Merge remote-tracking branch 'origin/master' into release-3.7

src/compiler/binder.ts

@@ -161,7 +161,12 @@ namespace ts {
         IsObjectLiteralOrClassExpressionMethod = 1 << 7,
     }
 
-    let flowNodeCreated: <T extends FlowNode>(node: T) => T = identity;
+    function initFlowNode<T extends FlowNode>(node: T) {
+        Debug.attachFlowNodeDebugInfo(node);
+        return node;
+    }
+
+    let flowNodeCreated: <T extends FlowNode>(node: T) => T = initFlowNode;
 
     const binder = createBinder();
 
@@ -238,6 +243,10 @@ namespace ts {
 
             Symbol = objectAllocator.getSymbolConstructor();
 
+            // Attach debugging information if necessary
+            Debug.attachFlowNodeDebugInfo(unreachableFlow);
+            Debug.attachFlowNodeDebugInfo(reportedUnreachableFlow);
+
             if (!file.locals) {
                 bind(file);
                 file.symbolCount = symbolCount;
@@ -626,7 +635,7 @@ namespace ts {
                 // A non-async, non-generator IIFE is considered part of the containing control flow. Return statements behave
                 // similarly to break statements that exit to a label just past the statement body.
                 if (!isIIFE) {
-                    currentFlow = { flags: FlowFlags.Start };
+                    currentFlow = initFlowNode({ flags: FlowFlags.Start });
                     if (containerFlags & (ContainerFlags.IsFunctionExpression | ContainerFlags.IsObjectLiteralOrClassExpressionMethod)) {
                         currentFlow.node = <FunctionExpression | ArrowFunction | MethodDeclaration>node;
                     }
@@ -638,7 +647,7 @@ namespace ts {
                 currentContinueTarget = undefined;
                 activeLabels = undefined;
                 hasExplicitReturn = false;
-                flowNodeCreated = identity;
+                flowNodeCreated = initFlowNode;
                 bindChildren(node);
                 // Reset all reachability check related flags on node (for incremental scenarios)
                 node.flags &= ~NodeFlags.ReachabilityAndEmitFlags;
@@ -812,9 +821,6 @@ namespace ts {
                 case SyntaxKind.JSDocEnumTag:
                     bindJSDocTypeAlias(node as JSDocTypedefTag | JSDocCallbackTag | JSDocEnumTag);
                     break;
-                case SyntaxKind.JSDocClassTag:
-                    bindJSDocClassTag(node as JSDocClassTag);
-                    break;
                 // In source files and blocks, bind functions first to match hoisting that occurs at runtime
                 case SyntaxKind.SourceFile: {
                     bindEachFunctionsFirst((node as SourceFile).statements);
@@ -856,9 +862,8 @@ namespace ts {
         function isNarrowableReference(expr: Expression): boolean {
             return expr.kind === SyntaxKind.Identifier || expr.kind === SyntaxKind.ThisKeyword || expr.kind === SyntaxKind.SuperKeyword ||
                 (isPropertyAccessExpression(expr) || isNonNullExpression(expr) || isParenthesizedExpression(expr)) && isNarrowableReference(expr.expression) ||
-                isElementAccessExpression(expr) &&
-                isStringOrNumericLiteralLike(expr.argumentExpression) &&
-                isNarrowableReference(expr.expression);
+                isElementAccessExpression(expr) && isStringOrNumericLiteralLike(expr.argumentExpression) && isNarrowableReference(expr.expression) ||
+                isOptionalChain(expr);
         }
 
         function hasNarrowableArgument(expr: CallExpression) {
@@ -920,11 +925,11 @@ namespace ts {
         }
 
         function createBranchLabel(): FlowLabel {
-            return { flags: FlowFlags.BranchLabel, antecedents: undefined };
+            return initFlowNode({ flags: FlowFlags.BranchLabel, antecedents: undefined });
         }
 
         function createLoopLabel(): FlowLabel {
-            return { flags: FlowFlags.LoopLabel, antecedents: undefined };
+            return initFlowNode({ flags: FlowFlags.LoopLabel, antecedents: undefined });
         }
 
