Merge branch 'master' of https://github.com/Microsoft/TypeScript into bug/29880

README.md

@@ -1,11 +1,13 @@
-[![Build Status](https://travis-ci.org/Microsoft/TypeScript.svg?branch=master)](https://travis-ci.org/Microsoft/TypeScript)
-[![VSTS Build Status](https://dev.azure.com/typescript/TypeScript/_apis/build/status/Typescript/node10)](https://dev.azure.com/typescript/TypeScript/_build/latest?definitionId=4&view=logs) 
-[![npm version](https://badge.fury.io/js/typescript.svg)](https://www.npmjs.com/package/typescript)
-[![Downloads](https://img.shields.io/npm/dm/typescript.svg)](https://www.npmjs.com/package/typescript)
 
 # TypeScript
 
 [![Join the chat at https://gitter.im/Microsoft/TypeScript](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Microsoft/TypeScript?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Build Status](https://travis-ci.org/microsoft/TypeScript.svg?branch=master)](https://travis-ci.org/Microsoft/TypeScript)
+[![VSTS Build Status](https://dev.azure.com/typescript/TypeScript/_apis/build/status/Typescript/node10)](https://dev.azure.com/typescript/TypeScript/_build/latest?definitionId=4&view=logs)
+[![npm version](https://badge.fury.io/js/typescript.svg)](https://www.npmjs.com/package/typescript)
+[![Downloads](https://img.shields.io/npm/dm/typescript.svg)](https://www.npmjs.com/package/typescript)
+
+
 
 [TypeScript](https://www.typescriptlang.org/) is a language for application-scale JavaScript. TypeScript adds optional types to JavaScript that support tools for large-scale JavaScript applications for any browser, for any host, on any OS. TypeScript compiles to readable, standards-based JavaScript. Try it out at the [playground](https://www.typescriptlang.org/play/), and stay up to date via [our blog](https://blogs.msdn.microsoft.com/typescript) and [Twitter account](https://twitter.com/typescript).
 
@@ -28,14 +30,14 @@ npm install -g typescript@next
 There are many ways to [contribute](https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md) to TypeScript.
 * [Submit bugs](https://github.com/Microsoft/TypeScript/issues) and help us verify fixes as they are checked in.
 * Review the [source code changes](https://github.com/Microsoft/TypeScript/pulls).
-* Engage with other TypeScript users and developers on [StackOverflow](https://stackoverflow.com/questions/tagged/typescript). 
+* Engage with other TypeScript users and developers on [StackOverflow](https://stackoverflow.com/questions/tagged/typescript).
 * Join the [#typescript](https://twitter.com/search?q=%23TypeScript) discussion on Twitter.
 * [Contribute bug fixes](https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md).
 * Read the language specification ([docx](https://github.com/Microsoft/TypeScript/blob/master/doc/TypeScript%20Language%20Specification.docx?raw=true),
  [pdf](https://github.com/Microsoft/TypeScript/blob/master/doc/TypeScript%20Language%20Specification.pdf?raw=true), [md](https://github.com/Microsoft/TypeScript/blob/master/doc/spec.md)).
 
-This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see 
-the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) 
+This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see
+the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com)
 with any additional questions or comments.
 
 ## Documentation
@@ -71,17 +73,17 @@ npm install
 Use one of the following to build and test:
 
 ```
-gulp local            # Build the compiler into built/local 
-gulp clean            # Delete the built compiler 
+gulp local            # Build the compiler into built/local
+gulp clean            # Delete the built compiler
 gulp LKG              # Replace the last known good with the built one.
                       # Bootstrapping step to be executed when the built compiler reaches a stable state.
-gulp tests            # Build the test infrastructure using the built compiler. 
-gulp runtests         # Run tests using the built compiler and test infrastructure. 
-                      # You can override the host or specify a test for this command. 
-                      # Use --host=<hostName> or --tests=<testPath>. 
+gulp tests            # Build the test infrastructure using the built compiler.
+gulp runtests         # Run tests using the built compiler and test infrastructure.
+                      # You can override the host or specify a test for this command.
+                      # Use --host=<hostName> or --tests=<testPath>.
 gulp baseline-accept  # This replaces the baseline test results with the results obtained from gulp runtests.
 gulp lint             # Runs tslint on the TypeScript source.
-gulp help             # List the above commands. 
+gulp help             # List the above commands.
 ```
 
 

src/compiler/binder.ts

@@ -2515,7 +2515,7 @@ namespace ts {
                     break;
 
                 default:
-                    Debug.fail(Debug.showSyntaxKind(thisContainer));
+                    Debug.failBadSyntaxKind(thisContainer);
             }
         }
 
@@ -2581,7 +2581,7 @@ namespace ts {
             // Fix up parent pointers since we're going to use these nodes before we bind into them
             node.left.parent = node;
             node.right.parent = node;
-            if (isIdentifier(lhs.expression) && container === file && isNameOfExportsOrModuleExportsAliasDeclaration(file, lhs.expression)) {
+            if (isIdentifier(lhs.expression) && container === file && isExportsOrModuleExportsOrAlias(file, lhs.expression)) {
                 // This can be an alias for the 'exports' or 'module.exports' names, e.g.
                 //    var util = module.exports;
                 //    util.property = function ...
@@ -2975,21 +2975,27 @@ namespace ts {
     }
 
     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, /*excludeCompoundAssignment*/ true) && (
-                isExportsOrModuleExportsOrAliasOrAssignment(sourceFile, node.left) || isExportsOrModuleExportsOrAliasOrAssignment(sourceFile, node.right)));
+        let i = 0;
+        const q = [node];
+        while (q.length && i < 100) {
+            i++;
+            node = q.shift()!;
+            if (isExportsIdentifier(node) || isModuleExportsPropertyAccessExpression(node)) {
+                return true;
+            }
+            else if (isIdentifier(node)) {
+                const symbol = lookupSymbolForNameWorker(sourceFile, node.escapedText);
+                if (!!symbol && !!symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration) && !!symbol.valueDeclaration.initializer) {
+                    const init = symbol.valueDeclaration.initializer;
+                    q.push(init);
+                    if (isAssignmentExpression(init, /*excludeCompoundAssignment*/ true)) {
+                        q.push(init.left);
+                        q.push(init.right);
+                    }
+                }
+            }
+        }
+        return false;
     }
 
     function lookupSymbolForNameWorker(container: Node, name: __String): Symbol | undefined {

src/compiler/commandLineParser.ts

@@ -2361,7 +2361,7 @@ namespace ts {
             if (!host.fileExists(extendedConfigPath) && !endsWith(extendedConfigPath, Extension.Json)) {
                 extendedConfigPath = `${extendedConfigPath}.json`;
                 if (!host.fileExists(extendedConfigPath)) {
-                    errors.push(createDiagnostic(Diagnostics.File_0_does_not_exist, extendedConfig));
+                    errors.push(createDiagnostic(Diagnostics.File_0_not_found, extendedConfig));
                     return undefined;
                 }
             }
@@ -2372,7 +2372,7 @@ namespace ts {
         if (resolved.resolvedModule) {
             return resolved.resolvedModule.resolvedFileName;
         }
-        errors.push(createDiagnostic(Diagnostics.File_0_does_not_exist, extendedConfig));
+        errors.push(createDiagnostic(Diagnostics.File_0_not_found, extendedConfig));
         return undefined;
     }
 

src/compiler/core.ts

@@ -239,7 +239,7 @@ namespace ts {
                     }
 
                     // When the deleted entry was the last one, we need to
-                    // adust the lastEntry reference.
+                    // adjust the lastEntry reference.
                     if (this.lastEntry === entry) {
                         this.lastEntry = previousEntry;
                     }
@@ -1255,7 +1255,7 @@ namespace ts {
     }
 
     /**
-     * Returns the only element of an array if it contains only one element; otheriwse, returns the
+     * Returns the only element of an array if it contains only one element; otherwise, returns the
      * array.
      */
     export function singleOrMany<T>(array: T[]): T | T[];
@@ -1400,8 +1400,8 @@ namespace ts {
     /** Shims `Array.from`. */
     export function arrayFrom<T, U>(iterator: Iterator<T> | IterableIterator<T>, map: (t: T) => U): U[];
     export function arrayFrom<T>(iterator: Iterator<T> | IterableIterator<T>): T[];
-    export function arrayFrom(iterator: Iterator<any> | IterableIterator<any>, map?: (t: any) => any): any[] {
-        const result: any[] = [];
+    export function arrayFrom<T, U>(iterator: Iterator<T> | IterableIterator<T>, map?: (t: T) => U): (T | U)[] {
+        const result: (T | U)[] = [];
         for (let { value, done } = iterator.next(); !done; { value, done } = iterator.next()) {
             result.push(map ? map(value) : value);
         }
@@ -1686,89 +1686,6 @@ namespace ts {
     export type AnyFunction = (...args: never[]) => void;
     export type AnyConstructor = new (...args: unknown[]) => unknown;
 
-    export namespace Debug {
-        export let currentAssertionLevel = AssertionLevel.None;
-        export let isDebugging = false;
-
-        export function shouldAssert(level: AssertionLevel): boolean {
-            return currentAssertionLevel >= level;
-        }
-
-        export function assert(expression: boolean, message?: string, verboseDebugInfo?: string | (() => string), stackCrawlMark?: AnyFunction): void {
-            if (!expression) {
-                if (verboseDebugInfo) {
-                    message += "\r\nVerbose Debug Information: " + (typeof verboseDebugInfo === "string" ? verboseDebugInfo : verboseDebugInfo());
-                }
-                fail(message ? "False expression: " + message : "False expression.", stackCrawlMark || assert);
-            }
-        }
-
-        export function assertEqual<T>(a: T, b: T, msg?: string, msg2?: string): void {
-            if (a !== b) {
-                const message = msg ? msg2 ? `${msg} ${msg2}` : msg : "";
-                fail(`Expected ${a} === ${b}. ${message}`);
-            }
-        }
-
-        export function assertLessThan(a: number, b: number, msg?: string): void {
-            if (a >= b) {
-                fail(`Expected ${a} < ${b}. ${msg || ""}`);
-            }
-        }
-
-        export function assertLessThanOrEqual(a: number, b: number): void {
-            if (a > b) {
-                fail(`Expected ${a} <= ${b}`);
-            }
-        }
-
-        export function assertGreaterThanOrEqual(a: number, b: number): void {
-            if (a < b) {
-                fail(`Expected ${a} >= ${b}`);
-            }
-        }
-
-        export function fail(message?: string, stackCrawlMark?: AnyFunction): never {
-            debugger;
-            const e = new Error(message ? `Debug Failure. ${message}` : "Debug Failure.");
-            if ((<any>Error).captureStackTrace) {
-                (<any>Error).captureStackTrace(e, stackCrawlMark || fail);
-            }
-            throw e;
-        }
-
-        export function assertDefined<T>(value: T | null | undefined, message?: string): T {
-            if (value === undefined || value === null) return fail(message);
-            return value;
-        }
-
-        export function assertEachDefined<T, A extends ReadonlyArray<T>>(value: A, message?: string): A {
-            for (const v of value) {
-                assertDefined(v, message);
-            }
-            return value;
-        }
-
-        export function assertNever(member: never, message = "Illegal value:", stackCrawlMark?: AnyFunction): never {
-            const detail = typeof member === "object" && "kind" in member && "pos" in member ? "SyntaxKind: " + showSyntaxKind(member as Node) : JSON.stringify(member);
-            return fail(`${message} ${detail}`, stackCrawlMark || assertNever);
-        }
-
-        export function getFunctionName(func: AnyFunction) {
-            if (typeof func !== "function") {
-                return "";
-            }
-            else if (func.hasOwnProperty("name")) {
-                return (<any>func).name;
-            }
-            else {
-                const text = Function.prototype.toString.call(func);
-                const match = /^function\s+([\w\$]+)\s*\(/.exec(text);
-                return match ? match[1] : "";
-            }
-        }
-    }
-
     export function equateValues<T>(a: T, b: T) {
         return a === b;
     }

src/compiler/debug.ts

@@ -0,0 +1,261 @@
+/* @internal */
+namespace ts {
+    export namespace Debug {
+        export let currentAssertionLevel = AssertionLevel.None;
+        export let isDebugging = false;
+
+        export function shouldAssert(level: AssertionLevel): boolean {
+            return currentAssertionLevel >= level;
+        }
+
+        export function assert(expression: boolean, message?: string, verboseDebugInfo?: string | (() => string), stackCrawlMark?: AnyFunction): void {
+            if (!expression) {
+                if (verboseDebugInfo) {
+                    message += "\r\nVerbose Debug Information: " + (typeof verboseDebugInfo === "string" ? verboseDebugInfo : verboseDebugInfo());
+                }
+                fail(message ? "False expression: " + message : "False expression.", stackCrawlMark || assert);
+            }
+        }
+
+        export function assertEqual<T>(a: T, b: T, msg?: string, msg2?: string): void {
+            if (a !== b) {
+                const message = msg ? msg2 ? `${msg} ${msg2}` : msg : "";
+                fail(`Expected ${a} === ${b}. ${message}`);
+            }
+        }
+
+        export function assertLessThan(a: number, b: number, msg?: string): void {
+            if (a >= b) {
+                fail(`Expected ${a} < ${b}. ${msg || ""}`);
+            }
+        }
+
+        export function assertLessThanOrEqual(a: number, b: number): void {
+            if (a > b) {
+                fail(`Expected ${a} <= ${b}`);
+            }
+        }
+
+        export function assertGreaterThanOrEqual(a: number, b: number): void {
+            if (a < b) {
+                fail(`Expected ${a} >= ${b}`);
+            }
+        }
+
+        export function fail(message?: string, stackCrawlMark?: AnyFunction): never {
+            debugger;
+            const e = new Error(message ? `Debug Failure. ${message}` : "Debug Failure.");
+            if ((<any>Error).captureStackTrace) {
+                (<any>Error).captureStackTrace(e, stackCrawlMark || fail);
+            }
+            throw e;
+        }
+
+        export function assertDefined<T>(value: T | null | undefined, message?: string): T {
+            if (value === undefined || value === null) return fail(message);
+            return value;
+        }
+
+        export function assertEachDefined<T, A extends ReadonlyArray<T>>(value: A, message?: string): A {
+            for (const v of value) {
+                assertDefined(v, message);
+            }
+            return value;
+        }
+
+        export function assertNever(member: never, message = "Illegal value:", stackCrawlMark?: AnyFunction): never {
+            const detail = typeof member === "object" && "kind" in member && "pos" in member && formatSyntaxKind ? "SyntaxKind: " + formatSyntaxKind((member as Node).kind) : JSON.stringify(member);
+            return fail(`${message} ${detail}`, stackCrawlMark || assertNever);
+        }
+
+        export function getFunctionName(func: AnyFunction) {
+            if (typeof func !== "function") {
+                return "";
+            }
+            else if (func.hasOwnProperty("name")) {
+                return (<any>func).name;
+            }
+            else {
+                const text = Function.prototype.toString.call(func);
+                const match = /^function\s+([\w\$]+)\s*\(/.exec(text);
+                return match ? match[1] : "";
+            }
+        }
+
+        export function formatSymbol(symbol: Symbol): string {
+            return `{ name: ${unescapeLeadingUnderscores(symbol.escapedName)}; flags: ${formatSymbolFlags(symbol.flags)}; declarations: ${map(symbol.declarations, node => formatSyntaxKind(node.kind))} }`;
+        }
+
+        /**
+         * Formats an enum value as a string for debugging and debug assertions.
+         */
+        export function formatEnum(value = 0, enumObject: any, isFlags?: boolean) {
+            const members = getEnumMembers(enumObject);
+            if (value === 0) {
+                return members.length > 0 && members[0][0] === 0 ? members[0][1] : "0";
+            }
+            if (isFlags) {
+                let result = "";
+                let remainingFlags = value;
+                for (let i = members.length - 1; i >= 0 && remainingFlags !== 0; i--) {
+                    const [enumValue, enumName] = members[i];
+                    if (enumValue !== 0 && (remainingFlags & enumValue) === enumValue) {
+                        remainingFlags &= ~enumValue;
+                        result = `${enumName}${result ? "|" : ""}${result}`;
+                    }
+                }
+                if (remainingFlags === 0) {
+                    return result;
+                }
+            }
+            else {
+                for (const [enumValue, enumName] of members) {
+                    if (enumValue === value) {
+                        return enumName;
+                    }
+                }
+            }
+            return value.toString();
+        }
+
+        function getEnumMembers(enumObject: any) {
+            const result: [number, string][] = [];
+            for (const name in enumObject) {
+                const value = enumObject[name];
+                if (typeof value === "number") {
+                    result.push([value, name]);
+                }
+            }
+
+            return stableSort<[number, string]>(result, (x, y) => compareValues(x[0], y[0]));
+        }
+
+        export function formatSyntaxKind(kind: SyntaxKind | undefined): string {
+            return formatEnum(kind, (<any>ts).SyntaxKind, /*isFlags*/ false);
+        }
+
+        export function formatNodeFlags(flags: NodeFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).NodeFlags, /*isFlags*/ true);
+        }
+
+        export function formatModifierFlags(flags: ModifierFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).ModifierFlags, /*isFlags*/ true);
+        }
+
+        export function formatTransformFlags(flags: TransformFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).TransformFlags, /*isFlags*/ true);
+        }
+
+        export function formatEmitFlags(flags: EmitFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).EmitFlags, /*isFlags*/ true);
+        }
+
+        export function formatSymbolFlags(flags: SymbolFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).SymbolFlags, /*isFlags*/ true);
+        }
+
+        export function formatTypeFlags(flags: TypeFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).TypeFlags, /*isFlags*/ true);
+        }
+
+        export function formatObjectFlags(flags: ObjectFlags | undefined): string {
+            return formatEnum(flags, (<any>ts).ObjectFlags, /*isFlags*/ true);
+        }
+
+        export function failBadSyntaxKind(node: Node, message?: string): never {
+            return fail(
+                `${message || "Unexpected node."}\r\nNode ${formatSyntaxKind(node.kind)} was unexpected.`,
+                failBadSyntaxKind);
+        }
+
+        export const assertEachNode = shouldAssert(AssertionLevel.Normal)
+            ? (nodes: Node[], test: (node: Node) => boolean, message?: string): void => assert(
+                test === undefined || every(nodes, test),
+                message || "Unexpected node.",
+                () => `Node array did not pass test '${getFunctionName(test)}'.`,
+                assertEachNode)
+            : noop;
+
+        export const assertNode = shouldAssert(AssertionLevel.Normal)
+            ? (node: Node | undefined, test: ((node: Node | undefined) => boolean) | undefined, message?: string): void => assert(
+                test === undefined || test(node),
+                message || "Unexpected node.",
+                () => `Node ${formatSyntaxKind(node!.kind)} did not pass test '${getFunctionName(test!)}'.`,
+                assertNode)
+            : noop;
+
+        export const assertOptionalNode = shouldAssert(AssertionLevel.Normal)
+            ? (node: Node, test: (node: Node) => boolean, message?: string): void => assert(
+                test === undefined || node === undefined || test(node),
+                message || "Unexpected node.",
+                () => `Node ${formatSyntaxKind(node.kind)} did not pass test '${getFunctionName(test)}'.`,
+                assertOptionalNode)
+            : noop;
+
+        export const assertOptionalToken = shouldAssert(AssertionLevel.Normal)
+            ? (node: Node, kind: SyntaxKind, message?: string): void => assert(
+                kind === undefined || node === undefined || node.kind === kind,
+                message || "Unexpected node.",
+                () => `Node ${formatSyntaxKind(node.kind)} was not a '${formatSyntaxKind(kind)}' token.`,
+                assertOptionalToken)
+            : noop;
+
+        export const assertMissingNode = shouldAssert(AssertionLevel.Normal)
+            ? (node: Node, message?: string): void => assert(
+                node === undefined,
+                message || "Unexpected node.",
+                () => `Node ${formatSyntaxKind(node.kind)} was unexpected'.`,
+                assertMissingNode)
+            : noop;
+
+        let isDebugInfoEnabled = false;
+
+        /**
+         * Injects debug information into frequently used types.
+         */
+        export function enableDebugInfo() {
+            if (isDebugInfoEnabled) return;
+
+            // Add additional properties in debug mode to assist with debugging.
+            Object.defineProperties(objectAllocator.getSymbolConstructor().prototype, {
+                __debugFlags: { get(this: Symbol) { return formatSymbolFlags(this.flags); } }
+            });
+
+            Object.defineProperties(objectAllocator.getTypeConstructor().prototype, {
+                __debugFlags: { get(this: Type) { return formatTypeFlags(this.flags); } },
+                __debugObjectFlags: { get(this: Type) { return this.flags & TypeFlags.Object ? formatObjectFlags((<ObjectType>this).objectFlags) : ""; } },
+                __debugTypeToString: { value(this: Type) { return this.checker.typeToString(this); } },
+            });
+
+            const nodeConstructors = [
+                objectAllocator.getNodeConstructor(),
+                objectAllocator.getIdentifierConstructor(),
+                objectAllocator.getTokenConstructor(),
+                objectAllocator.getSourceFileConstructor()
+            ];
+
+            for (const ctor of nodeConstructors) {
+                if (!ctor.prototype.hasOwnProperty("__debugKind")) {
+                    Object.defineProperties(ctor.prototype, {
+                        __debugKind: { get(this: Node) { return formatSyntaxKind(this.kind); } },
+                        __debugNodeFlags: { get(this: Node) { return formatNodeFlags(this.flags); } },
+                        __debugModifierFlags: { get(this: Node) { return formatModifierFlags(getModifierFlagsNoCache(this)); } },
+                        __debugTransformFlags: { get(this: Node) { return formatTransformFlags(this.transformFlags); } },
+                        __debugIsParseTreeNode: { get(this: Node) { return isParseTreeNode(this); } },
+                        __debugEmitFlags: { get(this: Node) { return formatEmitFlags(getEmitFlags(this)); } },
+                        __debugGetText: {
+                            value(this: Node, includeTrivia?: boolean) {
+                                if (nodeIsSynthesized(this)) return "";
+                                const parseNode = getParseTreeNode(this);
+                                const sourceFile = parseNode && getSourceFileOfNode(parseNode);
+                                return sourceFile ? getSourceTextOfNodeFromSourceFile(sourceFile, parseNode, includeTrivia) : "";
+                            }
+                        }
+                    });
+                }
+            }
+
+            isDebugInfoEnabled = true;
+        }
+    }
+}

src/compiler/diagnosticMessages.json

@@ -655,7 +655,7 @@
         "category": "Error",
         "code": 1207
     },
-    "Cannot compile namespaces when the '--isolatedModules' flag is provided.": {
+    "All files must be modules when the '--isolatedModules' flag is provided.": {
         "category": "Error",
         "code": 1208
     },
@@ -3811,10 +3811,6 @@
         "category": "Error",
         "code": 6189
     },
-    "Found 'package.json' at '{0}'. Package ID is '{1}'.": {
-        "category": "Message",
-        "code": 6190
-    },
     "Whether to keep outdated console output in watch mode instead of clearing the screen.": {
         "category": "Message",
         "code": 6191
@@ -3923,6 +3919,18 @@
         "category": "Message",
         "code": 6217
     },
+    "======== Module name '{0}' was successfully resolved to '{1}' with Package ID '{2}'. ========": {
+        "category": "Message",
+        "code": 6218
+    },
+    "======== Type reference directive '{0}' was successfully resolved to '{1}' with Package ID '{2}', primary: {3}. ========": {
+        "category": "Message",
+        "code": 6219
+    },
+    "'package.json' had a falsy '{0}' field.": {
+        "category": "Message",
+        "code": 6220
+    },
 
     "Projects to reference": {
         "category": "Message",
@@ -4284,6 +4292,14 @@
         "category": "Error",
         "code": 7052
     },
+    "Element implicitly has an 'any' type because expression of type '{0}' can't be used to index type '{1}'.": {
+        "category": "Error",
+        "code": 7053
+    },    
+    "No index signature with a parameter of type '{0}' was found on type '{1}'.": {
+        "category": "Error",
+        "code": 7054
+    },
     "You cannot rename this element.": {
         "category": "Error",
         "code": 8000
@@ -4962,7 +4978,20 @@
         "category": "Message",
         "code": 95076
     },
-    "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer." :{
+    "Extract type": {
+        "category": "Message",
+        "code": 95077
+    },
+    "Extract to type alias": {
+        "category": "Message",
+        "code": 95078
+    },
+    "Extract to typedef": {
+        "category": "Message",
+        "code": 95079
+    },
+
+    "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",
         "code": 18004
     },

src/compiler/emitter.ts

@@ -222,7 +222,7 @@ namespace ts {
 
     /*@internal*/
     // targetSourceFile is when users only want one file in entire project to be emitted. This is used in compileOnSave feature
-    export function emitFiles(resolver: EmitResolver, host: EmitHost, targetSourceFile: SourceFile | undefined, emitOnlyDtsFiles?: boolean, transformers?: TransformerFactory<Bundle | SourceFile>[], declarationTransformers?: TransformerFactory<Bundle | SourceFile>[], onlyBuildInfo?: boolean): EmitResult {
+    export function emitFiles(resolver: EmitResolver, host: EmitHost, targetSourceFile: SourceFile | undefined, { scriptTransformers, declarationTransformers }: EmitTransformers, emitOnlyDtsFiles?: boolean, onlyBuildInfo?: boolean): EmitResult {
         const compilerOptions = host.getCompilerOptions();
         const sourceMapDataList: SourceMapEmitResult[] | undefined = (compilerOptions.sourceMap || compilerOptions.inlineSourceMap || getAreDeclarationMapsEnabled(compilerOptions)) ? [] : undefined;
         const emittedFilesList: string[] | undefined = compilerOptions.listEmittedFiles ? [] : undefined;
@@ -303,7 +303,7 @@ namespace ts {
                 return;
             }
             // Transform the source files
-            const transform = transformNodes(resolver, host, compilerOptions, [sourceFileOrBundle], transformers!, /*allowDtsFiles*/ false);
+            const transform = transformNodes(resolver, host, compilerOptions, [sourceFileOrBundle], scriptTransformers, /*allowDtsFiles*/ false);
 
             const printerOptions: PrinterOptions = {
                 removeComments: compilerOptions.removeComments,
@@ -349,7 +349,7 @@ namespace ts {
                 // Do that here when emitting only dts files
                 nonJsFiles.forEach(collectLinkedAliases);
             }
-            const declarationTransform = transformNodes(resolver, host, compilerOptions, inputListOrBundle, concatenate([transformDeclarations], declarationTransformers), /*allowDtsFiles*/ false);
+            const declarationTransform = transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (length(declarationTransform.diagnostics)) {
                 for (const diagnostic of declarationTransform.diagnostics!) {
                     emitterDiagnostics.add(diagnostic);
@@ -723,7 +723,7 @@ namespace ts {
             useCaseSensitiveFileNames: () => host.useCaseSensitiveFileNames(),
             getProgramBuildInfo: returnUndefined
         };
-        emitFiles(notImplementedResolver, emitHost, /*targetSourceFile*/ undefined, /*emitOnlyDtsFiles*/ false, getTransformers(config.options));
+        emitFiles(notImplementedResolver, emitHost, /*targetSourceFile*/ undefined, getTransformers(config.options), /*emitOnlyDtsFiles*/ false);
         return outputFiles;
     }
 
@@ -4527,6 +4527,8 @@ namespace ts {
                 case SyntaxKind.GetAccessor:
                 case SyntaxKind.SetAccessor:
                     return generateNameForMethodOrAccessor(<MethodDeclaration | AccessorDeclaration>node);
+                case SyntaxKind.ComputedPropertyName:
+                    return makeTempVariableName(TempFlags.Auto, /*reserveInNestedScopes*/ true);
                 default:
                     return makeTempVariableName(TempFlags.Auto);
             }

src/compiler/factory.ts

@@ -1004,10 +1004,10 @@ namespace ts {
             : node;
     }
 
-    export function createPropertyAccess(expression: Expression, name: string | Identifier | undefined) {
+    export function createPropertyAccess(expression: Expression, name: string | Identifier) {
         const node = <PropertyAccessExpression>createSynthesizedNode(SyntaxKind.PropertyAccessExpression);
         node.expression = parenthesizeForAccess(expression);
-        node.name = asName(name)!; // TODO: GH#18217
+        node.name = asName(name);
         setEmitFlags(node, EmitFlags.NoIndentation);
         return node;
     }
@@ -2468,7 +2468,7 @@ namespace ts {
 
     export function createSpreadAssignment(expression: Expression) {
         const node = <SpreadAssignment>createSynthesizedNode(SyntaxKind.SpreadAssignment);
-        node.expression = expression !== undefined ? parenthesizeExpressionForList(expression) : undefined!; // TODO: GH#18217
+        node.expression = parenthesizeExpressionForList(expression);
         return node;
     }
 
