeparator];
@@ -2084,7 +2138,7 @@ namespace ts {
         const directoryComponents = getNormalizedPathOrUrlComponents(directoryPathOrUrl, currentDirectory);
         if (directoryComponents.length > 1 && lastOrUndefined(directoryComponents) === "") {
             // If the directory path given was of type test/cases/ then we really need components of directory to be only till its name
-            // that is  ["test", "cases", ""] needs to be actually ["test", "cases"]
+            // that is ["test", "cases", ""] needs to be actually ["test", "cases"]
             directoryComponents.pop();
         }
 
@@ -2326,7 +2380,6 @@ namespace ts {
 
     function getSubPatternFromSpec(spec: string, basePath: string, usage: "files" | "directories" | "exclude", { singleAsteriskRegexFragment, doubleAsteriskRegexFragment, replaceWildcardCharacter }: WildcardMatcher): string | undefined {
         let subpattern = "";
-        let hasRecursiveDirectoryWildcard = false;
         let hasWrittenComponent = false;
         const components = getNormalizedPathComponents(spec, basePath);
         const lastComponent = lastOrUndefined(components);
@@ -2345,12 +2398,7 @@ namespace ts {
         let optionalCount = 0;
         for (let component of components) {
             if (component === "**") {
-                if (hasRecursiveDirectoryWildcard) {
-                    return undefined;
-                }
-
                 subpattern += doubleAsteriskRegexFragment;
-                hasRecursiveDirectoryWildcard = true;
             }
             else {
                 if (usage === "directories") {
@@ -3213,4 +3261,8 @@ namespace ts {
             cachedReadDirectoryResult.clear();
         }
     }
+
+    export function singleElementArray<T>(t: T | undefined): T[] | undefined {
+        return t === undefined ? undefined : [t];
+    }
 }

src/compiler/declarationEmitter.ts

@@ -64,7 +64,7 @@ namespace ts {
         let currentIdentifiers: Map<string>;
         let isCurrentFileExternalModule: boolean;
         let reportedDeclarationError = false;
-        let errorNameNode: DeclarationName;
+        let errorNameNode: DeclarationName | QualifiedName;
         const emitJsDocComments = compilerOptions.removeComments ? noop : writeJsDocComments;
         const emit = compilerOptions.stripInternal ? stripInternal : emitNode;
         let needsDeclare = true;
@@ -148,8 +148,8 @@ namespace ts {
                 moduleElementDeclarationEmitInfo = [];
             }
 
-            if (!isBundledEmit && isExternalModule(sourceFile) && sourceFile.moduleAugmentations.length && !resultHasExternalModuleIndicator) {
-                // if file was external module with augmentations - this fact should be preserved in .d.ts as well.
+            if (!isBundledEmit && isExternalModule(sourceFile) && !resultHasExternalModuleIndicator) {
+                // if file was external module this fact should be preserved in .d.ts as well.
                 // in case if we didn't write any external module specifiers in .d.ts we need to emit something
                 // that will force compiler to think that this file is an external module - 'export {}' is a reasonable choice here.
                 write("export {};");
@@ -651,6 +651,9 @@ namespace ts {
         }
 
         function emitExportAssignment(node: ExportAssignment) {
+            if (isSourceFile(node.parent)) {
+                resultHasExternalModuleIndicator = true; // Top-level exports are external module indicators
+            }
             if (node.expression.kind === SyntaxKind.Identifier) {
                 write(node.isExportEquals ? "export = " : "export default ");
                 writeTextOfNode(currentText, node.expression);
@@ -745,6 +748,7 @@ namespace ts {
                 const modifiers = getModifierFlags(node);
                 // If the node is exported
                 if (modifiers & ModifierFlags.Export) {
+                    resultHasExternalModuleIndicator = true; // Top-level exports are external module indicators
                     write("export ");
                 }
 
@@ -901,6 +905,7 @@ namespace ts {
         }
 
         function emitExportDeclaration(node: ExportDeclaration) {
+            resultHasExternalModuleIndicator = true; // Top-level exports are external module indicators
             emitJsDocComments(node);
             write("export ");
             if (node.exportClause) {
@@ -1199,7 +1204,7 @@ namespace ts {
                         write(">");
                     }
                 }
-                else  {
+                else {
                     emitHeritageClause([baseTypeNode], /*isImplementsList*/ false);
                 }
             }
@@ -1372,7 +1377,7 @@ namespace ts {
             // if this is property of type literal,
             // or is parameter of method/call/construct/index signature of type literal
             // emit only if type is specified
-            if (node.type) {
+            if (hasType(node)) {
                 write(": ");
                 emitType(node.type);
             }
@@ -1866,6 +1871,7 @@ namespace ts {
                     // it allows emitSeparatedList to write separator appropriately)
                     // Example:
                     //      original: function foo([, x, ,]) {}
+                    //      tslint:disable-next-line no-double-space
                     //      emit    : function foo([ , x,  , ]) {}
                     write(" ");
                 }

src/compiler/diagnosticMessages.json

@@ -939,6 +939,14 @@
         "category": "Error",
         "code": 1335
     },
+    "An index signature parameter type cannot be a type alias. Consider writing '[{0}: {1}]: {2}' instead.": {
+        "category": "Error",
+        "code": 1336
+    },
+    "An index signature parameter type cannot be a union type. Consider using a mapped object type instead.": {
+        "category": "Error",
+        "code": 1337
+    },
 
     "Duplicate identifier '{0}'.": {
         "category": "Error",
@@ -1396,6 +1404,10 @@
         "category": "Error",
         "code": 2415
     },
+    "Property '{0}' in type '{1}' is not assignable to the same property in base type '{2}'.": {
+        "category": "Error",
+        "code": 2416
+    },
     "Class static side '{0}' incorrectly extends base class static side '{1}'.": {
         "category": "Error",
         "code": 2417
@@ -1612,7 +1624,7 @@
         "category": "Error",
         "code": 2474
     },
-    "'const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment.": {
+    "'const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment or type query.": {
         "category": "Error",
         "code": 2475
     },
@@ -2276,7 +2288,22 @@
         "category": "Error",
         "code": 2719
     },
-
+    "Class '{0}' incorrectly implements class '{1}'. Did you mean to extend '{1}' and inherit its members as a subclass?": {
+        "category": "Error",
+        "code": 2720
+    },
+    "Cannot invoke an object which is possibly 'null'.": {
+        "category": "Error",
+        "code": 2721
+    },
+    "Cannot invoke an object which is possibly 'undefined'.": {
+        "category": "Error",
+        "code": 2722
+    },
+    "Cannot invoke an object which is possibly 'null' or 'undefined'.": {
+        "category": "Error",
+        "code": 2723
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000
@@ -2623,10 +2650,6 @@
         "category": "Error",
         "code": 5010
     },
-    "File specification cannot contain multiple recursive directory wildcards ('**'): '{0}'.": {
-        "category": "Error",
-        "code": 5011
-    },
     "Cannot read file '{0}': {1}.": {
         "category": "Error",
         "code": 5012
@@ -2828,6 +2851,10 @@
         "category": "Message",
         "code": 6030
     },
+    "Starting compilation in watch mode...": {
+        "category": "Message",
+        "code": 6031
+    },
     "File change detected. Starting incremental compilation...": {
         "category": "Message",
         "code": 6032
@@ -3416,6 +3443,14 @@
         "category": "Message",
         "code": 6187
     },
+    "Numeric separators are not allowed here.": {
+        "category": "Error",
+        "code": 6188
+    },
+    "Multiple consecutive numeric separators are not permitted.": {
+        "category": "Error",
+        "code": 6189
+    },
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005
@@ -3528,7 +3563,18 @@
         "category": "Error",
         "code": 7036
     },
-
+    "Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'.": {
+        "category": "Message",
+        "code": 7037
+    },
+    "A namespace-style import cannot be called or constructed, and will cause a failure at runtime.": {
+        "category": "Error",
+        "code": 7038
+    },
+    "Mapped object type implicitly has an 'any' template type.": {
+        "category": "Error",
+        "code": 7039
+    },
     "You cannot rename this element.": {
         "category": "Error",
         "code": 8000
@@ -3831,6 +3877,10 @@
         "category": "Message",
         "code": 90028
     },
+    "Add async modifier to containing function": {
+        "category": "Message",
+        "code": 90029
+    },
     "Convert function to an ES2015 class": {
         "category": "Message",
         "code": 95001
@@ -3886,5 +3936,17 @@
     "Install '{0}'": {
         "category": "Message",
         "code": 95014
+    },
+    "Replace import with '{0}'.": {
+        "category": "Message",
+        "code": 95015
+    },
+    "Use synthetic 'default' member.": {
+        "category": "Message",
+        "code": 95016
+    },
+    "Convert to ES6 module": {
+        "category": "Message",
+        "code": 95017
     }
 }

src/compiler/emitter.ts

@@ -1194,27 +1194,15 @@ namespace ts {
         //
 
         function emitObjectBindingPattern(node: ObjectBindingPattern) {
-            const elements = node.elements;
-            if (elements.length === 0) {
-                write("{}");
-            }
-            else {
-                write("{");
-                emitList(node, elements, ListFormat.ObjectBindingPatternElements);
-                write("}");
-            }
+            write("{");
+            emitList(node, node.elements, ListFormat.ObjectBindingPatternElements);
+            write("}");
         }
 
         function emitArrayBindingPattern(node: ArrayBindingPattern) {
-            const elements = node.elements;
-            if (elements.length === 0) {
-                write("[]");
-            }
-            else {
-                write("[");
-                emitList(node, node.elements, ListFormat.ArrayBindingPatternElements);
-                write("]");
-            }
+            write("[");
+            emitList(node, node.elements, ListFormat.ArrayBindingPatternElements);
+            write("]");
         }
 
         function emitBindingElement(node: BindingElement) {
@@ -3167,8 +3155,8 @@ namespace ts {
         TupleTypeElements = CommaDelimited | SpaceBetweenSiblings | SingleLine | Indented,
         UnionTypeConstituents = BarDelimited | SpaceBetweenSiblings | SingleLine,
         IntersectionTypeConstituents = AmpersandDelimited | SpaceBetweenSiblings | SingleLine,
-        ObjectBindingPatternElements = SingleLine | AllowTrailingComma | SpaceBetweenBraces | CommaDelimited | SpaceBetweenSiblings,
-        ArrayBindingPatternElements = SingleLine | AllowTrailingComma | CommaDelimited | SpaceBetweenSiblings,
+        ObjectBindingPatternElements = SingleLine | AllowTrailingComma | SpaceBetweenBraces | CommaDelimited | SpaceBetweenSiblings | NoSpaceIfEmpty,
+        ArrayBindingPatternElements = SingleLine | AllowTrailingComma | CommaDelimited | SpaceBetweenSiblings | NoSpaceIfEmpty,
         ObjectLiteralExpressionProperties = PreserveLines | CommaDelimited | SpaceBetweenSiblings | SpaceBetweenBraces | Indented | Braces | NoSpaceIfEmpty,
         ArrayLiteralExpressionElements = PreserveLines | CommaDelimited | SpaceBetweenSiblings | AllowTrailingComma | Indented | SquareBrackets,
         CommaListElements = CommaDelimited | SpaceBetweenSiblings | SingleLine,

src/compiler/factory.ts

@@ -71,11 +71,11 @@ namespace ts {
     // Literals
 
     /** If a node is passed, creates a string literal whose source text is read from a source node during emit. */
-    export function createLiteral(value: string | StringLiteral | NumericLiteral | Identifier): StringLiteral;
+    export function createLiteral(value: string | StringLiteral | NoSubstitutionTemplateLiteral | NumericLiteral | Identifier): StringLiteral;
     export function createLiteral(value: number): NumericLiteral;
     export function createLiteral(value: boolean): BooleanLiteral;
     export function createLiteral(value: string | number | boolean): PrimaryExpression;
-    export function createLiteral(value: string | number | boolean | StringLiteral | NumericLiteral | Identifier): PrimaryExpression {
+    export function createLiteral(value: string | number | boolean | StringLiteral | NoSubstitutionTemplateLiteral | NumericLiteral | Identifier): PrimaryExpression {
         if (typeof value === "number") {
             return createNumericLiteral(value + "");
         }
@@ -101,7 +101,7 @@ namespace ts {
         return node;
     }
 
-    function createLiteralFromNode(sourceNode: StringLiteral | NumericLiteral | Identifier): StringLiteral {
+    function createLiteralFromNode(sourceNode: StringLiteralLike | NumericLiteral | Identifier): StringLiteral {
         const node = createStringLiteral(getTextOfIdentifierOrLiteral(sourceNode));
         node.textSourceNode = sourceNode;
         return node;
@@ -3626,7 +3626,7 @@ namespace ts {
         return qualifiedName;
     }
 
-    export function convertToFunctionBody(node: ConciseBody, multiLine?: boolean) {
+    export function convertToFunctionBody(node: ConciseBody, multiLine?: boolean): Block {
         return isBlock(node) ? node : setTextRange(createBlock([setTextRange(createReturn(node), node)], multiLine), node);
     }
 
@@ -3831,13 +3831,13 @@ namespace ts {
                 if (isLeftSideOfBinary) {
                     // No need to parenthesize the left operand when the binary operator is
                     // left associative:
-                    //  (a*b)/x    ->  a*b/x
-                    //  (a**b)/x   ->  a**b/x
+                    //  (a*b)/x    -> a*b/x
+                    //  (a**b)/x   -> a**b/x
                     //
                     // Parentheses are needed for the left operand when the binary operator is
                     // right associative:
-                    //  (a/b)**x   ->  (a/b)**x
-                    //  (a**b)**x  ->  (a**b)**x
+                    //  (a/b)**x   -> (a/b)**x
+                    //  (a**b)**x  -> (a**b)**x
                     return binaryOperatorAssociativity === Associativity.Right;
                 }
                 else {

src/compiler/moduleNameResolver.ts

@@ -64,9 +64,9 @@ namespace ts {
         return { fileName: resolved.path, packageId: resolved.packageId };
     }
 