         function setFlowNodeReferenced(flow: FlowNode) {
@@ -948,7 +953,7 @@ namespace ts {
             }
             if (expression.kind === SyntaxKind.TrueKeyword && flags & FlowFlags.FalseCondition ||
                 expression.kind === SyntaxKind.FalseKeyword && flags & FlowFlags.TrueCondition) {
-                if (!isOptionalChainRoot(expression.parent)) {
+                if (!isExpressionOfOptionalChainRoot(expression)) {
                     return unreachableFlow;
                 }
             }
@@ -1194,7 +1199,7 @@ namespace ts {
             // as possible antecedents of the start of the `catch` or `finally` blocks.
             // Don't bother intercepting the call if there's no finally or catch block that needs the information
             if (node.catchClause || node.finallyBlock) {
-                flowNodeCreated = node => (tryPriors.push(node), node);
+                flowNodeCreated = node => (tryPriors.push(node), initFlowNode(node));
             }
             bind(node.tryBlock);
             flowNodeCreated = oldFlowNodeCreated;
@@ -1263,7 +1268,7 @@ namespace ts {
                 //
                 // extra edges that we inject allows to control this behavior
                 // if when walking the flow we step on post-finally edge - we can mark matching pre-finally edge as locked so it will be skipped.
-                const preFinallyFlow: PreFinallyFlow = { flags: FlowFlags.PreFinally, antecedent: preFinallyPrior, lock: {} };
+                const preFinallyFlow: PreFinallyFlow = initFlowNode({ flags: FlowFlags.PreFinally, antecedent: preFinallyPrior, lock: {} });
                 addAntecedent(preFinallyLabel, preFinallyFlow);
 
                 currentFlow = finishFlowLabel(preFinallyLabel);
@@ -1333,7 +1338,7 @@ namespace ts {
                 bind(clause);
                 fallthroughFlow = currentFlow;
                 if (!(currentFlow.flags & FlowFlags.Unreachable) && i !== clauses.length - 1 && options.noFallthroughCasesInSwitch) {
-                    errorOnFirstToken(clause, Diagnostics.Fallthrough_case_in_switch);
+                    clause.fallthroughFlowNode = currentFlow;
                 }
             }
             clauses.transformFlags = subtreeTransformFlags | TransformFlags.HasComputedFlags;
@@ -1984,7 +1989,7 @@ namespace ts {
                 const host = getJSDocHost(typeAlias);
                 container = findAncestor(host.parent, n => !!(getContainerFlags(n) & ContainerFlags.IsContainer)) || file;
                 blockScopeContainer = getEnclosingBlockScopeContainer(host) || file;
-                currentFlow = { flags: FlowFlags.Start };
+                currentFlow = initFlowNode({ flags: FlowFlags.Start });
                 parent = typeAlias;
                 bind(typeAlias.typeExpression);
                 const declName = getNameOfDeclaration(typeAlias);
@@ -2446,6 +2451,8 @@ namespace ts {
                 case SyntaxKind.JSDocTypeLiteral:
                 case SyntaxKind.MappedType:
                     return bindAnonymousTypeWorker(node as TypeLiteralNode | MappedTypeNode | JSDocTypeLiteral);
+                case SyntaxKind.JSDocClassTag:
+                    return bindJSDocClassTag(node as JSDocClassTag);
                 case SyntaxKind.ObjectLiteralExpression:
                     return bindObjectLiteralExpression(<ObjectLiteralExpression>node);
                 case SyntaxKind.FunctionExpression:
@@ -2683,7 +2690,8 @@ namespace ts {
             const flags = exportAssignmentIsAlias(node)
                 ? SymbolFlags.Alias // An export= with an EntityNameExpression or a ClassExpression exports all meanings of that identifier or class
                 : SymbolFlags.Property | SymbolFlags.ExportValue | SymbolFlags.ValueModule;
-            declareSymbol(file.symbol.exports!, file.symbol, node, flags | SymbolFlags.Assignment, SymbolFlags.None);
+            const symbol = declareSymbol(file.symbol.exports!, file.symbol, node, flags | SymbolFlags.Assignment, SymbolFlags.None);
+            setValueDeclaration(symbol, node);
         }
 
         function bindThisPropertyAssignment(node: BindablePropertyAssignmentExpression | PropertyAccessExpression | LiteralLikeElementAccessExpression) {
@@ -2781,6 +2789,10 @@ namespace ts {
 
         function bindObjectDefinePrototypeProperty(node: BindableObjectDefinePropertyCall) {
             const namespaceSymbol = lookupSymbolForPropertyAccess((node.arguments[0] as PropertyAccessExpression).expression as EntityNameExpression);
+            if (namespaceSymbol) {
+                // Ensure the namespace symbol becomes class-like
+                addDeclarationToSymbol(namespaceSymbol, namespaceSymbol.valueDeclaration, SymbolFlags.Class);
+            }
             bindPotentiallyNewExpandoMemberToNamespace(node, namespaceSymbol, /*isPrototypeProperty*/ true);
         }
 
@@ -2862,7 +2874,7 @@ namespace ts {
                     }
                 });
             }
-            if (containerIsClass && namespaceSymbol) {
+            if (containerIsClass && namespaceSymbol && namespaceSymbol.valueDeclaration) {
                 addDeclarationToSymbol(namespaceSymbol, namespaceSymbol.valueDeclaration, SymbolFlags.Class);
             }
             return namespaceSymbol;

src/compiler/builder.ts

@@ -251,6 +251,7 @@ namespace ts {
             state.seenAffectedFiles = createMap<true>();
         }
 