@@ -2949,7 +2949,7 @@ namespace ts {
         return node;
     }
 
-    export function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends: ReadonlyArray<UnparsedSource> = emptyArray) {
+    export function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends: ReadonlyArray<UnparsedSource | InputFiles> = emptyArray) {
         if (node.sourceFiles !== sourceFiles || node.prepends !== prepends) {
             return createBundle(sourceFiles, prepends);
         }

src/compiler/moduleNameResolver.ts

@@ -16,12 +16,23 @@ namespace ts {
         push(value: T): void;
     }
 
-    function withPackageId(packageId: PackageId | undefined, r: PathAndExtension | undefined): Resolved | undefined {
+    function withPackageId(packageInfo: PackageJsonInfo | undefined, r: PathAndExtension | undefined): Resolved | undefined {
+        let packageId: PackageId | undefined;
+        if (r && packageInfo) {
+            const packageJsonContent = packageInfo.packageJsonContent as PackageJson;
+            if (typeof packageJsonContent.name === "string" && typeof packageJsonContent.version === "string") {
+                packageId = {
+                    name: packageJsonContent.name,
+                    subModuleName: r.path.slice(packageInfo.packageDirectory.length + directorySeparator.length),
+                    version: packageJsonContent.version
+                };
+            }
+        }
         return r && { path: r.path, extension: r.ext, packageId };
     }
 
     function noPackageId(r: PathAndExtension | undefined): Resolved | undefined {
-        return withPackageId(/*packageId*/ undefined, r);
+        return withPackageId(/*packageInfo*/ undefined, r);
     }
 
     function removeIgnoredPackageId(r: Resolved | undefined): PathAndExtension | undefined {
@@ -130,7 +141,15 @@ namespace ts {
 
     function readPackageJsonPathField<K extends "typings" | "types" | "main" | "tsconfig">(jsonContent: PackageJson, fieldName: K, baseDirectory: string, state: ModuleResolutionState): PackageJson[K] | undefined {
         const fileName = readPackageJsonField(jsonContent, fieldName, "string", state);
-        if (fileName === undefined) return;
+        if (fileName === undefined) {
+            return;
+        }
+        if (!fileName) {
+            if (state.traceEnabled) {
+                trace(state.host, Diagnostics.package_json_had_a_falsy_0_field, fieldName);
+            }
+            return;
+        }
         const path = normalizePath(combinePaths(baseDirectory, fileName));
         if (state.traceEnabled) {
             trace(state.host, Diagnostics.package_json_has_0_field_1_that_references_2, fieldName, fileName, path);
@@ -307,7 +326,12 @@ namespace ts {
             const { fileName, packageId } = resolved;
             const resolvedFileName = options.preserveSymlinks ? fileName : realPath(fileName, host, traceEnabled);
             if (traceEnabled) {
-                trace(host, Diagnostics.Type_reference_directive_0_was_successfully_resolved_to_1_primary_Colon_2, typeReferenceDirectiveName, resolvedFileName, primary);
+                if (packageId) {
+                    trace(host, Diagnostics.Type_reference_directive_0_was_successfully_resolved_to_1_with_Package_ID_2_primary_Colon_3, typeReferenceDirectiveName, resolvedFileName, packageIdToString(packageId), primary);
+                }
+                else {
+                    trace(host, Diagnostics.Type_reference_directive_0_was_successfully_resolved_to_1_primary_Colon_2, typeReferenceDirectiveName, resolvedFileName, primary);
+                }
             }
             resolvedTypeReferenceDirective = { primary, resolvedFileName, packageId, isExternalLibraryImport: pathContainsNodeModules(fileName) };
         }
@@ -663,7 +687,12 @@ namespace ts {
 
         if (traceEnabled) {
             if (result.resolvedModule) {
-                trace(host, Diagnostics.Module_name_0_was_successfully_resolved_to_1, moduleName, result.resolvedModule.resolvedFileName);
+                if (result.resolvedModule.packageId) {
+                    trace(host, Diagnostics.Module_name_0_was_successfully_resolved_to_1_with_Package_ID_2, moduleName, result.resolvedModule.resolvedFileName, packageIdToString(result.resolvedModule.packageId));
+                }
+                else {
+                    trace(host, Diagnostics.Module_name_0_was_successfully_resolved_to_1, moduleName, result.resolvedModule.resolvedFileName);
+                }
             }
             else {
                 trace(host, Diagnostics.Module_name_0_was_not_resolved, moduleName);
@@ -968,10 +997,9 @@ namespace ts {
             }
             const resolvedFromFile = loadModuleFromFile(extensions, candidate, onlyRecordFailures, state);
             if (resolvedFromFile) {
-                const nm = considerPackageJson ? parseNodeModuleFromPath(resolvedFromFile) : undefined;
-                const packageInfo = nm && getPackageJsonInfo(nm.packageDirectory, nm.subModuleName, /*onlyRecordFailures*/ false, state);
-                const packageId = packageInfo && packageInfo.packageId;
-                return withPackageId(packageId, resolvedFromFile);
+                const packageDirectory = considerPackageJson ? parseNodeModuleFromPath(resolvedFromFile) : undefined;
+                const packageInfo = packageDirectory ? getPackageJsonInfo(packageDirectory, /*onlyRecordFailures*/ false, state) : undefined;
+                return withPackageId(packageInfo, resolvedFromFile);
             }
         }
         if (!onlyRecordFailures) {
@@ -998,13 +1026,12 @@ namespace ts {
      * (Not neeeded for `loadModuleFromNodeModules` as that looks up the `package.json` as part of resolution.)
      *
      * packageDirectory is the directory of the package itself.
-     * subModuleName is the path within the package.
-     *   For `blah/node_modules/foo/index.d.ts` this is { packageDirectory: "foo", subModuleName: "index.d.ts" }. (Part before "/node_modules/" is ignored.)
-     *   For `/node_modules/foo/bar.d.ts` this is { packageDirectory: "foo", subModuleName": "bar/index.d.ts" }.
-     *   For `/node_modules/@types/foo/bar/index.d.ts` this is { packageDirectory: "@types/foo", subModuleName: "bar/index.d.ts" }.
-     *   For `/node_modules/foo/bar/index.d.ts` this is { packageDirectory: "foo", subModuleName": "bar/index.d.ts" }.
+     *   For `blah/node_modules/foo/index.d.ts` this is packageDirectory: "foo"
+     *   For `/node_modules/foo/bar.d.ts` this is packageDirectory: "foo"
+     *   For `/node_modules/@types/foo/bar/index.d.ts` this is packageDirectory: "@types/foo"
+     *   For `/node_modules/foo/bar/index.d.ts` this is packageDirectory: "foo"
      */
-    function parseNodeModuleFromPath(resolved: PathAndExtension): { packageDirectory: string, subModuleName: string } | undefined {
+    function parseNodeModuleFromPath(resolved: PathAndExtension): string | undefined {
         const path = normalizePath(resolved.path);
         const idx = path.lastIndexOf(nodeModulesPathPart);
         if (idx === -1) {
@@ -1016,9 +1043,7 @@ namespace ts {
         if (path.charCodeAt(indexAfterNodeModules) === CharacterCodes.at) {
             indexAfterPackageName = moveToNextDirectorySeparatorIfAvailable(path, indexAfterPackageName);
         }
-        const packageDirectory = path.slice(0, indexAfterPackageName);
-        const subModuleName = removeExtension(path.slice(indexAfterPackageName + 1), resolved.ext) + Extension.Dts;
-        return { packageDirectory, subModuleName };
+        return path.slice(0, indexAfterPackageName);
     }
 
     function moveToNextDirectorySeparatorIfAvailable(path: string, prevSeparatorIndex: number): number {
@@ -1026,19 +1051,6 @@ namespace ts {
         return nextSeparatorIndex === -1 ? prevSeparatorIndex : nextSeparatorIndex;
     }
 
-    function addExtensionAndIndex(path: string): string {
-        if (path === "") {
-            return "index.d.ts";
-        }
-        if (endsWith(path, ".d.ts")) {
-            return path;
-        }
-        if (path === "index" || endsWith(path, "/index")) {
-            return path + ".d.ts";
-        }
-        return path + "/index.d.ts";
-    }
-
     function loadModuleFromFileNoPackageId(extensions: Extensions, candidate: string, onlyRecordFailures: boolean, state: ModuleResolutionState): Resolved | undefined {
         return noPackageId(loadModuleFromFile(extensions, candidate, onlyRecordFailures, state));
     }
@@ -1119,61 +1131,29 @@ namespace ts {
     }
 
     function loadNodeModuleFromDirectory(extensions: Extensions, candidate: string, onlyRecordFailures: boolean, state: ModuleResolutionState, considerPackageJson = true) {
-        const packageInfo = considerPackageJson ? getPackageJsonInfo(candidate, "", onlyRecordFailures, state) : undefined;
-        const packageId = packageInfo && packageInfo.packageId;
+        const packageInfo = considerPackageJson ? getPackageJsonInfo(candidate, onlyRecordFailures, state) : undefined;
         const packageJsonContent = packageInfo && packageInfo.packageJsonContent;
         const versionPaths = packageInfo && packageInfo.versionPaths;
-        return withPackageId(packageId, loadNodeModuleFromDirectoryWorker(extensions, candidate, onlyRecordFailures, state, packageJsonContent, versionPaths));
+        return withPackageId(packageInfo, loadNodeModuleFromDirectoryWorker(extensions, candidate, onlyRecordFailures, state, packageJsonContent, versionPaths));
     }
 
     interface PackageJsonInfo {
-        packageJsonContent: PackageJsonPathFields | undefined;
-        packageId: PackageId | undefined;
+        packageDirectory: string;
+        packageJsonContent: PackageJsonPathFields;
         versionPaths: VersionPaths | undefined;
     }
 
-    function getPackageJsonInfo(packageDirectory: string, subModuleName: string, onlyRecordFailures: boolean, state: ModuleResolutionState): PackageJsonInfo | undefined {
+    function getPackageJsonInfo(packageDirectory: string, onlyRecordFailures: boolean, state: ModuleResolutionState): PackageJsonInfo | undefined {
         const { host, traceEnabled } = state;
         const directoryExists = !onlyRecordFailures && directoryProbablyExists(packageDirectory, host);
         const packageJsonPath = combinePaths(packageDirectory, "package.json");
         if (directoryExists && host.fileExists(packageJsonPath)) {
             const packageJsonContent = readJson(packageJsonPath, host) as PackageJson;
-            if (subModuleName === "") { // looking up the root - need to handle types/typings/main redirects for subModuleName
-                const path = readPackageJsonTypesFields(packageJsonContent, packageDirectory, state);
-                if (typeof path === "string") {
-                    subModuleName = addExtensionAndIndex(path.substring(packageDirectory.length + 1));
-                }
-                else {
-                    const jsPath = readPackageJsonMainField(packageJsonContent, packageDirectory, state);
-                    if (typeof jsPath === "string" && jsPath.length > packageDirectory.length) {
-                        const potentialSubModule = jsPath.substring(packageDirectory.length + 1);
-                        subModuleName = (forEach(supportedJSExtensions, extension =>
-                            tryRemoveExtension(potentialSubModule, extension)) || potentialSubModule) + Extension.Dts;
-                    }
-                    else {
-                        subModuleName = "index.d.ts";
-                    }
-                }
-            }
-
-            if (!endsWith(subModuleName, Extension.Dts)) {
-                subModuleName = addExtensionAndIndex(subModuleName);
-            }
-
-            const versionPaths = readPackageJsonTypesVersionPaths(packageJsonContent, state);
-            const packageId: PackageId | undefined = typeof packageJsonContent.name === "string" && typeof packageJsonContent.version === "string"
-                ? { name: packageJsonContent.name, subModuleName, version: packageJsonContent.version }
-                : undefined;
             if (traceEnabled) {
-                if (packageId) {
-                    trace(host, Diagnostics.Found_package_json_at_0_Package_ID_is_1, packageJsonPath, packageIdToString(packageId));
-                }
-                else {
-                    trace(host, Diagnostics.Found_package_json_at_0, packageJsonPath);
-                }
+                trace(host, Diagnostics.Found_package_json_at_0, packageJsonPath);
             }
-
-            return { packageJsonContent, packageId, versionPaths };
+            const versionPaths = readPackageJsonTypesVersionPaths(packageJsonContent, state);
+            return { packageDirectory, packageJsonContent, versionPaths };
         }
         else {
             if (directoryExists && traceEnabled) {
@@ -1328,27 +1308,36 @@ namespace ts {
         const candidate = normalizePath(combinePaths(nodeModulesDirectory, moduleName));
 
         // First look for a nested package.json, as in `node_modules/foo/bar/package.json`.
-        let packageJsonContent: PackageJsonPathFields | undefined;
-        let packageId: PackageId | undefined;
-        let versionPaths: VersionPaths | undefined;
-
-        const packageInfo = getPackageJsonInfo(candidate, "", !nodeModulesDirectoryExists, state);
+        let packageInfo = getPackageJsonInfo(candidate, !nodeModulesDirectoryExists, state);
         if (packageInfo) {
-            ({ packageJsonContent, packageId, versionPaths } = packageInfo);
             const fromFile = loadModuleFromFile(extensions, candidate, !nodeModulesDirectoryExists, state);
             if (fromFile) {
                 return noPackageId(fromFile);
             }
 
-            const fromDirectory = loadNodeModuleFromDirectoryWorker(extensions, candidate, !nodeModulesDirectoryExists, state, packageJsonContent, versionPaths);
-            return withPackageId(packageId, fromDirectory);
+            const fromDirectory = loadNodeModuleFromDirectoryWorker(
+                extensions,
+                candidate,
+                !nodeModulesDirectoryExists,
+                state,
+                packageInfo.packageJsonContent,
+                packageInfo.versionPaths
+            );
+            return withPackageId(packageInfo, fromDirectory);
         }
 
         const loader: ResolutionKindSpecificLoader = (extensions, candidate, onlyRecordFailures, state) => {
             const pathAndExtension =
                 loadModuleFromFile(extensions, candidate, onlyRecordFailures, state) ||
-                loadNodeModuleFromDirectoryWorker(extensions, candidate, onlyRecordFailures, state, packageJsonContent, versionPaths);
-            return withPackageId(packageId, pathAndExtension);
+                loadNodeModuleFromDirectoryWorker(
+                    extensions,
+                    candidate,
+                    onlyRecordFailures,
+                    state,
+                    packageInfo && packageInfo.packageJsonContent,
+                    packageInfo && packageInfo.versionPaths
+                );
+            return withPackageId(packageInfo, pathAndExtension);
         };
 
         const { packageName, rest } = parsePackageName(moduleName);
@@ -1356,14 +1345,13 @@ namespace ts {
             const packageDirectory = combinePaths(nodeModulesDirectory, packageName);
 
             // Don't use a "types" or "main" from here because we're not loading the root, but a subdirectory -- just here for the packageId and path mappings.
-            const packageInfo = getPackageJsonInfo(packageDirectory, rest, !nodeModulesDirectoryExists, state);
-            if (packageInfo) ({ packageId, versionPaths } = packageInfo);
-            if (versionPaths) {
+            packageInfo = getPackageJsonInfo(packageDirectory, !nodeModulesDirectoryExists, state);
+            if (packageInfo && packageInfo.versionPaths) {
                 if (state.traceEnabled) {
-                    trace(state.host, Diagnostics.package_json_has_a_typesVersions_entry_0_that_matches_compiler_version_1_looking_for_a_pattern_to_match_module_name_2, versionPaths.version, version, rest);
+                    trace(state.host, Diagnostics.package_json_has_a_typesVersions_entry_0_that_matches_compiler_version_1_looking_for_a_pattern_to_match_module_name_2, packageInfo.versionPaths.version, version, rest);
                 }
                 const packageDirectoryExists = nodeModulesDirectoryExists && directoryProbablyExists(packageDirectory, state.host);
-                const fromPaths = tryLoadModuleUsingPaths(extensions, rest, packageDirectory, versionPaths.paths, loader, !packageDirectoryExists, state);
+                const fromPaths = tryLoadModuleUsingPaths(extensions, rest, packageDirectory, packageInfo.versionPaths.paths, loader, !packageDirectoryExists, state);
                 if (fromPaths) {
                     return fromPaths.value;
                 }

src/compiler/moduleSpecifiers.ts

@@ -175,9 +175,9 @@ namespace ts.moduleSpecifiers {
 
     function discoverProbableSymlinks(files: ReadonlyArray<SourceFile>, getCanonicalFileName: GetCanonicalFileName, cwd: string): ReadonlyMap<string> {
         const result = createMap<string>();
-        const symlinks = mapDefined(files, sf =>
-            sf.resolvedModules && firstDefinedIterator(sf.resolvedModules.values(), res =>
-                res && res.originalPath && res.resolvedFileName !== res.originalPath ? [res.resolvedFileName, res.originalPath] : undefined));
+        const symlinks = flatten<readonly [string, string]>(mapDefined(files, sf =>
+            sf.resolvedModules && compact(arrayFrom(mapIterator(sf.resolvedModules.values(), res =>
+                res && res.originalPath && res.resolvedFileName !== res.originalPath ? [res.resolvedFileName, res.originalPath] as const : undefined)))));
         for (const [resolvedPath, originalPath] of symlinks) {
             const [commonResolved, commonOriginal] = guessDirectorySymlink(resolvedPath, originalPath, cwd, getCanonicalFileName);
             result.set(commonOriginal, commonResolved);

src/compiler/parser.ts

@@ -1328,6 +1328,8 @@ namespace ts {
             return node;
         }
 
+        function createMissingNode<T extends Node>(kind: T["kind"], reportAtCurrentPosition: false, diagnosticMessage?: DiagnosticMessage, arg0?: any): T;
+        function createMissingNode<T extends Node>(kind: T["kind"], reportAtCurrentPosition: boolean, diagnosticMessage: DiagnosticMessage, arg0?: any): T;
         function createMissingNode<T extends Node>(kind: T["kind"], reportAtCurrentPosition: boolean, diagnosticMessage: DiagnosticMessage, arg0?: any): T {
             if (reportAtCurrentPosition) {
                 parseErrorAtPosition(scanner.getStartPos(), 0, diagnosticMessage, arg0);
@@ -3122,15 +3124,16 @@ namespace ts {
         }
 
         function parseUnionOrIntersectionType(kind: SyntaxKind.UnionType | SyntaxKind.IntersectionType, parseConstituentType: () => TypeNode, operator: SyntaxKind.BarToken | SyntaxKind.AmpersandToken): TypeNode {
-            parseOptional(operator);
+            const start = scanner.getStartPos();
+            const hasLeadingOperator = parseOptional(operator);
             let type = parseConstituentType();
-            if (token() === operator) {
+            if (token() === operator || hasLeadingOperator) {
                 const types = [type];
                 while (parseOptional(operator)) {
                     types.push(parseConstituentType());
                 }
-                const node = <UnionOrIntersectionTypeNode>createNode(kind, type.pos);
-                node.types = createNodeArray(types, type.pos);
+                const node = <UnionOrIntersectionTypeNode>createNode(kind, start);
+                node.types = createNodeArray(types, start);
                 type = finishNode(node);
             }
             return type;
@@ -4290,7 +4293,7 @@ namespace ts {
                     badNode.end = invalidElement.end;
                     badNode.left = result;
                     badNode.right = invalidElement;
-                    badNode.operatorToken = createMissingNode(SyntaxKind.CommaToken, /*reportAtCurrentPosition*/ false, /*diagnosticMessage*/ undefined!); // TODO: GH#18217
+                    badNode.operatorToken = createMissingNode(SyntaxKind.CommaToken, /*reportAtCurrentPosition*/ false);
                     badNode.operatorToken.pos = badNode.operatorToken.end = badNode.right.pos;
                     return <JsxElement><Node>badNode;
                 }

src/compiler/program.ts

@@ -1453,9 +1453,8 @@ namespace ts {
                 notImplementedResolver,
                 getEmitHost(writeFileCallback),
                 /*targetSourceFile*/ undefined,
+                /*transformers*/ noTransformers,
                 /*emitOnlyDtsFiles*/ false,
-                /*transformers*/ undefined,
-                /*declaraitonTransformers*/ undefined,
                 /*onlyBuildInfo*/ true
             );
 
@@ -1574,14 +1573,12 @@ namespace ts {
 
             performance.mark("beforeEmit");
 
-            const transformers = emitOnlyDtsFiles ? [] : getTransformers(options, customTransformers);
             const emitResult = emitFiles(
                 emitResolver,
                 getEmitHost(writeFileCallback),
                 sourceFile,
+                getTransformers(options, customTransformers, emitOnlyDtsFiles),
                 emitOnlyDtsFiles,
-                transformers,
-                customTransformers && customTransformers.afterDeclarations
             );
 
             performance.mark("afterEmit");
@@ -2235,7 +2232,10 @@ namespace ts {
                     if (isRedirect) {
                         inputName = getProjectReferenceRedirect(fileName) || fileName;
                     }
-                    if (getNormalizedAbsolutePath(checkedName, currentDirectory) !== getNormalizedAbsolutePath(inputName, currentDirectory)) {
+                    // Check if it differs only in drive letters its ok to ignore that error:
+                    const checkedAbsolutePath = getNormalizedAbsolutePathWithoutRoot(checkedName, currentDirectory);
+                    const inputAbsolutePath = getNormalizedAbsolutePathWithoutRoot(inputName, currentDirectory);
+                    if (checkedAbsolutePath !== inputAbsolutePath) {
                         reportFileNamesDifferOnlyInCasingError(inputName, checkedName, refFile, refPos, refEnd);
                     }
                 }
@@ -2688,6 +2688,7 @@ namespace ts {
                     return undefined;
                 }
                 sourceFile = Debug.assertDefined(commandLine.options.configFile);
+                Debug.assert(!sourceFile.path || sourceFile.path === sourceFilePath);
                 addFileToFilesByName(sourceFile, sourceFilePath, /*redirectedPath*/ undefined);
             }
             else {
@@ -2699,11 +2700,12 @@ namespace ts {
                     projectReferenceRedirects.set(sourceFilePath, false);
                     return undefined;
                 }
-                sourceFile.path = sourceFilePath;
-                sourceFile.resolvedPath = sourceFilePath;
-                sourceFile.originalFileName = refPath;
                 commandLine = parseJsonSourceFileConfigFileContent(sourceFile, configParsingHost, basePath, /*existingOptions*/ undefined, refPath);
             }
+            sourceFile.path = sourceFilePath;
+            sourceFile.resolvedPath = sourceFilePath;
+            sourceFile.originalFileName = refPath;
+
             const resolvedRef: ResolvedProjectReference = { commandLine, sourceFile };
             projectReferenceRedirects.set(sourceFilePath, resolvedRef);
             if (commandLine.projectReferences) {
@@ -2856,10 +2858,10 @@ namespace ts {
                     createDiagnosticForOptionName(Diagnostics.Option_isolatedModules_can_only_be_used_when_either_option_module_is_provided_or_option_target_is_ES2015_or_higher, "isolatedModules", "target");
                 }
 
-                const firstNonExternalModuleSourceFile = find(files, f => !isExternalModule(f) && !f.isDeclarationFile && f.scriptKind !== ScriptKind.JSON);
+                const firstNonExternalModuleSourceFile = find(files, f => !isExternalModule(f) && !isSourceFileJS(f) && !f.isDeclarationFile && f.scriptKind !== ScriptKind.JSON);
                 if (firstNonExternalModuleSourceFile) {
                     const span = getErrorSpanForNode(firstNonExternalModuleSourceFile, firstNonExternalModuleSourceFile);
-                    programDiagnostics.add(createFileDiagnostic(firstNonExternalModuleSourceFile, span.start, span.length, Diagnostics.Cannot_compile_namespaces_when_the_isolatedModules_flag_is_provided));
+                    programDiagnostics.add(createFileDiagnostic(firstNonExternalModuleSourceFile, span.start, span.length, Diagnostics.All_files_must_be_modules_when_the_isolatedModules_flag_is_provided));
                 }
             }
             else if (firstNonAmbientExternalModuleSourceFile && languageVersion < ScriptTarget.ES2015 && options.module === ModuleKind.None) {

src/compiler/transformer.ts

@@ -24,13 +24,24 @@ namespace ts {
         EmitNotifications = 1 << 1,
     }
 
-    export function getTransformers(compilerOptions: CompilerOptions, customTransformers?: CustomTransformers) {
+    export const noTransformers: EmitTransformers = { scriptTransformers: emptyArray, declarationTransformers: emptyArray };
+
+    export function getTransformers(compilerOptions: CompilerOptions, customTransformers?: CustomTransformers, emitOnlyDtsFiles?: boolean): EmitTransformers {
+        return {
+            scriptTransformers: getScriptTransformers(compilerOptions, customTransformers, emitOnlyDtsFiles),
+            declarationTransformers: getDeclarationTransformers(customTransformers),
+        };
+    }
+
+    function getScriptTransformers(compilerOptions: CompilerOptions, customTransformers?: CustomTransformers, emitOnlyDtsFiles?: boolean) {
+        if (emitOnlyDtsFiles) return emptyArray;
+
         const jsx = compilerOptions.jsx;
         const languageVersion = getEmitScriptTarget(compilerOptions);
         const moduleKind = getEmitModuleKind(compilerOptions);
         const transformers: TransformerFactory<SourceFile | Bundle>[] = [];
 
-        addRange(transformers, customTransformers && customTransformers.before);
+        addRange(transformers, customTransformers && map(customTransformers.before, wrapScriptTransformerFactory));
 
         transformers.push(transformTypeScript);
 
@@ -71,11 +82,44 @@ namespace ts {
             transformers.push(transformES5);
         }
 
-        addRange(transformers, customTransformers && customTransformers.after);
-
+        addRange(transformers, customTransformers && map(customTransformers.after, wrapScriptTransformerFactory));
         return transformers;
     }
 
+    function getDeclarationTransformers(customTransformers?: CustomTransformers) {
+        const transformers: TransformerFactory<SourceFile | Bundle>[] = [];
+        transformers.push(transformDeclarations);
+        addRange(transformers, customTransformers && map(customTransformers.afterDeclarations, wrapDeclarationTransformerFactory));
+        return transformers;
+    }
+
+    /**
+     * Wrap a custom script or declaration transformer object in a `Transformer` callback with fallback support for transforming bundles.
+     */
+    function wrapCustomTransformer(transformer: CustomTransformer): Transformer<Bundle | SourceFile> {
+        return node => isBundle(node) ? transformer.transformBundle(node) : transformer.transformSourceFile(node);
+    }
+
+    /**
+     * Wrap a transformer factory that may return a custom script or declaration transformer object.
+     */
+    function wrapCustomTransformerFactory<T extends SourceFile | Bundle>(transformer: TransformerFactory<T> | CustomTransformerFactory, handleDefault: (node: Transformer<T>) => Transformer<Bundle | SourceFile>): TransformerFactory<Bundle | SourceFile> {
+        return context => {
+            const customTransformer = transformer(context);
+            return typeof customTransformer === "function"
+                ? handleDefault(customTransformer)
+                : wrapCustomTransformer(customTransformer);
+        };
+    }
+
+    function wrapScriptTransformerFactory(transformer: TransformerFactory<SourceFile> | CustomTransformerFactory): TransformerFactory<Bundle | SourceFile> {
+        return wrapCustomTransformerFactory(transformer, chainBundle);
+    }
+
+    function wrapDeclarationTransformerFactory(transformer: TransformerFactory<Bundle | SourceFile> | CustomTransformerFactory): TransformerFactory<Bundle | SourceFile> {
+        return wrapCustomTransformerFactory(transformer, identity);
+    }
+
     export function noEmitSubstitution(_hint: EmitHint, node: Node) {
         return node;
     }

src/compiler/transformers/destructuring.ts

@@ -521,8 +521,10 @@ namespace ts {
                 for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
                     t[p] = s[p];
                 if (s != null && typeof Object.getOwnPropertySymbols === "function")
-                    for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
-                        t[p[i]] = s[p[i]];
+                    for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) {
+                        if (e.indexOf(p[i]) < 0 && Object.prototype.propertyIsEnumerable.call(s, p[i]))
+                            t[p[i]] = s[p[i]];
+                    }
                 return t;
             };`
     };

src/compiler/transformers/es2015.ts

@@ -145,7 +145,7 @@ namespace ts {
         loopOutParameters: LoopOutParameter[];
     }
 
-    type LoopConverter = (node: IterationStatement, outermostLabeledStatement: LabeledStatement | undefined, convertedLoopBodyStatements: Statement[] | undefined) => Statement;
+    type LoopConverter = (node: IterationStatement, outermostLabeledStatement: LabeledStatement | undefined, convertedLoopBodyStatements: Statement[] | undefined, ancestorFacts: HierarchyFacts) => Statement;
 
     // Facts we track as we traverse the tree
     const enum HierarchyFacts {
@@ -163,11 +163,12 @@ namespace ts {
         ExportedVariableStatement = 1 << 5,     // Enclosed in an exported variable statement in the current scope
         TopLevel = 1 << 6,                      // Enclosing block-scoped container is a top-level container
         Block = 1 << 7,                         // Enclosing block-scoped container is a Block
-        IterationStatement = 1 << 8,            // Enclosed in an IterationStatement
+        IterationStatement = 1 << 8,            // Immediately enclosed in an IterationStatement
         IterationStatementBlock = 1 << 9,       // Enclosing Block is enclosed in an IterationStatement
-        ForStatement = 1 << 10,                 // Enclosing block-scoped container is a ForStatement
-        ForInOrForOfStatement = 1 << 11,        // Enclosing block-scoped container is a ForInStatement or ForOfStatement
-        ConstructorWithCapturedSuper = 1 << 12, // Enclosed in a constructor that captures 'this' for use with 'super'
+        IterationContainer = 1 << 10,           // Enclosed in an outer IterationStatement
+        ForStatement = 1 << 11,                 // Enclosing block-scoped container is a ForStatement
+        ForInOrForOfStatement = 1 << 12,        // Enclosing block-scoped container is a ForInStatement or ForOfStatement
+        ConstructorWithCapturedSuper = 1 << 13, // Enclosed in a constructor that captures 'this' for use with 'super'
         // NOTE: do not add more ancestor flags without also updating AncestorFactsMask below.
         // NOTE: when adding a new ancestor flag, be sure to update the subtree flags below.
 