-    function createResolvedModuleWithFailedLookupLocations(resolved: Resolved | undefined, isExternalLibraryImport: boolean, failedLookupLocations: string[]): ResolvedModuleWithFailedLookupLocations {
+    function createResolvedModuleWithFailedLookupLocations(resolved: Resolved | undefined, originalPath: string | undefined, isExternalLibraryImport: boolean, failedLookupLocations: string[]): ResolvedModuleWithFailedLookupLocations {
         return {
-            resolvedModule: resolved && { resolvedFileName: resolved.path, extension: resolved.extension, isExternalLibraryImport, packageId: resolved.packageId },
+            resolvedModule: resolved && { resolvedFileName: resolved.path, originalPath, extension: resolved.extension, isExternalLibraryImport, packageId: resolved.packageId },
             failedLookupLocations
         };
     }
@@ -732,12 +732,12 @@ namespace ts {
 
         const result = jsOnly ? tryResolve(Extensions.JavaScript) : (tryResolve(Extensions.TypeScript) || tryResolve(Extensions.JavaScript));
         if (result && result.value) {
-            const { resolved, isExternalLibraryImport } = result.value;
-            return createResolvedModuleWithFailedLookupLocations(resolved, isExternalLibraryImport, failedLookupLocations);
+            const { resolved, originalPath, isExternalLibraryImport } = result.value;
+            return createResolvedModuleWithFailedLookupLocations(resolved, originalPath, isExternalLibraryImport, failedLookupLocations);
         }
         return { resolvedModule: undefined, failedLookupLocations };
 
-        function tryResolve(extensions: Extensions): SearchResult<{ resolved: Resolved, isExternalLibraryImport: boolean }> {
+        function tryResolve(extensions: Extensions): SearchResult<{ resolved: Resolved, originalPath?: string, isExternalLibraryImport: boolean }> {
             const loader: ResolutionKindSpecificLoader = (extensions, candidate, failedLookupLocations, onlyRecordFailures, state) => nodeLoadModuleByRelativeName(extensions, candidate, failedLookupLocations, onlyRecordFailures, state, /*considerPackageJson*/ true);
             const resolved = tryLoadModuleUsingOptionalResolutionSettings(extensions, moduleName, containingDirectory, loader, failedLookupLocations, state);
             if (resolved) {
@@ -752,11 +752,17 @@ namespace ts {
                 if (!resolved) return undefined;
 
                 let resolvedValue = resolved.value;
-                if (!compilerOptions.preserveSymlinks) {
-                    resolvedValue = resolvedValue && { ...resolved.value, path: realPath(resolved.value.path, host, traceEnabled), extension: resolved.value.extension };
+                let originalPath: string | undefined;
+                if (!compilerOptions.preserveSymlinks && resolvedValue) {
+                    originalPath = resolvedValue.path;
+                    const path = realPath(resolved.value.path, host, traceEnabled);
+                    if (path === originalPath) {
+                        originalPath = undefined;
+                    }
+                    resolvedValue = { ...resolvedValue, path };
                 }
                 // For node_modules lookups, get the real path so that multiple accesses to an `npm link`-ed module do not create duplicate files.
-                return { value: resolvedValue && { resolved: resolvedValue, isExternalLibraryImport: true } };
+                return { value: resolvedValue && { resolved: resolvedValue, originalPath, isExternalLibraryImport: true } };
             }
             else {
                 const { path: candidate, parts } = normalizePathAndParts(combinePaths(containingDirectory, moduleName));
@@ -1115,7 +1121,8 @@ namespace ts {
         const containingDirectory = getDirectoryPath(containingFile);
 
         const resolved = tryResolve(Extensions.TypeScript) || tryResolve(Extensions.JavaScript);
-        return createResolvedModuleWithFailedLookupLocations(resolved && resolved.value, /*isExternalLibraryImport*/ false, failedLookupLocations);
+        // No originalPath because classic resolution doesn't resolve realPath
+        return createResolvedModuleWithFailedLookupLocations(resolved && resolved.value, /*originalPath*/ undefined, /*isExternalLibraryImport*/ false, failedLookupLocations);
 
         function tryResolve(extensions: Extensions): SearchResult<Resolved> {
             const resolvedUsingSettings = tryLoadModuleUsingOptionalResolutionSettings(extensions, moduleName, containingDirectory, loadModuleFromFileNoPackageId, failedLookupLocations, state);
@@ -1162,7 +1169,7 @@ namespace ts {
         const state: ModuleResolutionState = { compilerOptions, host, traceEnabled };
         const failedLookupLocations: string[] = [];
         const resolved = loadModuleFromNodeModulesOneLevel(Extensions.DtsOnly, moduleName, globalCache, failedLookupLocations, state);
-        return createResolvedModuleWithFailedLookupLocations(resolved, /*isExternalLibraryImport*/ true, failedLookupLocations);
+        return createResolvedModuleWithFailedLookupLocations(resolved, /*originalPath*/ undefined, /*isExternalLibraryImport*/ true, failedLookupLocations);
     }
 
     /**

src/compiler/parser.ts

@@ -88,20 +88,48 @@ namespace ts {
             case SyntaxKind.SpreadAssignment:
                 return visitNode(cbNode, (<SpreadAssignment>node).expression);
             case SyntaxKind.Parameter:
+                return visitNodes(cbNode, cbNodes, node.decorators) ||
+                    visitNodes(cbNode, cbNodes, node.modifiers) ||
+                    visitNode(cbNode, (<ParameterDeclaration>node).dotDotDotToken) ||
+                    visitNode(cbNode, (<ParameterDeclaration>node).name) ||
+                    visitNode(cbNode, (<ParameterDeclaration>node).questionToken) ||
+                    visitNode(cbNode, (<ParameterDeclaration>node).type) ||
+                    visitNode(cbNode, (<ParameterDeclaration>node).initializer);
             case SyntaxKind.PropertyDeclaration:
+                return visitNodes(cbNode, cbNodes, node.decorators) ||
+                    visitNodes(cbNode, cbNodes, node.modifiers) ||
+                    visitNode(cbNode, (<PropertyDeclaration>node).name) ||
+                    visitNode(cbNode, (<PropertyDeclaration>node).questionToken) ||
+                    visitNode(cbNode, (<PropertyDeclaration>node).exclamationToken) ||
+                    visitNode(cbNode, (<PropertyDeclaration>node).type) ||
+                    visitNode(cbNode, (<PropertyDeclaration>node).initializer);
             case SyntaxKind.PropertySignature:
+                return visitNodes(cbNode, cbNodes, node.decorators) ||
+                    visitNodes(cbNode, cbNodes, node.modifiers) ||
+                    visitNode(cbNode, (<PropertySignature>node).name) ||
+                    visitNode(cbNode, (<PropertySignature>node).questionToken) ||
+                    visitNode(cbNode, (<PropertySignature>node).type) ||
+                    visitNode(cbNode, (<PropertySignature>node).initializer);
             case SyntaxKind.PropertyAssignment:
+                return visitNodes(cbNode, cbNodes, node.decorators) ||
+                    visitNodes(cbNode, cbNodes, node.modifiers) ||
+                    visitNode(cbNode, (<PropertyAssignment>node).name) ||
+                    visitNode(cbNode, (<PropertyAssignment>node).questionToken) ||
+                    visitNode(cbNode, (<PropertyAssignment>node).initializer);
             case SyntaxKind.VariableDeclaration:
+                return visitNodes(cbNode, cbNodes, node.decorators) ||
+                    visitNodes(cbNode, cbNodes, node.modifiers) ||
+                    visitNode(cbNode, (<VariableDeclaration>node).name) ||
+                    visitNode(cbNode, (<VariableDeclaration>node).exclamationToken) ||
+                    visitNode(cbNode, (<VariableDeclaration>node).type) ||
+                    visitNode(cbNode, (<VariableDeclaration>node).initializer);
             case SyntaxKind.BindingElement:
                 return visitNodes(cbNode, cbNodes, node.decorators) ||
                     visitNodes(cbNode, cbNodes, node.modifiers) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).propertyName) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).dotDotDotToken) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).name) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).questionToken) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).exclamationToken) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).type) ||
-                    visitNode(cbNode, (<VariableLikeDeclaration>node).initializer);
+                    visitNode(cbNode, (<BindingElement>node).propertyName) ||
+                    visitNode(cbNode, (<BindingElement>node).dotDotDotToken) ||
+                    visitNode(cbNode, (<BindingElement>node).name) ||
+                    visitNode(cbNode, (<BindingElement>node).initializer);
             case SyntaxKind.FunctionType:
             case SyntaxKind.ConstructorType:
             case SyntaxKind.CallSignature:
@@ -557,7 +585,7 @@ namespace ts {
         // 'disallow-in' set to 'false'.  Otherwise, if we had 'allowsIn' set to 'true', then almost
         // all nodes would need extra state on them to store this info.
         //
-        // Note:  'allowIn' and 'allowYield' track 1:1 with the [in] and [yield] concepts in the ES6
+        // Note: 'allowIn' and 'allowYield' track 1:1 with the [in] and [yield] concepts in the ES6
         // grammar specification.
         //
         // An important thing about these context concepts.  By default they are effectively inherited
@@ -673,7 +701,7 @@ namespace ts {
 
         function getLanguageVariant(scriptKind: ScriptKind) {
             // .tsx and .jsx files are treated as jsx language variant.
-            return scriptKind === ScriptKind.TSX || scriptKind === ScriptKind.JSX || scriptKind === ScriptKind.JS  || scriptKind === ScriptKind.JSON ? LanguageVariant.JSX : LanguageVariant.Standard;
+            return scriptKind === ScriptKind.TSX || scriptKind === ScriptKind.JSX || scriptKind === ScriptKind.JS || scriptKind === ScriptKind.JSON ? LanguageVariant.JSX : LanguageVariant.Standard;
         }
 
         function initializeState(_sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor, scriptKind: ScriptKind) {
@@ -758,15 +786,7 @@ namespace ts {
             const comments = getJSDocCommentRanges(node, sourceFile.text);
             if (comments) {
                 for (const comment of comments) {
-                    const jsDoc = JSDocParser.parseJSDocComment(node, comment.pos, comment.end - comment.pos);
-                    if (jsDoc) {
-                        if (!node.jsDoc) {
-                            node.jsDoc = [jsDoc];
-                        }
-                        else {
-                            node.jsDoc.push(jsDoc);
-                        }
-                    }
+                    node.jsDoc = append(node.jsDoc, JSDocParser.parseJSDocComment(node, comment.pos, comment.end - comment.pos));
                 }
             }
 
@@ -1401,9 +1421,13 @@ namespace ts {
                     return token() === SyntaxKind.CommaToken || token() === SyntaxKind.DotDotDotToken || isIdentifierOrPattern();
                 case ParsingContext.TypeParameters:
                     return isIdentifier();
-                case ParsingContext.ArgumentExpressions:
                 case ParsingContext.ArrayLiteralMembers:
-                    return token() === SyntaxKind.CommaToken || token() === SyntaxKind.DotDotDotToken || isStartOfExpression();
+                    if (token() === SyntaxKind.CommaToken) {
+                        return true;
+                    }
+                    // falls through
+                case ParsingContext.ArgumentExpressions:
+                    return token() === SyntaxKind.DotDotDotToken || isStartOfExpression();
                 case ParsingContext.Parameters:
                     return isStartOfParameter();
                 case ParsingContext.TypeArguments:
@@ -1425,7 +1449,7 @@ namespace ts {
         function isValidHeritageClauseObjectLiteral() {
             Debug.assert(token() === SyntaxKind.OpenBraceToken);
             if (nextToken() === SyntaxKind.CloseBraceToken) {
-                // if we see  "extends {}" then only treat the {} as what we're extending (and not
+                // if we see "extends {}" then only treat the {} as what we're extending (and not
                 // the class body) if we have:
                 //
                 //      extends {} {
@@ -1521,7 +1545,7 @@ namespace ts {
 
         function isVariableDeclaratorListTerminator(): boolean {
             // If we can consume a semicolon (either explicitly, or with ASI), then consider us done
-            // with parsing the list of  variable declarators.
+            // with parsing the list of variable declarators.
             if (canParseSemicolon()) {
                 return true;
             }
@@ -1647,6 +1671,11 @@ namespace ts {
                 return undefined;
             }
 
+            if ((node as JSDocContainer).jsDocCache) {
+                // jsDocCache may include tags from parent nodes, which might have been modified.
+                (node as JSDocContainer).jsDocCache = undefined;
+            }
+
             return node;
         }
 
@@ -2241,7 +2270,7 @@ namespace ts {
                     //
                     //      <T extends "">
                     //
-                    // We do *not* want to consume the  >  as we're consuming the expression for "".
+                    // We do *not* want to consume the `>` as we're consuming the expression for "".
                     node.expression = parseUnaryExpressionOrHigher();
                 }
             }
@@ -3061,7 +3090,7 @@ namespace ts {
             // And production (2) is parsed in "tryParseParenthesizedArrowFunctionExpression".
             //
             // If we do successfully parse arrow-function, we must *not* recurse for productions 1, 2 or 3. An ArrowFunction is
-            // not a  LeftHandSideExpression, nor does it start a ConditionalExpression.  So we are done
+            // not a LeftHandSideExpression, nor does it start a ConditionalExpression.  So we are done
             // with AssignmentExpression if we see one.
             const arrowExpression = tryParseParenthesizedArrowFunctionExpression() || tryParseAsyncSimpleArrowFunctionExpression();
             if (arrowExpression) {
@@ -3091,7 +3120,7 @@ namespace ts {
             // we're in '2' or '3'. Consume the assignment and return.
             //
             // Note: we call reScanGreaterToken so that we get an appropriately merged token
-            // for cases like > > =  becoming >>=
+            // for cases like `> > =` becoming `>>=`
             if (isLeftHandSideExpression(expr) && isAssignmentOperator(reScanGreaterToken())) {
                 return makeBinaryExpression(expr, <BinaryOperatorToken>parseTokenNode(), parseAssignmentExpressionOrHigher());
             }
@@ -3247,7 +3276,7 @@ namespace ts {
 
             if (first === SyntaxKind.OpenParenToken) {
                 if (second === SyntaxKind.CloseParenToken) {
-                    // Simple cases: "() =>", "(): ", and  "() {".
+                    // Simple cases: "() =>", "(): ", and "() {".
                     // This is an arrow function with no parameters.
                     // The last one is not actually an arrow function,
                     // but this is probably what the user intended.
@@ -3472,7 +3501,9 @@ namespace ts {
             node.whenTrue = doOutsideOfContext(disallowInAndDecoratorContext, parseAssignmentExpressionOrHigher);
             node.colonToken = parseExpectedToken(SyntaxKind.ColonToken, /*reportAtCurrentPosition*/ false,
                 Diagnostics._0_expected, tokenToString(SyntaxKind.ColonToken));
-            node.whenFalse = parseAssignmentExpressionOrHigher();
+            node.whenFalse = nodeIsPresent(node.colonToken)
+                ? parseAssignmentExpressionOrHigher()
+                : createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentPosition*/ false, Diagnostics._0_expected, tokenToString(SyntaxKind.ColonToken));
             return finishNode(node);
         }
 