+        state.emittedBuildInfo = !state.changedFilesSet.size && !state.affectedFilesPendingEmit;
         return state;
     }
 
@@ -1118,7 +1119,7 @@ namespace ts {
 
         const state: ReusableBuilderProgramState = {
             fileInfos,
-            compilerOptions: convertFromReusableCompilerOptions(program.options, toAbsolutePath),
+            compilerOptions: convertToOptionsWithAbsolutePaths(program.options, toAbsolutePath),
             referencedMap: getMapOfReferencedSet(program.referencedMap, toPath),
             exportedModulesMap: getMapOfReferencedSet(program.exportedModulesMap, toPath),
             semanticDiagnosticsPerFile: program.semanticDiagnosticsPerFile && arrayToMap(program.semanticDiagnosticsPerFile, value => toPath(isString(value) ? value : value[0]), value => isString(value) ? emptyArray : value[1]),
@@ -1156,40 +1157,6 @@ namespace ts {
         }
     }
 
-    function convertFromReusableCompilerOptions(options: CompilerOptions, toAbsolutePath: (path: string) => string) {
-        const result: CompilerOptions = {};
-        const optionsNameMap = getOptionNameMap().optionNameMap;
-
-        for (const name in options) {
-            if (hasProperty(options, name)) {
-                result[name] = convertFromReusableCompilerOptionValue(
-                    optionsNameMap.get(name.toLowerCase()),
-                    options[name] as CompilerOptionsValue,
-                    toAbsolutePath
-                );
-            }
-        }
-        if (result.configFilePath) {
-            result.configFilePath = toAbsolutePath(result.configFilePath);
-        }
-        return result;
-    }
-
-    function convertFromReusableCompilerOptionValue(option: CommandLineOption | undefined, value: CompilerOptionsValue, toAbsolutePath: (path: string) => string) {
-        if (option) {
-            if (option.type === "list") {
-                const values = value as readonly (string | number)[];
-                if (option.element.isFilePath && values.length) {
-                    return values.map(toAbsolutePath);
-                }
-            }
-            else if (option.isFilePath) {
-                return toAbsolutePath(value as string);
-            }
-        }
-        return value;
-    }
-
     export function createRedirectedBuilderProgram(state: { program: Program | undefined; compilerOptions: CompilerOptions; }, configFileParsingDiagnostics: readonly Diagnostic[]): BuilderProgram {
         return {
             getState: notImplemented,

src/compiler/commandLineParser.ts

@@ -216,6 +216,15 @@ namespace ts {
             isCommandLineOnly: true,
             description: Diagnostics.Print_the_final_configuration_instead_of_building
         },
+        {
+            name: "listFilesOnly",
+            type: "boolean",
+            category: Diagnostics.Command_line_Options,
+            affectsSemanticDiagnostics: true,
+            affectsEmit: true,
+            isCommandLineOnly: true,
+            description: Diagnostics.Print_names_of_files_that_are_part_of_the_compilation_and_then_stop_processing
+        },
 
         // Basic
         {
@@ -1227,7 +1236,7 @@ namespace ts {
     }
 
     /*@internal*/
-    export function parseBuildCommand(args: string[]): ParsedBuildCommand {
+    export function parseBuildCommand(args: readonly string[]): ParsedBuildCommand {
         let buildOptionNameMap: OptionNameMap | undefined;
         const returnBuildOptionNameMap = () => (buildOptionNameMap || (buildOptionNameMap = createOptionNameMap(buildOpts)));
         const { options, fileNames: projects, errors } = parseCommandLineWorker(returnBuildOptionNameMap, [
@@ -1258,125 +1267,12 @@ namespace ts {
         return { buildOptions, projects, errors };
     }
 
-    function getDiagnosticText(_message: DiagnosticMessage, ..._args: any[]): string {
+    /* @internal */
+    export function getDiagnosticText(_message: DiagnosticMessage, ..._args: any[]): string {
         const diagnostic = createCompilerDiagnostic.apply(undefined, arguments);
         return <string>diagnostic.messageText;
     }
 