@@ -184,11 +185,11 @@ namespace ts {
 
         // A source file is a top-level block scope.
         SourceFileIncludes = TopLevel,
-        SourceFileExcludes = BlockScopeExcludes & ~TopLevel,
+        SourceFileExcludes = BlockScopeExcludes & ~TopLevel | IterationContainer,
 
         // Functions, methods, and accessors are both new lexical scopes and new block scopes.
         FunctionIncludes = Function | TopLevel,
-        FunctionExcludes = BlockScopeExcludes & ~TopLevel | ArrowFunction | AsyncFunctionBody | CapturesThis | NonStaticClassElement | ConstructorWithCapturedSuper,
+        FunctionExcludes = BlockScopeExcludes & ~TopLevel | ArrowFunction | AsyncFunctionBody | CapturesThis | NonStaticClassElement | ConstructorWithCapturedSuper | IterationContainer,
 
         AsyncFunctionBodyIncludes = FunctionIncludes | AsyncFunctionBody,
         AsyncFunctionBodyExcludes = FunctionExcludes & ~NonStaticClassElement,
@@ -205,16 +206,16 @@ namespace ts {
         // 'do' and 'while' statements are not block scopes. We track that the subtree is contained
         // within an IterationStatement to indicate whether the embedded statement is an
         // IterationStatementBlock.
-        DoOrWhileStatementIncludes = IterationStatement,
+        DoOrWhileStatementIncludes = IterationStatement | IterationContainer,
         DoOrWhileStatementExcludes = None,
 
         // 'for' statements are new block scopes and have special handling for 'let' declarations.
-        ForStatementIncludes = IterationStatement | ForStatement,
+        ForStatementIncludes = IterationStatement | ForStatement | IterationContainer,
         ForStatementExcludes = BlockScopeExcludes & ~ForStatement,
 
         // 'for-in' and 'for-of' statements are new block scopes and have special handling for
         // 'let' declarations.
-        ForInOrForOfStatementIncludes = IterationStatement | ForInOrForOfStatement,
+        ForInOrForOfStatementIncludes = IterationStatement | ForInOrForOfStatement | IterationContainer,
         ForInOrForOfStatementExcludes = BlockScopeExcludes & ~ForInOrForOfStatement,
 
         // Blocks (other than function bodies) are new block scopes.
@@ -228,8 +229,8 @@ namespace ts {
         // Subtree facts
         //
 
-        NewTarget = 1 << 13,                            // Contains a 'new.target' meta-property
-        CapturedLexicalThis = 1 << 14,                  // Contains a lexical `this` reference captured by an arrow function.
+        NewTarget = 1 << 14,                            // Contains a 'new.target' meta-property
+        CapturedLexicalThis = 1 << 15,                  // Contains a lexical `this` reference captured by an arrow function.
 
         //
         // Subtree masks
@@ -1639,7 +1640,7 @@ namespace ts {
             // arguments are both mapped contiguously to the accessor name.
             const target = getMutableClone(receiver);
             setEmitFlags(target, EmitFlags.NoComments | EmitFlags.NoTrailingSourceMap);
-            setSourceMapRange(target, firstAccessor.name); // TODO: GH#18217
+            setSourceMapRange(target, firstAccessor.name);
 
             const propertyName = createExpressionForPropertyName(visitNode(firstAccessor.name, visitor, isPropertyName));
             setEmitFlags(propertyName, EmitFlags.NoComments | EmitFlags.NoLeadingSourceMap);
@@ -2227,7 +2228,7 @@ namespace ts {
 
         function visitIterationStatementWithFacts(excludeFacts: HierarchyFacts, includeFacts: HierarchyFacts, node: IterationStatement, outermostLabeledStatement: LabeledStatement | undefined, convert?: LoopConverter) {
             const ancestorFacts = enterSubtree(excludeFacts, includeFacts);
-            const updated = convertIterationStatementBodyIfNecessary(node, outermostLabeledStatement, convert);
+            const updated = convertIterationStatementBodyIfNecessary(node, outermostLabeledStatement, ancestorFacts, convert);
             exitSubtree(ancestorFacts, HierarchyFacts.None, HierarchyFacts.None);
             return updated;
         }
@@ -2434,7 +2435,7 @@ namespace ts {
             return restoreEnclosingLabel(forStatement, outermostLabeledStatement, convertedLoopState && resetLabel);
         }
 
-        function convertForOfStatementForIterable(node: ForOfStatement, outermostLabeledStatement: LabeledStatement, convertedLoopBodyStatements: Statement[]): Statement {
+        function convertForOfStatementForIterable(node: ForOfStatement, outermostLabeledStatement: LabeledStatement, convertedLoopBodyStatements: Statement[], ancestorFacts: HierarchyFacts): Statement {
             const expression = visitNode(node.expression, visitor, isExpression);
             const iterator = isIdentifier(expression) ? getGeneratedNameForNode(expression) : createTempVariable(/*recordTempVariable*/ undefined);
             const result = isIdentifier(expression) ? getGeneratedNameForNode(iterator) : createTempVariable(/*recordTempVariable*/ undefined);
@@ -2447,13 +2448,18 @@ namespace ts {
             hoistVariableDeclaration(errorRecord);
             hoistVariableDeclaration(returnMethod);
 
+            // if we are enclosed in an outer loop ensure we reset 'errorRecord' per each iteration
+            const initializer = ancestorFacts & HierarchyFacts.IterationContainer
+                ? inlineExpressions([createAssignment(errorRecord, createVoidZero()), values])
+                : values;
+
             const forStatement = setEmitFlags(
                 setTextRange(
                     createFor(
                         /*initializer*/ setEmitFlags(
                             setTextRange(
                                 createVariableDeclarationList([
-                                    setTextRange(createVariableDeclaration(iterator, /*type*/ undefined, values), node.expression),
+                                    setTextRange(createVariableDeclaration(iterator, /*type*/ undefined, initializer), node.expression),
                                     createVariableDeclaration(result, /*type*/ undefined, next)
                                 ]),
                                 node.expression
@@ -2665,7 +2671,7 @@ namespace ts {
             }
         }
 
-        function convertIterationStatementBodyIfNecessary(node: IterationStatement, outermostLabeledStatement: LabeledStatement | undefined, convert?: LoopConverter): VisitResult<Statement> {
+        function convertIterationStatementBodyIfNecessary(node: IterationStatement, outermostLabeledStatement: LabeledStatement | undefined, ancestorFacts: HierarchyFacts, convert?: LoopConverter): VisitResult<Statement> {
             if (!shouldConvertIterationStatement(node)) {
                 let saveAllowedNonLabeledJumps: Jump | undefined;
                 if (convertedLoopState) {
@@ -2676,7 +2682,7 @@ namespace ts {
                 }
 
                 const result = convert
-                    ? convert(node, outermostLabeledStatement, /*convertedLoopBodyStatements*/ undefined)
+                    ? convert(node, outermostLabeledStatement, /*convertedLoopBodyStatements*/ undefined, ancestorFacts)
                     : restoreEnclosingLabel(visitEachChild(node, visitor, context), outermostLabeledStatement, convertedLoopState && resetLabel);
 
                 if (convertedLoopState) {
@@ -2708,7 +2714,7 @@ namespace ts {
             let loop: Statement;
             if (bodyFunction) {
                 if (convert) {
-                    loop = convert(node, outermostLabeledStatement, bodyFunction.part);
+                    loop = convert(node, outermostLabeledStatement, bodyFunction.part, ancestorFacts);
                 }
                 else {
                     const clone = convertIterationStatementCore(node, initializerFunction, createBlock(bodyFunction.part, /*multiLine*/ true));

src/compiler/transformers/es2018.ts

@@ -77,6 +77,8 @@ namespace ts {
                     return visitObjectLiteralExpression(node as ObjectLiteralExpression);
                 case SyntaxKind.BinaryExpression:
                     return visitBinaryExpression(node as BinaryExpression, noDestructuringValue);
+                case SyntaxKind.CatchClause:
+                    return visitCatchClause(node as CatchClause);
                 case SyntaxKind.VariableDeclaration:
                     return visitVariableDeclaration(node as VariableDeclaration);
                 case SyntaxKind.ForOfStatement:
@@ -272,6 +274,28 @@ namespace ts {
             return visitEachChild(node, visitor, context);
         }
 
+        function visitCatchClause(node: CatchClause) {
+            if (node.variableDeclaration &&
+                isBindingPattern(node.variableDeclaration.name) &&
+                node.variableDeclaration.name.transformFlags & TransformFlags.ContainsObjectRestOrSpread) {
+                const name = getGeneratedNameForNode(node.variableDeclaration.name);
+                const updatedDecl = updateVariableDeclaration(node.variableDeclaration, node.variableDeclaration.name, /*type*/ undefined, name);
+                const visitedBindings = flattenDestructuringBinding(updatedDecl, visitor, context, FlattenLevel.ObjectRest);
+                let block = visitNode(node.block, visitor, isBlock);
+                if (some(visitedBindings)) {
+                    block = updateBlock(block, [
+                        createVariableStatement(/*modifiers*/ undefined, visitedBindings),
+                        ...block.statements,
+                    ]);
+                }
+                return updateCatchClause(
+                    node,
+                    updateVariableDeclaration(node.variableDeclaration, name, /*type*/ undefined, /*initializer*/ undefined),
+                    block);
+            }
+            return visitEachChild(node, visitor, context);
+        }
+
         /**
          * Visits a VariableDeclaration node with a binding pattern.
          *

src/compiler/tsconfig.json

@@ -8,6 +8,7 @@
 
     "files": [
         "core.ts",
+        "debug.ts",
         "performance.ts",
         "semver.ts",
 

src/compiler/types.ts

@@ -2546,6 +2546,8 @@ namespace ts {
         Shared         = 1 << 10, // Referenced as antecedent more than once
         PreFinally     = 1 << 11, // Injected edge that links pre-finally label and pre-try flow
         AfterFinally   = 1 << 12, // Injected edge that links post-finally flow with the rest of the graph
+        /** @internal */
+        Cached         = 1 << 13, // Indicates that at least one cross-call cache entry exists for this node, even if not a loop participant
         Label = BranchLabel | LoopLabel,
         Condition = TrueCondition | FalseCondition
     }
@@ -2614,7 +2616,7 @@ namespace ts {
 
     // Incomplete types occur during control flow analysis of loops. An IncompleteType
     // is distinguished from a regular type by a flags value of zero. Incomplete type
-    // objects are internal to the getFlowTypeOfRefecence function and never escape it.
+    // objects are internal to the getFlowTypeOfReference function and never escape it.
     export interface IncompleteType {
         flags: TypeFlags;  // No flags set
         type: Type;        // The type marked incomplete
@@ -3011,13 +3013,26 @@ namespace ts {
         Completely  = 1 << 1,
     }
 
+    export type CustomTransformerFactory = (context: TransformationContext) => CustomTransformer;
+
+    export interface CustomTransformer {
+        transformSourceFile(node: SourceFile): SourceFile;
+        transformBundle(node: Bundle): Bundle;
+    }
+
     export interface CustomTransformers {
         /** Custom transformers to evaluate before built-in .js transformations. */
-        before?: TransformerFactory<SourceFile>[];
+        before?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .js transformations. */
-        after?: TransformerFactory<SourceFile>[];
+        after?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .d.ts transformations. */
-        afterDeclarations?: TransformerFactory<Bundle | SourceFile>[];
+        afterDeclarations?: (TransformerFactory<Bundle | SourceFile> | CustomTransformerFactory)[];
+    }
+
+    /*@internal*/
+    export interface EmitTransformers {
+        scriptTransformers: readonly TransformerFactory<SourceFile | Bundle>[];
+        declarationTransformers: readonly TransformerFactory<SourceFile | Bundle>[];
     }
 
     export interface SourceMapSpan {
@@ -3139,6 +3154,7 @@ namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
 
@@ -3735,7 +3751,7 @@ namespace ts {
         specifierCache?: Map<string>;     // For symbols corresponding to external modules, a cache of incoming path -> module specifier name mappings
         extendedContainers?: Symbol[];      // Containers (other than the parent) which this symbol is aliased in
         extendedContainersByFile?: Map<Symbol[]>;      // Containers (other than the parent) which this symbol is aliased in
-        variances?: Variance[];             // Alias symbol type argument variance cache
+        variances?: VarianceFlags[];             // Alias symbol type argument variance cache
     }
 
     /* @internal */
@@ -3951,6 +3967,8 @@ namespace ts {
         StructuredOrInstantiable = StructuredType | Instantiable,
         /* @internal */
         ObjectFlagsType = Nullable | Never | Object | Union | Intersection,
+        /* @internal */
+        Simplifiable = IndexedAccess | Conditional,
         // 'Narrowable' types are types where narrowing actually narrows.
         // This *should* be every type other than null, undefined, void, and never
         Narrowable = Any | Unknown | StructuredOrInstantiable | StringLike | NumberLike | BigIntLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
@@ -4131,12 +4149,16 @@ namespace ts {
     }
 
     /* @internal */
-    export const enum Variance {
-        Invariant     = 0,  // Neither covariant nor contravariant
-        Covariant     = 1,  // Covariant
-        Contravariant = 2,  // Contravariant
-        Bivariant     = 3,  // Both covariant and contravariant
-        Independent   = 4,  // Unwitnessed type parameter
+    export const enum VarianceFlags {
+        Invariant     =      0,  // Neither covariant nor contravariant
+        Covariant     = 1 << 0,  // Covariant
+        Contravariant = 1 << 1,  // Contravariant
+        Bivariant     = Covariant | Contravariant,  // Both covariant and contravariant
+        Independent   = 1 << 2,  // Unwitnessed type parameter
+        VarianceMask  = Invariant | Covariant | Contravariant | Independent, // Mask containing all measured variances without the unmeasurable flag
+        Unmeasurable  = 1 << 3,  // Variance result is unusable - relationship relies on structural comparisons which are not reflected in generic relationships
+        Unreliable    = 1 << 4,  // Variance result is unreliable - relationship relies on structural comparisons which are not reflected in generic relationships
+        AllowsStructuralFallback = Unmeasurable | Unreliable,
     }
 
     // Generic class and interface types
@@ -4144,7 +4166,7 @@ namespace ts {
         /* @internal */
         instantiations: Map<TypeReference>;  // Generic instantiation cache
         /* @internal */
-        variances?: Variance[];  // Variance of each type parameter
+        variances?: VarianceFlags[];  // Variance of each type parameter
     }
 
     export interface TupleType extends GenericType {
@@ -4319,8 +4341,8 @@ namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
         /* @internal */
         resolvedInferredTrueType?: Type; // The `trueType` instantiated with the `combinedMapper`, if present
         /* @internal */
@@ -4405,15 +4427,16 @@ namespace ts {
     export type TypeMapper = (t: TypeParameter) => Type;
 
     export const enum InferencePriority {
-        NakedTypeVariable           = 1 << 0,  // Naked type variable in union or intersection type
-        HomomorphicMappedType       = 1 << 1,  // Reverse inference for homomorphic mapped type
-        MappedTypeConstraint        = 1 << 2,  // Reverse inference for mapped type
-        ReturnType                  = 1 << 3,  // Inference made from return type of generic function
-        LiteralKeyof                = 1 << 4,  // Inference made from a string literal to a keyof T
-        NoConstraints               = 1 << 5,  // Don't infer from constraints of instantiable types
-        AlwaysStrict                = 1 << 6,  // Always use strict rules for contravariant inferences
+        NakedTypeVariable            = 1 << 0,  // Naked type variable in union or intersection type
+        HomomorphicMappedType        = 1 << 1,  // Reverse inference for homomorphic mapped type
+        PartialHomomorphicMappedType = 1 << 2,  // Partial reverse inference for homomorphic mapped type
+        MappedTypeConstraint         = 1 << 3,  // Reverse inference for mapped type
+        ReturnType                   = 1 << 4,  // Inference made from return type of generic function
+        LiteralKeyof                 = 1 << 5,  // Inference made from a string literal to a keyof T
+        NoConstraints                = 1 << 6,  // Don't infer from constraints of instantiable types
+        AlwaysStrict                 = 1 << 7,  // Always use strict rules for contravariant inferences
 
-        PriorityImpliesCombination  = ReturnType | MappedTypeConstraint | LiteralKeyof,  // These priorities imply that the resulting type should be a combination of all candidates
+        PriorityImpliesCombination = ReturnType | MappedTypeConstraint | LiteralKeyof,  // These priorities imply that the resulting type should be a combination of all candidates
     }
 
     /* @internal */
@@ -5133,7 +5156,7 @@ namespace ts {
         createHash?(data: string): string;
         getParsedCommandLine?(fileName: string): ParsedCommandLine | undefined;
 
-        // TODO: later handle this in better way in builder host instead once the api for tsbuild finalizes and doesnt use compilerHost as base
+        // TODO: later handle this in better way in builder host instead once the api for tsbuild finalizes and doesn't use compilerHost as base
         /*@internal*/createDirectory?(directory: string): void;
     }
 

src/compiler/utilities.ts

@@ -2073,7 +2073,7 @@ namespace ts {
     }
 
     export function importFromModuleSpecifier(node: StringLiteralLike): AnyValidImportOrReExport {
-        return tryGetImportFromModuleSpecifier(node) || Debug.fail(Debug.showSyntaxKind(node.parent));
+        return tryGetImportFromModuleSpecifier(node) || Debug.failBadSyntaxKind(node.parent);
     }
 
     export function tryGetImportFromModuleSpecifier(node: StringLiteralLike): AnyValidImportOrReExport | undefined {
@@ -4186,78 +4186,6 @@ namespace ts {
         return getNewLine ? getNewLine() : sys ? sys.newLine : carriageReturnLineFeed;
     }
 
-    /**
-     * Formats an enum value as a string for debugging and debug assertions.
-     */
-    function formatEnum(value = 0, enumObject: any, isFlags?: boolean) {
-        const members = getEnumMembers(enumObject);
-        if (value === 0) {
-            return members.length > 0 && members[0][0] === 0 ? members[0][1] : "0";
-        }
-        if (isFlags) {
-            let result = "";
-            let remainingFlags = value;
-            for (let i = members.length - 1; i >= 0 && remainingFlags !== 0; i--) {
-                const [enumValue, enumName] = members[i];
-                if (enumValue !== 0 && (remainingFlags & enumValue) === enumValue) {
-                    remainingFlags &= ~enumValue;
-                    result = `${enumName}${result ? ", " : ""}${result}`;
-                }
-            }
-            if (remainingFlags === 0) {
-                return result;
-            }
-        }
-        else {
-            for (const [enumValue, enumName] of members) {
-                if (enumValue === value) {
-                    return enumName;
-                }
-            }
-        }
-        return value.toString();
-    }
-
-    function getEnumMembers(enumObject: any) {
-        const result: [number, string][] = [];
-        for (const name in enumObject) {
-            const value = enumObject[name];
-            if (typeof value === "number") {
-                result.push([value, name]);
-            }
-        }
-
-        return stableSort<[number, string]>(result, (x, y) => compareValues(x[0], y[0]));
-    }
-
-    export function formatSyntaxKind(kind: SyntaxKind | undefined): string {
-        return formatEnum(kind, (<any>ts).SyntaxKind, /*isFlags*/ false);
-    }
-
-    export function formatModifierFlags(flags: ModifierFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).ModifierFlags, /*isFlags*/ true);
-    }
-
-    export function formatTransformFlags(flags: TransformFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).TransformFlags, /*isFlags*/ true);
-    }
-
-    export function formatEmitFlags(flags: EmitFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).EmitFlags, /*isFlags*/ true);
-    }
-
-    export function formatSymbolFlags(flags: SymbolFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).SymbolFlags, /*isFlags*/ true);
-    }
-
-    export function formatTypeFlags(flags: TypeFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).TypeFlags, /*isFlags*/ true);
-    }
-
-    export function formatObjectFlags(flags: ObjectFlags | undefined): string {
-        return formatEnum(flags, (<any>ts).ObjectFlags, /*isFlags*/ true);
-    }
-
     /**
      * Creates a new TextRange from the provided pos and end.
      *
@@ -7646,6 +7574,14 @@ namespace ts {
         return root + pathComponents.slice(1).join(directorySeparator);
     }
 
+    export function getNormalizedAbsolutePathWithoutRoot(fileName: string, currentDirectory: string | undefined) {
+        return getPathWithoutRoot(getNormalizedPathComponents(fileName, currentDirectory));
+    }
+
+    function getPathWithoutRoot(pathComponents: ReadonlyArray<string>) {
+        if (pathComponents.length === 0) return "";
+        return pathComponents.slice(1).join(directorySeparator);
+    }
 }
 
 /* @internal */
@@ -8420,29 +8356,6 @@ namespace ts {
         return pathext ? path.slice(0, path.length - pathext.length) + (startsWith(ext, ".") ? ext : "." + ext) : path;
     }
 
-    export namespace Debug {
-        export function showSymbol(symbol: Symbol): string {
-            const symbolFlags = (ts as any).SymbolFlags;
-            return `{ flags: ${symbolFlags ? showFlags(symbol.flags, symbolFlags) : symbol.flags}; declarations: ${map(symbol.declarations, showSyntaxKind)} }`;
-        }
-
-        function showFlags(flags: number, flagsEnum: { [flag: number]: string }): string {
-            const out: string[] = [];
-            for (let pow = 0; pow <= 30; pow++) {
-                const n = 1 << pow;
-                if (flags & n) {
-                    out.push(flagsEnum[n]);
-                }
-            }
-            return out.join("|");
-        }
-
-        export function showSyntaxKind(node: Node): string {
-            const syntaxKind = (ts as any).SyntaxKind;
-            return syntaxKind ? syntaxKind[node.kind] : node.kind.toString();
-        }
-    }
-
     export function tryParsePattern(pattern: string): Pattern | undefined {
         // This should be verified outside of here and a proper error thrown.
         Debug.assert(hasZeroOrOneAsteriskCharacter(pattern));

src/compiler/visitor.ts

@@ -1558,100 +1558,4 @@ namespace ts {
     function aggregateTransformFlagsForChildNodes(transformFlags: TransformFlags, nodes: NodeArray<Node>): TransformFlags {
         return transformFlags | aggregateTransformFlagsForNodeArray(nodes);
     }
-
-    export namespace Debug {
-        let isDebugInfoEnabled = false;
-
-        export function failBadSyntaxKind(node: Node, message?: string): never {
-            return fail(
-                `${message || "Unexpected node."}\r\nNode ${formatSyntaxKind(node.kind)} was unexpected.`,
-                failBadSyntaxKind);
-        }
-
-        export const assertEachNode = shouldAssert(AssertionLevel.Normal)
-            ? (nodes: Node[], test: (node: Node) => boolean, message?: string): void => assert(
-                test === undefined || every(nodes, test),
-                message || "Unexpected node.",
-                () => `Node array did not pass test '${getFunctionName(test)}'.`,
-                assertEachNode)
-            : noop;
-
-        export const assertNode = shouldAssert(AssertionLevel.Normal)
-            ? (node: Node | undefined, test: ((node: Node | undefined) => boolean) | undefined, message?: string): void => assert(
-                test === undefined || test(node),
-                message || "Unexpected node.",
-                () => `Node ${formatSyntaxKind(node!.kind)} did not pass test '${getFunctionName(test!)}'.`,
-                assertNode)
-            : noop;
-
-        export const assertOptionalNode = shouldAssert(AssertionLevel.Normal)
-            ? (node: Node, test: (node: Node) => boolean, message?: string): void => assert(
-                test === undefined || node === undefined || test(node),
-                message || "Unexpected node.",
-                () => `Node ${formatSyntaxKind(node.kind)} did not pass test '${getFunctionName(test)}'.`,
-                assertOptionalNode)
-            : noop;
-
-        export const assertOptionalToken = shouldAssert(AssertionLevel.Normal)
-            ? (node: Node, kind: SyntaxKind, message?: string): void => assert(
-                kind === undefined || node === undefined || node.kind === kind,
-                message || "Unexpected node.",
-                () => `Node ${formatSyntaxKind(node.kind)} was not a '${formatSyntaxKind(kind)}' token.`,
-                assertOptionalToken)
-            : noop;
-
-        export const assertMissingNode = shouldAssert(AssertionLevel.Normal)
-            ? (node: Node, message?: string): void => assert(
-                node === undefined,
-                message || "Unexpected node.",
-                () => `Node ${formatSyntaxKind(node.kind)} was unexpected'.`,
-                assertMissingNode)
-            : noop;
-
-        /**
-         * Injects debug information into frequently used types.
-         */
-        export function enableDebugInfo() {
-            if (isDebugInfoEnabled) return;
-
-            // Add additional properties in debug mode to assist with debugging.
-            Object.defineProperties(objectAllocator.getSymbolConstructor().prototype, {
-                __debugFlags: { get(this: Symbol) { return formatSymbolFlags(this.flags); } }
-            });
-
-            Object.defineProperties(objectAllocator.getTypeConstructor().prototype, {
-                __debugFlags: { get(this: Type) { return formatTypeFlags(this.flags); } },
-                __debugObjectFlags: { get(this: Type) { return this.flags & TypeFlags.Object ? formatObjectFlags((<ObjectType>this).objectFlags) : ""; } },
-                __debugTypeToString: { value(this: Type) { return this.checker.typeToString(this); } },
-            });
-
-            const nodeConstructors = [
-                objectAllocator.getNodeConstructor(),
-                objectAllocator.getIdentifierConstructor(),
-                objectAllocator.getTokenConstructor(),
-                objectAllocator.getSourceFileConstructor()
-            ];
-
-            for (const ctor of nodeConstructors) {
-                if (!ctor.prototype.hasOwnProperty("__debugKind")) {
-                    Object.defineProperties(ctor.prototype, {
-                        __debugKind: { get(this: Node) { return formatSyntaxKind(this.kind); } },
-                        __debugModifierFlags: { get(this: Node) { return formatModifierFlags(getModifierFlagsNoCache(this)); } },
-                        __debugTransformFlags: { get(this: Node) { return formatTransformFlags(this.transformFlags); } },
-                        __debugEmitFlags: { get(this: Node) { return formatEmitFlags(getEmitFlags(this)); } },
-                        __debugGetText: {
-                            value(this: Node, includeTrivia?: boolean) {
-                                if (nodeIsSynthesized(this)) return "";
-                                const parseNode = getParseTreeNode(this);
-                                const sourceFile = parseNode && getSourceFileOfNode(parseNode);
-                                return sourceFile ? getSourceTextOfNodeFromSourceFile(sourceFile, parseNode, includeTrivia) : "";
-                            }
-                        }
-                    });
-                }
-            }
-
-            isDebugInfoEnabled = true;
-        }
-    }
 }

src/harness/client.ts

@@ -424,6 +424,10 @@ namespace ts.server {
             return renameInfo;
         }
 