@@ -3867,7 +3898,8 @@ namespace ts {
                 // We don't want to eagerly consume all import keyword as import call expression so we look a head to find "("
                 // For example:
                 //      var foo3 = require("subfolder
-                //      import * as foo1 from "module-from-node  -> we want this import to be a statement rather than import call expression
+                //      import * as foo1 from "module-from-node
+                // We want this import to be a statement rather than import call expression
                 sourceFile.flags |= NodeFlags.PossiblyContainsDynamicImport;
                 expression = parseTokenNode<PrimaryExpression>();
             }
@@ -3917,7 +3949,7 @@ namespace ts {
             // treated as the invocation of "new Foo".  We disambiguate that in code (to match
             // the original grammar) by making sure that if we see an ObjectCreationExpression
             // we always consume arguments if they are there. So we treat "new Foo()" as an
-            // object creation only, and not at all as an invocation)  Another way to think
+            // object creation only, and not at all as an invocation.  Another way to think
             // about this is that for every "new" that we see, we will consume an argument list if
             // it is there as part of the *associated* object creation node.  Any additional
             // argument lists we see, will become invocation expressions.
@@ -4333,7 +4365,7 @@ namespace ts {
 
             const typeArguments = parseDelimitedList(ParsingContext.TypeArguments, parseType);
             if (!parseExpected(SyntaxKind.GreaterThanToken)) {
-                // If it doesn't have the closing >  then it's definitely not an type argument list.
+                // If it doesn't have the closing `>` then it's definitely not an type argument list.
                 return undefined;
             }
 
@@ -5366,8 +5398,8 @@ namespace ts {
             // off. The grammar would look something like this:
             //
             //    MemberVariableDeclaration[Yield]:
-            //        AccessibilityModifier_opt   PropertyName   TypeAnnotation_opt   Initializer_opt[In];
-            //        AccessibilityModifier_opt  static_opt  PropertyName   TypeAnnotation_opt   Initializer_opt[In, ?Yield];
+            //        AccessibilityModifier_opt PropertyName TypeAnnotation_opt Initializer_opt[In];
+            //        AccessibilityModifier_opt static_opt PropertyName TypeAnnotation_opt Initializer_opt[In, ?Yield];
             //
             // The checker may still error in the static case to explicitly disallow the yield expression.
             node.initializer = hasModifier(node, ModifierFlags.Static)
@@ -5462,6 +5494,7 @@ namespace ts {
                 switch (token()) {
                     case SyntaxKind.OpenParenToken:     // Method declaration
                     case SyntaxKind.LessThanToken:      // Generic Method declaration
+                    case SyntaxKind.ExclamationToken:   // Non-null assertion on property name
                     case SyntaxKind.ColonToken:         // Type Annotation for declaration
                     case SyntaxKind.EqualsToken:        // Initializer for declaration
                     case SyntaxKind.QuestionToken:      // Not valid, but permitted so that it gets caught later on.
@@ -6240,17 +6273,17 @@ namespace ts {
                         indent += text.length;
                     }
 
-                    nextJSDocToken();
-                    while (token() === SyntaxKind.WhitespaceTrivia) {
-                        nextJSDocToken();
+                    let t = nextJSDocToken();
+                    while (t === SyntaxKind.WhitespaceTrivia) {
+                        t = nextJSDocToken();
                     }
-                    if (token() === SyntaxKind.NewLineTrivia) {
+                    if (t === SyntaxKind.NewLineTrivia) {
                         state = JSDocState.BeginningOfLine;
                         indent = 0;
-                        nextJSDocToken();
+                        t = nextJSDocToken();
                     }
-                    while (token() !== SyntaxKind.EndOfFileToken) {
-                        switch (token()) {
+                    loop: while (true) {
+                        switch (t) {
                             case SyntaxKind.AtToken:
                                 if (state === JSDocState.BeginningOfLine || state === JSDocState.SawAsterisk) {
                                     removeTrailingNewlines(comments);
@@ -6304,7 +6337,7 @@ namespace ts {
                                 indent += whitespace.length;
                                 break;
                             case SyntaxKind.EndOfFileToken:
-                                break;
+                                break loop;
                             default:
                                 // anything other than whitespace or asterisk at the beginning of the line starts the comment text
                                 state = JSDocState.SavingComments;
@@ -6312,10 +6345,11 @@ namespace ts {
                                 break;
                         }
                         if (advanceToken) {
-                            nextJSDocToken();
+                            t = nextJSDocToken();
                         }
                         else {
                             advanceToken = true;
+                            t = currentToken as JsDocSyntaxKind;
                         }
                     }
                     removeLeadingNewlines(comments);
@@ -6426,8 +6460,9 @@ namespace ts {
                         comments.push(text);
                         indent += text.length;
                     }
-                    while (token() !== SyntaxKind.AtToken && token() !== SyntaxKind.EndOfFileToken) {
-                        switch (token()) {
+                    let tok = token() as JsDocSyntaxKind;
+                    loop: while (true) {
+                        switch (tok) {
                             case SyntaxKind.NewLineTrivia:
                                 if (state >= JSDocState.SawAsterisk) {
                                     state = JSDocState.BeginningOfLine;
@@ -6436,8 +6471,9 @@ namespace ts {
                                 indent = 0;
                                 break;
                             case SyntaxKind.AtToken:
+                            case SyntaxKind.EndOfFileToken:
                                 // Done
-                                break;
+                                break loop;
                             case SyntaxKind.WhitespaceTrivia:
                                 if (state === JSDocState.SavingComments) {
                                     pushComment(scanner.getTokenText());
@@ -6465,11 +6501,7 @@ namespace ts {
                                 pushComment(scanner.getTokenText());
                                 break;
                         }
-                        if (token() === SyntaxKind.AtToken) {
-                            // Done
-                            break;
-                        }
-                        nextJSDocToken();
+                        tok = nextJSDocToken();
                     }
 
                     removeLeadingNewlines(comments);
@@ -6571,10 +6603,7 @@ namespace ts {
                         const start = scanner.getStartPos();
                         let children: JSDocParameterTag[];
                         while (child = tryParse(() => parseChildParameterOrPropertyTag(PropertyLikeParse.Parameter, name))) {
-                            if (!children) {
-                                children = [];
-                            }
-                            children.push(child);
+                            children = append(children, child);
                         }
                         if (children) {
                             jsdocTypeLiteral = <JSDocTypeLiteral>createNode(SyntaxKind.JSDocTypeLiteral, start);
@@ -6691,10 +6720,7 @@ namespace ts {
                                 }
                             }
                             else {
-                                if (!jsdocTypeLiteral.jsDocPropertyTags) {
-                                    jsdocTypeLiteral.jsDocPropertyTags = [] as MutableNodeArray<JSDocPropertyTag>;
-                                }
-                                (jsdocTypeLiteral.jsDocPropertyTags as MutableNodeArray<JSDocPropertyTag>).push(child);
+                                jsdocTypeLiteral.jsDocPropertyTags = append(jsdocTypeLiteral.jsDocPropertyTags as MutableNodeArray<JSDocPropertyTag>, child);
                             }
                         }
                         if (jsdocTypeLiteral) {
@@ -6747,8 +6773,7 @@ namespace ts {
                     let canParseTag = true;
                     let seenAsterisk = false;
                     while (true) {
-                        nextJSDocToken();
-                        switch (token()) {
+                        switch (nextJSDocToken()) {
                             case SyntaxKind.AtToken:
                                 if (canParseTag) {
                                     const child = tryParseChildTag(target);
@@ -6844,7 +6869,7 @@ namespace ts {
                     return result;
                 }
 
-                function nextJSDocToken(): SyntaxKind {
+                function nextJSDocToken(): JsDocSyntaxKind {
                     return currentToken = scanner.scanJSDocToken();
                 }
 
@@ -7048,7 +7073,7 @@ namespace ts {
 
             // If the 'pos' is before the start of the change, then we don't need to touch it.
             // If it isn't, then the 'pos' must be inside the change.  How we update it will
-            // depend if delta is  positive or negative.  If delta is positive then we have
+            // depend if delta is positive or negative. If delta is positive then we have
             // something like:
             //
             //  -------------------AAA-----------------
@@ -7073,7 +7098,7 @@ namespace ts {
 
             // If the 'end' is after the change range, then we always adjust it by the delta
             // amount.  However, if the end is in the change range, then how we adjust it
-            // will depend on if delta is  positive or negative.  If delta is positive then we
+            // will depend on if delta is positive or negative.  If delta is positive then we
             // have something like:
             //
             //  -------------------AAA-----------------

src/compiler/program.ts

@@ -6,7 +6,7 @@
 namespace ts {
     const ignoreDiagnosticCommentRegEx = /(^\s*$)|(^\s*\/\/\/?\s*(@ts-ignore)?)/;
 
-    export function findConfigFile(searchPath: string, fileExists: (fileName: string) => boolean, configName = "tsconfig.json"): string {
+    export function findConfigFile(searchPath: string, fileExists: (fileName: string) => boolean, configName = "tsconfig.json"): string | undefined {
         return forEachAncestorDirectory(searchPath, ancestor => {
             const fileName = combinePaths(ancestor, configName);
             return fileExists(fileName) ? fileName : undefined;
@@ -241,22 +241,28 @@ namespace ts {
         return errorMessage;
     }
 
-    const redForegroundEscapeSequence = "\u001b[91m";
-    const yellowForegroundEscapeSequence = "\u001b[93m";
-    const blueForegroundEscapeSequence = "\u001b[93m";
+    /** @internal */
+    export enum ForegroundColorEscapeSequences {
+        Grey = "\u001b[90m",
+        Red = "\u001b[91m",
+        Yellow = "\u001b[93m",
+        Blue = "\u001b[94m",
+        Cyan = "\u001b[96m"
+    }
     const gutterStyleSequence = "\u001b[30;47m";
     const gutterSeparator = " ";
     const resetEscapeSequence = "\u001b[0m";
     const ellipsis = "...";
     function getCategoryFormat(category: DiagnosticCategory): string {
         switch (category) {
-            case DiagnosticCategory.Warning: return yellowForegroundEscapeSequence;
-            case DiagnosticCategory.Error: return redForegroundEscapeSequence;
-            case DiagnosticCategory.Message: return blueForegroundEscapeSequence;
+            case DiagnosticCategory.Warning: return ForegroundColorEscapeSequences.Yellow;
+            case DiagnosticCategory.Error: return ForegroundColorEscapeSequences.Red;
+            case DiagnosticCategory.Message: return ForegroundColorEscapeSequences.Blue;
         }
     }
 
-    function formatAndReset(text: string, formatStyle: string) {
+    /** @internal */
+    export function formatColorAndReset(text: string, formatStyle: string) {
         return formatStyle + text + resetEscapeSequence;
     }
 
@@ -289,7 +295,7 @@ namespace ts {
                     // If the error spans over 5 lines, we'll only show the first 2 and last 2 lines,
                     // so we'll skip ahead to the second-to-last line.
                     if (hasMoreThanFiveLines && firstLine + 1 < i && i < lastLine - 1) {
-                        context += formatAndReset(padLeft(ellipsis, gutterWidth), gutterStyleSequence) + gutterSeparator + host.getNewLine();
+                        context += formatColorAndReset(padLeft(ellipsis, gutterWidth), gutterStyleSequence) + gutterSeparator + host.getNewLine();
                         i = lastLine - 1;
                     }
 
@@ -300,12 +306,12 @@ namespace ts {
                     lineContent = lineContent.replace("\t", " ");    // convert tabs to single spaces
 
                     // Output the gutter and the actual contents of the line.
-                    context += formatAndReset(padLeft(i + 1 + "", gutterWidth), gutterStyleSequence) + gutterSeparator;
+                    context += formatColorAndReset(padLeft(i + 1 + "", gutterWidth), gutterStyleSequence) + gutterSeparator;
                     context += lineContent + host.getNewLine();
 
                     // Output the gutter and the error span for the line using tildes.
-                    context += formatAndReset(padLeft("", gutterWidth), gutterStyleSequence) + gutterSeparator;
-                    context += redForegroundEscapeSequence;
+                    context += formatColorAndReset(padLeft("", gutterWidth), gutterStyleSequence) + gutterSeparator;
+                    context += ForegroundColorEscapeSequences.Red;
                     if (i === firstLine) {
                         // If we're on the last line, then limit it to the last character of the last line.
                         // Otherwise, we'll just squiggle the rest of the line, giving 'slice' no end position.
@@ -324,13 +330,19 @@ namespace ts {
                     context += resetEscapeSequence;
                 }
 