-    /* @internal */
-    export function printVersion() {
-        sys.write(getDiagnosticText(Diagnostics.Version_0, version) + sys.newLine);
-    }
-
-    /* @internal */
-    export function printHelp(optionsList: readonly CommandLineOption[], syntaxPrefix = "") {
-        const output: string[] = [];
-
-        // We want to align our "syntax" and "examples" commands to a certain margin.
-        const syntaxLength = getDiagnosticText(Diagnostics.Syntax_Colon_0, "").length;
-        const examplesLength = getDiagnosticText(Diagnostics.Examples_Colon_0, "").length;
-        let marginLength = Math.max(syntaxLength, examplesLength);
-
-        // Build up the syntactic skeleton.
-        let syntax = makePadding(marginLength - syntaxLength);
-        syntax += `tsc ${syntaxPrefix}[${getDiagnosticText(Diagnostics.options)}] [${getDiagnosticText(Diagnostics.file)}...]`;
-
-        output.push(getDiagnosticText(Diagnostics.Syntax_Colon_0, syntax));
-        output.push(sys.newLine + sys.newLine);
-
-        // Build up the list of examples.
-        const padding = makePadding(marginLength);
-        output.push(getDiagnosticText(Diagnostics.Examples_Colon_0, makePadding(marginLength - examplesLength) + "tsc hello.ts") + sys.newLine);
-        output.push(padding + "tsc --outFile file.js file.ts" + sys.newLine);
-        output.push(padding + "tsc @args.txt" + sys.newLine);
-        output.push(padding + "tsc --build tsconfig.json" + sys.newLine);
-        output.push(sys.newLine);
-
-        output.push(getDiagnosticText(Diagnostics.Options_Colon) + sys.newLine);
-
-        // We want our descriptions to align at the same column in our output,
-        // so we keep track of the longest option usage string.
-        marginLength = 0;
-        const usageColumn: string[] = []; // Things like "-d, --declaration" go in here.
-        const descriptionColumn: string[] = [];
-
-        const optionsDescriptionMap = createMap<string[]>();  // Map between option.description and list of option.type if it is a kind
-
-        for (const option of optionsList) {
-            // If an option lacks a description,
-            // it is not officially supported.
-            if (!option.description) {
-                continue;
-            }
-
-            let usageText = " ";
-            if (option.shortName) {
-                usageText += "-" + option.shortName;
-                usageText += getParamType(option);
-                usageText += ", ";
-            }
-
-            usageText += "--" + option.name;
-            usageText += getParamType(option);
-
-            usageColumn.push(usageText);
-            let description: string;
-
-            if (option.name === "lib") {
-                description = getDiagnosticText(option.description);
-                const element = (<CommandLineOptionOfListType>option).element;
-                const typeMap = <Map<number | string>>element.type;
-                optionsDescriptionMap.set(description, arrayFrom(typeMap.keys()).map(key => `'${key}'`));
-            }
-            else {
-                description = getDiagnosticText(option.description);
-            }
-
-            descriptionColumn.push(description);
-
-            // Set the new margin for the description column if necessary.
-            marginLength = Math.max(usageText.length, marginLength);
-        }
-
-        // Special case that can't fit in the loop.
-        const usageText = " @<" + getDiagnosticText(Diagnostics.file) + ">";
-        usageColumn.push(usageText);
-        descriptionColumn.push(getDiagnosticText(Diagnostics.Insert_command_line_options_and_files_from_a_file));
-        marginLength = Math.max(usageText.length, marginLength);
-
-        // Print out each row, aligning all the descriptions on the same column.
-        for (let i = 0; i < usageColumn.length; i++) {
-            const usage = usageColumn[i];
-            const description = descriptionColumn[i];
-            const kindsList = optionsDescriptionMap.get(description);
-            output.push(usage + makePadding(marginLength - usage.length + 2) + description + sys.newLine);
-
-            if (kindsList) {
-                output.push(makePadding(marginLength + 4));
-                for (const kind of kindsList) {
-                    output.push(kind + " ");
-                }
-                output.push(sys.newLine);
-            }
-        }
-
-        for (const line of output) {
-            sys.write(line);
-        }
-        return;
-
-        function getParamType(option: CommandLineOption) {
-            if (option.paramType !== undefined) {
-                return " " + getDiagnosticText(option.paramType);
-            }
-            return "";
-        }
-
-        function makePadding(paddingLength: number): string {
-            return Array(paddingLength + 1).join(" ");
-        }
-    }
-
     export type DiagnosticReporter = (diagnostic: Diagnostic) => void;
     /**
      * Reports config file diagnostics
@@ -1801,6 +1697,12 @@ namespace ts {
         references: readonly ProjectReference[] | undefined;
     }
 