+        getSmartSelectionRange() {
+            return notImplemented();
+        }
+
         findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean): RenameLocation[] {
             if (!this.lastRenameEntry ||
                 this.lastRenameEntry.inputs.fileName !== fileName ||

src/harness/fourslash.ts

@@ -798,8 +798,8 @@ namespace FourSlash {
         }
 
         private verifyCompletionEntry(actual: ts.CompletionEntry, expected: FourSlashInterface.ExpectedCompletionEntry) {
-            const { insertText, replacementSpan, hasAction, isRecommended, kind, kindModifiers, text, documentation, tags, source, sourceDisplay } = typeof expected === "string"
-                ? { insertText: undefined, replacementSpan: undefined, hasAction: undefined, isRecommended: undefined, kind: undefined, kindModifiers: undefined, text: undefined, documentation: undefined, tags: undefined, source: undefined, sourceDisplay: undefined }
+            const { insertText, replacementSpan, hasAction, isRecommended, kind, kindModifiers, text, documentation, tags, source, sourceDisplay, sortText } = typeof expected === "string"
+                ? { insertText: undefined, replacementSpan: undefined, hasAction: undefined, isRecommended: undefined, kind: undefined, kindModifiers: undefined, text: undefined, documentation: undefined, tags: undefined, source: undefined, sourceDisplay: undefined, sortText: undefined }
                 : expected;
 
             if (actual.insertText !== insertText) {
@@ -825,6 +825,7 @@ namespace FourSlash {
             assert.equal(actual.hasAction, hasAction);
             assert.equal(actual.isRecommended, isRecommended);
             assert.equal(actual.source, source);
+            assert.equal(actual.sortText, sortText || ts.Completions.SortText.LocationPriority, this.messageAtLastKnownMarker(`Actual entry: ${JSON.stringify(actual)}`));
 
             if (text !== undefined) {
                 const actualDetails = this.getCompletionEntryDetails(actual.name, actual.source)!;
@@ -1417,12 +1418,7 @@ Actual: ${stringify(fullActual)}`);
         }
 
         public baselineCurrentFileBreakpointLocations() {
-            let baselineFile = this.testData.globalOptions[MetadataOptionNames.baselineFile];
-            if (!baselineFile) {
-                baselineFile = this.activeFile.fileName.replace(this.basePath + "/breakpointValidation", "bpSpan");
-                baselineFile = baselineFile.replace(ts.Extension.Ts, ".baseline");
-
-            }
+            const baselineFile = this.getBaselineFileName().replace("breakpointValidation", "bpSpan");
             Harness.Baseline.runBaseline(baselineFile, this.baselineCurrentFileLocations(pos => this.getBreakpointStatementLocation(pos)!));
         }
 
@@ -1497,8 +1493,7 @@ Actual: ${stringify(fullActual)}`);
         }
 
         public baselineQuickInfo() {
-            const baselineFile = this.testData.globalOptions[MetadataOptionNames.baselineFile] ||
-                ts.getBaseFileName(this.activeFile.fileName).replace(ts.Extension.Ts, ".baseline");
+            const baselineFile = this.getBaselineFileName();
             Harness.Baseline.runBaseline(
                 baselineFile,
                 stringify(
@@ -1508,6 +1503,39 @@ Actual: ${stringify(fullActual)}`);
                     }))));
         }
 
+        public baselineSmartSelection() {
+            const n = "\n";
+            const baselineFile = this.getBaselineFileName();
+            const markers = this.getMarkers();
+            const fileContent = this.activeFile.content;
+            const text = markers.map(marker => {
+                const baselineContent = [fileContent.slice(0, marker.position) + "/**/" + fileContent.slice(marker.position) + n];
+                let selectionRange: ts.SelectionRange | undefined = this.languageService.getSmartSelectionRange(this.activeFile.fileName, marker.position);
+                while (selectionRange) {
+                    const { textSpan } = selectionRange;
+                    let masked = Array.from(fileContent).map((char, index) => {
+                        const charCode = char.charCodeAt(0);
+                        if (index >= textSpan.start && index < ts.textSpanEnd(textSpan)) {
+                            return char === " " ? "•" : ts.isLineBreak(charCode) ? `↲${n}` : char;
+                        }
+                        return ts.isLineBreak(charCode) ? char : " ";
+                    }).join("");
+                    masked = masked.replace(/^\s*$\r?\n?/gm, ""); // Remove blank lines
+                    const isRealCharacter = (char: string) => char !== "•" && char !== "↲" && !ts.isWhiteSpaceLike(char.charCodeAt(0));
+                    const leadingWidth = Array.from(masked).findIndex(isRealCharacter);
+                    const trailingWidth = ts.findLastIndex(Array.from(masked), isRealCharacter);
+                    masked = masked.slice(0, leadingWidth)
+                        + masked.slice(leadingWidth, trailingWidth).replace(/•/g, " ").replace(/↲/g, "")
+                        + masked.slice(trailingWidth);
+                    baselineContent.push(masked);
+                    selectionRange = selectionRange.parent;
+                }
+                return baselineContent.join(fileContent.includes("\n") ? n + n : n);
+            }).join(n.repeat(2) + "=".repeat(80) + n.repeat(2));
+
+            Harness.Baseline.runBaseline(baselineFile, text);
+        }
+
         public printBreakpointLocation(pos: number) {
             Harness.IO.log("\n**Pos: " + pos + " " + this.spanInfoToString(this.getBreakpointStatementLocation(pos)!, "  "));
         }
@@ -1562,6 +1590,11 @@ Actual: ${stringify(fullActual)}`);
             Harness.IO.log(stringify(help.items[help.selectedItemIndex]));
         }
 
+        private getBaselineFileName() {
+            return this.testData.globalOptions[MetadataOptionNames.baselineFile] ||
+                ts.getBaseFileName(this.activeFile.fileName).replace(ts.Extension.Ts, ".baseline");
+        }
+
         private getSignatureHelp({ triggerReason }: FourSlashInterface.VerifySignatureHelpOptions): ts.SignatureHelpItems | undefined {
             return this.languageService.getSignatureHelpItems(this.activeFile.fileName, this.currentCaretPosition, {
                 triggerReason
@@ -3960,6 +3993,10 @@ namespace FourSlashInterface {
             this.state.baselineQuickInfo();
         }
 
+        public baselineSmartSelection() {
+            this.state.baselineSmartSelection();
+        }
+
         public nameOrDottedNameSpanTextIs(text: string) {
             this.state.verifyCurrentNameOrDottedNameSpanText(text);
         }
@@ -4398,18 +4435,63 @@ namespace FourSlashInterface {
         }
     }
     export namespace Completion {
-        const functionEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "function", kindModifiers: "declare" });
-        const varEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "var", kindModifiers: "declare" });
-        const moduleEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "module", kindModifiers: "declare" });
-        const keywordEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "keyword" });
-        const methodEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "method", kindModifiers: "declare" });
-        const propertyEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "property", kindModifiers: "declare" });
-        const interfaceEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "interface", kindModifiers: "declare" });
-        const typeEntry = (name: string): ExpectedCompletionEntryObject => ({ name, kind: "type", kindModifiers: "declare" });
+        export import SortText = ts.Completions.SortText;
+
+        const functionEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "function",
+            kindModifiers: "declare",
+            sortText: SortText.GlobalsOrKeywords
+        });
+        const varEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "var",
+            kindModifiers: "declare",
+            sortText: SortText.GlobalsOrKeywords
+        });
+        const moduleEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "module",
+            kindModifiers: "declare",
+            sortText: SortText.GlobalsOrKeywords
+        });
+        const keywordEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "keyword",
+            sortText: SortText.GlobalsOrKeywords
+        });
+        const methodEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "method",
+            kindModifiers: "declare",
+            sortText: SortText.LocationPriority
+        });
+        const propertyEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "property",
+            kindModifiers: "declare",
+            sortText: SortText.LocationPriority
+        });
+        const interfaceEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "interface",
+            kindModifiers: "declare",
+            sortText: SortText.GlobalsOrKeywords
+        });
+        const typeEntry = (name: string): ExpectedCompletionEntryObject => ({
+            name,
+            kind: "type",
+            kindModifiers: "declare",
+            sortText: SortText.GlobalsOrKeywords
+        });
 
         const res: ExpectedCompletionEntryObject[] = [];
         for (let i = ts.SyntaxKind.FirstKeyword; i <= ts.SyntaxKind.LastKeyword; i++) {
-            res.push({ name: ts.Debug.assertDefined(ts.tokenToString(i)), kind: "keyword" });
+            res.push({
+                name: ts.Debug.assertDefined(ts.tokenToString(i)),
+                kind: "keyword",
+                sortText: SortText.GlobalsOrKeywords
+            });
         }
         export const keywordsWithUndefined: ReadonlyArray<ExpectedCompletionEntryObject> = res;
         export const keywords: ReadonlyArray<ExpectedCompletionEntryObject> = keywordsWithUndefined.filter(k => k.name !== "undefined");
@@ -4516,11 +4598,15 @@ namespace FourSlashInterface {
             moduleEntry("Intl"),
         ];
 
+        export const globalThisEntry: ExpectedCompletionEntry = {
+            name: "globalThis",
+            kind: "module",
+            sortText: SortText.GlobalsOrKeywords
+        };
         export const globalTypes = globalTypesPlus([]);
-
         export function globalTypesPlus(plus: ReadonlyArray<ExpectedCompletionEntry>): ReadonlyArray<ExpectedCompletionEntry> {
             return [
-                { name: "globalThis", kind: "module" },
+                globalThisEntry,
                 ...globalTypeDecls,
                 ...plus,
                 ...typeKeywords,
@@ -4569,7 +4655,11 @@ namespace FourSlashInterface {
         export const classElementInJsKeywords = getInJsKeywords(classElementKeywords);
 
         export const constructorParameterKeywords: ReadonlyArray<ExpectedCompletionEntryObject> =
-            ["private", "protected", "public", "readonly"].map((name): ExpectedCompletionEntryObject => ({ name, kind: "keyword" }));
+            ["private", "protected", "public", "readonly"].map((name): ExpectedCompletionEntryObject => ({
+                name,
+                kind: "keyword",
+                sortText: SortText.GlobalsOrKeywords
+            }));
 
         export const functionMembers: ReadonlyArray<ExpectedCompletionEntryObject> = [
             methodEntry("apply"),
@@ -4798,13 +4888,18 @@ namespace FourSlashInterface {
             "await",
         ].map(keywordEntry);
 
+        export const undefinedVarEntry: ExpectedCompletionEntry = {
+            name: "undefined",
+            kind: "var",
+            sortText: SortText.GlobalsOrKeywords
+        };
         // TODO: many of these are inappropriate to always provide
         export const globalsInsideFunction = (plus: ReadonlyArray<ExpectedCompletionEntry>): ReadonlyArray<ExpectedCompletionEntry> => [
             { name: "arguments", kind: "local var" },
             ...plus,
-            { name: "globalThis", kind: "module" },
+            globalThisEntry,
             ...globalsVars,
-            { name: "undefined", kind: "var" },
+            undefinedVarEntry,
             ...globalKeywordsInsideFunction,
         ];
 
@@ -4813,10 +4908,10 @@ namespace FourSlashInterface {
         // TODO: many of these are inappropriate to always provide
         export const globalsInJsInsideFunction = (plus: ReadonlyArray<ExpectedCompletionEntry>): ReadonlyArray<ExpectedCompletionEntry> => [
             { name: "arguments", kind: "local var" },
-            { name: "globalThis", kind: "module" },
+            globalThisEntry,
             ...globalsVars,
             ...plus,
-            { name: "undefined", kind: "var" },
+            undefinedVarEntry,
             ...globalInJsKeywordsInsideFunction,
         ];
 
@@ -4954,34 +5049,34 @@ namespace FourSlashInterface {
         })();
 
         export const globals: ReadonlyArray<ExpectedCompletionEntryObject> = [
-            { name: "globalThis", kind: "module" },
+            globalThisEntry,
             ...globalsVars,
-            { name: "undefined", kind: "var" },
+            undefinedVarEntry,
             ...globalKeywords
         ];
 
         export const globalsInJs: ReadonlyArray<ExpectedCompletionEntryObject> = [
-            { name: "globalThis", kind: "module" },
+            globalThisEntry,
             ...globalsVars,
-            { name: "undefined", kind: "var" },
+            undefinedVarEntry,
             ...globalInJsKeywords
         ];
 
         export function globalsPlus(plus: ReadonlyArray<ExpectedCompletionEntry>): ReadonlyArray<ExpectedCompletionEntry> {
             return [
-                { name: "globalThis", kind: "module" },
+                globalThisEntry,
                 ...globalsVars,
                 ...plus,
-                { name: "undefined", kind: "var" },
+                undefinedVarEntry,
                 ...globalKeywords];
         }
 
         export function globalsInJsPlus(plus: ReadonlyArray<ExpectedCompletionEntry>): ReadonlyArray<ExpectedCompletionEntry> {
             return [
-                { name: "globalThis", kind: "module" },
+                globalThisEntry,
                 ...globalsVars,
                 ...plus,
-                { name: "undefined", kind: "var" },
+                undefinedVarEntry,
                 ...globalInJsKeywords];
         }
     }
@@ -5014,6 +5109,7 @@ namespace FourSlashInterface {
         readonly documentation?: string;
         readonly sourceDisplay?: string;
         readonly tags?: ReadonlyArray<ts.JSDocTagInfo>;
+        readonly sortText?: ts.Completions.SortText;
     }
 
     export interface VerifyCompletionsOptions {

src/harness/harnessLanguageService.ts

@@ -472,6 +472,9 @@ namespace Harness.LanguageService {
         getRenameInfo(fileName: string, position: number, options?: ts.RenameInfoOptions): ts.RenameInfo {
             return unwrapJSONCallResult(this.shim.getRenameInfo(fileName, position, options));
         }
+        getSmartSelectionRange(fileName: string, position: number): ts.SelectionRange {
+            return unwrapJSONCallResult(this.shim.getSmartSelectionRange(fileName, position));
+        }
         findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean, providePrefixAndSuffixTextForRename?: boolean): ts.RenameLocation[] {
             return unwrapJSONCallResult(this.shim.findRenameLocations(fileName, position, findInStrings, findInComments, providePrefixAndSuffixTextForRename));
         }

src/lib/dom.generated.d.ts

@@ -17328,7 +17328,8 @@ interface WorkerEventMap extends AbstractWorkerEventMap {
 /** An interface of the Web Workers API represents a background task that can be easily created and can send messages back to its creator. Creating a worker is as simple as calling the Worker() constructor and specifying a script to be run in the worker thread. */
 interface Worker extends EventTarget, AbstractWorker {
     onmessage: ((this: Worker, ev: MessageEvent) => any) | null;
-    postMessage(message: any, transfer?: Transferable[]): void;
+    postMessage(message: any, transfer: Transferable[]): void;
+    postMessage(message: any, options?: PostMessageOptions): void;
     terminate(): void;
     addEventListener<K extends keyof WorkerEventMap>(type: K, listener: (this: Worker, ev: WorkerEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
     addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;

src/lib/es5.d.ts

@@ -513,7 +513,7 @@ interface Boolean {
 
 interface BooleanConstructor {
     new(value?: any): Boolean;
-    <T>(value?: T): value is Exclude<T, false | null | undefined | '' | 0>;
+    <T>(value?: T): boolean;
     readonly prototype: Boolean;
 }
 
@@ -1446,9 +1446,7 @@ type Extract<T, U> = T extends U ? T : never;
 /**
  * Construct a type with the properties of T except for those in type K.
  */
-type Omit<T, K extends keyof any> = {
-    [P in Exclude<keyof T, K>]: T[P]
-};
+type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
 
 /**
  * Exclude null and undefined from T

src/lib/webworker.generated.d.ts

@@ -4231,7 +4231,8 @@ interface WorkerEventMap extends AbstractWorkerEventMap {
 /** An interface of the Web Workers API represents a background task that can be easily created and can send messages back to its creator. Creating a worker is as simple as calling the Worker() constructor and specifying a script to be run in the worker thread. */
 interface Worker extends EventTarget, AbstractWorker {
     onmessage: ((this: Worker, ev: MessageEvent) => any) | null;
-    postMessage(message: any, transfer?: Transferable[]): void;
+    postMessage(message: any, transfer: Transferable[]): void;
+    postMessage(message: any, options?: PostMessageOptions): void;
     terminate(): void;
     addEventListener<K extends keyof WorkerEventMap>(type: K, listener: (this: Worker, ev: WorkerEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
     addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;

src/server/protocol.ts

@@ -130,7 +130,10 @@ namespace ts.server.protocol {
         GetEditsForFileRename = "getEditsForFileRename",
         /* @internal */
         GetEditsForFileRenameFull = "getEditsForFileRename-full",
-        ConfigurePlugin = "configurePlugin"
+        ConfigurePlugin = "configurePlugin",
+        SelectionRange = "selectionRange",
+        /* @internal */
+        SelectionRangeFull = "selectionRange-full",
 
         // NOTE: If updating this, be sure to also update `allCommandNames` in `harness/unittests/session.ts`.
     }
@@ -1395,6 +1398,24 @@ namespace ts.server.protocol {
     export interface ConfigurePluginResponse extends Response {
     }
 
+    export interface SelectionRangeRequest extends FileRequest {
+        command: CommandTypes.SelectionRange;
+        arguments: SelectionRangeRequestArgs;
+    }
+
+    export interface SelectionRangeRequestArgs extends FileRequestArgs {
+        locations: Location[];
+    }
+
+    export interface SelectionRangeResponse extends Response {
+        body?: SelectionRange[];
+    }
+
+    export interface SelectionRange {
+        textSpan: TextSpan;
+        parent?: SelectionRange;
+    }
+
     /**
      *  Information found in an "open" request.
      */

src/server/session.ts

@@ -1318,11 +1318,11 @@ namespace ts.server {
             this.projectService.openClientFileWithNormalizedPath(fileName, fileContent, scriptKind, /*hasMixedContent*/ false, projectRootPath);
         }
 
-        private getPosition(args: protocol.FileLocationRequestArgs, scriptInfo: ScriptInfo): number {
+        private getPosition(args: protocol.Location & { position?: number }, scriptInfo: ScriptInfo): number {
             return args.position !== undefined ? args.position : scriptInfo.lineOffsetToPosition(args.line, args.offset);
         }
 
-        private getPositionInFile(args: protocol.FileLocationRequestArgs, file: NormalizedPath): number {
+        private getPositionInFile(args: protocol.Location & { position?: number }, file: NormalizedPath): number {
             const scriptInfo = this.projectService.getScriptInfoForNormalizedPath(file)!;
             return this.getPosition(args, scriptInfo);
         }
@@ -2059,6 +2059,28 @@ namespace ts.server {
             this.projectService.configurePlugin(args);
         }
 
+        private getSmartSelectionRange(args: protocol.SelectionRangeRequestArgs, simplifiedResult: boolean) {
+            const { locations } = args;
+            const { file, languageService } = this.getFileAndLanguageServiceForSyntacticOperation(args);
+            const scriptInfo = Debug.assertDefined(this.projectService.getScriptInfo(file));
+
+            return map(locations, location => {
+                const pos = this.getPosition(location, scriptInfo);
+                const selectionRange = languageService.getSmartSelectionRange(file, pos);
+                return simplifiedResult ? this.mapSelectionRange(selectionRange, scriptInfo) : selectionRange;
+            });
+        }
+
+        private mapSelectionRange(selectionRange: SelectionRange, scriptInfo: ScriptInfo): protocol.SelectionRange {
+            const result: protocol.SelectionRange = {
+                textSpan: this.toLocationTextSpan(selectionRange.textSpan, scriptInfo),
+            };
+            if (selectionRange.parent) {
+                result.parent = this.mapSelectionRange(selectionRange.parent, scriptInfo);
+            }
+            return result;
+        }
+
         getCanonicalFileName(fileName: string) {
             const name = this.host.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase();
             return normalizePath(name);
@@ -2414,7 +2436,13 @@ namespace ts.server {
                 this.configurePlugin(request.arguments);
                 this.doOutput(/*info*/ undefined, CommandNames.ConfigurePlugin, request.seq, /*success*/ true);
                 return this.notRequired();
-            }
+            },
+            [CommandNames.SelectionRange]: (request: protocol.SelectionRangeRequest) => {
+                return this.requiredResponse(this.getSmartSelectionRange(request.arguments, /*simplifiedResult*/ true));
+            },
+            [CommandNames.SelectionRangeFull]: (request: protocol.SelectionRangeRequest) => {
+                return this.requiredResponse(this.getSmartSelectionRange(request.arguments, /*simplifiedResult*/ false));
+            },
         });
 
         public addProtocolHandler(command: string, handler: (request: protocol.Request) => HandlerResponse) {

src/services/codefixes/addNameToNamelessParameter.ts

@@ -15,11 +15,11 @@ namespace ts.codefix {
     function makeChange(changeTracker: textChanges.ChangeTracker, sourceFile: SourceFile, pos: number) {
         const token = getTokenAtPosition(sourceFile, pos);
         if (!isIdentifier(token)) {
-            return Debug.fail("add-name-to-nameless-parameter operates on identifiers, but got a " + formatSyntaxKind(token.kind));
+            return Debug.fail("add-name-to-nameless-parameter operates on identifiers, but got a " + Debug.formatSyntaxKind(token.kind));
         }
         const param = token.parent;
         if (!isParameter(param)) {
-            return Debug.fail("Tried to add a parameter name to a non-parameter: " + formatSyntaxKind(token.kind));
+            return Debug.fail("Tried to add a parameter name to a non-parameter: " + Debug.formatSyntaxKind(token.kind));
         }
         const i = param.parent.parameters.indexOf(param);
         Debug.assert(!param.type, "Tried to add a parameter name to a parameter that already had one.");

src/services/completions.ts

@@ -1,5 +1,12 @@
 /* @internal */
 namespace ts.Completions {
+    export enum SortText {
+        LocationPriority = "0",
+        SuggestedClassMembers = "1",
+        GlobalsOrKeywords = "2",
+        AutoImportSuggestions = "3",
+        JavascriptIdentifiers = "4"
+    }
     export type Log = (message: string) => void;
 
     const enum SymbolOriginInfoKind { ThisType, SymbolMemberNoExport, SymbolMemberExport, Export }
@@ -22,6 +29,8 @@ namespace ts.Completions {
      */
     type SymbolOriginInfoMap = (SymbolOriginInfo | undefined)[];
 
+    type SymbolSortTextMap = (SortText | undefined)[];
+
     const enum KeywordCompletionFilters {
         None,                           // No keywords
         All,                            // Every possible keyword (TODO: This is never appropriate)
@@ -78,7 +87,21 @@ namespace ts.Completions {
     }
 
     function completionInfoFromData(sourceFile: SourceFile, typeChecker: TypeChecker, compilerOptions: CompilerOptions, log: Log, completionData: CompletionData, preferences: UserPreferences): CompletionInfo | undefined {
-        const { symbols, completionKind, isInSnippetScope, isNewIdentifierLocation, location, propertyAccessToConvert, keywordFilters, literals, symbolToOriginInfoMap, recommendedCompletion, isJsxInitializer, insideJsDocTagTypeExpression } = completionData;
+        const {
+            symbols,
+            completionKind,
+            isInSnippetScope,
+            isNewIdentifierLocation,
+            location,
+            propertyAccessToConvert,
+            keywordFilters,
+            literals,
+            symbolToOriginInfoMap,
+            recommendedCompletion,
+            isJsxInitializer,
+            insideJsDocTagTypeExpression,
+            symbolToSortTextMap,
+        } = completionData;
 
         if (location && location.parent && isJsxClosingElement(location.parent)) {
             // In the TypeScript JSX element, if such element is not defined. When users query for completion at closing tag,
@@ -93,7 +116,7 @@ namespace ts.Completions {
                 name: tagName.getFullText(sourceFile) + (hasClosingAngleBracket ? "" : ">"),
                 kind: ScriptElementKind.classElement,
                 kindModifiers: undefined,
-                sortText: "0",
+                sortText: SortText.LocationPriority,
             };
             return { isGlobalCompletion: false, isMemberCompletion: true, isNewIdentifierLocation: false, entries: [entry] };
         }
@@ -101,7 +124,22 @@ namespace ts.Completions {
         const entries: CompletionEntry[] = [];
 
         if (isUncheckedFile(sourceFile, compilerOptions)) {
-            const uniqueNames = getCompletionEntriesFromSymbols(symbols, entries, location, sourceFile, typeChecker, compilerOptions.target!, log, completionKind, preferences, propertyAccessToConvert, isJsxInitializer, recommendedCompletion, symbolToOriginInfoMap);
+            const uniqueNames = getCompletionEntriesFromSymbols(
+                symbols,
+                entries,
+                location,
+                sourceFile,
+                typeChecker,
+                compilerOptions.target!,
+                log,
+                completionKind,
+                preferences,
+                propertyAccessToConvert,
+                isJsxInitializer,
+                recommendedCompletion,
+                symbolToOriginInfoMap,
+                symbolToSortTextMap
+            );
             getJSCompletionEntries(sourceFile, location!.pos, uniqueNames, compilerOptions.target!, entries); // TODO: GH#18217
         }
         else {
@@ -109,7 +147,22 @@ namespace ts.Completions {
                 return undefined;
             }
 
-            getCompletionEntriesFromSymbols(symbols, entries, location, sourceFile, typeChecker, compilerOptions.target!, log, completionKind, preferences, propertyAccessToConvert, isJsxInitializer, recommendedCompletion, symbolToOriginInfoMap);
+            getCompletionEntriesFromSymbols(
+                symbols,
+                entries,
+                location,
+                sourceFile,
+                typeChecker,
+                compilerOptions.target!,
+                log,
+                completionKind,
+                preferences,
+                propertyAccessToConvert,
+                isJsxInitializer,
+                recommendedCompletion,
+                symbolToOriginInfoMap,
+                symbolToSortTextMap
+            );
         }
 
         if (keywordFilters !== KeywordCompletionFilters.None) {
@@ -160,7 +213,7 @@ namespace ts.Completions {
                     name: realName,
                     kind: ScriptElementKind.warning,
                     kindModifiers: "",
-                    sortText: "1"
+                    sortText: SortText.JavascriptIdentifiers
                 });
             }
         });
@@ -169,28 +222,23 @@ namespace ts.Completions {
     const completionNameForLiteral = (literal: string | number | PseudoBigInt) =>
         typeof literal === "object" ? pseudoBigIntToString(literal) + "n" : JSON.stringify(literal);
     function createCompletionEntryForLiteral(literal: string | number | PseudoBigInt): CompletionEntry {
-        return { name: completionNameForLiteral(literal), kind: ScriptElementKind.string, kindModifiers: ScriptElementKindModifier.none, sortText: "0" };
+        return { name: completionNameForLiteral(literal), kind: ScriptElementKind.string, kindModifiers: ScriptElementKindModifier.none, sortText: SortText.LocationPriority };
     }
 
     function createCompletionEntry(
         symbol: Symbol,
+        sortText: SortText,
         location: Node | undefined,
         sourceFile: SourceFile,
         typeChecker: TypeChecker,
-        target: ScriptTarget,
-        kind: CompletionKind,
+        name: string,
+        needsConvertPropertyAccess: boolean,
         origin: SymbolOriginInfo | undefined,
         recommendedCompletion: Symbol | undefined,
         propertyAccessToConvert: PropertyAccessExpression | undefined,
         isJsxInitializer: IsJsxInitializer | undefined,
         preferences: UserPreferences,
     ): CompletionEntry | undefined {
-        const info = getCompletionEntryDisplayNameForSymbol(symbol, target, origin, kind);
-        if (!info) {
-            return undefined;
-        }
-        const { name, needsConvertPropertyAccess } = info;
-
         let insertText: string | undefined;
         let replacementSpan: TextSpan | undefined;
         if (origin && origin.kind === SymbolOriginInfoKind.ThisType) {
@@ -230,7 +278,7 @@ namespace ts.Completions {
             name,
             kind: SymbolDisplay.getSymbolKind(typeChecker, symbol, location!), // TODO: GH#18217
             kindModifiers: SymbolDisplay.getSymbolModifiers(symbol),
-            sortText: "0",
+            sortText,
             source: getSourceFromOrigin(origin),
             hasAction: trueOrUndefined(!!origin && originIsExport(origin)),
             isRecommended: trueOrUndefined(isRecommendedCompletionMatch(symbol, recommendedCompletion, typeChecker)),
@@ -266,6 +314,7 @@ namespace ts.Completions {
         isJsxInitializer?: IsJsxInitializer,
         recommendedCompletion?: Symbol,
         symbolToOriginInfoMap?: SymbolOriginInfoMap,
+        symbolToSortTextMap?: SymbolSortTextMap,
     ): Map<true> {
         const start = timestamp();
         // Tracks unique names.
@@ -275,13 +324,30 @@ namespace ts.Completions {
         const uniques = createMap<true>();
         for (const symbol of symbols) {
             const origin = symbolToOriginInfoMap ? symbolToOriginInfoMap[getSymbolId(symbol)] : undefined;
-            const entry = createCompletionEntry(symbol, location, sourceFile, typeChecker, target, kind, origin, recommendedCompletion, propertyAccessToConvert, isJsxInitializer, preferences);
-            if (!entry) {
+            const info = getCompletionEntryDisplayNameForSymbol(symbol, target, origin, kind);
+            if (!info) {
+                continue;
+            }
+            const { name, needsConvertPropertyAccess } = info;
+            if (uniques.has(name)) {
                 continue;
             }
 