-                output += host.getNewLine();
-                output += `${ relativeFileName }(${ firstLine + 1 },${ firstLineChar + 1 }): `;
+                output += formatColorAndReset(relativeFileName, ForegroundColorEscapeSequences.Cyan);
+                output += ":";
+                output += formatColorAndReset(`${ firstLine + 1 }`, ForegroundColorEscapeSequences.Yellow);
+                output += ":";
+                output += formatColorAndReset(`${ firstLineChar + 1 }`, ForegroundColorEscapeSequences.Yellow);
+                output += " - ";
             }
 
             const categoryColor = getCategoryFormat(diagnostic.category);
             const category = DiagnosticCategory[diagnostic.category].toLowerCase();
-            output += `${ formatAndReset(category, categoryColor) } TS${ diagnostic.code }: ${ flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine()) }`;
+            output += formatColorAndReset(category, categoryColor);
+            output += formatColorAndReset(` TS${ diagnostic.code }: `, ForegroundColorEscapeSequences.Grey);
+            output += flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine());
 
             if (diagnostic.file) {
                 output += host.getNewLine();
@@ -339,7 +351,7 @@ namespace ts {
 
             output += host.getNewLine();
         }
-        return output;
+        return output + host.getNewLine();
     }
 
     export function flattenDiagnosticMessageText(messageText: string | DiagnosticMessageChain, newLine: string): string {
@@ -704,7 +716,7 @@ namespace ts {
 
         interface OldProgramState {
             program: Program | undefined;
-            file: SourceFile;
+            oldSourceFile: SourceFile | undefined;
             /** The collection of paths modified *since* the old program. */
             modifiedFilePaths: Path[];
         }
@@ -754,7 +766,6 @@ namespace ts {
             /** A transient placeholder 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];
                 // If the source file is unchanged and doesnt have invalidated resolution, reuse the module resolutions
@@ -825,9 +836,13 @@ namespace ts {
             // If we change our policy of rechecking failed lookups on each program create,
             // we should adjust the value returned here.
             function moduleNameResolvesToAmbientModuleInNonModifiedFile(moduleName: string, oldProgramState: OldProgramState): boolean {
-                const resolutionToFile = getResolvedModule(oldProgramState.file, moduleName);
-                if (resolutionToFile) {
-                    // module used to be resolved to file - ignore it
+                const resolutionToFile = getResolvedModule(oldProgramState.oldSourceFile, moduleName);
+                const resolvedFile = resolutionToFile && oldProgramState.program && oldProgramState.program.getSourceFile(resolutionToFile.resolvedFileName);
+                if (resolutionToFile && resolvedFile && !resolvedFile.externalModuleIndicator) {
+                    // In the old program, we resolved to an ambient module that was in the same
+                    //   place as we expected to find an actual module file.
+                    // We actually need to return 'false' here even though this seems like a 'true' case
+                    //   because the normal module resolution algorithm will find this anyway.
                     return false;
                 }
                 const ambientModule = oldProgramState.program && oldProgramState.program.getTypeChecker().tryFindAmbientModuleWithoutAugmentations(moduleName);
@@ -1001,7 +1016,7 @@ namespace ts {
                 const newSourceFilePath = getNormalizedAbsolutePath(newSourceFile.fileName, currentDirectory);
                 if (resolveModuleNamesWorker) {
                     const moduleNames = getModuleNames(newSourceFile);
-                    const oldProgramState = { program: oldProgram, file: oldSourceFile, modifiedFilePaths };
+                    const oldProgramState: OldProgramState = { program: oldProgram, oldSourceFile, modifiedFilePaths };
                     const resolutions = resolveModuleNamesReusingOldState(moduleNames, newSourceFilePath, newSourceFile, oldProgramState);
                     // ensure that module resolution results are still correct
                     const resolutionsChanged = hasChangesInResolutions(moduleNames, resolutions, oldSourceFile.resolvedModules, moduleResolutionIsEqualTo);
@@ -1586,6 +1601,7 @@ namespace ts {
                 // synthesize 'import "tslib"' declaration
                 const externalHelpersModuleReference = createLiteral(externalHelpersModuleNameText);
                 const importDecl = createImportDeclaration(/*decorators*/ undefined, /*modifiers*/ undefined, /*importClause*/ undefined);
+                addEmitFlags(importDecl, EmitFlags.NeverApplyImportHelper);
                 externalHelpersModuleReference.parent = importDecl;
                 importDecl.parent = file;
                 imports = [externalHelpersModuleReference];
@@ -1945,7 +1961,7 @@ namespace ts {
             if (file.imports.length || file.moduleAugmentations.length) {
                 // Because global augmentation doesn't have string literal name, we can check for global augmentation as such.
                 const moduleNames = getModuleNames(file);
-                const oldProgramState = { program: oldProgram, file, modifiedFilePaths };
+                const oldProgramState: OldProgramState = { program: oldProgram, oldSourceFile: oldProgram && oldProgram.getSourceFile(file.fileName), modifiedFilePaths };
                 const resolutions = resolveModuleNamesReusingOldState(moduleNames, getNormalizedAbsolutePath(file.fileName, currentDirectory), file, oldProgramState);
                 Debug.assert(resolutions.length === moduleNames.length);
                 for (let i = 0; i < moduleNames.length; i++) {

src/compiler/scanner.ts

@@ -35,7 +35,7 @@ namespace ts {
         scanJsxAttributeValue(): SyntaxKind;
         reScanJsxToken(): SyntaxKind;
         scanJsxToken(): SyntaxKind;
-        scanJSDocToken(): SyntaxKind;
+        scanJSDocToken(): JsDocSyntaxKind;
         scan(): SyntaxKind;
         getText(): string;
         // Sets the text for the scanner to scan.  An optional subrange starting point and length
@@ -193,7 +193,7 @@ namespace ts {
     /*
         As per ECMAScript Language Specification 3th Edition, Section 7.6: Identifiers
         IdentifierStart ::
-            Can contain Unicode 3.0.0  categories:
+            Can contain Unicode 3.0.0 categories:
             Uppercase letter (Lu),
             Lowercase letter (Ll),
             Titlecase letter (Lt),
@@ -201,7 +201,7 @@ namespace ts {
             Other letter (Lo), or
             Letter number (Nl).
         IdentifierPart :: =
-            Can contain IdentifierStart + Unicode 3.0.0  categories:
+            Can contain IdentifierStart + Unicode 3.0.0 categories:
             Non-spacing mark (Mn),
             Combining spacing mark (Mc),
             Decimal number (Nd), or
@@ -216,7 +216,7 @@ namespace ts {
     /*
         As per ECMAScript Language Specification 5th Edition, Section 7.6: ISyntaxToken Names and Identifiers
         IdentifierStart ::
-            Can contain Unicode 6.2  categories:
+            Can contain Unicode 6.2 categories:
             Uppercase letter (Lu),
             Lowercase letter (Ll),
             Titlecase letter (Lt),
@@ -224,7 +224,7 @@ namespace ts {
             Other letter (Lo), or
             Letter number (Nl).
         IdentifierPart ::
-            Can contain IdentifierStart + Unicode 6.2  categories:
+            Can contain IdentifierStart + Unicode 6.2 categories:
             Non-spacing mark (Mn),
             Combining spacing mark (Mc),
             Decimal number (Nd),
@@ -561,9 +561,9 @@ namespace ts {
         return false;
     }
 
-    function scanConflictMarkerTrivia(text: string, pos: number, error?: ErrorCallback) {
+    function scanConflictMarkerTrivia(text: string, pos: number, error?: (diag: DiagnosticMessage, pos?: number, len?: number) => void) {
         if (error) {
-            error(Diagnostics.Merge_conflict_marker_encountered, mergeConflictMarkerLength);
+            error(Diagnostics.Merge_conflict_marker_encountered, pos, mergeConflictMarkerLength);
         }
 
         const ch = text.charCodeAt(pos);
@@ -852,34 +852,92 @@ namespace ts {
             scanRange,
         };
 
-        function error(message: DiagnosticMessage, length?: number): void {
+        function error(message: DiagnosticMessage): void;
+        function error(message: DiagnosticMessage, errPos: number, length: number): void;
+        function error(message: DiagnosticMessage, errPos: number = pos, length?: number): void {
             if (onError) {
+                const oldPos = pos;
+                pos = errPos;
                 onError(message, length || 0);
+                pos = oldPos;
             }
         }
 
+        function scanNumberFragment(): string {
+            let start = pos;
+            let allowSeparator = false;
+            let isPreviousTokenSeparator = false;
+            let result = "";
+            while (true) {
+                const ch = text.charCodeAt(pos);
+                if (ch === CharacterCodes._) {
+                    tokenFlags |= TokenFlags.ContainsSeparator;
+                    if (allowSeparator) {
+                        allowSeparator = false;
+                        isPreviousTokenSeparator = true;
+                        result += text.substring(start, pos);
+                    }
+                    else if (isPreviousTokenSeparator) {
+                        error(Diagnostics.Multiple_consecutive_numeric_separators_are_not_permitted, pos, 1);
+                    }
+                    else {
+                        error(Diagnostics.Numeric_separators_are_not_allowed_here, pos, 1);
+                    }
+                    pos++;
+                    start = pos;
+                    continue;
+                }
+                if (isDigit(ch)) {
+                    allowSeparator = true;
+                    isPreviousTokenSeparator = false;
+                    pos++;
+                    continue;
+                }
+                break;
+            }
+            if (text.charCodeAt(pos - 1) === CharacterCodes._) {
+                error(Diagnostics.Numeric_separators_are_not_allowed_here, pos - 1, 1);
+            }
+            return result + text.substring(start, pos);
+        }
+
         function scanNumber(): string {
             const start = pos;
-            while (isDigit(text.charCodeAt(pos))) pos++;
+            const mainFragment = scanNumberFragment();
+            let decimalFragment: string;
+            let scientificFragment: string;
             if (text.charCodeAt(pos) === CharacterCodes.dot) {
                 pos++;
-                while (isDigit(text.charCodeAt(pos))) pos++;
+                decimalFragment = scanNumberFragment();
             }
             let end = pos;
             if (text.charCodeAt(pos) === CharacterCodes.E || text.charCodeAt(pos) === CharacterCodes.e) {
                 pos++;
                 tokenFlags |= TokenFlags.Scientific;
                 if (text.charCodeAt(pos) === CharacterCodes.plus || text.charCodeAt(pos) === CharacterCodes.minus) pos++;
-                if (isDigit(text.charCodeAt(pos))) {
-                    pos++;
-                    while (isDigit(text.charCodeAt(pos))) pos++;
-                    end = pos;
-                }
-                else {
+                const preNumericPart = pos;
+                const finalFragment = scanNumberFragment();
+                if (!finalFragment) {
                     error(Diagnostics.Digit_expected);
                 }
+                else {
+                    scientificFragment = text.substring(end, preNumericPart) + finalFragment;
+                    end = pos;
+                }
+            }
+            if (tokenFlags & TokenFlags.ContainsSeparator) {
+                let result = mainFragment;
+                if (decimalFragment) {
+                    result += "." + decimalFragment;
+                }
+                if (scientificFragment) {
+                    result += scientificFragment;
+                }
+                return "" + +result;
+            }
+            else {
+                return "" + +(text.substring(start, end)); // No need to use all the fragments; no _ removal needed
             }
-            return "" + +(text.substring(start, end));
         }
 
         function scanOctalDigits(): number {
@@ -894,23 +952,41 @@ namespace ts {
          * Scans the given number of hexadecimal digits in the text,
          * returning -1 if the given number is unavailable.
          */
-        function scanExactNumberOfHexDigits(count: number): number {
-            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ false);
+        function scanExactNumberOfHexDigits(count: number, canHaveSeparators: boolean): number {
+            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ false, canHaveSeparators);
         }
 
         /**
          * Scans as many hexadecimal digits as are available in the text,
          * returning -1 if the given number of digits was unavailable.
          */
-        function scanMinimumNumberOfHexDigits(count: number): number {
-            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ true);
+        function scanMinimumNumberOfHexDigits(count: number, canHaveSeparators: boolean): number {
+            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ true, canHaveSeparators);
         }
 
-        function scanHexDigits(minCount: number, scanAsManyAsPossible: boolean): number {
+        function scanHexDigits(minCount: number, scanAsManyAsPossible: boolean, canHaveSeparators: boolean): number {
             let digits = 0;
             let value = 0;
+            let allowSeparator = false;
+            let isPreviousTokenSeparator = false;
             while (digits < minCount || scanAsManyAsPossible) {
                 const ch = text.charCodeAt(pos);
+                if (canHaveSeparators && ch === CharacterCodes._) {
+                    tokenFlags |= TokenFlags.ContainsSeparator;
+                    if (allowSeparator) {
+                        allowSeparator = false;
+                        isPreviousTokenSeparator = true;
+                    }
+                    else if (isPreviousTokenSeparator) {
+                        error(Diagnostics.Multiple_consecutive_numeric_separators_are_not_permitted, pos, 1);
+                    }
+                    else {
+                        error(Diagnostics.Numeric_separators_are_not_allowed_here, pos, 1);
+                    }
+                    pos++;
+                    continue;
+                }
+                allowSeparator = canHaveSeparators;
                 if (ch >= CharacterCodes._0 && ch <= CharacterCodes._9) {
                     value = value * 16 + ch - CharacterCodes._0;
                 }
@@ -925,10 +1001,14 @@ namespace ts {
                 }
                 pos++;
                 digits++;
+                isPreviousTokenSeparator = false;
             }
             if (digits < minCount) {
                 value = -1;
             }
+            if (text.charCodeAt(pos - 1) === CharacterCodes._) {
+                error(Diagnostics.Numeric_separators_are_not_allowed_here, pos - 1, 1);
+            }
             return value;
         }
 
@@ -1097,7 +1177,7 @@ namespace ts {
         }
 
         function scanHexadecimalEscape(numDigits: number): string {
-            const escapedValue = scanExactNumberOfHexDigits(numDigits);
+            const escapedValue = scanExactNumberOfHexDigits(numDigits, /*canHaveSeparators*/ false);
 
             if (escapedValue >= 0) {
                 return String.fromCharCode(escapedValue);
@@ -1109,7 +1189,7 @@ namespace ts {
         }
 
         function scanExtendedUnicodeEscape(): string {
-            const escapedValue = scanMinimumNumberOfHexDigits(1);
+            const escapedValue = scanMinimumNumberOfHexDigits(1, /*canHaveSeparators*/ false);
             let isInvalidExtendedEscape = false;
 