+    /** @internal */
+    export interface ConvertToTSConfigHost {
+        getCurrentDirectory(): string;
+        useCaseSensitiveFileNames: boolean;
+    }
+
     /**
      * Generate an uncommented, complete tsconfig for use with "--showConfig"
      * @param configParseResult options to be generated into tsconfig.json
@@ -1808,7 +1710,7 @@ namespace ts {
      * @param host provides current directory and case sensitivity services
      */
     /** @internal */
-    export function convertToTSConfig(configParseResult: ParsedCommandLine, configFileName: string, host: { getCurrentDirectory(): string, useCaseSensitiveFileNames: boolean }): TSConfig {
+    export function convertToTSConfig(configParseResult: ParsedCommandLine, configFileName: string, host: ConvertToTSConfigHost): TSConfig {
         const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames);
         const files = map(
             filter(
@@ -1816,7 +1718,8 @@ namespace ts {
                 (!configParseResult.configFileSpecs || !configParseResult.configFileSpecs.validatedIncludeSpecs) ? _ => true : matchesSpecs(
                     configFileName,
                     configParseResult.configFileSpecs.validatedIncludeSpecs,
-                    configParseResult.configFileSpecs.validatedExcludeSpecs
+                    configParseResult.configFileSpecs.validatedExcludeSpecs,
+                    host,
                 )
             ),
             f => getRelativePathFromFile(getNormalizedAbsolutePath(configFileName, host.getCurrentDirectory()), getNormalizedAbsolutePath(f, host.getCurrentDirectory()), getCanonicalFileName)
@@ -1854,11 +1757,11 @@ namespace ts {
         return specs;
     }
 
-    function matchesSpecs(path: string, includeSpecs: readonly string[] | undefined, excludeSpecs: readonly string[] | undefined): (path: string) => boolean {
+    function matchesSpecs(path: string, includeSpecs: readonly string[] | undefined, excludeSpecs: readonly string[] | undefined, host: ConvertToTSConfigHost): (path: string) => boolean {
         if (!includeSpecs) return _ => true;
-        const patterns = getFileMatcherPatterns(path, excludeSpecs, includeSpecs, sys.useCaseSensitiveFileNames, sys.getCurrentDirectory());
-        const excludeRe = patterns.excludePattern && getRegexFromPattern(patterns.excludePattern, sys.useCaseSensitiveFileNames);
-        const includeRe = patterns.includeFilePattern && getRegexFromPattern(patterns.includeFilePattern, sys.useCaseSensitiveFileNames);
+        const patterns = getFileMatcherPatterns(path, excludeSpecs, includeSpecs, host.useCaseSensitiveFileNames, host.getCurrentDirectory());
+        const excludeRe = patterns.excludePattern && getRegexFromPattern(patterns.excludePattern, host.useCaseSensitiveFileNames);
+        const includeRe = patterns.includeFilePattern && getRegexFromPattern(patterns.includeFilePattern, host.useCaseSensitiveFileNames);
         if (includeRe) {
             if (excludeRe) {
                 return path => !(includeRe.test(path) && !excludeRe.test(path));
@@ -2041,6 +1944,41 @@ namespace ts {
         }
     }
 
+    /* @internal */
+    export function convertToOptionsWithAbsolutePaths(options: CompilerOptions, toAbsolutePath: (path: string) => string) {
+        const result: CompilerOptions = {};
+        const optionsNameMap = getOptionNameMap().optionNameMap;
+
+        for (const name in options) {
+            if (hasProperty(options, name)) {
+                result[name] = convertToOptionValueWithAbsolutePaths(
+                    optionsNameMap.get(name.toLowerCase()),
+                    options[name] as CompilerOptionsValue,
+                    toAbsolutePath
+                );
+            }
+        }
+        if (result.configFilePath) {
+            result.configFilePath = toAbsolutePath(result.configFilePath);
+        }
+        return result;
+    }
+
+    function convertToOptionValueWithAbsolutePaths(option: CommandLineOption | undefined, value: CompilerOptionsValue, toAbsolutePath: (path: string) => string) {
+        if (option) {
+            if (option.type === "list") {
+                const values = value as readonly (string | number)[];
+                if (option.element.isFilePath && values.length) {
+                    return values.map(toAbsolutePath);
+                }
+            }
+            else if (option.isFilePath) {
+                return toAbsolutePath(value as string);
+            }
+        }
+        return value;
+    }
+
     /**
      * Parse the contents of a config file (tsconfig.json).
      * @param json The contents of the config file to parse
@@ -2604,7 +2542,7 @@ namespace ts {
 
     function normalizeNonListOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue {
         if (option.isFilePath) {
-            value = normalizePath(combinePaths(basePath, value));
+            value = getNormalizedAbsolutePath(value, basePath);
             if (value === "") {
                 value = ".";
             }

src/compiler/core.ts

@@ -42,6 +42,12 @@ namespace ts {
         clear(): void;
     }
 
+    /* @internal */
+    export interface MapConstructor {
+        // eslint-disable-next-line @typescript-eslint/prefer-function-type
+        new <T>(): Map<T>;
+    }
+
     /** ES6 Iterator type. */
     export interface Iterator<T> {
         next(): { value: T, done?: false } | { value: never, done: true };
@@ -66,28 +72,40 @@ namespace ts {
     }
 }
 