-            const { name } = entry;
-            if (uniques.has(name)) {
+            const entry = createCompletionEntry(
+                symbol,
+                symbolToSortTextMap && symbolToSortTextMap[getSymbolId(symbol)] || SortText.LocationPriority,
+                location,
+                sourceFile,
+                typeChecker,
+                name,
+                needsConvertPropertyAccess,
+                origin,
+                recommendedCompletion,
+                propertyAccessToConvert,
+                isJsxInitializer,
+                preferences
+            );
+            if (!entry) {
                 continue;
             }
 
@@ -321,7 +387,7 @@ namespace ts.Completions {
                         name,
                         kindModifiers: ScriptElementKindModifier.none,
                         kind: ScriptElementKind.label,
-                        sortText: "0"
+                        sortText: SortText.LocationPriority
                     });
                 }
             }
@@ -358,7 +424,7 @@ namespace ts.Completions {
         // We don't need to perform character checks here because we're only comparing the
         // name against 'entryName' (which is known to be good), not building a new
         // completion entry.
-        return firstDefined<Symbol, SymbolCompletion>(symbols, (symbol): SymbolCompletion | undefined => { // TODO: Shouldn't need return type annotation (GH#12632)
+        return firstDefined(symbols, (symbol): SymbolCompletion | undefined => {
             const origin = symbolToOriginInfoMap[getSymbolId(symbol)];
             const info = getCompletionEntryDisplayNameForSymbol(symbol, compilerOptions.target!, origin, completionKind);
             return info && info.name === entryId.name && getSourceFromOrigin(origin) === entryId.source
@@ -512,6 +578,7 @@ namespace ts.Completions {
         readonly previousToken: Node | undefined;
         readonly isJsxInitializer: IsJsxInitializer;
         readonly insideJsDocTagTypeExpression: boolean;
+        readonly symbolToSortTextMap: SymbolSortTextMap;
     }
     type Request = { readonly kind: CompletionDataKind.JsDocTagName | CompletionDataKind.JsDocTag } | { readonly kind: CompletionDataKind.JsDocParameterName, tag: JSDocParameterTag };
 
@@ -804,6 +871,7 @@ namespace ts.Completions {
         let keywordFilters = KeywordCompletionFilters.None;
         let symbols: Symbol[] = [];
         const symbolToOriginInfoMap: SymbolOriginInfoMap = [];
+        const symbolToSortTextMap: SymbolSortTextMap = [];
 
         if (isRightOfDot) {
             getTypeScriptMemberSymbols();
@@ -853,7 +921,8 @@ namespace ts.Completions {
             recommendedCompletion,
             previousToken,
             isJsxInitializer,
-            insideJsDocTagTypeExpression
+            insideJsDocTagTypeExpression,
+            symbolToSortTextMap
         };
 
         type JSDocTagWithTypeExpression = JSDocParameterTag | JSDocPropertyTag | JSDocReturnTag | JSDocTypeTag | JSDocTypedefTag;
@@ -1057,6 +1126,12 @@ namespace ts.Completions {
             const symbolMeanings = (isTypeOnly ? SymbolFlags.None : SymbolFlags.Value) | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias;
 
             symbols = Debug.assertEachDefined(typeChecker.getSymbolsInScope(scopeNode, symbolMeanings), "getSymbolsInScope() should all be defined");
+            for (const symbol of symbols) {
+                if (!typeChecker.isArgumentsSymbol(symbol) &&
+                    !some(symbol.declarations, d => d.getSourceFile() === sourceFile)) {
+                    symbolToSortTextMap[getSymbolId(symbol)] = SortText.GlobalsOrKeywords;
+                }
+            }
 
             // Need to insert 'this.' before properties of `this` type, so only do that if `includeInsertTextCompletions`
             if (preferences.includeCompletionsWithInsertText && scopeNode.kind !== SyntaxKind.SourceFile) {
@@ -1065,6 +1140,7 @@ namespace ts.Completions {
                     for (const symbol of getPropertiesForCompletion(thisType, typeChecker)) {
                         symbolToOriginInfoMap[getSymbolId(symbol)] = { kind: SymbolOriginInfoKind.ThisType };
                         symbols.push(symbol);
+                        symbolToSortTextMap[getSymbolId(symbol)] = SortText.SuggestedClassMembers;
                     }
                 }
             }
@@ -1198,6 +1274,7 @@ namespace ts.Completions {
                     // So in `declare namespace foo {} declare module "foo" { export = foo; }`, there will just be the global completion for `foo`.
                     some(resolvedModuleSymbol.declarations, d => !!d.getSourceFile().externalModuleIndicator)) {
                     symbols.push(resolvedModuleSymbol);
+                    symbolToSortTextMap[getSymbolId(resolvedModuleSymbol)] = SortText.AutoImportSuggestions;
                     symbolToOriginInfoMap[getSymbolId(resolvedModuleSymbol)] = { kind: SymbolOriginInfoKind.Export, moduleSymbol, isDefaultExport: false };
                 }
 
@@ -1223,6 +1300,7 @@ namespace ts.Completions {
                     const origin: SymbolOriginInfoExport = { kind: SymbolOriginInfoKind.Export, moduleSymbol, isDefaultExport };
                     if (detailsEntryId || stringContainsCharactersInOrder(getSymbolName(symbol, origin, target).toLowerCase(), tokenTextLowerCase)) {
                         symbols.push(symbol);
+                        symbolToSortTextMap[getSymbolId(symbol)] = SortText.AutoImportSuggestions;
                         symbolToOriginInfoMap[getSymbolId(symbol)] = origin;
                     }
                 }
@@ -1944,7 +2022,7 @@ namespace ts.Completions {
                 name: tokenToString(i)!,
                 kind: ScriptElementKind.keyword,
                 kindModifiers: ScriptElementKindModifier.none,
-                sortText: "0"
+                sortText: SortText.GlobalsOrKeywords
             });
         }
         return res;

src/services/findAllReferences.ts

@@ -635,7 +635,7 @@ namespace ts.FindAllReferences.Core {
                 // Ignore UMD module and global merge
                 if (symbol.flags & SymbolFlags.Transient) return undefined;
                 // Assertions for GH#21814. We should be handling SourceFile symbols in `getReferencedSymbolsForModule` instead of getting here.
-                Debug.fail(`Unexpected symbol at ${Debug.showSyntaxKind(node)}: ${Debug.showSymbol(symbol)}`);
+                Debug.fail(`Unexpected symbol at ${Debug.formatSyntaxKind(node.kind)}: ${Debug.formatSymbol(symbol)}`);
             }
             return isTypeLiteralNode(decl.parent) && isUnionTypeNode(decl.parent.parent)
                 ? checker.getPropertyOfType(checker.getTypeFromTypeNode(decl.parent.parent), symbol.name)

src/services/importTracker.ts

@@ -133,7 +133,7 @@ namespace ts.FindAllReferences {
                             break;
 
                         default:
-                            Debug.assertNever(direct, `Unexpected import kind: ${Debug.showSyntaxKind(direct)}`);
+                            Debug.failBadSyntaxKind(direct, "Unexpected import kind.");
                     }
                 }
             }
@@ -515,7 +515,7 @@ namespace ts.FindAllReferences {
                 const sym = useLhsSymbol ? checker.getSymbolAtLocation(cast(node.left, isPropertyAccessExpression).name) : symbol;
                 // Better detection for GH#20803
                 if (sym && !(checker.getMergedSymbol(sym.parent!).flags & SymbolFlags.Module)) {
-                    Debug.fail(`Special property assignment kind does not have a module as its parent. Assignment is ${Debug.showSymbol(sym)}, parent is ${Debug.showSymbol(sym.parent!)}`);
+                    Debug.fail(`Special property assignment kind does not have a module as its parent. Assignment is ${Debug.formatSymbol(sym)}, parent is ${Debug.formatSymbol(sym.parent!)}`);
                 }
                 return sym && exportInfo(sym, kind);
             }

src/services/refactors/extractType.ts

@@ -0,0 +1,147 @@
+/* @internal */
+namespace ts.refactor {
+    const refactorName = "Extract type";
+    const extractToTypeAlias = "Extract to type alias";
+    const extractToTypeDef = "Extract to typedef";
+    registerRefactor(refactorName, {
+        getAvailableActions(context): ReadonlyArray<ApplicableRefactorInfo> {
+            const info = getRangeToExtract(context);
+            if (!info) return emptyArray;
+
+            return [{
+                name: refactorName,
+                description: getLocaleSpecificMessage(Diagnostics.Extract_type),
+                actions: [info.isJS ? {
+                    name: extractToTypeDef, description: getLocaleSpecificMessage(Diagnostics.Extract_to_typedef)
+                } : {
+                        name: extractToTypeAlias, description: getLocaleSpecificMessage(Diagnostics.Extract_to_type_alias)
+                    }]
+            }];
+        },
+        getEditsForAction(context, actionName): RefactorEditInfo {
+            Debug.assert(actionName === extractToTypeAlias || actionName === extractToTypeDef);
+            const { file } = context;
+            const info = Debug.assertDefined(getRangeToExtract(context));
+            Debug.assert(actionName === extractToTypeAlias && !info.isJS || actionName === extractToTypeDef && info.isJS);
+
+            const name = getUniqueName("NewType", file);
+            const edits = textChanges.ChangeTracker.with(context, changes => info.isJS ?
+                doTypedefChange(changes, file, name, info.firstStatement, info.selection, info.typeParameters) :
+                doTypeAliasChange(changes, file, name, info.firstStatement, info.selection, info.typeParameters));
+
+            const renameFilename = file.fileName;
+            const renameLocation = getRenameLocation(edits, renameFilename, name, /*preferLastLocation*/ false);
+            return { edits, renameFilename, renameLocation };
+        }
+    });
+
+    interface Info { isJS: boolean; selection: TypeNode; firstStatement: Statement; typeParameters: ReadonlyArray<TypeParameterDeclaration>; }
+
+    function getRangeToExtract(context: RefactorContext): Info | undefined {
+        const { file, startPosition } = context;
+        const isJS = isSourceFileJS(file);
+        const current = getTokenAtPosition(file, startPosition);
+        const range = createTextRangeFromSpan(getRefactorContextSpan(context));
+
+        const selection = findAncestor(current, (node => node.parent && rangeContainsSkipTrivia(range, node, file) && !rangeContainsSkipTrivia(range, node.parent, file)));
+        if (!selection || !isTypeNode(selection)) return undefined;
+
+        const checker = context.program.getTypeChecker();
+        const firstStatement = Debug.assertDefined(isJS ? findAncestor(selection, isStatementAndHasJSDoc) : findAncestor(selection, isStatement));
+        const typeParameters = collectTypeParameters(checker, selection, firstStatement, file);
+        if (!typeParameters) return undefined;
+
+        return { isJS, selection, firstStatement, typeParameters };
+    }
+
+    function isStatementAndHasJSDoc(n: Node): n is (Statement & HasJSDoc) {
+        return isStatement(n) && hasJSDocNodes(n);
+    }
+
+    function rangeContainsSkipTrivia(r1: TextRange, node: Node, file: SourceFile): boolean {
+        return rangeContainsStartEnd(r1, skipTrivia(file.text, node.pos), node.end);
+    }
+
+    function collectTypeParameters(checker: TypeChecker, selection: TypeNode, statement: Statement, file: SourceFile): TypeParameterDeclaration[] | undefined {
+        const result: TypeParameterDeclaration[] = [];
+        return visitor(selection) ? undefined : result;
+
+        function visitor(node: Node): true | undefined {
+            if (isTypeReferenceNode(node)) {
+                if (isIdentifier(node.typeName)) {
+                    const symbol = checker.resolveName(node.typeName.text, node.typeName, SymbolFlags.TypeParameter, /* excludeGlobals */ true);
+                    if (symbol) {
+                        const declaration = cast(first(symbol.declarations), isTypeParameterDeclaration);
+                        if (rangeContainsSkipTrivia(statement, declaration, file) && !rangeContainsSkipTrivia(selection, declaration, file)) {
+                            result.push(declaration);
+                        }
+                    }
+                }
+            }
+            else if (isInferTypeNode(node)) {
+                const conditionalTypeNode = findAncestor(node, n => isConditionalTypeNode(n) && rangeContainsSkipTrivia(n.extendsType, node, file));
+                if (!conditionalTypeNode || !rangeContainsSkipTrivia(selection, conditionalTypeNode, file)) {
+                    return true;
+                }
+            }
+            else if ((isTypePredicateNode(node) || isThisTypeNode(node))) {
+                const functionLikeNode = findAncestor(node.parent, isFunctionLike);
+                if (functionLikeNode && functionLikeNode.type && rangeContainsSkipTrivia(functionLikeNode.type, node, file) && !rangeContainsSkipTrivia(selection, functionLikeNode, file)) {
+                    return true;
+                }
+            }
+            else if (isTypeQueryNode(node)) {
+                if (isIdentifier(node.exprName)) {
+                    const symbol = checker.resolveName(node.exprName.text, node.exprName, SymbolFlags.Value, /* excludeGlobals */ false);
+                    if (symbol && rangeContainsSkipTrivia(statement, symbol.valueDeclaration, file) && !rangeContainsSkipTrivia(selection, symbol.valueDeclaration, file)) {
+                        return true;
+                    }
+                }
+                else {
+                    if (isThisIdentifier(node.exprName.left) && !rangeContainsSkipTrivia(selection, node.parent, file)) {
+                        return true;
+                    }
+                }
+            }
+            return forEachChild(node, visitor);
+        }
+    }
+
+    function doTypeAliasChange(changes: textChanges.ChangeTracker, file: SourceFile, name: string, firstStatement: Statement, selection: TypeNode, typeParameters: ReadonlyArray<TypeParameterDeclaration>) {
+        const newTypeNode = createTypeAliasDeclaration(
+            /* decorators */ undefined,
+            /* modifiers */ undefined,
+            name,
+            typeParameters.map(id => updateTypeParameterDeclaration(id, id.name, id.constraint, /* defaultType */ undefined)),
+            selection
+        );
+        changes.insertNodeBefore(file, firstStatement, newTypeNode, /* blankLineBetween */ true);
+        changes.replaceNode(file, selection, createTypeReferenceNode(name, typeParameters.map(id => createTypeReferenceNode(id.name, /* typeArguments */ undefined))));
+    }
+
+    function doTypedefChange(changes: textChanges.ChangeTracker, file: SourceFile, name: string, firstStatement: Statement, selection: TypeNode, typeParameters: ReadonlyArray<TypeParameterDeclaration>) {
+        const node = <JSDocTypedefTag>createNode(SyntaxKind.JSDocTypedefTag);
+        node.tagName = createIdentifier("typedef"); // TODO: jsdoc factory https://github.com/Microsoft/TypeScript/pull/29539
+        node.fullName = createIdentifier(name);
+        node.name = node.fullName;
+        node.typeExpression = createJSDocTypeExpression(selection);
+
+        const templates: JSDocTemplateTag[] = [];
+        forEach(typeParameters, typeParameter => {
+            const constraint = getEffectiveConstraintOfTypeParameter(typeParameter);
+
+            const template = <JSDocTemplateTag>createNode(SyntaxKind.JSDocTemplateTag);
+            template.tagName = createIdentifier("template");
+            template.constraint = constraint && cast(constraint, isJSDocTypeExpression);
+
+            const parameter = <TypeParameterDeclaration>createNode(SyntaxKind.TypeParameter);
+            parameter.name = typeParameter.name;
+            template.typeParameters = createNodeArray([parameter]);
+
+            templates.push(template);
+        });
+
+        changes.insertNodeBefore(file, firstStatement, createJSDocComment(/* comment */ undefined, createNodeArray(concatenate<JSDocTag>(templates, [node]))), /* blankLineBetween */ true);
+        changes.replaceNode(file, selection, createTypeReferenceNode(name, typeParameters.map(id => createTypeReferenceNode(id.name, /* typeArguments */ undefined))));
+    }
+}

src/services/services.ts

@@ -173,7 +173,7 @@ namespace ts {
             const textPos = scanner.getTextPos();
             if (textPos <= end) {
                 if (token === SyntaxKind.Identifier) {
-                    Debug.fail(`Did not expect ${Debug.showSyntaxKind(parent)} to have an Identifier in its trivia`);
+                    Debug.fail(`Did not expect ${Debug.formatSyntaxKind(parent.kind)} to have an Identifier in its trivia`);
                 }
                 nodes.push(createNode(token, pos, textPos, parent));
             }
@@ -1467,33 +1467,41 @@ namespace ts {
             }
 
             const typeChecker = program.getTypeChecker();
-            const symbol = getSymbolAtLocationForQuickInfo(node, typeChecker);
+            const nodeForQuickInfo = getNodeForQuickInfo(node);
+            const symbol = getSymbolAtLocationForQuickInfo(nodeForQuickInfo, typeChecker);
 
             if (!symbol || typeChecker.isUnknownSymbol(symbol)) {
-                const type = shouldGetType(sourceFile, node, position) ? typeChecker.getTypeAtLocation(node) : undefined;
+                const type = shouldGetType(sourceFile, nodeForQuickInfo, position) ? typeChecker.getTypeAtLocation(nodeForQuickInfo) : undefined;
                 return type && {
                     kind: ScriptElementKind.unknown,
                     kindModifiers: ScriptElementKindModifier.none,
-                    textSpan: createTextSpanFromNode(node, sourceFile),
-                    displayParts: typeChecker.runWithCancellationToken(cancellationToken, typeChecker => typeToDisplayParts(typeChecker, type, getContainerNode(node))),
+                    textSpan: createTextSpanFromNode(nodeForQuickInfo, sourceFile),
+                    displayParts: typeChecker.runWithCancellationToken(cancellationToken, typeChecker => typeToDisplayParts(typeChecker, type, getContainerNode(nodeForQuickInfo))),
                     documentation: type.symbol ? type.symbol.getDocumentationComment(typeChecker) : undefined,
                     tags: type.symbol ? type.symbol.getJsDocTags() : undefined
                 };
             }
 
             const { symbolKind, displayParts, documentation, tags } = typeChecker.runWithCancellationToken(cancellationToken, typeChecker =>
-                SymbolDisplay.getSymbolDisplayPartsDocumentationAndSymbolKind(typeChecker, symbol, sourceFile, getContainerNode(node), node)
+                SymbolDisplay.getSymbolDisplayPartsDocumentationAndSymbolKind(typeChecker, symbol, sourceFile, getContainerNode(nodeForQuickInfo), nodeForQuickInfo)
             );
             return {
                 kind: symbolKind,
                 kindModifiers: SymbolDisplay.getSymbolModifiers(symbol),
-                textSpan: createTextSpanFromNode(node, sourceFile),
+                textSpan: createTextSpanFromNode(nodeForQuickInfo, sourceFile),
                 displayParts,
                 documentation,
                 tags,
             };
         }
 
+        function getNodeForQuickInfo(node: Node): Node {
+            if (isNewExpression(node.parent) && node.pos === node.parent.pos) {
+                return node.parent.expression;
+            }
+            return node;
+        }
+
         function shouldGetType(sourceFile: SourceFile, node: Node, position: number): boolean {
             switch (node.kind) {
                 case SyntaxKind.Identifier:
@@ -2072,6 +2080,10 @@ namespace ts {
             };
         }
 
+        function getSmartSelectionRange(fileName: string, position: number): SelectionRange {
+            return SmartSelectionRange.getSmartSelectionRange(position, syntaxTreeCache.getCurrentSourceFile(fileName));
+        }
+
         function getApplicableRefactors(fileName: string, positionOrRange: number | TextRange, preferences: UserPreferences = emptyOptions): ApplicableRefactorInfo[] {
             synchronizeHostData();
             const file = getValidSourceFile(fileName);
@@ -2119,6 +2131,7 @@ namespace ts {
             getBreakpointStatementAtPosition,
             getNavigateToItems,
             getRenameInfo,
+            getSmartSelectionRange,
             findRenameLocations,
             getNavigationBarItems,
             getNavigationTree,

src/services/shims.ts

@@ -165,6 +165,7 @@ namespace ts {
          * { canRename: boolean, localizedErrorMessage: string, displayName: string, fullDisplayName: string, kind: string, kindModifiers: string, triggerSpan: { start; length } }
          */
         getRenameInfo(fileName: string, position: number, options?: RenameInfoOptions): string;
+        getSmartSelectionRange(fileName: string, position: number): string;
 
         /**
          * Returns a JSON-encoded value of the type:
@@ -838,6 +839,13 @@ namespace ts {
             );
         }
 
+        public getSmartSelectionRange(fileName: string, position: number): string {
+            return this.forwardJSONCall(
+                `getSmartSelectionRange('${fileName}', ${position})`,
+                () => this.languageService.getSmartSelectionRange(fileName, position)
+            );
+        }
+
         public findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean, providePrefixAndSuffixTextForRename?: boolean): string {
             return this.forwardJSONCall(
                 `findRenameLocations('${fileName}', ${position}, ${findInStrings}, ${findInComments}, ${providePrefixAndSuffixTextForRename})`,

src/services/signatureHelp.ts

@@ -455,7 +455,7 @@ namespace ts.SignatureHelp {
         for (let n = node; !isSourceFile(n) && (isManuallyInvoked || !isBlock(n)); n = n.parent) {
             // If the node is not a subspan of its parent, this is a big problem.
             // There have been crashes that might be caused by this violation.
-            Debug.assert(rangeContainsRange(n.parent, n), "Not a subspan", () => `Child: ${Debug.showSyntaxKind(n)}, parent: ${Debug.showSyntaxKind(n.parent)}`);
+            Debug.assert(rangeContainsRange(n.parent, n), "Not a subspan", () => `Child: ${Debug.formatSyntaxKind(n.kind)}, parent: ${Debug.formatSyntaxKind(n.parent.kind)}`);
             const argumentInfo = getImmediatelyContainingArgumentOrContextualParameterInfo(n, position, sourceFile, checker);
             if (argumentInfo) {
                 return argumentInfo;

src/services/smartSelection.ts

@@ -0,0 +1,266 @@
+/* @internal */
+namespace ts.SmartSelectionRange {
+    export function getSmartSelectionRange(pos: number, sourceFile: SourceFile): SelectionRange {
+        let selectionRange: SelectionRange = {
+            textSpan: createTextSpanFromBounds(sourceFile.getFullStart(), sourceFile.getEnd())
+        };
+
+        let parentNode: Node = sourceFile;
+        outer: while (true) {
+            const children = getSelectionChildren(parentNode);
+            if (!children.length) break;
+            for (let i = 0; i < children.length; i++) {
+                const prevNode: Node | undefined = children[i - 1];
+                const node: Node = children[i];
+                const nextNode: Node | undefined = children[i + 1];
+                if (node.getStart(sourceFile) > pos) {
+                    break outer;
+                }
+
+                if (positionShouldSnapToNode(pos, node, nextNode)) {
+                    // 1. Blocks are effectively redundant with SyntaxLists.
+                    // 2. TemplateSpans, along with the SyntaxLists containing them, are a somewhat unintuitive grouping
+                    //    of things that should be considered independently.
+                    // 3. A VariableStatement’s children are just a VaraiableDeclarationList and a semicolon.
+                    // 4. A lone VariableDeclaration in a VaraibleDeclaration feels redundant with the VariableStatement.
+                    //
+                    // Dive in without pushing a selection range.
+                    if (isBlock(node)
+                        || isTemplateSpan(node) || isTemplateHead(node)
+                        || prevNode && isTemplateHead(prevNode)
+                        || isVariableDeclarationList(node) && isVariableStatement(parentNode)
+                        || isSyntaxList(node) && isVariableDeclarationList(parentNode)
+                        || isVariableDeclaration(node) && isSyntaxList(parentNode) && children.length === 1) {
+                        parentNode = node;
+                        break;
+                    }
+
+                    // Synthesize a stop for '${ ... }' since '${' and '}' actually belong to siblings.
+                    if (isTemplateSpan(parentNode) && nextNode && isTemplateMiddleOrTemplateTail(nextNode)) {
+                        const start = node.getFullStart() - "${".length;
+                        const end = nextNode.getStart() + "}".length;
+                        pushSelectionRange(start, end);
+                    }
+
+                    // Blocks with braces, brackets, parens, or JSX tags on separate lines should be
+                    // selected from open to close, including whitespace but not including the braces/etc. themselves.
+                    const isBetweenMultiLineBookends = isSyntaxList(node)
+                        && isListOpener(prevNode)
+                        && isListCloser(nextNode)
+                        && !positionsAreOnSameLine(prevNode.getStart(), nextNode.getStart(), sourceFile);
+                    const jsDocCommentStart = hasJSDocNodes(node) && node.jsDoc![0].getStart();
+                    const start = isBetweenMultiLineBookends ? prevNode.getEnd() : node.getStart();
+                    const end = isBetweenMultiLineBookends ? nextNode.getStart() : node.getEnd();
+                    if (isNumber(jsDocCommentStart)) {
+                        pushSelectionRange(jsDocCommentStart, end);
+                    }
+                    pushSelectionRange(start, end);
+
+                    // String literals should have a stop both inside and outside their quotes.
+                    if (isStringLiteral(node) || isTemplateLiteral(node)) {
+                        pushSelectionRange(start + 1, end - 1);
+                    }
+
+                    parentNode = node;
+                    break;
+                }
+            }
+        }
+
+        return selectionRange;
+
+        function pushSelectionRange(start: number, end: number): void {
+            // Skip empty ranges
+            if (start !== end) {
+                // Skip ranges that are identical to the parent
+                const textSpan = createTextSpanFromBounds(start, end);
+                if (!selectionRange || !textSpansEqual(textSpan, selectionRange.textSpan)) {
+                    selectionRange = { textSpan, ...selectionRange && { parent: selectionRange } };
+                }
+            }
+        }
+    }
+
+    /**
+     * Like `ts.positionBelongsToNode`, except positions immediately after nodes
+     * count too, unless that position belongs to the next node. In effect, makes
+     * selections able to snap to preceding tokens when the cursor is on the tail
+     * end of them with only whitespace ahead.
+     * @param pos The position to check.
+     * @param node The candidate node to snap to.
+     * @param nextNode The next sibling node in the tree.
+     * @param sourceFile The source file containing the nodes.
+     */
+    function positionShouldSnapToNode(pos: number, node: Node, nextNode: Node | undefined) {
+        // Can’t use 'ts.positionBelongsToNode()' here because it cleverly accounts
+        // for missing nodes, which can’t really be considered when deciding what
+        // to select.
+        Debug.assert(node.pos <= pos);
+        if (pos < node.end) {
+            return true;
+        }
+        const nodeEnd = node.getEnd();
+        const nextNodeStart = nextNode && nextNode.getStart();
+        if (nodeEnd === pos) {
+            return pos !== nextNodeStart;
+        }
+        return false;
+    }
+
+    const isImport = or(isImportDeclaration, isImportEqualsDeclaration);
+
+    /**
+     * Gets the children of a node to be considered for selection ranging,
+     * transforming them into an artificial tree according to their intuitive
+     * grouping where no grouping actually exists in the parse tree. For example,
+     * top-level imports are grouped into their own SyntaxList so they can be
+     * selected all together, even though in the AST they’re just siblings of each
+     * other as well as of other top-level statements and declarations.
+     */
+    function getSelectionChildren(node: Node): ReadonlyArray<Node> {
+        // Group top-level imports
+        if (isSourceFile(node)) {
+            return groupChildren(node.getChildAt(0).getChildren(), isImport);
+        }
+
+        // Mapped types _look_ like ObjectTypes with a single member,
+        // but in fact don’t contain a SyntaxList or a node containing
+        // the “key/value” pair like ObjectTypes do, but it seems intuitive
+        // that the selection would snap to those points. The philosophy
+        // of choosing a selection range is not so much about what the
+        // syntax currently _is_ as what the syntax might easily become
+        // if the user is making a selection; e.g., we synthesize a selection
+        // around the “key/value” pair not because there’s a node there, but
+        // because it allows the mapped type to become an object type with a
+        // few keystrokes.
+        if (isMappedTypeNode(node)) {
+            const [openBraceToken, ...children] = node.getChildren();
+            const closeBraceToken = Debug.assertDefined(children.pop());
+            Debug.assertEqual(openBraceToken.kind, SyntaxKind.OpenBraceToken);
+            Debug.assertEqual(closeBraceToken.kind, SyntaxKind.CloseBraceToken);
+            // Group `-/+readonly` and `-/+?`
+            const groupedWithPlusMinusTokens = groupChildren(children, child =>
+                child === node.readonlyToken || child.kind === SyntaxKind.ReadonlyKeyword ||
+                child === node.questionToken || child.kind === SyntaxKind.QuestionToken);
+            // Group type parameter with surrounding brackets
+            const groupedWithBrackets = groupChildren(groupedWithPlusMinusTokens, ({ kind }) =>
+                kind === SyntaxKind.OpenBracketToken ||
+                kind === SyntaxKind.TypeParameter ||
+                kind === SyntaxKind.CloseBracketToken
+            );
+            return [
+                openBraceToken,
+                // Pivot on `:`
+                createSyntaxList(splitChildren(groupedWithBrackets, ({ kind }) => kind === SyntaxKind.ColonToken)),
+                closeBraceToken,
+            ];
+        }
+
+        // Group modifiers and property name, then pivot on `:`.
+        if (isPropertySignature(node)) {
+            const children = groupChildren(node.getChildren(), child =>
+                child === node.name || contains(node.modifiers, child));
+            return splitChildren(children, ({ kind }) => kind === SyntaxKind.ColonToken);
+        }
+
+        // Group the parameter name with its `...`, then that group with its `?`, then pivot on `=`.
+        if (isParameter(node)) {
+            const groupedDotDotDotAndName = groupChildren(node.getChildren(), child =>
+                child === node.dotDotDotToken || child === node.name);
+            const groupedWithQuestionToken = groupChildren(groupedDotDotDotAndName, child =>
+                child === groupedDotDotDotAndName[0] || child === node.questionToken);
+            return splitChildren(groupedWithQuestionToken, ({ kind }) => kind === SyntaxKind.EqualsToken);
+        }
+
+        // Pivot on '='
+        if (isBindingElement(node)) {
+            return splitChildren(node.getChildren(), ({ kind }) => kind === SyntaxKind.EqualsToken);
+        }
+
+        return node.getChildren();
+    }
+
+    /**
+     * Groups sibling nodes together into their own SyntaxList if they
+     * a) are adjacent, AND b) match a predicate function.
+     */
+    function groupChildren(children: Node[], groupOn: (child: Node) => boolean): Node[] {
+        const result: Node[] = [];
+        let group: Node[] | undefined;
+        for (const child of children) {
+            if (groupOn(child)) {
+                group = group || [];
+                group.push(child);
+            }
+            else {
+                if (group) {
+                    result.push(createSyntaxList(group));
+                    group = undefined;
+                }
+                result.push(child);
+            }
+        }
+        if (group) {
+            result.push(createSyntaxList(group));
+        }
+
+        return result;
+    }
+
+    /**
+     * Splits sibling nodes into up to four partitions:
+     * 1) everything left of the first node matched by `pivotOn`,
+     * 2) the first node matched by `pivotOn`,
+     * 3) everything right of the first node matched by `pivotOn`,
+     * 4) a trailing semicolon, if `separateTrailingSemicolon` is enabled.
+     * The left and right groups, if not empty, will each be grouped into their own containing SyntaxList.
+     * @param children The sibling nodes to split.
+     * @param pivotOn The predicate function to match the node to be the pivot. The first node that matches
+     * the predicate will be used; any others that may match will be included into the right-hand group.
+     * @param separateTrailingSemicolon If the last token is a semicolon, it will be returned as a separate
+     * child rather than be included in the right-hand group.
+     */
+    function splitChildren(children: Node[], pivotOn: (child: Node) => boolean, separateTrailingSemicolon = true): Node[] {
+        if (children.length < 2) {
+            return children;
+        }
+        const splitTokenIndex = findIndex(children, pivotOn);
+        if (splitTokenIndex === -1) {
+            return children;
+        }
+        const leftChildren = children.slice(0, splitTokenIndex);
+        const splitToken = children[splitTokenIndex];
+        const lastToken = last(children);
+        const separateLastToken = separateTrailingSemicolon && lastToken.kind === SyntaxKind.SemicolonToken;
+        const rightChildren = children.slice(splitTokenIndex + 1, separateLastToken ? children.length - 1 : undefined);
+        const result = compact([
+            leftChildren.length ? createSyntaxList(leftChildren) : undefined,
+            splitToken,
+            rightChildren.length ? createSyntaxList(rightChildren) : undefined,
+        ]);
+        return separateLastToken ? result.concat(lastToken) : result;
+    }
+
+    function createSyntaxList(children: Node[]): SyntaxList {
+        Debug.assertGreaterThanOrEqual(children.length, 1);
+        const syntaxList = createNode(SyntaxKind.SyntaxList, children[0].pos, last(children).end) as SyntaxList;
+        syntaxList._children = children;
+        return syntaxList;
+    }
+
+    function isListOpener(token: Node | undefined): token is Node {
+        const kind = token && token.kind;
+        return kind === SyntaxKind.OpenBraceToken
+            || kind === SyntaxKind.OpenBracketToken
+            || kind === SyntaxKind.OpenParenToken
+            || kind === SyntaxKind.JsxOpeningElement;
+    }
+
+    function isListCloser(token: Node | undefined): token is Node {
+        const kind = token && token.kind;
+        return kind === SyntaxKind.CloseBraceToken
+            || kind === SyntaxKind.CloseBracketToken
+            || kind === SyntaxKind.CloseParenToken
+            || kind === SyntaxKind.JsxClosingElement;
+    }
+}