             // Validate the value of the digit
@@ -1162,7 +1242,7 @@ namespace ts {
             if (pos + 5 < end && text.charCodeAt(pos + 1) === CharacterCodes.u) {
                 const start = pos;
                 pos += 2;
-                const value = scanExactNumberOfHexDigits(4);
+                const value = scanExactNumberOfHexDigits(4, /*canHaveSeparators*/ false);
                 pos = start;
                 return value;
             }
@@ -1218,8 +1298,27 @@ namespace ts {
             // For counting number of digits; Valid binaryIntegerLiteral must have at least one binary digit following B or b.
             // Similarly valid octalIntegerLiteral must have at least one octal digit following o or O.
             let numberOfDigits = 0;
+            let separatorAllowed = false;
+            let isPreviousTokenSeparator = false;
             while (true) {
                 const ch = text.charCodeAt(pos);
+                // Numeric seperators are allowed anywhere within a numeric literal, except not at the beginning, or following another separator
+                if (ch === CharacterCodes._) {
+                    tokenFlags |= TokenFlags.ContainsSeparator;
+                    if (separatorAllowed) {
+                        separatorAllowed = false;
+                        isPreviousTokenSeparator = true;
+                    }
+                    else if (isPreviousTokenSeparator) {
+                        error(Diagnostics.Multiple_consecutive_numeric_separators_are_not_permitted, pos, 1);
+                    }
+                    else {
+                        error(Diagnostics.Numeric_separators_are_not_allowed_here, pos, 1);
+                    }
+                    pos++;
+                    continue;
+                }
+                separatorAllowed = true;
                 const valueOfCh = ch - CharacterCodes._0;
                 if (!isDigit(ch) || valueOfCh >= base) {
                     break;
@@ -1227,11 +1326,17 @@ namespace ts {
                 value = value * base + valueOfCh;
                 pos++;
                 numberOfDigits++;
+                isPreviousTokenSeparator = false;
             }
             // Invalid binaryIntegerLiteral or octalIntegerLiteral
             if (numberOfDigits === 0) {
                 return -1;
             }
+            if (text.charCodeAt(pos - 1) === CharacterCodes._) {
+                // Literal ends with underscore - not allowed
+                error(Diagnostics.Numeric_separators_are_not_allowed_here, pos - 1, 1);
+                return value;
+            }
             return value;
         }
 
@@ -1435,7 +1540,7 @@ namespace ts {
                     case CharacterCodes._0:
                         if (pos + 2 < end && (text.charCodeAt(pos + 1) === CharacterCodes.X || text.charCodeAt(pos + 1) === CharacterCodes.x)) {
                             pos += 2;
-                            let value = scanMinimumNumberOfHexDigits(1);
+                            let value = scanMinimumNumberOfHexDigits(1, /*canHaveSeparators*/ true);
                             if (value < 0) {
                                 error(Diagnostics.Hexadecimal_digit_expected);
                                 value = 0;
@@ -1489,7 +1594,7 @@ namespace ts {
                         return token = SyntaxKind.NumericLiteral;
                     case CharacterCodes.colon:
                         pos++;
-                        return  token = SyntaxKind.ColonToken;
+                        return token = SyntaxKind.ColonToken;
                     case CharacterCodes.semicolon:
                         pos++;
                         return token = SyntaxKind.SemicolonToken;
@@ -1800,7 +1905,7 @@ namespace ts {
                         break;
                     }
                 }
-                tokenValue += text.substr(firstCharPosition, pos - firstCharPosition);
+                tokenValue += text.substring(firstCharPosition, pos);
             }
             return token;
         }
@@ -1819,7 +1924,7 @@ namespace ts {
             }
         }
 
-        function scanJSDocToken(): SyntaxKind {
+        function scanJSDocToken(): JsDocSyntaxKind {
             if (pos >= end) {
                 return token = SyntaxKind.EndOfFileToken;
             }
@@ -1828,6 +1933,7 @@ namespace ts {
             tokenPos = pos;
 
             const ch = text.charCodeAt(pos);
+            pos++;
             switch (ch) {
                 case CharacterCodes.tab:
                 case CharacterCodes.verticalTab:
@@ -1838,56 +1944,31 @@ namespace ts {
                     }
                     return token = SyntaxKind.WhitespaceTrivia;
                 case CharacterCodes.at:
-                    pos++;
                     return token = SyntaxKind.AtToken;
                 case CharacterCodes.lineFeed:
                 case CharacterCodes.carriageReturn:
-                    pos++;
                     return token = SyntaxKind.NewLineTrivia;
                 case CharacterCodes.asterisk:
-                    pos++;
                     return token = SyntaxKind.AsteriskToken;
                 case CharacterCodes.openBrace:
-                    pos++;
                     return token = SyntaxKind.OpenBraceToken;
                 case CharacterCodes.closeBrace:
-                    pos++;
                     return token = SyntaxKind.CloseBraceToken;
                 case CharacterCodes.openBracket:
-                    pos++;
                     return token = SyntaxKind.OpenBracketToken;
                 case CharacterCodes.closeBracket:
-                    pos++;
                     return token = SyntaxKind.CloseBracketToken;
                 case CharacterCodes.lessThan:
-                    pos++;
                     return token = SyntaxKind.LessThanToken;
-                case CharacterCodes.greaterThan:
-                    pos++;
-                    return token = SyntaxKind.GreaterThanToken;
                 case CharacterCodes.equals:
-                    pos++;
                     return token = SyntaxKind.EqualsToken;
                 case CharacterCodes.comma:
-                    pos++;
                     return token = SyntaxKind.CommaToken;
                 case CharacterCodes.dot:
-                    pos++;
-                    if (text.substr(tokenPos, pos + 2) === "...") {
-                        pos += 2;
-                        return token = SyntaxKind.DotDotDotToken;
-                    }
                     return token = SyntaxKind.DotToken;
-                case CharacterCodes.exclamation:
-                    pos++;
-                    return token = SyntaxKind.ExclamationToken;
-                case CharacterCodes.question:
-                    pos++;
-                    return token = SyntaxKind.QuestionToken;
             }
 
             if (isIdentifierStart(ch, ScriptTarget.Latest)) {
-                pos++;
                 while (isIdentifierPart(text.charCodeAt(pos), ScriptTarget.Latest) && pos < end) {
                     pos++;
                 }
@@ -1895,7 +1976,7 @@ namespace ts {
                 return token = SyntaxKind.Identifier;
             }
             else {
-                return pos += 1, token = SyntaxKind.Unknown;
+                return token = SyntaxKind.Unknown;
             }
         }
 

src/compiler/sourcemap.ts

@@ -420,7 +420,7 @@ namespace ts {
                 host.getCanonicalFileName,
                 /*isAbsolutePathAnUrl*/ true);
 
-            sourceMapSourceIndex = indexOf(sourceMapData.sourceMapSources, source);
+            sourceMapSourceIndex = sourceMapData.sourceMapSources.indexOf(source);
             if (sourceMapSourceIndex === -1) {
                 sourceMapSourceIndex = sourceMapData.sourceMapSources.length;
                 sourceMapData.sourceMapSources.push(source);

src/compiler/symbolWalker.ts

@@ -2,6 +2,7 @@
 namespace ts {
     export function createGetSymbolWalker(
         getRestTypeOfSignature: (sig: Signature) => Type,
+        getTypePredicateOfSignature: (sig: Signature) => TypePredicate | undefined,
         getReturnTypeOfSignature: (sig: Signature) => Type,
         getBaseTypes: (type: Type) => Type[],
         resolveStructuredTypeMembers: (type: ObjectType) => ResolvedType,
@@ -117,8 +118,9 @@ namespace ts {
             }
 
             function visitSignature(signature: Signature): void {
-                if (signature.typePredicate) {
-                    visitType(signature.typePredicate.type);
+                const typePredicate = getTypePredicateOfSignature(signature);
+                if (typePredicate) {
+                    visitType(typePredicate.type);
                 }
                 forEach(signature.typeParameters, visitType);
 

src/compiler/transformers/es2015.ts

@@ -859,7 +859,7 @@ namespace ts {
                 statements.push(
                     setTextRange(
                         createStatement(
-                            createExtendsHelper(context, getLocalName(node))
+                            createExtendsHelper(context, getInternalName(node))
                         ),
                         /*location*/ extendsClauseElement
                     )

src/compiler/transformers/esnext.ts

@@ -968,7 +968,7 @@ namespace ts {
         name: "typescript:asyncValues",
         scoped: false,
         text: `
-            var __asyncValues = (this && this.__asyncIterator) || function (o) {
+            var __asyncValues = (this && this.__asyncValues) || function (o) {
                 if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
                 var m = o[Symbol.asyncIterator];
                 return m ? m.call(o) : typeof __values === "function" ? __values(o) : o[Symbol.iterator]();

src/compiler/transformers/generators.ts

@@ -3190,8 +3190,8 @@ namespace ts {
     // `throw` methods that step through the generator when invoked.
     //
     // parameters:
-    //  thisArg  The value to use as the `this` binding for the transformed generator body.
-    //  body     A function that acts as the transformed generator body.
+    //  @param thisArg  The value to use as the `this` binding for the transformed generator body.
+    //  @param body     A function that acts as the transformed generator body.
     //
     // variables:
     //  _       Persistent state for the generator that is shared between the helper and the

src/compiler/transformers/module/es2015.ts

@@ -25,14 +25,14 @@ namespace ts {
                 if (externalHelpersModuleName) {
                     const statements: Statement[] = [];
                     const statementOffset = addPrologue(statements, node.statements);
-                    append(statements,
-                        createImportDeclaration(
-                            /*decorators*/ undefined,
-                            /*modifiers*/ undefined,
-                            createImportClause(/*name*/ undefined, createNamespaceImport(externalHelpersModuleName)),
-                            createLiteral(externalHelpersModuleNameText)
-                        )
+                    const tslibImport = createImportDeclaration(
+                        /*decorators*/ undefined,
+                        /*modifiers*/ undefined,
+                        createImportClause(/*name*/ undefined, createNamespaceImport(externalHelpersModuleName)),
+                        createLiteral(externalHelpersModuleNameText)
                     );
+                    addEmitFlags(tslibImport, EmitFlags.NeverApplyImportHelper);
+                    append(statements, tslibImport);
 
                     addRange(statements, visitNodes(node.statements, visitor, isStatement, statementOffset));
                     return updateSourceFileNode(

src/compiler/transformers/module/module.ts

@@ -148,7 +148,7 @@ namespace ts {
             // Create an updated SourceFile:
             //
             //     define(moduleName?, ["module1", "module2"], function ...
-            return updateSourceFileNode(node,
+            const updated = updateSourceFileNode(node,
                 setTextRange(
                     createNodeArray([
                         createStatement(
@@ -192,6 +192,9 @@ namespace ts {
                     /*location*/ node.statements
                 )
             );
+
+            addEmitHelpers(updated, context.readEmitHelpers());
+            return updated;
         }
 
         /**
@@ -296,7 +299,7 @@ namespace ts {
             //      }
             //  })(function ...)
 
-            return updateSourceFileNode(
+            const updated = updateSourceFileNode(
                 node,
                 setTextRange(
                     createNodeArray([
@@ -328,6 +331,9 @@ namespace ts {
                     /*location*/ node.statements
                 )
             );
+
+            addEmitHelpers(updated, context.readEmitHelpers());
+            return updated;
         }
 
         /**
@@ -385,6 +391,18 @@ namespace ts {
             return { aliasedModuleNames, unaliasedModuleNames, importAliasNames };
         }
 
+        function getAMDImportExpressionForImport(node: ImportDeclaration | ExportDeclaration | ImportEqualsDeclaration) {
+            if (isImportEqualsDeclaration(node) || isExportDeclaration(node) || !getExternalModuleNameLiteral(node, currentSourceFile, host, resolver, compilerOptions)) {
+                return undefined;
+            }
+            const name = getLocalNameForExternalImport(node, currentSourceFile);
+            const expr = getHelperExpressionForImport(node, name);
+            if (expr === name) {
+                return undefined;
+            }
+            return createStatement(createAssignment(name, expr));
+        }
+
         /**
          * Transforms a SourceFile into an AMD or UMD module body.
          *
@@ -402,6 +420,9 @@ namespace ts {
 
             // Visit each statement of the module body.
             append(statements, visitNode(currentModuleInfo.externalHelpersImportDeclaration, sourceElementVisitor, isStatement));
+            if (moduleKind === ModuleKind.AMD) {
+                addRange(statements, mapDefined(currentModuleInfo.externalImports, getAMDImportExpressionForImport));
+            }
             addRange(statements, visitNodes(node.statements, sourceElementVisitor, isStatement, statementOffset));
 
             // Append the 'export =' statement if provided.
@@ -617,7 +638,12 @@ namespace ts {
                 }
             }
 
-            return createNew(createIdentifier("Promise"), /*typeArguments*/ undefined, [func]);
+            const promise = createNew(createIdentifier("Promise"), /*typeArguments*/ undefined, [func]);
+            if (compilerOptions.esModuleInterop) {
+                context.requestEmitHelper(importStarHelper);
+                return createCall(createPropertyAccess(promise, createIdentifier("then")), /*typeArguments*/ undefined, [getHelperName("__importStar")]);
+            }
+            return promise;
         }
 
         function createImportCallExpressionCommonJS(arg: Expression | undefined, containsLexicalThis: boolean): Expression {
@@ -627,7 +653,11 @@ namespace ts {
             // We have to wrap require in then callback so that require is done in asynchronously
             // if we simply do require in resolve callback in Promise constructor. We will execute the loading immediately
             const promiseResolveCall = createCall(createPropertyAccess(createIdentifier("Promise"), "resolve"), /*typeArguments*/ undefined, /*argumentsArray*/ []);
-            const requireCall = createCall(createIdentifier("require"), /*typeArguments*/ undefined, arg ? [arg] : []);
+            let requireCall = createCall(createIdentifier("require"), /*typeArguments*/ undefined, arg ? [arg] : []);
+            if (compilerOptions.esModuleInterop) {
+                context.requestEmitHelper(importStarHelper);
+                requireCall = createCall(getHelperName("__importStar"), /*typeArguments*/ undefined, [requireCall]);
+            }
 
             let func: FunctionExpression | ArrowFunction;
             if (languageVersion >= ScriptTarget.ES2015) {
@@ -660,6 +690,22 @@ namespace ts {
             return createCall(createPropertyAccess(promiseResolveCall, "then"), /*typeArguments*/ undefined, [func]);
         }
 