+/* @internal */
+namespace ts {
+    // Natives
+    // NOTE: This must be declared in a separate block from the one below so that we don't collide with the exported definition of `Map`.
+    declare const Map: (new <T>() => Map<T>) | undefined;
+
+    /**
+     * Returns the native Map implementation if it is available and compatible (i.e. supports iteration).
+     */
+    export function tryGetNativeMap(): MapConstructor | undefined {
+        // Internet Explorer's Map doesn't support iteration, so don't use it.
+        // eslint-disable-next-line no-in-operator
+        return typeof Map !== "undefined" && "entries" in Map.prototype ? Map : undefined;
+    }
+}
+
 /* @internal */
 namespace ts {
     export const emptyArray: never[] = [] as never[];
 
-    /** Create a MapLike with good performance. */
-    function createDictionaryObject<T>(): MapLike<T> {
-        const map = Object.create(/*prototype*/ null); // eslint-disable-line no-null/no-null
+    export const Map: MapConstructor = tryGetNativeMap() || (() => {
+        // NOTE: createMapShim will be defined for typescriptServices.js but not for tsc.js, so we must test for it.
+        if (typeof createMapShim === "function") {
+            return createMapShim();
+        }
+        throw new Error("TypeScript requires an environment that provides a compatible native Map implementation.");
+    })();
 
-        // Using 'delete' on an object causes V8 to put the object in dictionary mode.
-        // This disables creation of hidden classes, which are expensive when an object is
-        // constantly changing shape.
-        map.__ = undefined;
-        delete map.__;
-
-        return map;
-    }
-
-    /** Create a new map. If a template object is provided, the map will copy entries from it. */
+    /** Create a new map. */
     export function createMap<T>(): Map<T> {
-        return new MapCtr<T>();
+        return new Map<T>();
     }
 
+    /** Create a new map from an array of entries. */
     export function createMapFromEntries<T>(entries: [string, T][]): Map<T> {
         const map = createMap<T>();
         for (const [key, value] of entries) {
@@ -96,8 +114,9 @@ namespace ts {
         return map;
     }
 
+    /** Create a new map from a template object is provided, the map will copy entries from it. */
     export function createMapFromTemplate<T>(template: MapLike<T>): Map<T> {
-        const map: Map<T> = new MapCtr<T>();
+        const map: Map<T> = new Map<T>();
 
         // Copies keys/values from template. Note that for..in will not throw if
         // template is undefined, and instead will just exit the loop.
@@ -110,204 +129,6 @@ namespace ts {
         return map;
     }
 