src/services/stringCompletions.ts

@@ -21,7 +21,17 @@ namespace ts.Completions.StringCompletions {
                 return convertPathCompletions(completion.paths);
             case StringLiteralCompletionKind.Properties: {
                 const entries: CompletionEntry[] = [];
-                getCompletionEntriesFromSymbols(completion.symbols, entries, sourceFile, sourceFile, checker, ScriptTarget.ESNext, log, CompletionKind.String, preferences); // Target will not be used, so arbitrary
+                getCompletionEntriesFromSymbols(
+                    completion.symbols,
+                    entries,
+                    sourceFile,
+                    sourceFile,
+                    checker,
+                    ScriptTarget.ESNext,
+                    log,
+                    CompletionKind.String,
+                    preferences
+                ); // Target will not be used, so arbitrary
                 return { isGlobalCompletion: false, isMemberCompletion: true, isNewIdentifierLocation: completion.hasIndexSignature, entries };
             }
             case StringLiteralCompletionKind.Types: {
@@ -60,7 +70,7 @@ namespace ts.Completions.StringCompletions {
         const isGlobalCompletion = false; // We don't want the editor to offer any other completions, such as snippets, inside a comment.
         const isNewIdentifierLocation = true; // The user may type in a path that doesn't yet exist, creating a "new identifier" with respect to the collection of identifiers the server is aware of.
         const entries = pathCompletions.map(({ name, kind, span, extension }): CompletionEntry =>
-            ({ name, kind, kindModifiers: kindModifiersFromExtension(extension), sortText: "0", replacementSpan: span }));
+            ({ name, kind, kindModifiers: kindModifiersFromExtension(extension), sortText: SortText.LocationPriority, replacementSpan: span }));
         return { isGlobalCompletion, isMemberCompletion: false, isNewIdentifierLocation, entries };
     }
     function kindModifiersFromExtension(extension: Extension | undefined): ScriptElementKindModifier {

src/services/tsconfig.json

@@ -28,6 +28,7 @@
         "patternMatcher.ts",
         "preProcess.ts",
         "rename.ts",
+        "smartSelection.ts",
         "signatureHelp.ts",
         "sourcemaps.ts",
         "suggestionDiagnostics.ts",
@@ -80,6 +81,7 @@
         "refactors/convertExport.ts",
         "refactors/convertImport.ts",
         "refactors/extractSymbol.ts",
+        "refactors/extractType.ts",
         "refactors/generateGetAccessorAndSetAccessor.ts",
         "refactors/moveToNewFile.ts",
         "refactors/addOrRemoveBracesToArrowFunction.ts",

src/services/types.ts

@@ -296,6 +296,8 @@ namespace ts {
         getRenameInfo(fileName: string, position: number, options?: RenameInfoOptions): RenameInfo;
         findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean, providePrefixAndSuffixTextForRename?: boolean): ReadonlyArray<RenameLocation> | undefined;
 
+        getSmartSelectionRange(fileName: string, position: number): SelectionRange;
+
         getDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
         getDefinitionAndBoundSpan(fileName: string, position: number): DefinitionInfoAndBoundSpan | undefined;
         getTypeDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
@@ -848,6 +850,11 @@ namespace ts {
         isOptional: boolean;
     }
 
+    export interface SelectionRange {
+        textSpan: TextSpan;
+        parent?: SelectionRange;
+    }
+
     /**
      * Represents a single signature to show in signature help.
      * The id is used for subsequent calls into the language service to ask questions about the

src/testRunner/tsconfig.json

@@ -142,6 +142,7 @@
         "unittests/tsserver/reload.ts",
         "unittests/tsserver/rename.ts",
         "unittests/tsserver/resolutionCache.ts",
+        "unittests/tsserver/smartSelection.ts",
         "unittests/tsserver/session.ts",
         "unittests/tsserver/skipLibCheck.ts",
         "unittests/tsserver/symLinks.ts",

src/testRunner/unittests/config/configurationExtension.ts

@@ -197,13 +197,13 @@ namespace ts {
     const caseSensitiveBasePath = "/dev/";
     const caseSensitiveHost = new fakes.ParseConfigHost(createFileSystem(/*ignoreCase*/ false, caseSensitiveBasePath, "/"));
 
-    function verifyDiagnostics(actual: Diagnostic[], expected: {code: number, category: DiagnosticCategory, messageText: string}[]) {
+    function verifyDiagnostics(actual: Diagnostic[], expected: { code: number; messageText: string; }[]) {
         assert.isTrue(expected.length === actual.length, `Expected error: ${JSON.stringify(expected)}. Actual error: ${JSON.stringify(actual)}.`);
         for (let i = 0; i < actual.length; i++) {
             const actualError = actual[i];
             const expectedError = expected[i];
             assert.equal(actualError.code, expectedError.code, "Error code mismatch");
-            assert.equal(actualError.category, expectedError.category, "Category mismatch");
+            assert.equal(actualError.category, DiagnosticCategory.Error, "Category mismatch"); // Should always be error
             assert.equal(flattenDiagnosticMessageText(actualError.messageText, "\n"), expectedError.messageText);
         }
     }
@@ -246,7 +246,7 @@ namespace ts {
                 });
             }
 
-            function testFailure(name: string, entry: string, expectedDiagnostics: { code: number, category: DiagnosticCategory, messageText: string }[]) {
+            function testFailure(name: string, entry: string, expectedDiagnostics: { code: number; messageText: string; }[]) {
                 it(name, () => {
                     const parsed = getParseCommandLine(entry);
                     verifyDiagnostics(parsed.errors, expectedDiagnostics);
@@ -280,26 +280,22 @@ namespace ts {
                 testFailure("can report errors on circular imports", "circular.json", [
                     {
                         code: 18000,
-                        category: DiagnosticCategory.Error,
                         messageText: `Circularity detected while resolving configuration: ${[combinePaths(basePath, "circular.json"), combinePaths(basePath, "circular2.json"), combinePaths(basePath, "circular.json")].join(" -> ")}`
                     }
                 ]);
 
                 testFailure("can report missing configurations", "missing.json", [{
-                    code: 6096,
-                    category: DiagnosticCategory.Message,
-                    messageText: `File './missing2' does not exist.`
+                    code: 6053,
+                    messageText: `File './missing2' not found.`
                 }]);
 
                 testFailure("can report errors in extended configs", "failure.json", [{
                     code: 6114,
-                    category: DiagnosticCategory.Error,
                     messageText: `Unknown option 'excludes'. Did you mean 'exclude'?`
                 }]);
 
                 testFailure("can error when 'extends' is not a string", "extends.json", [{
                     code: 5024,
-                    category: DiagnosticCategory.Error,
                     messageText: `Compiler option 'extends' requires a value of type string.`
                 }]);
 

src/testRunner/unittests/customTransforms.ts

@@ -140,22 +140,28 @@ namespace ts {
             ],
             {
                 before: [
-                    context => node => visitNode(node, function visitor(node: Node): Node {
-                        if (isIdentifier(node) && node.text === "original") {
-                            const newNode = createIdentifier("changed");
-                            setSourceMapRange(newNode, {
-                              pos: 0,
-                              end: 7,
-                              // Do not provide a custom skipTrivia function for `source`.
-                              source: createSourceMapSource("another.html", "changed;")
-                            });
-                            return newNode;
-                        }
-                        return visitEachChild(node, visitor, context);
-                    })
+                    context => {
+                        const transformSourceFile: Transformer<SourceFile> = node => visitNode(node, function visitor(node: Node): Node {
+                            if (isIdentifier(node) && node.text === "original") {
+                                const newNode = createIdentifier("changed");
+                                setSourceMapRange(newNode, {
+                                    pos: 0,
+                                    end: 7,
+                                    // Do not provide a custom skipTrivia function for `source`.
+                                    source: createSourceMapSource("another.html", "changed;")
+                                });
+                                return newNode;
+                            }
+                            return visitEachChild(node, visitor, context);
+                        });
+                        return {
+                            transformSourceFile,
+                            transformBundle: node => createBundle(map(node.sourceFiles, transformSourceFile), node.prepends),
+                        };
+                    }
                 ]
             },
-            { sourceMap: true }
+            { sourceMap: true, outFile: "source.js" }
         );
 
     });

src/testRunner/unittests/factory.ts

@@ -1,7 +1,7 @@
 namespace ts {
     describe("unittests:: FactoryAPI", () => {
         function assertSyntaxKind(node: Node, expected: SyntaxKind) {
-            assert.strictEqual(node.kind, expected, `Actual: ${Debug.showSyntaxKind(node)} Expected: ${(ts as any).SyntaxKind[expected]}`);
+            assert.strictEqual(node.kind, expected, `Actual: ${Debug.formatSyntaxKind(node.kind)} Expected: ${Debug.formatSyntaxKind(expected)}`);
         }
         describe("createExportAssignment", () => {
             it("parenthesizes default export if necessary", () => {

src/testRunner/unittests/jsDocParsing.ts

@@ -37,6 +37,8 @@ namespace ts {
                 parsesCorrectly("callSignatureInRecordType", "{{(): number}}");
                 parsesCorrectly("methodInRecordType", "{{foo(): number}}");
                 parsesCorrectly("unionType", "{(number|string)}");
+                parsesCorrectly("unionTypeWithLeadingOperator", "{( | number | string )}");
+                parsesCorrectly("unionTypeWithOneElementAndLeadingOperator", "{( | number )}");
                 parsesCorrectly("topLevelNoParenUnionType", "{number|string}");
                 parsesCorrectly("functionType1", "{function()}");
                 parsesCorrectly("functionType2", "{function(string, boolean)}");

src/testRunner/unittests/moduleResolution.ts

@@ -530,7 +530,7 @@ export = C;
         });
     });
 
-    describe("unittests:: moduleResolution:: Files with different casing", () => {
+    describe("unittests:: moduleResolution:: Files with different casing with forceConsistentCasingInFileNames", () => {
         let library: SourceFile;
         function test(files: Map<string>, options: CompilerOptions, currentDirectory: string, useCaseSensitiveFileNames: boolean, rootFiles: string[], diagnosticCodes: number[]): void {
             const getCanonicalFileName = createGetCanonicalFileName(useCaseSensitiveFileNames);
@@ -649,6 +649,22 @@ import b = require("./moduleB");
             });
             test(files, { module: ModuleKind.CommonJS, forceConsistentCasingInFileNames: true }, "/a/B/c", /*useCaseSensitiveFileNames*/ false, ["moduleD.ts"], []);
         });
+
+        it("should succeed when the two files in program differ only in drive letter in their names", () => {
+            const files = createMapFromTemplate({
+                "d:/someFolder/moduleA.ts": `import a = require("D:/someFolder/moduleC")`,
+                "d:/someFolder/moduleB.ts": `import a = require("./moduleC")`,
+                "D:/someFolder/moduleC.ts": "export const x = 10",
+            });
+            test(
+                files,
+                { module: ModuleKind.CommonJS, forceConsistentCasingInFileNames: true },
+                "d:/someFolder",
+                /*useCaseSensitiveFileNames*/ false,
+                ["d:/someFolder/moduleA.ts", "d:/someFolder/moduleB.ts"],
+                []
+            );
+        });
     });
 
     describe("unittests:: moduleResolution:: baseUrl augmented module resolution", () => {

src/testRunner/unittests/tsserver/completions.ts

@@ -36,7 +36,7 @@ namespace ts.projectSystem {
                 kindModifiers: ScriptElementKindModifier.exportedModifier,
                 name: "foo",
                 replacementSpan: undefined,
-                sortText: "0",
+                sortText: Completions.SortText.AutoImportSuggestions,
                 source: "/a",
             };
             assert.deepEqual<protocol.CompletionInfo | undefined>(response, {

src/testRunner/unittests/tsserver/session.ts

@@ -264,6 +264,7 @@ namespace ts.server {
                 CommandNames.OrganizeImportsFull,
                 CommandNames.GetEditsForFileRename,
                 CommandNames.GetEditsForFileRenameFull,
+                CommandNames.SelectionRange,
             ];
 
             it("should not throw when commands are executed with invalid arguments", () => {

src/testRunner/unittests/tsserver/smartSelection.ts

@@ -0,0 +1,66 @@
+namespace ts.projectSystem {
+    function setup(fileName: string, content: string) {
+        const file: File = { path: fileName, content };
+        const host = createServerHost([file, libFile]);
+        const session = createSession(host);
+        openFilesForSession([file], session);
+        return function getSmartSelectionRange(locations: protocol.SelectionRangeRequestArgs["locations"]) {
+            return executeSessionRequest<protocol.SelectionRangeRequest, protocol.SelectionRangeResponse>(
+                session,
+                CommandNames.SelectionRange,
+                { file: fileName, locations });
+        };
+    }
+
+    // More tests in fourslash/smartSelection_*
+    describe("unittests:: tsserver:: smartSelection", () => {
+        it("works for simple JavaScript", () => {
+            const getSmartSelectionRange = setup("/file.js", `
+class Foo {
+    bar(a, b) {
+        if (a === b) {
+            return true;
+        }
+        return false;
+    }
+}`);
+
+            const locations = getSmartSelectionRange([
+                { line: 4, offset: 13 }, // a === b
+            ]);
+
+            assert.deepEqual(locations, [{
+                textSpan: { // a
+                    start: { line: 4, offset: 13 },
+                    end: { line: 4, offset: 14 } },
+                parent: {
+                    textSpan: { // a === b
+                        start: { line: 4, offset: 13 },
+                        end: { line: 4, offset: 20 } },
+                    parent: {
+                        textSpan: { // IfStatement
+                            start: { line: 4, offset: 9 },
+                            end: { line: 6, offset: 10 } },
+                        parent: {
+                            textSpan: { // SyntaxList + whitespace (body of method)
+                                start: { line: 3, offset: 16 },
+                                end: { line: 8, offset: 5 } },
+                            parent: {
+                                textSpan: { // MethodDeclaration
+                                    start: { line: 3, offset: 5 },
+                                    end: { line: 8, offset: 6 } },
+                                parent: {
+                                    textSpan: { // SyntaxList + whitespace (body of class)
+                                        start: { line: 2, offset: 12 },
+                                        end: { line: 9, offset: 1 } },
+                                    parent: {
+                                        textSpan: { // ClassDeclaration
+                                            start: { line: 2, offset: 1 },
+                                            end: { line: 9, offset: 2 } },
+                                        parent: {
+                                            textSpan: { // SourceFile (all text)
+                                                start: { line: 1, offset: 1 },
+                                                end: { line: 9, offset: 2 }, } } } } } } } } }]);
+        });
+    });
+}

tests/baselines/reference/ES5For-of37.js

@@ -0,0 +1,64 @@
+//// [ES5For-of37.ts]
+// https://github.com/microsoft/TypeScript/issues/30083
+
+for (const i of [0, 1, 2, 3, 4]) {
+    try {
+        // Ensure catch binding for the following loop is reset per iteration:
+        for (const j of [1, 2, 3]) {
+            if (i === 2) {
+                throw new Error('ERR');
+            }
+        }
+        console.log(i);
+    } catch (err) {
+        console.log('E %s %s', i, err);
+    }
+}
+
+//// [ES5For-of37.js]
+// https://github.com/microsoft/TypeScript/issues/30083
+var __values = (this && this.__values) || function (o) {
+    var m = typeof Symbol === "function" && o[Symbol.iterator], i = 0;
+    if (m) return m.call(o);
+    return {
+        next: function () {
+            if (o && i >= o.length) o = void 0;
+            return { value: o && o[i++], done: !o };
+        }
+    };
+};
+var e_1, _a, e_2, _b;
+try {
+    for (var _c = __values([0, 1, 2, 3, 4]), _d = _c.next(); !_d.done; _d = _c.next()) {
+        var i = _d.value;
+        try {
+            try {
+                // Ensure catch binding for the following loop is reset per iteration:
+                for (var _e = (e_2 = void 0, __values([1, 2, 3])), _f = _e.next(); !_f.done; _f = _e.next()) {
+                    var j = _f.value;
+                    if (i === 2) {
+                        throw new Error('ERR');
+                    }
+                }
+            }
+            catch (e_2_1) { e_2 = { error: e_2_1 }; }
+            finally {
+                try {
+                    if (_f && !_f.done && (_b = _e["return"])) _b.call(_e);
+                }
+                finally { if (e_2) throw e_2.error; }
+            }
+            console.log(i);
+        }
+        catch (err) {
+            console.log('E %s %s', i, err);
+        }
+    }
+}
+catch (e_1_1) { e_1 = { error: e_1_1 }; }
+finally {
+    try {
+        if (_d && !_d.done && (_a = _c["return"])) _a.call(_c);
+    }
+    finally { if (e_1) throw e_1.error; }
+}

tests/baselines/reference/ES5For-of37.symbols

@@ -0,0 +1,35 @@
+=== tests/cases/conformance/statements/for-ofStatements/ES5For-of37.ts ===
+// https://github.com/microsoft/TypeScript/issues/30083
+
+for (const i of [0, 1, 2, 3, 4]) {
+>i : Symbol(i, Decl(ES5For-of37.ts, 2, 10))
+
+    try {
+        // Ensure catch binding for the following loop is reset per iteration:
+        for (const j of [1, 2, 3]) {
+>j : Symbol(j, Decl(ES5For-of37.ts, 5, 18))
+
+            if (i === 2) {
+>i : Symbol(i, Decl(ES5For-of37.ts, 2, 10))
+
+                throw new Error('ERR');
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+            }
+        }
+        console.log(i);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>i : Symbol(i, Decl(ES5For-of37.ts, 2, 10))
+
+    } catch (err) {
+>err : Symbol(err, Decl(ES5For-of37.ts, 11, 13))
+
+        console.log('E %s %s', i, err);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>i : Symbol(i, Decl(ES5For-of37.ts, 2, 10))
+>err : Symbol(err, Decl(ES5For-of37.ts, 11, 13))
+    }
+}

tests/baselines/reference/ES5For-of37.types

@@ -0,0 +1,52 @@
+=== tests/cases/conformance/statements/for-ofStatements/ES5For-of37.ts ===
+// https://github.com/microsoft/TypeScript/issues/30083
+
+for (const i of [0, 1, 2, 3, 4]) {
+>i : number
+>[0, 1, 2, 3, 4] : number[]
+>0 : 0
+>1 : 1
+>2 : 2
+>3 : 3
+>4 : 4
+
+    try {
+        // Ensure catch binding for the following loop is reset per iteration:
+        for (const j of [1, 2, 3]) {
+>j : number
+>[1, 2, 3] : number[]
+>1 : 1
+>2 : 2
+>3 : 3
+
+            if (i === 2) {
+>i === 2 : boolean
+>i : number
+>2 : 2
+
+                throw new Error('ERR');
+>new Error('ERR') : Error
+>Error : ErrorConstructor
+>'ERR' : "ERR"
+            }
+        }
+        console.log(i);
+>console.log(i) : void
+>console.log : (message?: any, ...optionalParams: any[]) => void
+>console : Console
+>log : (message?: any, ...optionalParams: any[]) => void
+>i : number
+
+    } catch (err) {
+>err : any
+
+        console.log('E %s %s', i, err);
+>console.log('E %s %s', i, err) : void
+>console.log : (message?: any, ...optionalParams: any[]) => void
+>console : Console
+>log : (message?: any, ...optionalParams: any[]) => void
+>'E %s %s' : "E %s %s"
+>i : number
+>err : any
+    }
+}

tests/baselines/reference/ES5For-of7.errors.txt

@@ -10,4 +10,5 @@ tests/cases/conformance/statements/for-ofStatements/ES5For-of7.ts(6,9): error TS
         var x = [w, v];
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'any', but here has type 'any[]'.
+!!! related TS6203 tests/cases/conformance/statements/for-ofStatements/ES5For-of7.ts:2:9: 'x' was also declared here.
     }

tests/baselines/reference/FunctionAndModuleWithSameNameAndCommonRoot.errors.txt

@@ -24,6 +24,7 @@ tests/cases/conformance/internalModules/DeclarationMerging/test.ts(2,5): error T
     var fn = A.Point;
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'fn' must be of type '() => { x: number; y: number; }', but here has type 'typeof Point'.
+!!! related TS6203 tests/cases/conformance/internalModules/DeclarationMerging/test.ts:1:5: 'fn' was also declared here.
     
     var cl: { x: number; y: number; }
     var cl = A.Point();
@@ -46,6 +47,7 @@ tests/cases/conformance/internalModules/DeclarationMerging/test.ts(2,5): error T
     var fn = B.Point;  // not expected to be an error. bug 840000: [corelang] Function of fundule not assignalbe as expected
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'fn' must be of type '() => { x: number; y: number; }', but here has type 'typeof Point'.
+!!! related TS6203 tests/cases/conformance/internalModules/DeclarationMerging/test.ts:1:5: 'fn' was also declared here.
     
     var cl: { x: number; y: number; }
     var cl = B.Point();

tests/baselines/reference/JSDocParsing/TypeExpressions.parsesCorrectly.unionTypeWithLeadingOperator.json

@@ -0,0 +1,37 @@
+{
+    "kind": "ParenthesizedType",
+    "pos": 1,
+    "end": 22,
+    "flags": "JSDoc",
+    "modifierFlagsCache": 0,
+    "transformFlags": 0,
+    "type": {
+        "kind": "UnionType",
+        "pos": 2,
+        "end": 20,
+        "flags": "JSDoc",
+        "modifierFlagsCache": 0,
+        "transformFlags": 0,
+        "types": {
+            "0": {
+                "kind": "NumberKeyword",
+                "pos": 4,
+                "end": 11,
+                "flags": "JSDoc",
+                "modifierFlagsCache": 0,
+                "transformFlags": 0
+            },
+            "1": {
+                "kind": "StringKeyword",
+                "pos": 13,
+                "end": 20,
+                "flags": "JSDoc",
+                "modifierFlagsCache": 0,
+                "transformFlags": 0
+            },
+            "length": 2,
+            "pos": 2,
+            "end": 20
+        }
+    }
+}

tests/baselines/reference/JSDocParsing/TypeExpressions.parsesCorrectly.unionTypeWithOneElementAndLeadingOperator.json

@@ -0,0 +1,29 @@
+{
+    "kind": "ParenthesizedType",
+    "pos": 1,
+    "end": 13,
+    "flags": "JSDoc",
+    "modifierFlagsCache": 0,
+    "transformFlags": 0,
+    "type": {
+        "kind": "UnionType",
+        "pos": 2,
+        "end": 11,
+        "flags": "JSDoc",
+        "modifierFlagsCache": 0,
+        "transformFlags": 0,
+        "types": {
+            "0": {
+                "kind": "NumberKeyword",
+                "pos": 4,
+                "end": 11,
+                "flags": "JSDoc",
+                "modifierFlagsCache": 0,
+                "transformFlags": 0
+            },
+            "length": 1,
+            "pos": 2,
+            "end": 11
+        }
+    }
+}