+
+        function getHelperExpressionForImport(node: ImportDeclaration, innerExpr: Expression) {
+            if (!compilerOptions.esModuleInterop || getEmitFlags(node) & EmitFlags.NeverApplyImportHelper) {
+                return innerExpr;
+            }
+            if (getNamespaceDeclarationNode(node)) {
+                context.requestEmitHelper(importStarHelper);
+                return createCall(getHelperName("__importStar"), /*typeArguments*/ undefined, [innerExpr]);
+            }
+            if (isDefaultImport(node)) {
+                context.requestEmitHelper(importDefaultHelper);
+                return createCall(getHelperName("__importDefault"), /*typeArguments*/ undefined, [innerExpr]);
+            }
+            return innerExpr;
+        }
+
         /**
          * Visits an ImportDeclaration node.
          *
@@ -681,7 +727,7 @@ namespace ts {
                             createVariableDeclaration(
                                 getSynthesizedClone(namespaceDeclaration.name),
                                 /*type*/ undefined,
-                                createRequireCall(node)
+                                getHelperExpressionForImport(node, createRequireCall(node))
                             )
                         );
                     }
@@ -694,7 +740,7 @@ namespace ts {
                             createVariableDeclaration(
                                 getGeneratedNameForNode(node),
                                 /*type*/ undefined,
-                                createRequireCall(node)
+                                getHelperExpressionForImport(node, createRequireCall(node))
                             )
                         );
 
@@ -1671,4 +1717,28 @@ namespace ts {
         text: `
             var __syncRequire = typeof module === "object" && typeof module.exports === "object";`
     };
+
+    // emit helper for `import * as Name from "foo"`
+    const importStarHelper: EmitHelper = {
+        name: "typescript:commonjsimportstar",
+        scoped: false,
+        text: `
+var __importStar = (this && this.__importStar) || function (mod) {
+    if (mod && mod.__esModule) return mod;
+    var result = {};
+    if (mod != null) for (var k in mod) if (Object.hasOwnProperty.call(mod, k)) result[k] = mod[k];
+    result["default"] = mod;
+    return result;
+}`
+    };
+
+    // emit helper for `import Name from "foo"`
+    const importDefaultHelper: EmitHelper = {
+        name: "typescript:commonjsimportdefault",
+        scoped: false,
+        text: `
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+}`
+    };
 }

src/compiler/transformers/ts.ts

@@ -81,7 +81,7 @@ namespace ts {
         let classAliases: Identifier[];
 
         /**
-         * Keeps track of whether  we are within any containing namespaces when performing
+         * Keeps track of whether we are within any containing namespaces when performing
          * just-in-time substitution while printing an expression identifier.
          */
         let applicableSubstitutions: TypeScriptSubstitutionFlags;

src/compiler/transformers/utilities.ts

@@ -143,6 +143,7 @@ namespace ts {
             createLiteral(externalHelpersModuleNameText));
 
         if (externalHelpersImportDeclaration) {
+            addEmitFlags(externalHelpersImportDeclaration, EmitFlags.NeverApplyImportHelper);
             externalImports.unshift(externalHelpersImportDeclaration);
         }
 

src/compiler/types.ts

@@ -58,6 +58,23 @@ namespace ts {
         end: number;
     }
 
+    export type JsDocSyntaxKind =
+        | SyntaxKind.EndOfFileToken
+        | SyntaxKind.WhitespaceTrivia
+        | SyntaxKind.AtToken
+        | SyntaxKind.NewLineTrivia
+        | SyntaxKind.AsteriskToken
+        | SyntaxKind.OpenBraceToken
+        | SyntaxKind.CloseBraceToken
+        | SyntaxKind.LessThanToken
+        | SyntaxKind.OpenBracketToken
+        | SyntaxKind.CloseBracketToken
+        | SyntaxKind.EqualsToken
+        | SyntaxKind.CommaToken
+        | SyntaxKind.DotToken
+        | SyntaxKind.Identifier
+        | SyntaxKind.Unknown;
+
     // token > SyntaxKind.Identifer => token is a keyword
     // Also, If you add a new SyntaxKind be sure to keep the `Markers` section at the bottom in sync
     export const enum SyntaxKind {
@@ -438,24 +455,24 @@ namespace ts {
     }
 
     export const enum NodeFlags {
-        None =               0,
-        Let =                1 << 0,  // Variable declaration
-        Const =              1 << 1,  // Variable declaration
-        NestedNamespace =    1 << 2,  // Namespace declaration
-        Synthesized =        1 << 3,  // Node was synthesized during transformation
-        Namespace =          1 << 4,  // Namespace declaration
-        ExportContext =      1 << 5,  // Export context (initialized by binding)
-        ContainsThis =       1 << 6,  // Interface contains references to "this"
-        HasImplicitReturn =  1 << 7,  // If function implicitly returns on one of codepaths (initialized by binding)
-        HasExplicitReturn =  1 << 8,  // If function has explicit reachable return on one of codepaths (initialized by binding)
+        None               = 0,
+        Let                = 1 << 0,  // Variable declaration
+        Const              = 1 << 1,  // Variable declaration
+        NestedNamespace    = 1 << 2,  // Namespace declaration
+        Synthesized        = 1 << 3,  // Node was synthesized during transformation
+        Namespace          = 1 << 4,  // Namespace declaration
+        ExportContext      = 1 << 5,  // Export context (initialized by binding)
+        ContainsThis       = 1 << 6,  // Interface contains references to "this"
+        HasImplicitReturn  = 1 << 7,  // If function implicitly returns on one of codepaths (initialized by binding)
+        HasExplicitReturn  = 1 << 8,  // If function has explicit reachable return on one of codepaths (initialized by binding)
         GlobalAugmentation = 1 << 9,  // Set if module declaration is an augmentation for the global scope
-        HasAsyncFunctions =  1 << 10, // If the file has async functions (initialized by binding)
-        DisallowInContext =  1 << 11, // If node was parsed in a context where 'in-expressions' are not allowed
-        YieldContext =       1 << 12, // If node was parsed in the 'yield' context created when parsing a generator
-        DecoratorContext =   1 << 13, // If node was parsed as part of a decorator
-        AwaitContext =       1 << 14, // If node was parsed in the 'await' context created when parsing an async function
-        ThisNodeHasError =   1 << 15, // If the parser encountered an error when parsing the code that created this node
-        JavaScriptFile =     1 << 16, // If node was parsed in a JavaScript
+        HasAsyncFunctions  = 1 << 10, // If the file has async functions (initialized by binding)
+        DisallowInContext  = 1 << 11, // If node was parsed in a context where 'in-expressions' are not allowed
+        YieldContext       = 1 << 12, // If node was parsed in the 'yield' context created when parsing a generator
+        DecoratorContext   = 1 << 13, // If node was parsed as part of a decorator
+        AwaitContext       = 1 << 14, // If node was parsed in the 'await' context created when parsing an async function
+        ThisNodeHasError   = 1 << 15, // If the parser encountered an error when parsing the code that created this node
+        JavaScriptFile     = 1 << 16, // If node was parsed in a JavaScript
         ThisNodeOrAnySubNodesHasError = 1 << 17, // If this node or any of its children had an error
         HasAggregatedChildData = 1 << 18, // If we've computed data from children and cached it in this node
 
@@ -584,6 +601,40 @@ namespace ts {
         | JSDocFunctionType
         | EndOfFileToken;
 
+    export type HasType =
+        | SignatureDeclaration
+        | VariableDeclaration
+        | ParameterDeclaration
+        | PropertySignature
+        | PropertyDeclaration
+        | TypePredicateNode
+        | ParenthesizedTypeNode
+        | TypeOperatorNode
+        | MappedTypeNode
+        | AssertionExpression
+        | TypeAliasDeclaration
+        | JSDocTypeExpression
+        | JSDocNonNullableType
+        | JSDocNullableType
+        | JSDocOptionalType
+        | JSDocVariadicType;
+
+    export type HasInitializer =
+        | HasExpressionInitializer
+        | ForStatement
+        | ForInStatement
+        | ForOfStatement
+        | JsxAttribute;
+
+    export type HasExpressionInitializer =
+        | VariableDeclaration
+        | ParameterDeclaration
+        | BindingElement
+        | PropertySignature
+        | PropertyDeclaration
+        | PropertyAssignment
+        | EnumMember;
+
     /* @internal */
     export type MutableNodeArray<T extends Node> = NodeArray<T> & T[];
 
@@ -793,6 +844,9 @@ namespace ts {
         initializer?: Expression;           // Optional initializer
     }
 
+    /*@internal*/
+    export type BindingElementGrandparent = BindingElement["parent"]["parent"];
+
     export interface PropertySignature extends TypeElement, JSDocContainer {
         kind: SyntaxKind.PropertySignature;
         name: PropertyName;                 // Declared property name
@@ -848,25 +902,18 @@ namespace ts {
         expression: Expression;
     }
 
-    // SyntaxKind.VariableDeclaration
-    // SyntaxKind.Parameter
-    // SyntaxKind.BindingElement
-    // SyntaxKind.Property
-    // SyntaxKind.PropertyAssignment
-    // SyntaxKind.JsxAttribute
-    // SyntaxKind.ShorthandPropertyAssignment
-    // SyntaxKind.EnumMember
-    // SyntaxKind.JSDocPropertyTag
-    // SyntaxKind.JSDocParameterTag
-    export interface VariableLikeDeclaration extends NamedDeclaration {
-        propertyName?: PropertyName;
-        dotDotDotToken?: DotDotDotToken;
-        name: DeclarationName;
-        questionToken?: QuestionToken;
-        exclamationToken?: ExclamationToken;
-        type?: TypeNode;
-        initializer?: Expression;
-    }
+    export type VariableLikeDeclaration =
+        | VariableDeclaration
+        | ParameterDeclaration
+        | BindingElement
+        | PropertyDeclaration
+        | PropertyAssignment
+        | PropertySignature
+        | JsxAttribute
+        | ShorthandPropertyAssignment
+        | EnumMember
+        | JSDocPropertyTag
+        | JSDocParameterTag;
 
     export interface PropertyLikeDeclaration extends NamedDeclaration {
         name: PropertyName;
@@ -949,7 +996,7 @@ namespace ts {
 
     export interface ConstructorDeclaration extends FunctionLikeDeclarationBase, ClassElement, JSDocContainer {
         kind: SyntaxKind.Constructor;
-        parent?: ClassDeclaration | ClassExpression;
+        parent?: ClassLikeDeclaration;
         body?: FunctionBody;
         /* @internal */ returnFlowNode?: FlowNode;
     }
@@ -957,14 +1004,14 @@ namespace ts {
     /** For when we encounter a semicolon in a class declaration. ES6 allows these as class elements. */
     export interface SemicolonClassElement extends ClassElement {
         kind: SyntaxKind.SemicolonClassElement;
-        parent?: ClassDeclaration | ClassExpression;
+        parent?: ClassLikeDeclaration;
     }
 
     // See the comment on MethodDeclaration for the intuition behind GetAccessorDeclaration being a
     // ClassElement and an ObjectLiteralElement.
     export interface GetAccessorDeclaration extends FunctionLikeDeclarationBase, ClassElement, ObjectLiteralElement, JSDocContainer {
         kind: SyntaxKind.GetAccessor;
-        parent?: ClassDeclaration | ClassExpression | ObjectLiteralExpression;
+        parent?: ClassLikeDeclaration | ObjectLiteralExpression;
         name: PropertyName;
         body?: FunctionBody;
     }
@@ -973,7 +1020,7 @@ namespace ts {
     // ClassElement and an ObjectLiteralElement.
     export interface SetAccessorDeclaration extends FunctionLikeDeclarationBase, ClassElement, ObjectLiteralElement, JSDocContainer {
         kind: SyntaxKind.SetAccessor;
-        parent?: ClassDeclaration | ClassExpression | ObjectLiteralExpression;
+        parent?: ClassLikeDeclaration | ObjectLiteralExpression;
         name: PropertyName;
         body?: FunctionBody;
     }
@@ -982,7 +1029,7 @@ namespace ts {
 
     export interface IndexSignatureDeclaration extends SignatureDeclarationBase, ClassElement, TypeElement {
         kind: SyntaxKind.IndexSignature;
-        parent?: ClassDeclaration | ClassExpression | InterfaceDeclaration | TypeLiteralNode;
+        parent?: ClassLikeDeclaration | InterfaceDeclaration | TypeLiteralNode;
     }
 
     export interface TypeNode extends Node {
@@ -1102,11 +1149,13 @@ namespace ts {
 
     export interface StringLiteral extends LiteralExpression {
         kind: SyntaxKind.StringLiteral;
-        /* @internal */ textSourceNode?: Identifier | StringLiteral | NumericLiteral; // Allows a StringLiteral to get its text from another node (used by transforms).
+        /* @internal */ textSourceNode?: Identifier | StringLiteralLike | NumericLiteral; // Allows a StringLiteral to get its text from another node (used by transforms).
         /** Note: this is only set when synthesizing a node, not during parsing. */
         /* @internal */ singleQuote?: boolean;
     }
 