-    // The global Map object. This may not be available, so we must test for it.
-    declare const Map: (new <T>() => Map<T>) | undefined;
-    // Internet Explorer's Map doesn't support iteration, so don't use it.
-    // eslint-disable-next-line no-in-operator
-    export const MapCtr = typeof Map !== "undefined" && "entries" in Map.prototype ? Map : shimMap();
-
-    // Keep the class inside a function so it doesn't get compiled if it's not used.
-    export function shimMap(): new <T>() => Map<T> {
-
-        interface MapEntry<T> {
-            readonly key?: string;
-            value?: T;
-
-            // Linked list references for iterators.
-            nextEntry?: MapEntry<T>;
-            previousEntry?: MapEntry<T>;
-
-            /**
-             * Specifies if iterators should skip the next entry.
-             * This will be set when an entry is deleted.
-             * See https://github.com/Microsoft/TypeScript/pull/27292 for more information.
-             */
-            skipNext?: boolean;
-        }
-
-        class MapIterator<T, U extends (string | T | [string, T])> {
-            private currentEntry?: MapEntry<T>;
-            private selector: (key: string, value: T) => U;
-
-            constructor(currentEntry: MapEntry<T>, selector: (key: string, value: T) => U) {
-                this.currentEntry = currentEntry;
-                this.selector = selector;
-            }
-
-            public next(): { value: U, done: false } | { value: never, done: true } {
-                // Navigate to the next entry.
-                while (this.currentEntry) {
-                    const skipNext = !!this.currentEntry.skipNext;
-                    this.currentEntry = this.currentEntry.nextEntry;
-
-                    if (!skipNext) {
-                        break;
-                    }
-                }
-
-                if (this.currentEntry) {
-                    return { value: this.selector(this.currentEntry.key!, this.currentEntry.value!), done: false };
-                }
-                else {
-                    return { value: undefined as never, done: true };
-                }
-            }
-        }
-
-        return class <T> implements Map<T> {
-            private data = createDictionaryObject<MapEntry<T>>();
-            public size = 0;
-
-            // Linked list references for iterators.
-            // See https://github.com/Microsoft/TypeScript/pull/27292
-            // for more information.
-
-            /**
-             * The first entry in the linked list.
-             * Note that this is only a stub that serves as starting point
-             * for iterators and doesn't contain a key and a value.
-             */
-            private readonly firstEntry: MapEntry<T>;
-            private lastEntry: MapEntry<T>;
-
-            constructor() {
-                // Create a first (stub) map entry that will not contain a key
-                // and value but serves as starting point for iterators.
-                this.firstEntry = {};
-                // When the map is empty, the last entry is the same as the
-                // first one.
-                this.lastEntry = this.firstEntry;
-            }
-
-            get(key: string): T | undefined {
-                const entry = this.data[key] as MapEntry<T> | undefined;
-                return entry && entry.value!;
-            }
-
-            set(key: string, value: T): this {
-                if (!this.has(key)) {
-                    this.size++;
-
-                    // Create a new entry that will be appended at the
-                    // end of the linked list.
-                    const newEntry: MapEntry<T> = {
-                        key,
-                        value
-                    };
-                    this.data[key] = newEntry;
-
-                    // Adjust the references.
-                    const previousLastEntry = this.lastEntry;
-                    previousLastEntry.nextEntry = newEntry;
-                    newEntry.previousEntry = previousLastEntry;
-                    this.lastEntry = newEntry;
-                }
-                else {
-                    this.data[key].value = value;
-                }
-
-                return this;
-            }
-
-            has(key: string): boolean {
-                // eslint-disable-next-line no-in-operator
-                return key in this.data;
-            }
-
-            delete(key: string): boolean {
-                if (this.has(key)) {
-                    this.size--;
-                    const entry = this.data[key];
-                    delete this.data[key];
-
-                    // Adjust the linked list references of the neighbor entries.
-                    const previousEntry = entry.previousEntry!;
-                    previousEntry.nextEntry = entry.nextEntry;
-                    if (entry.nextEntry) {
-                        entry.nextEntry.previousEntry = previousEntry;
-                    }
-
-                    // When the deleted entry was the last one, we need to
-                    // adjust the lastEntry reference.
-                    if (this.lastEntry === entry) {
-                        this.lastEntry = previousEntry;
-                    }
-
-                    // Adjust the forward reference of the deleted entry
-                    // in case an iterator still references it. This allows us
-                    // to throw away the entry, but when an active iterator
-                    // (which points to the current entry) continues, it will
-                    // navigate to the entry that originally came before the
-                    // current one and skip it.
-                    entry.previousEntry = undefined;
-                    entry.nextEntry = previousEntry;
-                    entry.skipNext = true;
-
-                    return true;
-                }
-                return false;
-            }
-
-            clear(): void {
-                this.data = createDictionaryObject<MapEntry<T>>();
-                this.size = 0;
-
-                // Reset the linked list. Note that we must adjust the forward
-                // references of the deleted entries to ensure iterators stuck
-                // in the middle of the list don't continue with deleted entries,
-                // but can continue with new entries added after the clear()
-                // operation.
-                const firstEntry = this.firstEntry;
-                let currentEntry = firstEntry.nextEntry;
-                while (currentEntry) {
-                    const nextEntry = currentEntry.nextEntry;
-                    currentEntry.previousEntry = undefined;
-                    currentEntry.nextEntry = firstEntry;
-                    currentEntry.skipNext = true;
-
-                    currentEntry = nextEntry;
-                }
-                firstEntry.nextEntry = undefined;
-                this.lastEntry = firstEntry;
-            }
-
-            keys(): Iterator<string> {
-                return new MapIterator(this.firstEntry, key => key);
-            }
-
-            values(): Iterator<T> {
-                return new MapIterator(this.firstEntry, (_key, value) => value);
-            }
-
-            entries(): Iterator<[string, T]> {
-                return new MapIterator(this.firstEntry, (key, value) => [key, value] as [string, T]);
-            }
-
-            forEach(action: (value: T, key: string) => void): void {
-                const iterator = this.entries();
-                while (true) {
-                    const iterResult = iterator.next();
-                    if (iterResult.done) {
-                        break;
-                    }
-
-                    const [key, value] = iterResult.value;
-                    action(value, key);
-                }
-            }
-        };
-    }
-
     export function length(array: readonly any[] | undefined): number {
         return array ? array.length : 0;
     }
@@ -2052,20 +1873,6 @@ namespace ts {
         return str.indexOf(substring) !== -1;
     }
 
-    export function fileExtensionIs(path: string, extension: string): boolean {
-        return path.length > extension.length && endsWith(path, extension);
-    }
-
-    export function fileExtensionIsOneOf(path: string, extensions: readonly string[]): boolean {
-        for (const extension of extensions) {
-            if (fileExtensionIs(path, extension)) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
     /**
      * Takes a string like "jquery-min.4.2.3" and returns "jquery"
      */

src/compiler/debug.ts

@@ -221,6 +221,40 @@ namespace ts {
 
         let isDebugInfoEnabled = false;
 