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -1879,13 +1879,18 @@ declare namespace ts {
         sourceFile: SourceFile;
         references?: ReadonlyArray<ResolvedProjectReference | undefined>;
     }
+    type CustomTransformerFactory = (context: TransformationContext) => CustomTransformer;
+    interface CustomTransformer {
+        transformSourceFile(node: SourceFile): SourceFile;
+        transformBundle(node: Bundle): Bundle;
+    }
     interface CustomTransformers {
         /** Custom transformers to evaluate before built-in .js transformations. */
-        before?: TransformerFactory<SourceFile>[];
+        before?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .js transformations. */
-        after?: TransformerFactory<SourceFile>[];
+        after?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .d.ts transformations. */
-        afterDeclarations?: TransformerFactory<Bundle | SourceFile>[];
+        afterDeclarations?: (TransformerFactory<Bundle | SourceFile> | CustomTransformerFactory)[];
     }
     interface SourceMapSpan {
         /** Line number in the .js file. */
@@ -1964,6 +1969,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;
@@ -2385,8 +2391,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;
@@ -2413,12 +2419,13 @@ declare namespace ts {
     enum InferencePriority {
         NakedTypeVariable = 1,
         HomomorphicMappedType = 2,
-        MappedTypeConstraint = 4,
-        ReturnType = 8,
-        LiteralKeyof = 16,
-        NoConstraints = 32,
-        AlwaysStrict = 64,
-        PriorityImpliesCombination = 28
+        PartialHomomorphicMappedType = 4,
+        MappedTypeConstraint = 8,
+        ReturnType = 16,
+        LiteralKeyof = 32,
+        NoConstraints = 64,
+        AlwaysStrict = 128,
+        PriorityImpliesCombination = 56
     }
     /** @deprecated Use FileExtensionInfo instead. */
     type JsFileExtensionInfo = FileExtensionInfo;
@@ -3856,7 +3863,7 @@ declare namespace ts {
     function updateArrayLiteral(node: ArrayLiteralExpression, elements: ReadonlyArray<Expression>): ArrayLiteralExpression;
     function createObjectLiteral(properties?: ReadonlyArray<ObjectLiteralElementLike>, multiLine?: boolean): ObjectLiteralExpression;
     function updateObjectLiteral(node: ObjectLiteralExpression, properties: ReadonlyArray<ObjectLiteralElementLike>): ObjectLiteralExpression;
-    function createPropertyAccess(expression: Expression, name: string | Identifier | undefined): PropertyAccessExpression;
+    function createPropertyAccess(expression: Expression, name: string | Identifier): PropertyAccessExpression;
     function updatePropertyAccess(node: PropertyAccessExpression, expression: Expression, name: Identifier): PropertyAccessExpression;
     function createElementAccess(expression: Expression, index: number | Expression): ElementAccessExpression;
     function updateElementAccess(node: ElementAccessExpression, expression: Expression, argumentExpression: Expression): ElementAccessExpression;
@@ -4071,7 +4078,7 @@ declare namespace ts {
     function createInputFiles(javascriptText: string, declarationText: string): InputFiles;
     function createInputFiles(readFileText: (path: string) => string | undefined, javascriptPath: string, javascriptMapPath: string | undefined, declarationPath: string, declarationMapPath: string | undefined, buildInfoPath: string | undefined): InputFiles;
     function createInputFiles(javascriptText: string, declarationText: string, javascriptMapPath: string | undefined, javascriptMapText: string | undefined, declarationMapPath: string | undefined, declarationMapText: string | undefined): InputFiles;
-    function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends?: ReadonlyArray<UnparsedSource>): Bundle;
+    function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends?: ReadonlyArray<UnparsedSource | InputFiles>): Bundle;
     function createImmediatelyInvokedFunctionExpression(statements: ReadonlyArray<Statement>): CallExpression;
     function createImmediatelyInvokedFunctionExpression(statements: ReadonlyArray<Statement>, param: ParameterDeclaration, paramValue: Expression): CallExpression;
     function createImmediatelyInvokedArrowFunction(statements: ReadonlyArray<Statement>): CallExpression;
@@ -4803,6 +4810,7 @@ declare namespace ts {
         getSignatureHelpItems(fileName: string, position: number, options: SignatureHelpItemsOptions | undefined): SignatureHelpItems | undefined;
         getRenameInfo(fileName: string, position: number, options?: RenameInfoOptions): RenameInfo;
         findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean, providePrefixAndSuffixTextForRename?: boolean): ReadonlyArray<RenameLocation> | undefined;
+        getSmartSelectionRange(fileName: string, position: number): SelectionRange;
         getDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
         getDefinitionAndBoundSpan(fileName: string, position: number): DefinitionInfoAndBoundSpan | undefined;
         getTypeDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
@@ -5247,6 +5255,10 @@ declare namespace ts {
         displayParts: SymbolDisplayPart[];
         isOptional: boolean;
     }
+    interface SelectionRange {
+        textSpan: TextSpan;
+        parent?: SelectionRange;
+    }
     /**
      * Represents a single signature to show in signature help.
      * The id is used for subsequent calls into the language service to ask questions about the
@@ -5794,7 +5806,8 @@ declare namespace ts.server.protocol {
         GetEditsForRefactor = "getEditsForRefactor",
         OrganizeImports = "organizeImports",
         GetEditsForFileRename = "getEditsForFileRename",
-        ConfigurePlugin = "configurePlugin"
+        ConfigurePlugin = "configurePlugin",
+        SelectionRange = "selectionRange",
     }
     /**
      * A TypeScript Server message
@@ -6757,6 +6770,20 @@ declare namespace ts.server.protocol {
     }
     interface ConfigurePluginResponse extends Response {
     }
+    interface SelectionRangeRequest extends FileRequest {
+        command: CommandTypes.SelectionRange;
+        arguments: SelectionRangeRequestArgs;
+    }
+    interface SelectionRangeRequestArgs extends FileRequestArgs {
+        locations: Location[];
+    }
+    interface SelectionRangeResponse extends Response {
+        body?: SelectionRange[];
+    }
+    interface SelectionRange {
+        textSpan: TextSpan;
+        parent?: SelectionRange;
+    }
     /**
      *  Information found in an "open" request.
      */
@@ -9033,6 +9060,8 @@ declare namespace ts.server {
         private getBraceMatching;
         private getDiagnosticsForProject;
         private configurePlugin;
+        private getSmartSelectionRange;
+        private mapSelectionRange;
         getCanonicalFileName(fileName: string): string;
         exit(): void;
         private notRequired;

tests/baselines/reference/api/typescript.d.ts

@@ -1879,13 +1879,18 @@ declare namespace ts {
         sourceFile: SourceFile;
         references?: ReadonlyArray<ResolvedProjectReference | undefined>;
     }
+    type CustomTransformerFactory = (context: TransformationContext) => CustomTransformer;
+    interface CustomTransformer {
+        transformSourceFile(node: SourceFile): SourceFile;
+        transformBundle(node: Bundle): Bundle;
+    }
     interface CustomTransformers {
         /** Custom transformers to evaluate before built-in .js transformations. */
-        before?: TransformerFactory<SourceFile>[];
+        before?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .js transformations. */
-        after?: TransformerFactory<SourceFile>[];
+        after?: (TransformerFactory<SourceFile> | CustomTransformerFactory)[];
         /** Custom transformers to evaluate after built-in .d.ts transformations. */
-        afterDeclarations?: TransformerFactory<Bundle | SourceFile>[];
+        afterDeclarations?: (TransformerFactory<Bundle | SourceFile> | CustomTransformerFactory)[];
     }
     interface SourceMapSpan {
         /** Line number in the .js file. */
@@ -1964,6 +1969,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;
@@ -2385,8 +2391,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;
@@ -2413,12 +2419,13 @@ declare namespace ts {
     enum InferencePriority {
         NakedTypeVariable = 1,
         HomomorphicMappedType = 2,
-        MappedTypeConstraint = 4,
-        ReturnType = 8,
-        LiteralKeyof = 16,
-        NoConstraints = 32,
-        AlwaysStrict = 64,
-        PriorityImpliesCombination = 28
+        PartialHomomorphicMappedType = 4,
+        MappedTypeConstraint = 8,
+        ReturnType = 16,
+        LiteralKeyof = 32,
+        NoConstraints = 64,
+        AlwaysStrict = 128,
+        PriorityImpliesCombination = 56
     }
     /** @deprecated Use FileExtensionInfo instead. */
     type JsFileExtensionInfo = FileExtensionInfo;
@@ -3856,7 +3863,7 @@ declare namespace ts {
     function updateArrayLiteral(node: ArrayLiteralExpression, elements: ReadonlyArray<Expression>): ArrayLiteralExpression;
     function createObjectLiteral(properties?: ReadonlyArray<ObjectLiteralElementLike>, multiLine?: boolean): ObjectLiteralExpression;
     function updateObjectLiteral(node: ObjectLiteralExpression, properties: ReadonlyArray<ObjectLiteralElementLike>): ObjectLiteralExpression;
-    function createPropertyAccess(expression: Expression, name: string | Identifier | undefined): PropertyAccessExpression;
+    function createPropertyAccess(expression: Expression, name: string | Identifier): PropertyAccessExpression;
     function updatePropertyAccess(node: PropertyAccessExpression, expression: Expression, name: Identifier): PropertyAccessExpression;
     function createElementAccess(expression: Expression, index: number | Expression): ElementAccessExpression;
     function updateElementAccess(node: ElementAccessExpression, expression: Expression, argumentExpression: Expression): ElementAccessExpression;
@@ -4071,7 +4078,7 @@ declare namespace ts {
     function createInputFiles(javascriptText: string, declarationText: string): InputFiles;
     function createInputFiles(readFileText: (path: string) => string | undefined, javascriptPath: string, javascriptMapPath: string | undefined, declarationPath: string, declarationMapPath: string | undefined, buildInfoPath: string | undefined): InputFiles;
     function createInputFiles(javascriptText: string, declarationText: string, javascriptMapPath: string | undefined, javascriptMapText: string | undefined, declarationMapPath: string | undefined, declarationMapText: string | undefined): InputFiles;
-    function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends?: ReadonlyArray<UnparsedSource>): Bundle;
+    function updateBundle(node: Bundle, sourceFiles: ReadonlyArray<SourceFile>, prepends?: ReadonlyArray<UnparsedSource | InputFiles>): Bundle;
     function createImmediatelyInvokedFunctionExpression(statements: ReadonlyArray<Statement>): CallExpression;
     function createImmediatelyInvokedFunctionExpression(statements: ReadonlyArray<Statement>, param: ParameterDeclaration, paramValue: Expression): CallExpression;
     function createImmediatelyInvokedArrowFunction(statements: ReadonlyArray<Statement>): CallExpression;
@@ -4803,6 +4810,7 @@ declare namespace ts {
         getSignatureHelpItems(fileName: string, position: number, options: SignatureHelpItemsOptions | undefined): SignatureHelpItems | undefined;
         getRenameInfo(fileName: string, position: number, options?: RenameInfoOptions): RenameInfo;
         findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean, providePrefixAndSuffixTextForRename?: boolean): ReadonlyArray<RenameLocation> | undefined;
+        getSmartSelectionRange(fileName: string, position: number): SelectionRange;
         getDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
         getDefinitionAndBoundSpan(fileName: string, position: number): DefinitionInfoAndBoundSpan | undefined;
         getTypeDefinitionAtPosition(fileName: string, position: number): ReadonlyArray<DefinitionInfo> | undefined;
@@ -5247,6 +5255,10 @@ declare namespace ts {
         displayParts: SymbolDisplayPart[];
         isOptional: boolean;
     }
+    interface SelectionRange {
+        textSpan: TextSpan;
+        parent?: SelectionRange;
+    }
     /**
      * Represents a single signature to show in signature help.
      * The id is used for subsequent calls into the language service to ask questions about the

tests/baselines/reference/assigningFunctionToTupleIssuesError.errors.txt

@@ -0,0 +1,8 @@
+tests/cases/compiler/assigningFunctionToTupleIssuesError.ts(2,5): error TS2322: Type '() => void' is not assignable to type '[string]'.
+
+
+==== tests/cases/compiler/assigningFunctionToTupleIssuesError.ts (1 errors) ====
+    declare let a: () => void;
+    let b: [string] = a;
+        ~
+!!! error TS2322: Type '() => void' is not assignable to type '[string]'.

tests/baselines/reference/assigningFunctionToTupleIssuesError.js

@@ -0,0 +1,6 @@
+//// [assigningFunctionToTupleIssuesError.ts]
+declare let a: () => void;
+let b: [string] = a;
+
+//// [assigningFunctionToTupleIssuesError.js]
+var b = a;

tests/baselines/reference/assigningFunctionToTupleIssuesError.symbols

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/assigningFunctionToTupleIssuesError.ts ===
+declare let a: () => void;
+>a : Symbol(a, Decl(assigningFunctionToTupleIssuesError.ts, 0, 11))
+
+let b: [string] = a;
+>b : Symbol(b, Decl(assigningFunctionToTupleIssuesError.ts, 1, 3))
+>a : Symbol(a, Decl(assigningFunctionToTupleIssuesError.ts, 0, 11))
+

tests/baselines/reference/assigningFunctionToTupleIssuesError.types

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/assigningFunctionToTupleIssuesError.ts ===
+declare let a: () => void;
+>a : () => void
+
+let b: [string] = a;
+>b : [string]
+>a : () => void
+

tests/baselines/reference/asyncArrowFunction5_es2017.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es2017/asyncArrowFunction/asyncArrowFunction5_es20
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

tests/baselines/reference/asyncArrowFunction5_es5.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction5_es5.ts(
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

tests/baselines/reference/asyncArrowFunction5_es6.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction5_es6.ts(
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

tests/baselines/reference/asyncArrowFunction9_es2017.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es2017/asyncArrowFunction/asyncArrowFunction9_es20
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

tests/baselines/reference/asyncArrowFunction9_es5.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction9_es5.ts(
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

tests/baselines/reference/asyncArrowFunction9_es6.errors.txt

@@ -16,6 +16,7 @@ tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction9_es6.ts(
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

tests/baselines/reference/asyncFunctionTempVariableScoping.js

@@ -45,8 +45,10 @@ var __rest = (this && this.__rest) || function (s, e) {
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
     if (s != null && typeof Object.getOwnPropertySymbols === "function")
-        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
-            t[p[i]] = s[p[i]];
+        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) {
+            if (e.indexOf(p[i]) < 0 && Object.prototype.propertyIsEnumerable.call(s, p[i]))
+                t[p[i]] = s[p[i]];
+        }
     return t;
 };
 var _this = this;

tests/baselines/reference/augmentedTypesVar.errors.txt

@@ -30,6 +30,7 @@ tests/cases/compiler/augmentedTypesVar.ts(31,8): error TS2300: Duplicate identif
     var x3 = () => { } // error
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x3' must be of type 'number', but here has type '() => void'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesVar.ts:9:5: 'x3' was also declared here.
     
     // var then class
     var x4 = 1; // error

tests/baselines/reference/binderUninitializedModuleExportsAssignment.symbols

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/salsa/loop.js ===
+var loop1 = loop2;
+>loop1 : Symbol(loop1, Decl(loop.js, 0, 3))
+>loop2 : Symbol(loop2, Decl(loop.js, 1, 3))
+
+var loop2 = loop1;
+>loop2 : Symbol(loop2, Decl(loop.js, 1, 3))
+>loop1 : Symbol(loop1, Decl(loop.js, 0, 3))
+
+module.exports = loop2;
+>module.exports : Symbol("tests/cases/conformance/salsa/loop", Decl(loop.js, 0, 0))
+>module : Symbol(export=, Decl(loop.js, 1, 18))
+>exports : Symbol(export=, Decl(loop.js, 1, 18))
+>loop2 : Symbol(loop2, Decl(loop.js, 1, 3))
+

tests/baselines/reference/binderUninitializedModuleExportsAssignment.types

@@ -0,0 +1,16 @@
+=== tests/cases/conformance/salsa/loop.js ===
+var loop1 = loop2;
+>loop1 : any
+>loop2 : any
+
+var loop2 = loop1;
+>loop2 : any
+>loop1 : any
+
+module.exports = loop2;
+>module.exports = loop2 : any
+>module.exports : any
+>module : { "tests/cases/conformance/salsa/loop": any; }
+>exports : any
+>loop2 : any
+

tests/baselines/reference/booleanFilterAnyArray.js

@@ -0,0 +1,37 @@
+//// [booleanFilterAnyArray.ts]
+interface Bullean { }
+interface BulleanConstructor {
+    new(v1?: any): Bullean;
+    <T>(v2?: T): v2 is T;
+}
+
+interface Ari<T> {
+    filter<S extends T>(cb1: (value: T) => value is S): T extends any ? Ari<any> : Ari<S>;
+    filter(cb2: (value: T) => unknown): Ari<T>;
+}
+declare var Bullean: BulleanConstructor;
+declare let anys: Ari<any>;
+var xs: Ari<any>;
+var xs = anys.filter(Bullean)
+
+declare let realanys: any[];
+var ys: any[];
+var ys = realanys.filter(Boolean)
+
+var foo = [{ name: 'x' }]
+var foor: Array<{name: string}>
+var foor = foo.filter(x => x.name)
+var foos: Array<boolean>
+var foos = [true, true, false, null].filter((thing): thing is boolean => thing !== null)
+
+
+//// [booleanFilterAnyArray.js]
+var xs;
+var xs = anys.filter(Bullean);
+var ys;
+var ys = realanys.filter(Boolean);
+var foo = [{ name: 'x' }];
+var foor;
+var foor = foo.filter(function (x) { return x.name; });
+var foos;
+var foos = [true, true, false, null].filter(function (thing) { return thing !== null; });

tests/baselines/reference/booleanFilterAnyArray.symbols

@@ -0,0 +1,108 @@
+=== tests/cases/compiler/booleanFilterAnyArray.ts ===
+interface Bullean { }
+>Bullean : Symbol(Bullean, Decl(booleanFilterAnyArray.ts, 0, 0), Decl(booleanFilterAnyArray.ts, 10, 11))
+
+interface BulleanConstructor {
+>BulleanConstructor : Symbol(BulleanConstructor, Decl(booleanFilterAnyArray.ts, 0, 21))
+
+    new(v1?: any): Bullean;
+>v1 : Symbol(v1, Decl(booleanFilterAnyArray.ts, 2, 8))
+>Bullean : Symbol(Bullean, Decl(booleanFilterAnyArray.ts, 0, 0), Decl(booleanFilterAnyArray.ts, 10, 11))
+
+    <T>(v2?: T): v2 is T;
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 3, 5))
+>v2 : Symbol(v2, Decl(booleanFilterAnyArray.ts, 3, 8))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 3, 5))
+>v2 : Symbol(v2, Decl(booleanFilterAnyArray.ts, 3, 8))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 3, 5))
+}
+
+interface Ari<T> {
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+
+    filter<S extends T>(cb1: (value: T) => value is S): T extends any ? Ari<any> : Ari<S>;
+>filter : Symbol(Ari.filter, Decl(booleanFilterAnyArray.ts, 6, 18), Decl(booleanFilterAnyArray.ts, 7, 90))
+>S : Symbol(S, Decl(booleanFilterAnyArray.ts, 7, 11))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+>cb1 : Symbol(cb1, Decl(booleanFilterAnyArray.ts, 7, 24))
+>value : Symbol(value, Decl(booleanFilterAnyArray.ts, 7, 30))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+>value : Symbol(value, Decl(booleanFilterAnyArray.ts, 7, 30))
+>S : Symbol(S, Decl(booleanFilterAnyArray.ts, 7, 11))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+>S : Symbol(S, Decl(booleanFilterAnyArray.ts, 7, 11))
+
+    filter(cb2: (value: T) => unknown): Ari<T>;
+>filter : Symbol(Ari.filter, Decl(booleanFilterAnyArray.ts, 6, 18), Decl(booleanFilterAnyArray.ts, 7, 90))
+>cb2 : Symbol(cb2, Decl(booleanFilterAnyArray.ts, 8, 11))
+>value : Symbol(value, Decl(booleanFilterAnyArray.ts, 8, 17))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+>T : Symbol(T, Decl(booleanFilterAnyArray.ts, 6, 14))
+}
+declare var Bullean: BulleanConstructor;
+>Bullean : Symbol(Bullean, Decl(booleanFilterAnyArray.ts, 0, 0), Decl(booleanFilterAnyArray.ts, 10, 11))
+>BulleanConstructor : Symbol(BulleanConstructor, Decl(booleanFilterAnyArray.ts, 0, 21))
+
+declare let anys: Ari<any>;
+>anys : Symbol(anys, Decl(booleanFilterAnyArray.ts, 11, 11))
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+
+var xs: Ari<any>;
+>xs : Symbol(xs, Decl(booleanFilterAnyArray.ts, 12, 3), Decl(booleanFilterAnyArray.ts, 13, 3))
+>Ari : Symbol(Ari, Decl(booleanFilterAnyArray.ts, 4, 1))
+
+var xs = anys.filter(Bullean)
+>xs : Symbol(xs, Decl(booleanFilterAnyArray.ts, 12, 3), Decl(booleanFilterAnyArray.ts, 13, 3))
+>anys.filter : Symbol(Ari.filter, Decl(booleanFilterAnyArray.ts, 6, 18), Decl(booleanFilterAnyArray.ts, 7, 90))
+>anys : Symbol(anys, Decl(booleanFilterAnyArray.ts, 11, 11))
+>filter : Symbol(Ari.filter, Decl(booleanFilterAnyArray.ts, 6, 18), Decl(booleanFilterAnyArray.ts, 7, 90))
+>Bullean : Symbol(Bullean, Decl(booleanFilterAnyArray.ts, 0, 0), Decl(booleanFilterAnyArray.ts, 10, 11))
+
+declare let realanys: any[];
+>realanys : Symbol(realanys, Decl(booleanFilterAnyArray.ts, 15, 11))
+
+var ys: any[];
+>ys : Symbol(ys, Decl(booleanFilterAnyArray.ts, 16, 3), Decl(booleanFilterAnyArray.ts, 17, 3))
+
+var ys = realanys.filter(Boolean)
+>ys : Symbol(ys, Decl(booleanFilterAnyArray.ts, 16, 3), Decl(booleanFilterAnyArray.ts, 17, 3))
+>realanys.filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>realanys : Symbol(realanys, Decl(booleanFilterAnyArray.ts, 15, 11))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>Boolean : Symbol(Boolean, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+var foo = [{ name: 'x' }]
+>foo : Symbol(foo, Decl(booleanFilterAnyArray.ts, 19, 3))
+>name : Symbol(name, Decl(booleanFilterAnyArray.ts, 19, 12))
+
+var foor: Array<{name: string}>
+>foor : Symbol(foor, Decl(booleanFilterAnyArray.ts, 20, 3), Decl(booleanFilterAnyArray.ts, 21, 3))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>name : Symbol(name, Decl(booleanFilterAnyArray.ts, 20, 17))
+
+var foor = foo.filter(x => x.name)
+>foor : Symbol(foor, Decl(booleanFilterAnyArray.ts, 20, 3), Decl(booleanFilterAnyArray.ts, 21, 3))
+>foo.filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>foo : Symbol(foo, Decl(booleanFilterAnyArray.ts, 19, 3))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>x : Symbol(x, Decl(booleanFilterAnyArray.ts, 21, 22))
+>x.name : Symbol(name, Decl(booleanFilterAnyArray.ts, 19, 12))
+>x : Symbol(x, Decl(booleanFilterAnyArray.ts, 21, 22))
+>name : Symbol(name, Decl(booleanFilterAnyArray.ts, 19, 12))
+
+var foos: Array<boolean>
+>foos : Symbol(foos, Decl(booleanFilterAnyArray.ts, 22, 3), Decl(booleanFilterAnyArray.ts, 23, 3))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+var foos = [true, true, false, null].filter((thing): thing is boolean => thing !== null)
+>foos : Symbol(foos, Decl(booleanFilterAnyArray.ts, 22, 3), Decl(booleanFilterAnyArray.ts, 23, 3))
+>[true, true, false, null].filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>thing : Symbol(thing, Decl(booleanFilterAnyArray.ts, 23, 45))
+>thing : Symbol(thing, Decl(booleanFilterAnyArray.ts, 23, 45))
+>thing : Symbol(thing, Decl(booleanFilterAnyArray.ts, 23, 45))
+

tests/baselines/reference/booleanFilterAnyArray.types

@@ -0,0 +1,94 @@
+=== tests/cases/compiler/booleanFilterAnyArray.ts ===
+interface Bullean { }
+interface BulleanConstructor {
+    new(v1?: any): Bullean;
+>v1 : any
+
+    <T>(v2?: T): v2 is T;
+>v2 : T
+}
+
+interface Ari<T> {
+    filter<S extends T>(cb1: (value: T) => value is S): T extends any ? Ari<any> : Ari<S>;
+>filter : { <S extends T>(cb1: (value: T) => value is S): T extends any ? Ari<any> : Ari<S>; (cb2: (value: T) => unknown): Ari<T>; }
+>cb1 : (value: T) => value is S
+>value : T
+
+    filter(cb2: (value: T) => unknown): Ari<T>;
+>filter : { <S extends T>(cb1: (value: T) => value is S): T extends any ? Ari<any> : Ari<S>; (cb2: (value: T) => unknown): Ari<T>; }
+>cb2 : (value: T) => unknown
+>value : T
+}
+declare var Bullean: BulleanConstructor;
+>Bullean : BulleanConstructor
+
+declare let anys: Ari<any>;
+>anys : Ari<any>
+
+var xs: Ari<any>;
+>xs : Ari<any>
+
+var xs = anys.filter(Bullean)
+>xs : Ari<any>
+>anys.filter(Bullean) : Ari<any>
+>anys.filter : { <S extends any>(cb1: (value: any) => value is S): Ari<any>; (cb2: (value: any) => unknown): Ari<any>; }
+>anys : Ari<any>
+>filter : { <S extends any>(cb1: (value: any) => value is S): Ari<any>; (cb2: (value: any) => unknown): Ari<any>; }
+>Bullean : BulleanConstructor
+
+declare let realanys: any[];
+>realanys : any[]
+
+var ys: any[];
+>ys : any[]
+
+var ys = realanys.filter(Boolean)
+>ys : any[]
+>realanys.filter(Boolean) : any[]
+>realanys.filter : { <S extends any>(callbackfn: (value: any, index: number, array: any[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: any, index: number, array: any[]) => unknown, thisArg?: any): any[]; }
+>realanys : any[]
+>filter : { <S extends any>(callbackfn: (value: any, index: number, array: any[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: any, index: number, array: any[]) => unknown, thisArg?: any): any[]; }
+>Boolean : BooleanConstructor
+
+var foo = [{ name: 'x' }]
+>foo : { name: string; }[]
+>[{ name: 'x' }] : { name: string; }[]
+>{ name: 'x' } : { name: string; }
+>name : string
+>'x' : "x"
+
+var foor: Array<{name: string}>
+>foor : { name: string; }[]
+>name : string
+
+var foor = foo.filter(x => x.name)
+>foor : { name: string; }[]
+>foo.filter(x => x.name) : { name: string; }[]
+>foo.filter : { <S extends { name: string; }>(callbackfn: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
+>foo : { name: string; }[]
+>filter : { <S extends { name: string; }>(callbackfn: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
+>x => x.name : (x: { name: string; }) => string
+>x : { name: string; }
+>x.name : string
+>x : { name: string; }
+>name : string
+
+var foos: Array<boolean>
+>foos : boolean[]
+
+var foos = [true, true, false, null].filter((thing): thing is boolean => thing !== null)
+>foos : boolean[]
+>[true, true, false, null].filter((thing): thing is boolean => thing !== null) : boolean[]
+>[true, true, false, null].filter : { <S extends boolean>(callbackfn: (value: boolean, index: number, array: boolean[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: boolean, index: number, array: boolean[]) => unknown, thisArg?: any): boolean[]; }
+>[true, true, false, null] : boolean[]
+>true : true
+>true : true
+>false : false
+>null : null
+>filter : { <S extends boolean>(callbackfn: (value: boolean, index: number, array: boolean[]) => value is S, thisArg?: any): S[]; (callbackfn: (value: boolean, index: number, array: boolean[]) => unknown, thisArg?: any): boolean[]; }
+>(thing): thing is boolean => thing !== null : (thing: boolean) => thing is boolean
+>thing : boolean
+>thing !== null : boolean
+>thing : boolean
+>null : null
+

tests/baselines/reference/castingTuple.errors.txt

@@ -71,6 +71,7 @@ tests/cases/conformance/types/tuple/castingTuple.ts(33,1): error TS2304: Cannot
     var array1 = <number[]>numStrTuple;
         ~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'array1' must be of type '{}[]', but here has type 'number[]'.
+!!! related TS6203 tests/cases/conformance/types/tuple/castingTuple.ts:23:5: 'array1' was also declared here.
     t4[2] = 10;
     ~~
 !!! error TS2304: Cannot find name 't4'.