+    /* @internal */ export type StringLiteralLike = StringLiteral | NoSubstitutionTemplateLiteral;
+
     // Note: 'brands' in our syntax nodes serve to give us a small amount of nominal typing.
     // Consider 'Expression'.  Without the brand, 'Expression' is actually no different
     // (structurally) than 'Node'.  Because of this you can pass any Node to a function that
@@ -1364,7 +1413,7 @@ namespace ts {
 
     export type BinaryOperatorToken = Token<BinaryOperator>;
 
-    export interface BinaryExpression extends Expression, Declaration  {
+    export interface BinaryExpression extends Expression, Declaration {
         kind: SyntaxKind.BinaryExpression;
         left: Expression;
         operatorToken: BinaryOperatorToken;
@@ -1452,6 +1501,7 @@ namespace ts {
         kind: SyntaxKind.ArrowFunction;
         equalsGreaterThanToken: EqualsGreaterThanToken;
         body: ConciseBody;
+        name: never;
     }
 
     // The text property of a LiteralExpression stores the interpreted value of the literal in text form. For a StringLiteral,
@@ -1490,8 +1540,9 @@ namespace ts {
         HexSpecifier = 1 << 6,      // e.g. `0x00000000`
         BinarySpecifier = 1 << 7,   // e.g. `0b0110010000000000`
         OctalSpecifier = 1 << 8,    // e.g. `0o777`
+        ContainsSeparator = 1 << 9, // e.g. `0b1100_0101`
         BinaryOrOctalSpecifier = BinarySpecifier | OctalSpecifier,
-        NumericLiteralFlags = Scientific | Octal | HexSpecifier | BinarySpecifier | OctalSpecifier
+        NumericLiteralFlags = Scientific | Octal | HexSpecifier | BinarySpecifier | OctalSpecifier | ContainsSeparator
     }
 
     export interface NumericLiteral extends LiteralExpression {
@@ -1986,7 +2037,7 @@ namespace ts {
 
     export interface HeritageClause extends Node {
         kind: SyntaxKind.HeritageClause;
-        parent?: InterfaceDeclaration | ClassDeclaration | ClassExpression;
+        parent?: InterfaceDeclaration | ClassLikeDeclaration;
         token: SyntaxKind.ExtendsKeyword | SyntaxKind.ImplementsKeyword;
         types: NodeArray<ExpressionWithTypeArguments>;
     }
@@ -2108,6 +2159,7 @@ namespace ts {
     export interface ExportDeclaration extends DeclarationStatement {
         kind: SyntaxKind.ExportDeclaration;
         parent?: SourceFile | ModuleBlock;
+        /** Will not be assigned in the case of `export * from "foo";` */
         exportClause?: NamedExports;
         /** If this is not a StringLiteral it will be a grammar error. */
         moduleSpecifier?: Expression;
@@ -2478,7 +2530,7 @@ namespace ts {
         // Stores a mapping 'external module reference text' -> 'resolved file name' | undefined
         // It is used to resolve module names in the checker.
         // Content of this field should never be used directly - use getResolvedModuleFileName/setResolvedModuleFileName functions instead
-        /* @internal */ resolvedModules: Map<ResolvedModuleFull>;
+        /* @internal */ resolvedModules: Map<ResolvedModuleFull | undefined>;
         /* @internal */ resolvedTypeReferenceDirectiveNames: Map<ResolvedTypeReferenceDirective>;
         /* @internal */ imports: ReadonlyArray<StringLiteral>;
         // Identifier only if `declare global`
@@ -2509,7 +2561,7 @@ namespace ts {
     export interface ParseConfigHost {
         useCaseSensitiveFileNames: boolean;
 
-        readDirectory(rootDir: string, extensions: ReadonlyArray<string>, excludes: ReadonlyArray<string>, includes: ReadonlyArray<string>, depth: number): string[];
+        readDirectory(rootDir: string, extensions: ReadonlyArray<string>, excludes: ReadonlyArray<string> | undefined, includes: ReadonlyArray<string>, depth?: number): string[];
 
         /**
          * Gets a value indicating whether the specified path exists and is a file.
@@ -2738,6 +2790,8 @@ namespace ts {
         getAugmentedPropertiesOfType(type: Type): Symbol[];
         getRootSymbols(symbol: Symbol): Symbol[];
         getContextualType(node: Expression): Type | undefined;
+        /* @internal */ isContextSensitive(node: Expression | MethodDeclaration | ObjectLiteralElementLike | JsxAttributeLike): boolean;
+
         /**
          * returns unknownSignature in the case of an error.
          * @param argumentCount Apparent number of arguments, passed in case of a possibly incomplete call. This should come from an ArgumentListInfo. See `signatureHelp.ts`.
@@ -2752,6 +2806,8 @@ namespace ts {
 
         getConstantValue(node: EnumMember | PropertyAccessExpression | ElementAccessExpression): string | number | undefined;
         isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName, propertyName: string): boolean;
+        /** Exclude accesses to private properties or methods with a `this` parameter that `type` doesn't satisfy. */
+        /* @internal */ isValidPropertyAccessForCompletions(node: PropertyAccessExpression, type: Type, property: Symbol): boolean;
         /** Follow all aliases to get the original symbol. */
         getAliasedSymbol(symbol: Symbol): Symbol;
         /** Follow a *single* alias to get the immediately aliased symbol. */
@@ -2786,12 +2842,22 @@ namespace ts {
         /* @internal */ getNullType(): Type;
         /* @internal */ getESSymbolType(): Type;
         /* @internal */ getNeverType(): Type;
-        /* @internal */ getUnionType(types: Type[], subtypeReduction?: boolean): Type;
+        /* @internal */ getUnionType(types: Type[], subtypeReduction?: UnionReduction): Type;
         /* @internal */ createArrayType(elementType: Type): Type;
         /* @internal */ createPromiseType(type: Type): Type;
 
         /* @internal */ createAnonymousType(symbol: Symbol, members: SymbolTable, callSignatures: Signature[], constructSignatures: Signature[], stringIndexInfo: IndexInfo, numberIndexInfo: IndexInfo): Type;
-        /* @internal */ createSignature(declaration: SignatureDeclaration, typeParameters: TypeParameter[], thisParameter: Symbol | undefined, parameters: Symbol[], resolvedReturnType: Type, typePredicate: TypePredicate, minArgumentCount: number, hasRestParameter: boolean, hasLiteralTypes: boolean): Signature;
+        /* @internal */ createSignature(
+            declaration: SignatureDeclaration,
+            typeParameters: TypeParameter[],
+            thisParameter: Symbol | undefined,
+            parameters: Symbol[],
+            resolvedReturnType: Type,
+            typePredicate: TypePredicate | undefined,
+            minArgumentCount: number,
+            hasRestParameter: boolean,
+            hasLiteralTypes: boolean,
+        ): Signature;
         /* @internal */ createSymbol(flags: SymbolFlags, name: __String): TransientSymbol;
         /* @internal */ createIndexInfo(type: Type, isReadonly: boolean, declaration?: SignatureDeclaration): IndexInfo;
         /* @internal */ isSymbolAccessible(symbol: Symbol, enclosingDeclaration: Node, meaning: SymbolFlags, shouldComputeAliasToMarkVisible: boolean): SymbolAccessibilityResult;
@@ -2816,7 +2882,7 @@ namespace ts {
          */
         /* @internal */ isArrayLikeType(type: Type): boolean;
         /* @internal */ getAllPossiblePropertiesOfTypes(type: ReadonlyArray<Type>): Symbol[];
-        /* @internal */ resolveName(name: string, location: Node, meaning: SymbolFlags): Symbol | undefined;
+        /* @internal */ resolveName(name: string, location: Node, meaning: SymbolFlags, excludeGlobals: boolean): Symbol | undefined;
         /* @internal */ getJsxNamespace(): string;
 
         /**
@@ -2829,6 +2895,15 @@ namespace ts {
          * This should be called in a loop climbing parents of the symbol, so we'll get `N`.
          */
         /* @internal */ getAccessibleSymbolChain(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean): Symbol[] | undefined;
+
+        /* @internal */ resolveExternalModuleSymbol(symbol: Symbol): Symbol;
+    }
+
+    /* @internal */
+    export const enum UnionReduction {
+        None = 0,
+        Literal,
+        Subtype
     }
 
     export enum NodeBuilderFlags {
@@ -2925,9 +3000,9 @@ namespace ts {
         None = 0x00000000,
 
         // Write symbols's type argument if it is instantiated symbol
-        // eg. class C<T> { p: T }   <-- Show p as C<T>.p here
+        // eg. class C<T> { p: T } <-- Show p as C<T>.p here
         //     var a: C<number>;
-        //     var p = a.p;  <--- Here p is property of C<number> so show it as C<number>.p instead of just C.p
+        //     var p = a.p; <--- Here p is property of C<number> so show it as C<number>.p instead of just C.p
         WriteTypeParametersOrArguments = 0x00000001,
 
         // Use only external alias information to get the symbol name in the given context
@@ -3177,6 +3252,7 @@ namespace ts {
         bindingElement?: BindingElement;    // Binding element associated with property symbol
         exportsSomeValue?: boolean;         // True if module exports some value (not just types)
         enumKind?: EnumKind;                // Enum declaration classification
+        originatingImport?: ImportDeclaration | ImportCall; // Import declaration which produced the symbol, present if the symbol is marked as uncallable but had call signatures in `resolveESModuleSymbol`
         lateSymbol?: Symbol;                // Late-bound symbol for a computed property
     }
 
@@ -3199,6 +3275,7 @@ namespace ts {
         ContainsPrivate   = 1 << 8,         // Synthetic property with private constituent(s)
         ContainsStatic    = 1 << 9,         // Synthetic property with static constituent(s)
         Late              = 1 << 10,        // Late-bound symbol for a computed property with a dynamic name
+        ReverseMapped     = 1 << 11,        // property of reverse-inferred homomorphic mapped type.
         Synthetic = SyntheticProperty | SyntheticMethod
     }
 
@@ -3208,6 +3285,12 @@ namespace ts {
         isRestParameter?: boolean;
     }
 
+    /* @internal */
+    export interface ReverseMappedSymbol extends TransientSymbol {
+        propertyType: Type;
+        mappedType: MappedType;
+    }
+
     export const enum InternalSymbolName {
         Call = "__call", // Call signatures
         Constructor = "__constructor", // Constructor implementations
@@ -3313,7 +3396,7 @@ namespace ts {
         resolvedJsxElementAttributesType?: Type;  // resolved element attributes type of a JSX openinglike element
         resolvedJsxElementAllAttributesType?: Type;  // resolved all element attributes type of a JSX openinglike element
         hasSuperCall?: boolean;           // recorded result when we try to find super-call. We only try to find one if this flag is undefined, indicating that we haven't made an attempt.
-        superCall?: ExpressionStatement;  // Cached first super-call found in the constructor. Used in checking whether super is called before this-accessing
+        superCall?: SuperCall;  // Cached first super-call found in the constructor. Used in checking whether super is called before this-accessing
         switchTypes?: Type[];             // Cached array of switch case expression types
     }
 
@@ -3442,6 +3525,7 @@ namespace ts {
         EvolvingArray    = 1 << 8,  // Evolving array type
         ObjectLiteralPatternWithComputedProperties = 1 << 9,  // Object literal pattern with computed properties
         ContainsSpread   = 1 << 10, // Object literal contains spread operation
+        ReverseMapped = 1 << 11,    // Object contains a property from a reverse-mapped type
         ClassOrInterface = Class | Interface
     }
 
@@ -3549,6 +3633,12 @@ namespace ts {
         finalArrayType?: Type;  // Final array type of evolving array type
     }
 
+    /* @internal */
+    export interface ReverseMappedType extends ObjectType {
+        source: Type;
+        mappedType: MappedType;
+    }
+
     /* @internal */
     // Resolved object, union, or intersection type
     export interface ResolvedType extends ObjectType, UnionOrIntersectionType {
@@ -3562,7 +3652,7 @@ namespace ts {
 
     /* @internal */
     // Object literals are initially marked fresh. Freshness disappears following an assignment,
-    // before a type assertion, or when  an object literal's type is widened. The regular
+    // before a type assertion, or when an object literal's type is widened. The regular
     // version of a fresh type is identical except for the TypeFlags.FreshObjectLiteral flag.
     export interface FreshObjectLiteralType extends ResolvedType {
         regularType: ResolvedType;  // Regular version of fresh type
@@ -3638,7 +3728,13 @@ namespace ts {
         /* @internal */
         thisParameter?: Symbol;             // symbol of this-type parameter
         /* @internal */
-        resolvedReturnType: Type;           // Resolved return type
+        // See comment in `instantiateSignature` for why these are set lazily.
+        resolvedReturnType: Type | undefined; // Lazily set by `getReturnTypeOfSignature`.
+        /* @internal */
+        // Lazily set by `getTypePredicateOfSignature`.
+        // `undefined` indicates a type predicate that has not yet been computed.
+        // Uses a special `noTypePredicate` sentinel value to indicate that there is no type predicate. This looks like a TypePredicate at runtime to avoid polymorphism.
+        resolvedTypePredicate: TypePredicate | undefined;
         /* @internal */
         minArgumentCount: number;           // Number of non-optional parameters
         /* @internal */
@@ -3658,8 +3754,6 @@ namespace ts {
         /* @internal */
         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
     }
 
@@ -3889,6 +3983,7 @@ namespace ts {
         typeRoots?: string[];
         /*@internal*/ version?: boolean;
         /*@internal*/ watch?: boolean;
+        esModuleInterop?: boolean;
 