tests/baselines/reference/checkInfiniteExpansionTermination.errors.txt

@@ -0,0 +1,32 @@
+tests/cases/compiler/checkInfiniteExpansionTermination.ts(16,1): error TS2322: Type 'ISubject<Bar>' is not assignable to type 'IObservable<Foo>'.
+  Types of property 'n' are incompatible.
+    Type 'IObservable<Bar[]>' is not assignable to type 'IObservable<Foo[]>'.
+      Type 'Bar[]' is not assignable to type 'Foo[]'.
+        Property 'x' is missing in type 'Bar' but required in type 'Foo'.
+
+
+==== tests/cases/compiler/checkInfiniteExpansionTermination.ts (1 errors) ====
+    // Regression test for #1002
+    // Before fix this code would cause infinite loop
+    
+    interface IObservable<T> {
+        n: IObservable<T[]>; // Needed, must be T[]
+    }
+    
+    // Needed
+    interface ISubject<T> extends IObservable<T> { }
+    
+    interface Foo { x }
+    interface Bar { y }
+    
+    var values: IObservable<Foo>;
+    var values2: ISubject<Bar>;
+    values = values2;
+    ~~~~~~
+!!! error TS2322: Type 'ISubject<Bar>' is not assignable to type 'IObservable<Foo>'.
+!!! error TS2322:   Types of property 'n' are incompatible.
+!!! error TS2322:     Type 'IObservable<Bar[]>' is not assignable to type 'IObservable<Foo[]>'.
+!!! error TS2322:       Type 'Bar[]' is not assignable to type 'Foo[]'.
+!!! error TS2322:         Property 'x' is missing in type 'Bar' but required in type 'Foo'.
+!!! related TS2728 tests/cases/compiler/checkInfiniteExpansionTermination.ts:11:17: 'x' is declared here.
+    

tests/baselines/reference/checkMergedGlobalUMDSymbol.errors.txt

@@ -15,6 +15,7 @@ tests/cases/compiler/global.d.ts(6,16): error TS2403: Subsequent variable declar
       export const THREE: typeof _three;
                    ~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'THREE' must be of type 'typeof import("tests/cases/compiler/global")', but here has type 'typeof import("tests/cases/compiler/three")'.
+!!! related TS6203 tests/cases/compiler/global.d.ts:1:1: 'THREE' was also declared here.
     }
     
 ==== tests/cases/compiler/test.ts (0 errors) ====

tests/baselines/reference/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt

@@ -11,22 +11,28 @@ tests/cases/compiler/circularlyConstrainedMappedTypeContainingConditionalNoInfin
                     Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
                       Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
                         Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                          Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | (TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                            Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                              Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                  Type 'GetProps<C>[keyof GetProps<C> & string] | (TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                    Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                      Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                        Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                          Type 'GetProps<C>[string] | (TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                            Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                              Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                  Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                    Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                      Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                        Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                          Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                            Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                              Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                  Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                    Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                      Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                        Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                          Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                            Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                              Type 'GetProps<C>[keyof GetProps<C> & string] | (TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                                Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                                  Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                    Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                                      Type 'GetProps<C>[string] | (TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                                        Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+                                                          Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                            Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                              Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                                Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                                  Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+                                                                    Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
 
 
 ==== tests/cases/compiler/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.ts (1 errors) ====
@@ -107,20 +113,26 @@ tests/cases/compiler/circularlyConstrainedMappedTypeContainingConditionalNoInfin
 !!! error TS2344:                     Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
 !!! error TS2344:                       Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
 !!! error TS2344:                         Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                           Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | (TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                             Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                               Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                 Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                   Type 'GetProps<C>[keyof GetProps<C> & string] | (TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                     Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                       Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                         Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                           Type 'GetProps<C>[string] | (TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                             Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                               Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                 Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                   Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                     Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                       Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                         Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                           Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                             Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                               Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                 Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                   Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                     Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                       Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                         Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                           Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                             Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                               Type 'GetProps<C>[keyof GetProps<C> & string] | (TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                                 Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                                   Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                     Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                                       Type 'GetProps<C>[string] | (TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                                         Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
+!!! error TS2344:                                                           Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                             Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                               Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                                 Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                                   Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
+!!! error TS2344:                                                                     Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
     

tests/baselines/reference/classWithDuplicateIdentifier.errors.txt

@@ -14,6 +14,7 @@ tests/cases/compiler/classWithDuplicateIdentifier.ts(11,5): error TS2717: Subseq
 !!! error TS2300: Duplicate identifier 'a'.
         ~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property 'a' must be of type '() => number', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/classWithDuplicateIdentifier.ts:2:5: 'a' was also declared here.
     }
     class K {
         b: number; // error: duplicate identifier
@@ -30,5 +31,6 @@ tests/cases/compiler/classWithDuplicateIdentifier.ts(11,5): error TS2717: Subseq
 !!! error TS2300: Duplicate identifier 'c'.
         ~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property 'c' must be of type 'number', but here has type 'string'.
+!!! related TS6203 tests/cases/compiler/classWithDuplicateIdentifier.ts:10:5: 'c' was also declared here.
     }
     

tests/baselines/reference/commonJsIsolatedModules.js

@@ -0,0 +1,8 @@
+//// [index.js]
+module.exports = {}
+var x = 1
+
+
+//// [index.js]
+module.exports = {};
+var x = 1;

tests/baselines/reference/commonJsIsolatedModules.symbols

@@ -0,0 +1,9 @@
+=== tests/cases/compiler/index.js ===
+module.exports = {}
+>module.exports : Symbol("tests/cases/compiler/index", Decl(index.js, 0, 0))
+>module : Symbol(module, Decl(index.js, 0, 0))
+>exports : Symbol("tests/cases/compiler/index", Decl(index.js, 0, 0))
+
+var x = 1
+>x : Symbol(x, Decl(index.js, 1, 3))
+

tests/baselines/reference/commonJsIsolatedModules.types

@@ -0,0 +1,12 @@
+=== tests/cases/compiler/index.js ===
+module.exports = {}
+>module.exports = {} : typeof import("tests/cases/compiler/index")
+>module.exports : typeof import("tests/cases/compiler/index")
+>module : { "tests/cases/compiler/index": typeof import("tests/cases/compiler/index"); }
+>exports : typeof import("tests/cases/compiler/index")
+>{} : {}
+
+var x = 1
+>x : number
+>1 : 1
+

tests/baselines/reference/conditionalTypes1.errors.txt

@@ -19,12 +19,8 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(104,5): error TS2
   'Pick<T, { [K in keyof T]: T[K] extends Function ? never : K; }[keyof T]>' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/conditional/conditionalTypes1.ts(106,5): error TS2322: Type 'Pick<T, { [K in keyof T]: T[K] extends Function ? never : K; }[keyof T]>' is not assignable to type 'Pick<T, { [K in keyof T]: T[K] extends Function ? K : never; }[keyof T]>'.
   Type 'T[keyof T] extends Function ? keyof T : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
-    Type 'keyof T' is not assignable to type 'never'.
-      Type 'string | number | symbol' is not assignable to type 'never'.
-        Type 'string' is not assignable to type 'never'.
 tests/cases/conformance/types/conditional/conditionalTypes1.ts(108,5): error TS2322: Type 'Pick<T, { [K in keyof T]: T[K] extends Function ? K : never; }[keyof T]>' is not assignable to type 'Pick<T, { [K in keyof T]: T[K] extends Function ? never : K; }[keyof T]>'.
   Type 'T[keyof T] extends Function ? never : keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
-    Type 'keyof T' is not assignable to type 'never'.
 tests/cases/conformance/types/conditional/conditionalTypes1.ts(114,5): error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
   Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
     Type 'string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
@@ -195,15 +191,11 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
         ~
 !!! error TS2322: Type 'Pick<T, { [K in keyof T]: T[K] extends Function ? never : K; }[keyof T]>' is not assignable to type 'Pick<T, { [K in keyof T]: T[K] extends Function ? K : never; }[keyof T]>'.
 !!! error TS2322:   Type 'T[keyof T] extends Function ? keyof T : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
-!!! error TS2322:     Type 'keyof T' is not assignable to type 'never'.
-!!! error TS2322:       Type 'string | number | symbol' is not assignable to type 'never'.
-!!! error TS2322:         Type 'string' is not assignable to type 'never'.
         z = x;
         z = y;  // Error
         ~
 !!! error TS2322: Type 'Pick<T, { [K in keyof T]: T[K] extends Function ? K : never; }[keyof T]>' is not assignable to type 'Pick<T, { [K in keyof T]: T[K] extends Function ? never : K; }[keyof T]>'.
 !!! error TS2322:   Type 'T[keyof T] extends Function ? never : keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
-!!! error TS2322:     Type 'keyof T' is not assignable to type 'never'.
     }
     
     function f8<T>(x: keyof T, y: FunctionPropertyNames<T>, z: NonFunctionPropertyNames<T>) {
@@ -399,6 +391,7 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
         var z: T2;  // Error, T2 is distributive, T1 isn't
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'T1', but here has type 'Foo<T & U>'.
+!!! related TS6203 tests/cases/conformance/types/conditional/conditionalTypes1.ts:262:9: 'z' was also declared here.
     }
     
     function f33<T, U>() {

tests/baselines/reference/conditionalTypes1.js

@@ -645,7 +645,7 @@ declare type T82 = Eq2<false, true>;
 declare type T83 = Eq2<false, false>;
 declare type Foo<T> = T extends string ? boolean : number;
 declare type Bar<T> = T extends string ? boolean : number;
-declare const convert: <U>(value: Foo<U>) => Foo<U>;
+declare const convert: <U>(value: Foo<U>) => Bar<U>;
 declare type Baz<T> = Foo<T>;
 declare const convert2: <T>(value: Foo<T>) => Foo<T>;
 declare function f31<T>(): void;

tests/baselines/reference/conditionalTypes1.types

@@ -779,8 +779,8 @@ type Bar<T> = T extends string ? boolean : number;
 >Bar : Bar<T>
 
 const convert = <U>(value: Foo<U>): Bar<U> => value;
->convert : <U>(value: Foo<U>) => Foo<U>
-><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Foo<U>
+>convert : <U>(value: Foo<U>) => Bar<U>
+><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Bar<U>
 >value : Foo<U>
 >value : Foo<U>
 
@@ -832,7 +832,7 @@ function f33<T, U>() {
 >T1 : Foo<T & U>
 
     type T2 = Bar<T & U>;
->T2 : Foo<T & U>
+>T2 : Bar<T & U>
 
     var z: T1;
 >z : Foo<T & U>

tests/baselines/reference/conditionalTypes2.errors.txt

@@ -267,4 +267,10 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
     };
     type PCCA = ProductComplementComplement['a'];
     type PCCB = ProductComplementComplement['b'];
+    
+    // Repro from #31326
+    
+    type Hmm<T, U extends T> = U extends T ? { [K in keyof U]: number } : never;
+    type What = Hmm<{}, { a: string }>
+    const w: What = { a: 4 };
     

tests/baselines/reference/conditionalTypes2.js

@@ -188,6 +188,12 @@ type ProductComplementComplement = {
 };
 type PCCA = ProductComplementComplement['a'];
 type PCCB = ProductComplementComplement['b'];
+
+// Repro from #31326
+
+type Hmm<T, U extends T> = U extends T ? { [K in keyof U]: number } : never;
+type What = Hmm<{}, { a: string }>
+const w: What = { a: 4 };
 
 
 //// [conditionalTypes2.js]
@@ -265,6 +271,7 @@ function foo(value) {
         toString2(value);
     }
 }
+var w = { a: 4 };
 
 
 //// [conditionalTypes2.d.ts]
@@ -392,3 +399,10 @@ declare type ProductComplementComplement = {
 };
 declare type PCCA = ProductComplementComplement['a'];
 declare type PCCB = ProductComplementComplement['b'];
+declare type Hmm<T, U extends T> = U extends T ? {
+    [K in keyof U]: number;
+} : never;
+declare type What = Hmm<{}, {
+    a: string;
+}>;
+declare const w: What;

tests/baselines/reference/conditionalTypes2.symbols

@@ -685,3 +685,25 @@ type PCCB = ProductComplementComplement['b'];
 >PCCB : Symbol(PCCB, Decl(conditionalTypes2.ts, 187, 45))
 >ProductComplementComplement : Symbol(ProductComplementComplement, Decl(conditionalTypes2.ts, 181, 34))
 
+// Repro from #31326
+
+type Hmm<T, U extends T> = U extends T ? { [K in keyof U]: number } : never;
+>Hmm : Symbol(Hmm, Decl(conditionalTypes2.ts, 188, 45))
+>T : Symbol(T, Decl(conditionalTypes2.ts, 192, 9))
+>U : Symbol(U, Decl(conditionalTypes2.ts, 192, 11))
+>T : Symbol(T, Decl(conditionalTypes2.ts, 192, 9))
+>U : Symbol(U, Decl(conditionalTypes2.ts, 192, 11))
+>T : Symbol(T, Decl(conditionalTypes2.ts, 192, 9))
+>K : Symbol(K, Decl(conditionalTypes2.ts, 192, 44))
+>U : Symbol(U, Decl(conditionalTypes2.ts, 192, 11))
+
+type What = Hmm<{}, { a: string }>
+>What : Symbol(What, Decl(conditionalTypes2.ts, 192, 76))
+>Hmm : Symbol(Hmm, Decl(conditionalTypes2.ts, 188, 45))
+>a : Symbol(a, Decl(conditionalTypes2.ts, 193, 21))
+
+const w: What = { a: 4 };
+>w : Symbol(w, Decl(conditionalTypes2.ts, 194, 5))
+>What : Symbol(What, Decl(conditionalTypes2.ts, 192, 76))
+>a : Symbol(a, Decl(conditionalTypes2.ts, 194, 17))
+

tests/baselines/reference/conditionalTypes2.types

@@ -431,3 +431,18 @@ type PCCA = ProductComplementComplement['a'];
 type PCCB = ProductComplementComplement['b'];
 >PCCB : Product<"b", 1>
 
+// Repro from #31326
+
+type Hmm<T, U extends T> = U extends T ? { [K in keyof U]: number } : never;
+>Hmm : Hmm<T, U>
+
+type What = Hmm<{}, { a: string }>
+>What : { a: number; }
+>a : string
+
+const w: What = { a: 4 };
+>w : { a: number; }
+>{ a: 4 } : { a: number; }
+>a : number
+>4 : 4
+

tests/baselines/reference/conditionalTypesSimplifyWhenTrivial.types

@@ -1,49 +1,49 @@
 === tests/cases/compiler/conditionalTypesSimplifyWhenTrivial.ts ===
 const fn1 = <Params>(
->fn1 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn1 : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params
 
     params: Pick<Params, Exclude<keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Exclude<keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Exclude<keyof Params, never>>
 
 function fn2<T>(x: Exclude<T, never>) {
->fn2 : <T>(x: T) => void
->x : T
+>fn2 : <T>(x: Exclude<T, never>) => void
+>x : Exclude<T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : Exclude<T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : Exclude<T, never>
 >y : T
 }
 
 const fn3 = <Params>(
->fn3 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn3 : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params
+><Params>(    params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params
 
     params: Pick<Params, Extract<keyof Params, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Extract<keyof Params, keyof Params>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Extract<keyof Params, keyof Params>>
 
 function fn4<T>(x: Extract<T, T>) {
->fn4 : <T>(x: T) => void
->x : T
+>fn4 : <T>(x: Extract<T, T>) => void
+>x : Extract<T, T>
 
     var y: T = x;
 >y : T
->x : T
+>x : Extract<T, T>
 
     x = y;
 >x = y : T
->x : T
+>x : Extract<T, T>
 >y : T
 }
 
@@ -57,50 +57,50 @@ type ExcludeWithDefault<T, U, D = never> = T extends U ? D : T;
 >ExcludeWithDefault : ExcludeWithDefault<T, U, D>
 
 const fn5 = <Params>(
->fn5 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn5 : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params
+><Params>(    params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params
 
     params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>
 
 function fn6<T>(x: ExcludeWithDefault<T, never>) {
->fn6 : <T>(x: T) => void
->x : T
+>fn6 : <T>(x: ExcludeWithDefault<T, never, never>) => void
+>x : ExcludeWithDefault<T, never, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : ExcludeWithDefault<T, never, never>
 
     x = y;
 >x = y : T
->x : T
+>x : ExcludeWithDefault<T, never, never>
 >y : T
 }
 
 const fn7 = <Params>(
->fn7 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn7 : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params
 
     params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>
 
 function fn8<T>(x: ExtractWithDefault<T, T>) {
->fn8 : <T>(x: T) => void
->x : T
+>fn8 : <T>(x: ExtractWithDefault<T, T, never>) => void
+>x : ExtractWithDefault<T, T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : ExtractWithDefault<T, T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : ExtractWithDefault<T, T, never>
 >y : T
 }
 
@@ -108,50 +108,50 @@ type TemplatedConditional<TCheck, TExtends, TTrue, TFalse> = TCheck extends TExt
 >TemplatedConditional : TemplatedConditional<TCheck, TExtends, TTrue, TFalse>
 
 const fn9 = <Params>(
->fn9 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn9 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params
+><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params
 
     params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>
 
 function fn10<T>(x: TemplatedConditional<T, never, never, T>) {
->fn10 : <T>(x: T) => void
->x : T
+>fn10 : <T>(x: TemplatedConditional<T, never, never, T>) => void
+>x : TemplatedConditional<T, never, never, T>
 
     var y: T = x;
 >y : T
->x : T
+>x : TemplatedConditional<T, never, never, T>
 
     x = y;
 >x = y : T
->x : T
+>x : TemplatedConditional<T, never, never, T>
 >y : T
 }
 
 const fn11 = <Params>(
->fn11 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn11 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params
 
     params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>
 
 function fn12<T>(x: TemplatedConditional<T, T, T, never>) {
->fn12 : <T>(x: T) => void
->x : T
+>fn12 : <T>(x: TemplatedConditional<T, T, T, never>) => void
+>x : TemplatedConditional<T, T, T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : TemplatedConditional<T, T, T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : TemplatedConditional<T, T, T, never>
 >y : T
 }
 

tests/baselines/reference/consistentAliasVsNonAliasRecordBehavior.errors.txt

@@ -0,0 +1,55 @@
+tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts(18,5): error TS2741: Property 'a' is missing in type 'Record<string, string>' but required in type 'Record2<"a", string>'.
+tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts(22,5): error TS2741: Property 'a' is missing in type 'Record2<string, string>' but required in type 'Record<"a", string>'.
+tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts(34,5): error TS2741: Property 'a' is missing in type 'Record<string, T>' but required in type 'Record2<"a", T>'.
+tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts(38,5): error TS2741: Property 'a' is missing in type 'Record2<string, T>' but required in type 'Record<"a", T>'.
+
+
+==== tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts (4 errors) ====
+    // TODO: FIXME: All the below cases labeled `no error` _should be an error_, and are only prevented from so being
+    // by incorrect variance-based relationships
+    // Ref: https://github.com/Microsoft/TypeScript/issues/29698
+    
+    type Record2<K extends keyof any, T> = {
+        [P in K]: T;
+    };
+    
+    function defaultRecord(x: Record<'a', string>, y: Record<string, string>) {
+        x = y; // no error, but error expected.
+    }
+    
+    function customRecord(x: Record2<'a', string>, y: Record2<string, string>) {
+        x = y; // no error, but error expected.
+    }
+    
+    function mixed1(x: Record2<'a', string>, y: Record<string, string>) {
+        x = y; // error
+        ~
+!!! error TS2741: Property 'a' is missing in type 'Record<string, string>' but required in type 'Record2<"a", string>'.
+    }
+    
+    function mixed2(x: Record<'a', string>, y: Record2<string, string>) {
+        x = y; // error
+        ~
+!!! error TS2741: Property 'a' is missing in type 'Record2<string, string>' but required in type 'Record<"a", string>'.
+    }
+    
+    function defaultRecord2<T>(x: Record<'a', T>, y: Record<string, T>) {
+        x = y; // no error, but error expected.
+    }
+    
+    function customRecord2<T>(x: Record2<'a', T>, y: Record2<string, T>) {
+        x = y; // no error, but error expected.
+    }
+    
+    function mixed3<T>(x: Record2<'a', T>, y: Record<string, T>) {
+        x = y; // error
+        ~
+!!! error TS2741: Property 'a' is missing in type 'Record<string, T>' but required in type 'Record2<"a", T>'.
+    }
+    
+    function mixed4<T>(x: Record<'a', T>, y: Record2<string, T>) {
+        x = y; // error
+        ~
+!!! error TS2741: Property 'a' is missing in type 'Record2<string, T>' but required in type 'Record<"a", T>'.
+    }
+    

tests/baselines/reference/consistentAliasVsNonAliasRecordBehavior.js

@@ -0,0 +1,70 @@
+//// [consistentAliasVsNonAliasRecordBehavior.ts]
+// TODO: FIXME: All the below cases labeled `no error` _should be an error_, and are only prevented from so being
+// by incorrect variance-based relationships
+// Ref: https://github.com/Microsoft/TypeScript/issues/29698
+
+type Record2<K extends keyof any, T> = {
+    [P in K]: T;
+};
+
+function defaultRecord(x: Record<'a', string>, y: Record<string, string>) {
+    x = y; // no error, but error expected.
+}
+
+function customRecord(x: Record2<'a', string>, y: Record2<string, string>) {
+    x = y; // no error, but error expected.
+}
+
+function mixed1(x: Record2<'a', string>, y: Record<string, string>) {
+    x = y; // error
+}
+
+function mixed2(x: Record<'a', string>, y: Record2<string, string>) {
+    x = y; // error
+}
+
+function defaultRecord2<T>(x: Record<'a', T>, y: Record<string, T>) {
+    x = y; // no error, but error expected.
+}
+
+function customRecord2<T>(x: Record2<'a', T>, y: Record2<string, T>) {
+    x = y; // no error, but error expected.
+}
+
+function mixed3<T>(x: Record2<'a', T>, y: Record<string, T>) {
+    x = y; // error
+}
+
+function mixed4<T>(x: Record<'a', T>, y: Record2<string, T>) {
+    x = y; // error
+}
+
+
+//// [consistentAliasVsNonAliasRecordBehavior.js]
+// TODO: FIXME: All the below cases labeled `no error` _should be an error_, and are only prevented from so being
+// by incorrect variance-based relationships
+// Ref: https://github.com/Microsoft/TypeScript/issues/29698
+function defaultRecord(x, y) {
+    x = y; // no error, but error expected.
+}
+function customRecord(x, y) {
+    x = y; // no error, but error expected.
+}
+function mixed1(x, y) {
+    x = y; // error
+}
+function mixed2(x, y) {
+    x = y; // error
+}
+function defaultRecord2(x, y) {
+    x = y; // no error, but error expected.
+}
+function customRecord2(x, y) {
+    x = y; // no error, but error expected.
+}
+function mixed3(x, y) {
+    x = y; // error
+}
+function mixed4(x, y) {
+    x = y; // error
+}

tests/baselines/reference/consistentAliasVsNonAliasRecordBehavior.symbols

@@ -0,0 +1,125 @@
+=== tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts ===
+// TODO: FIXME: All the below cases labeled `no error` _should be an error_, and are only prevented from so being
+// by incorrect variance-based relationships
+// Ref: https://github.com/Microsoft/TypeScript/issues/29698
+
+type Record2<K extends keyof any, T> = {
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>K : Symbol(K, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 4, 13))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 4, 33))
+
+    [P in K]: T;
+>P : Symbol(P, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 5, 5))
+>K : Symbol(K, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 4, 13))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 4, 33))
+
+};
+
+function defaultRecord(x: Record<'a', string>, y: Record<string, string>) {
+>defaultRecord : Symbol(defaultRecord, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 6, 2))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 8, 23))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 8, 46))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+
+    x = y; // no error, but error expected.
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 8, 23))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 8, 46))
+}
+
+function customRecord(x: Record2<'a', string>, y: Record2<string, string>) {
+>customRecord : Symbol(customRecord, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 10, 1))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 12, 22))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 12, 46))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+
+    x = y; // no error, but error expected.
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 12, 22))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 12, 46))
+}
+
+function mixed1(x: Record2<'a', string>, y: Record<string, string>) {
+>mixed1 : Symbol(mixed1, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 14, 1))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 16, 16))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 16, 40))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+
+    x = y; // error
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 16, 16))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 16, 40))
+}
+
+function mixed2(x: Record<'a', string>, y: Record2<string, string>) {
+>mixed2 : Symbol(mixed2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 18, 1))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 20, 16))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 20, 39))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+
+    x = y; // error
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 20, 16))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 20, 39))
+}
+
+function defaultRecord2<T>(x: Record<'a', T>, y: Record<string, T>) {
+>defaultRecord2 : Symbol(defaultRecord2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 22, 1))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 24))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 27))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 24))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 45))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 24))
+
+    x = y; // no error, but error expected.
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 27))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 24, 45))
+}
+
+function customRecord2<T>(x: Record2<'a', T>, y: Record2<string, T>) {
+>customRecord2 : Symbol(customRecord2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 26, 1))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 23))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 26))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 23))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 45))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 23))
+
+    x = y; // no error, but error expected.
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 26))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 28, 45))
+}
+
+function mixed3<T>(x: Record2<'a', T>, y: Record<string, T>) {
+>mixed3 : Symbol(mixed3, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 30, 1))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 16))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 19))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 16))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 38))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 16))
+
+    x = y; // error
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 19))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 32, 38))
+}
+
+function mixed4<T>(x: Record<'a', T>, y: Record2<string, T>) {
+>mixed4 : Symbol(mixed4, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 34, 1))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 16))
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 19))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 16))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 37))
+>Record2 : Symbol(Record2, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 0, 0))
+>T : Symbol(T, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 16))
+
+    x = y; // error
+>x : Symbol(x, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 19))
+>y : Symbol(y, Decl(consistentAliasVsNonAliasRecordBehavior.ts, 36, 37))
+}
+

tests/baselines/reference/consistentAliasVsNonAliasRecordBehavior.types

@@ -0,0 +1,99 @@
+=== tests/cases/compiler/consistentAliasVsNonAliasRecordBehavior.ts ===
+// TODO: FIXME: All the below cases labeled `no error` _should be an error_, and are only prevented from so being
+// by incorrect variance-based relationships
+// Ref: https://github.com/Microsoft/TypeScript/issues/29698
+
+type Record2<K extends keyof any, T> = {
+>Record2 : Record2<K, T>
+
+    [P in K]: T;
+};
+
+function defaultRecord(x: Record<'a', string>, y: Record<string, string>) {
+>defaultRecord : (x: Record<"a", string>, y: Record<string, string>) => void
+>x : Record<"a", string>
+>y : Record<string, string>
+
+    x = y; // no error, but error expected.
+>x = y : Record<string, string>
+>x : Record<"a", string>
+>y : Record<string, string>
+}
+
+function customRecord(x: Record2<'a', string>, y: Record2<string, string>) {
+>customRecord : (x: Record2<"a", string>, y: Record2<string, string>) => void
+>x : Record2<"a", string>
+>y : Record2<string, string>
+
+    x = y; // no error, but error expected.
+>x = y : Record2<string, string>
+>x : Record2<"a", string>
+>y : Record2<string, string>
+}
+
+function mixed1(x: Record2<'a', string>, y: Record<string, string>) {
+>mixed1 : (x: Record2<"a", string>, y: Record<string, string>) => void
+>x : Record2<"a", string>
+>y : Record<string, string>
+
+    x = y; // error
+>x = y : Record<string, string>
+>x : Record2<"a", string>
+>y : Record<string, string>
+}
+
+function mixed2(x: Record<'a', string>, y: Record2<string, string>) {
+>mixed2 : (x: Record<"a", string>, y: Record2<string, string>) => void
+>x : Record<"a", string>
+>y : Record2<string, string>
+
+    x = y; // error
+>x = y : Record2<string, string>
+>x : Record<"a", string>
+>y : Record2<string, string>
+}
+
+function defaultRecord2<T>(x: Record<'a', T>, y: Record<string, T>) {
+>defaultRecord2 : <T>(x: Record<"a", T>, y: Record<string, T>) => void
+>x : Record<"a", T>
+>y : Record<string, T>
+
+    x = y; // no error, but error expected.
+>x = y : Record<string, T>
+>x : Record<"a", T>
+>y : Record<string, T>
+}
+
+function customRecord2<T>(x: Record2<'a', T>, y: Record2<string, T>) {
+>customRecord2 : <T>(x: Record2<"a", T>, y: Record2<string, T>) => void
+>x : Record2<"a", T>
+>y : Record2<string, T>
+
+    x = y; // no error, but error expected.
+>x = y : Record2<string, T>
+>x : Record2<"a", T>
+>y : Record2<string, T>
+}
+
+function mixed3<T>(x: Record2<'a', T>, y: Record<string, T>) {
+>mixed3 : <T>(x: Record2<"a", T>, y: Record<string, T>) => void
+>x : Record2<"a", T>
+>y : Record<string, T>
+
+    x = y; // error
+>x = y : Record<string, T>
+>x : Record2<"a", T>
+>y : Record<string, T>
+}
+
+function mixed4<T>(x: Record<'a', T>, y: Record2<string, T>) {
+>mixed4 : <T>(x: Record<"a", T>, y: Record2<string, T>) => void
+>x : Record<"a", T>
+>y : Record2<string, T>
+
+    x = y; // error
+>x = y : Record2<string, T>
+>x : Record<"a", T>
+>y : Record2<string, T>
+}
+

tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.js

@@ -0,0 +1,36 @@
+//// [controlFlowForCompoundAssignmentToThisMember.ts]
+class DatasourceCommandWidgetElement {
+    _commandBased: boolean;
+    _commandElement: unknown;
+    commandElement: unknown;
+
+    constructor(target: unknown) {
+        if (target instanceof DatasourceCommandWidgetElement) {
+            this._commandBased = true;
+            this._commandElement = target.commandElement;
+        } else {
+            this._commandBased = false;
+        }
+
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+            this._commandElement = target.commandElement;
+        }
+    }
+}
+
+//// [controlFlowForCompoundAssignmentToThisMember.js]
+var DatasourceCommandWidgetElement = /** @class */ (function () {
+    function DatasourceCommandWidgetElement(target) {
+        if (target instanceof DatasourceCommandWidgetElement) {
+            this._commandBased = true;
+            this._commandElement = target.commandElement;
+        }
+        else {
+            this._commandBased = false;
+        }
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+            this._commandElement = target.commandElement;
+        }
+    }
+    return DatasourceCommandWidgetElement;
+}());