         [option: string]: CompilerOptionsValue | JsonSourceFile | undefined;
     }
@@ -4229,6 +4324,8 @@ namespace ts {
      * If changing this, remember to change `moduleResolutionIsEqualTo`.
      */
     export interface ResolvedModuleFull extends ResolvedModule {
+        /* @internal */
+        readonly originalPath?: string;
         /**
          * Extension of resolvedFileName. This must match what's at the end of resolvedFileName.
          * This is optional for backwards-compatibility, but will be added if not provided.
@@ -4308,11 +4405,11 @@ namespace ts {
          * If resolveModuleNames is implemented then implementation for members from ModuleResolutionHost can be just
          * 'throw new Error("NotImplemented")'
          */
-        resolveModuleNames?(moduleNames: string[], containingFile: string, reusedNames?: string[]): ResolvedModule[];
+        resolveModuleNames?(moduleNames: string[], containingFile: string, reusedNames?: string[]): (ResolvedModule | undefined)[];
         /**
          * This method is a companion for 'resolveModuleNames' and is used to resolve 'types' references to actual type declaration files
          */
-        resolveTypeReferenceDirectives?(typeReferenceDirectiveNames: string[], containingFile: string): ResolvedTypeReferenceDirective[];
+        resolveTypeReferenceDirectives?(typeReferenceDirectiveNames: string[], containingFile: string): (ResolvedTypeReferenceDirective | undefined)[];
         getEnvironmentVariable?(name: string): string;
         /* @internal */ onReleaseOldSourceFile?(oldSourceFile: SourceFile, oldOptions: CompilerOptions): void;
         /* @internal */ hasInvalidatedResolution?: HasInvalidatedResolution;
@@ -4454,6 +4551,7 @@ namespace ts {
         Iterator = 1 << 23,                     // The expression to a `yield*` should be treated as an Iterator when down-leveling, not an Iterable.
         NoAsciiEscaping = 1 << 24,              // When synthesizing nodes that lack an original node or textSourceNode, we want to write the text on the node with ASCII escaping substitutions.
         /*@internal*/ TypeScriptClassWrapper = 1 << 25, // The node is an IIFE class wrapper created by the ts transform.
+        /*@internal*/ NeverApplyImportHelper = 1 << 26, // Indicates the node should never be wrapped with an import star helper (because, for example, it imports tslib itself)
     }
 
     export interface EmitHelper {

src/compiler/utilities.ts

@@ -3,7 +3,9 @@
 /* @internal */
 namespace ts {
     export const emptyArray: never[] = [] as never[];
+    export const resolvingEmptyArray: never[] = [] as never[];
     export const emptyMap: ReadonlyMap<never> = createMap<never>();
+    export const emptyUnderscoreEscapedMap: ReadonlyUnderscoreEscapedMap<never> = emptyMap as ReadonlyUnderscoreEscapedMap<never>;
 
     export const externalHelpersModuleNameText = "tslib";
 
@@ -101,6 +103,7 @@ namespace ts {
         return oldResolution.isExternalLibraryImport === newResolution.isExternalLibraryImport &&
             oldResolution.extension === newResolution.extension &&
             oldResolution.resolvedFileName === newResolution.resolvedFileName &&
+            oldResolution.originalPath === newResolution.originalPath &&
             packageIdIsEqual(oldResolution.packageId, newResolution.packageId);
     }
 
@@ -345,7 +348,7 @@ namespace ts {
     export function getLiteralText(node: LiteralLikeNode, sourceFile: SourceFile) {
         // If we don't need to downlevel and we can reach the original source text using
         // the node's parent reference, then simply get the text as it was originally written.
-        if (!nodeIsSynthesized(node) && node.parent) {
+        if (!nodeIsSynthesized(node) && node.parent && !(isNumericLiteral(node) && node.numericLiteralFlags & TokenFlags.ContainsSeparator)) {
             return getSourceTextOfNodeFromSourceFile(sourceFile, node);
         }
 
@@ -547,7 +550,7 @@ namespace ts {
     // Return display name of an identifier
     // Computed property names will just be emitted as "[<expr>]", where <expr> is the source
     // text of the expression in the computed property.
-    export function declarationNameToString(name: DeclarationName) {
+    export function declarationNameToString(name: DeclarationName | QualifiedName) {
         return getFullWidth(name) === 0 ? "(Missing)" : getTextOfNode(name);
     }
 
@@ -783,7 +786,7 @@ namespace ts {
                     case SyntaxKind.PropertySignature:
                     case SyntaxKind.Parameter:
                     case SyntaxKind.VariableDeclaration:
-                        return node === (<VariableLikeDeclaration>parent).type;
+                        return node === (parent as HasType).type;
                     case SyntaxKind.FunctionDeclaration:
                     case SyntaxKind.FunctionExpression:
                     case SyntaxKind.ArrowFunction:
@@ -801,7 +804,7 @@ namespace ts {
                         return node === (<TypeAssertion>parent).type;
                     case SyntaxKind.CallExpression:
                     case SyntaxKind.NewExpression:
-                        return (<CallExpression>parent).typeArguments && indexOf((<CallExpression>parent).typeArguments, node) >= 0;
+                        return contains((<CallExpression>parent).typeArguments, node);
                     case SyntaxKind.TaggedTemplateExpression:
                         // TODO (drosen): TaggedTemplateExpressions may eventually support type arguments.
                         return false;
@@ -1339,7 +1342,7 @@ namespace ts {
             case SyntaxKind.EnumMember:
             case SyntaxKind.PropertyAssignment:
             case SyntaxKind.BindingElement:
-                return (<VariableLikeDeclaration>parent).initializer === node;
+                return (parent as HasInitializer).initializer === node;
             case SyntaxKind.ExpressionStatement:
             case SyntaxKind.IfStatement:
             case SyntaxKind.DoStatement:
@@ -1417,6 +1420,8 @@ namespace ts {
      * exactly one argument (of the form 'require("name")').
      * This function does not test if the node is in a JavaScript file or not.
      */
+    export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteral: true): callExpression is CallExpression & { expression: Identifier, arguments: [StringLiteralLike] };
+    export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteral: boolean): callExpression is CallExpression;
     export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteral: boolean): callExpression is CallExpression {
         if (callExpression.kind !== SyntaxKind.CallExpression) {
             return false;
@@ -1454,7 +1459,7 @@ namespace ts {
         return false;
     }
 
-    export function getRightMostAssignedExpression(node: Node) {
+    export function getRightMostAssignedExpression(node: Expression): Expression {
         while (isAssignmentExpression(node, /*excludeCompoundAssignements*/ true)) {
             node = node.right;
         }
@@ -1649,7 +1654,7 @@ namespace ts {
                 result = addRange(result, getJSDocParameterTags(node as ParameterDeclaration));
             }
 
-            if (isVariableLike(node) && node.initializer && hasJSDocNodes(node.initializer)) {
+            if (isVariableLike(node) && hasInitializer(node) && hasJSDocNodes(node.initializer)) {
                 result = addRange(result, node.initializer.jsDoc);
             }
 
@@ -2117,6 +2122,10 @@ namespace ts {
         return "__@" + symbolName as __String;
     }
 
+    export function isKnownSymbol(symbol: Symbol): boolean {
+        return startsWith(symbol.escapedName as string, "__@");
+    }
+
     /**
      * Includes the word "Symbol" with unicode escapes
      */
@@ -2815,8 +2824,8 @@ namespace ts {
      * Gets the effective type annotation of a variable, parameter, or property. If the node was
      * parsed in a JavaScript file, gets the type annotation from JSDoc.
      */
-    export function getEffectiveTypeAnnotationNode(node: VariableLikeDeclaration, checkJSDoc?: boolean): TypeNode | undefined {
-        if (node.type) {
+    export function getEffectiveTypeAnnotationNode(node: Node, checkJSDoc?: boolean): TypeNode | undefined {
+        if (hasType(node)) {
             return node.type;
         }
         if (checkJSDoc || isInJavaScriptFile(node)) {
@@ -3696,6 +3705,10 @@ namespace ts {
     export function typeHasCallOrConstructSignatures(type: Type, checker: TypeChecker) {
         return checker.getSignaturesOfType(type, SignatureKind.Call).length !== 0 || checker.getSignaturesOfType(type, SignatureKind.Construct).length !== 0;
     }
+
+    export function forSomeAncestorDirectory(directory: string, callback: (directory: string) => boolean): boolean {
+        return !!forEachAncestorDirectory(directory, d => callback(d) ? true : undefined);
+    }
 }
 
 namespace ts {
@@ -3911,8 +3924,8 @@ namespace ts {
             //
             // {
             //      oldStart3: Min(oldStart1, oldStart2),
-            //      oldEnd3  : Max(oldEnd1, oldEnd1 + (oldEnd2 - newEnd1)),
-            //      newEnd3  : Max(newEnd2, newEnd2 + (newEnd1 - oldEnd2))
+            //      oldEnd3: Max(oldEnd1, oldEnd1 + (oldEnd2 - newEnd1)),
+            //      newEnd3: Max(newEnd2, newEnd2 + (newEnd1 - oldEnd2))
             // }
 
             const oldStart1 = oldStartN;
@@ -4397,7 +4410,7 @@ namespace ts {
         return node.kind === SyntaxKind.RegularExpressionLiteral;
     }
 
-    export function isNoSubstitutionTemplateLiteral(node: Node): node is LiteralExpression {
+    export function isNoSubstitutionTemplateLiteral(node: Node): node is NoSubstitutionTemplateLiteral {
         return node.kind === SyntaxKind.NoSubstitutionTemplateLiteral;
     }
 
@@ -5228,6 +5241,18 @@ namespace ts {
         return node && (node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor);
     }
 
+    /* @internal */
+    export function isMethodOrAccessor(node: Node): node is MethodDeclaration | AccessorDeclaration {
+        switch (node.kind) {
+            case SyntaxKind.MethodDeclaration:
+            case SyntaxKind.GetAccessor:
+            case SyntaxKind.SetAccessor:
+                return true;
+            default:
+                return false;
+        }
+    }
+
     // Type members
 
     export function isTypeElement(node: Node): node is TypeElement {
@@ -5807,4 +5832,37 @@ namespace ts {
     export function hasJSDocNodes(node: Node): node is HasJSDoc {
         return !!(node as JSDocContainer).jsDoc && (node as JSDocContainer).jsDoc.length > 0;
     }
+
+    /** True if has type node attached to it. */
+    /* @internal */
+    export function hasType(node: Node): node is HasType {
+        return !!(node as HasType).type;
+    }
+
+    /** True if has initializer node attached to it. */
+    /* @internal */
+    export function hasInitializer(node: Node): node is HasInitializer {
+        return !!(node as HasInitializer).initializer;
+    }
+
+    /** True if has initializer node attached to it. */
+    /* @internal */
+    export function hasOnlyExpressionInitializer(node: Node): node is HasExpressionInitializer {
+        return hasInitializer(node) && !isForStatement(node) && !isForInStatement(node) && !isForOfStatement(node) && !isJsxAttribute(node);
+    }
+
+    export function isObjectLiteralElement(node: Node): node is ObjectLiteralElement {
+        switch (node.kind) {
+            case SyntaxKind.JsxAttribute:
+            case SyntaxKind.JsxSpreadAttribute:
+            case SyntaxKind.PropertyAssignment:
+            case SyntaxKind.ShorthandPropertyAssignment:
+            case SyntaxKind.MethodDeclaration:
+            case SyntaxKind.GetAccessor:
+            case SyntaxKind.SetAccessor:
+                return true;
+            default:
+                return false;
+        }
+    }
 }

src/compiler/visitor.ts

@@ -622,7 +622,7 @@ namespace ts {
 
             case SyntaxKind.ForOfStatement:
                 return updateForOf(<ForOfStatement>node,
-                    (<ForOfStatement>node).awaitModifier,
+                    visitNode((<ForOfStatement>node).awaitModifier, visitor, isToken),
                     visitNode((<ForOfStatement>node).initializer, visitor, isForInitializer),
                     visitNode((<ForOfStatement>node).expression, visitor, isExpression),
                     visitNode((<ForOfStatement>node).statement, visitor, isStatement, liftToBlock));

src/compiler/watch.ts

@@ -48,6 +48,15 @@ namespace ts {
         };
     }
 
+    /** @internal */
+    export function createWatchDiagnosticReporterWithColor(system = sys): DiagnosticReporter {
+        return diagnostic => {
+            let output = `[${ formatColorAndReset(new Date().toLocaleTimeString(), ForegroundColorEscapeSequences.Grey) }] `;
+            output += `${flattenDiagnosticMessageText(diagnostic.messageText, system.newLine)}${system.newLine + system.newLine + system.newLine}`;
+            system.write(output);
+        };
+    }
+
     export function reportDiagnostics(diagnostics: Diagnostic[], reportDiagnostic: DiagnosticReporter): void {
         for (const diagnostic of diagnostics) {
             reportDiagnostic(diagnostic);
@@ -131,7 +140,7 @@ namespace ts {
         reportWatchDiagnostic?: DiagnosticReporter
     ): WatchingSystemHost {
         reportDiagnostic = reportDiagnostic || createDiagnosticReporter(system, pretty ? reportDiagnosticWithColorAndContext : reportDiagnosticSimply);
-        reportWatchDiagnostic = reportWatchDiagnostic || createWatchDiagnosticReporter(system);
+        reportWatchDiagnostic = reportWatchDiagnostic || pretty ? createWatchDiagnosticReporterWithColor(system) : createWatchDiagnosticReporter(system);
         parseConfigFile = parseConfigFile || ts.parseConfigFile;
         return {
             system,
@@ -302,6 +311,8 @@ namespace ts {
         // There is no extra check needed since we can just rely on the program to decide emit
         const builder = createBuilder({ getCanonicalFileName, computeHash });
 
+        clearHostScreen();
+        reportWatchDiagnostic(createCompilerDiagnostic(Diagnostics.Starting_compilation_in_watch_mode));
         synchronizeProgram();
 
         // Update the wild card directory watch
@@ -492,10 +503,14 @@ namespace ts {
             scheduleProgramUpdate();
         }
 
-        function updateProgram() {
+        function clearHostScreen() {
             if (watchingHost.system.clearScreen) {
                 watchingHost.system.clearScreen();
             }
+        }
+
+        function updateProgram() {
+            clearHostScreen();
 
             timerToUpdateProgram = undefined;
             reportWatchDiagnostic(createCompilerDiagnostic(Diagnostics.File_change_detected_Starting_incremental_compilation));