+        interface ExtendedDebugModule {
+            init(_ts: typeof ts): void;
+            formatControlFlowGraph(flowNode: FlowNode): string;
+        }
+
+        let extendedDebugModule: ExtendedDebugModule | undefined;
+
+        function extendedDebug() {
+            enableDebugInfo();
+            if (!extendedDebugModule) {
+                throw new Error("Debugging helpers could not be loaded.");
+            }
+            return extendedDebugModule;
+        }
+
+        export function printControlFlowGraph(flowNode: FlowNode) {
+            return console.log(formatControlFlowGraph(flowNode));
+        }
+
+        export function formatControlFlowGraph(flowNode: FlowNode) {
+            return extendedDebug().formatControlFlowGraph(flowNode);
+        }
+
+        export function attachFlowNodeDebugInfo(flowNode: FlowNode) {
+            if (isDebugInfoEnabled) {
+                if (!("__debugFlowFlags" in flowNode)) { // eslint-disable-line no-in-operator
+                    Object.defineProperties(flowNode, {
+                        __debugFlowFlags: { get(this: FlowNode) { return formatEnum(this.flags, (ts as any).FlowFlags, /*isFlags*/ true); } },
+                        __debugToString: { value(this: FlowNode) { return formatControlFlowGraph(this); } }
+                    });
+                }
+            }
+        }
+
         /**
          * Injects debug information into frequently used types.
          */
@@ -266,6 +300,21 @@ namespace ts {
                 }
             }
 
+            // attempt to load extended debugging information
+            try {
+                if (sys && sys.require) {
+                    const basePath = getDirectoryPath(resolvePath(sys.getExecutingFilePath()));
+                    const result = sys.require(basePath, "./compiler-debug") as RequireResult<ExtendedDebugModule>;
+                    if (!result.error) {
+                        result.module.init(ts);
+                        extendedDebugModule = result.module;
+                    }
+                }
+            }
+            catch {
+                // do nothing
+            }
+
             isDebugInfoEnabled = true;
         }
 

src/compiler/diagnosticMessages.json

@@ -71,7 +71,7 @@
         "category": "Error",
         "code": 1022
     },
-    "An index signature parameter type must be 'string' or 'number'.": {
+    "An index signature parameter type must be either 'string' or 'number'.": {
         "category": "Error",
         "code": 1023
     },
@@ -903,7 +903,7 @@
         "category": "Error",
         "code": 1322
     },
-    "Dynamic import is only supported when '--module' flag is 'commonjs' or 'esNext'.": {
+    "Dynamic imports are only supported when the '--module' flag is set to 'esnext', 'commonjs',  'amd', 'system', or 'umd'.": {
         "category": "Error",
         "code": 1323
     },
@@ -1043,6 +1043,10 @@
         "category": "Error",
         "code": 1358
     },
+    "Identifier expected. '{0}' is a reserved word that cannot be used here.": {
+        "category": "Error",
+        "code": 1359
+    },
 
     "The types of '{0}' are incompatible between these types.": {
         "category": "Error",
@@ -1557,10 +1561,6 @@
         "category": "Error",
         "code": 2423
     },
-    "Class '{0}' defines instance member function '{1}', but extended class '{2}' defines it as instance member property.": {
-        "category": "Error",
-        "code": 2424
-    },
     "Class '{0}' defines instance member property '{1}', but extended class '{2}' defines it as instance member function.": {
         "category": "Error",
         "code": 2425
@@ -2249,6 +2249,14 @@
         "category": "Error",
         "code": 2612
     },
+    "Module '{0}' has no default export. Did you mean to use 'import { {1} } from {0}' instead?": {
+        "category": "Error",
+        "code": 2613
+    },
+    "Module '{0}' has no exported member '{1}'. Did you mean to use 'import {1} from {0}' instead?": {
+        "category": "Error",
+        "code": 2614
+    },
 
     "Cannot augment module '{0}' with value exports because it resolves to a non-module entity.": {
         "category": "Error",
@@ -4303,6 +4311,10 @@
         "category": "Message",
         "code": 6502
     },
+    "Print names of files that are part of the compilation and then stop processing.": {
+        "category": "Message",
+        "code": 6503
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",

src/compiler/emitter.ts

@@ -393,7 +393,9 @@ namespace ts {
             declarationFilePath: string | undefined,
             declarationMapPath: string | undefined,
             relativeToBuildInfo: (path: string) => string) {
-            if (!sourceFileOrBundle || !declarationFilePath) {
+            if (!sourceFileOrBundle) return;
+            if (!declarationFilePath) {
+                if (emitOnlyDtsFiles || compilerOptions.emitDeclarationOnly) emitSkipped = true;
                 return;
             }
             const sourceFiles = isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;

src/compiler/factory.ts

@@ -1065,7 +1065,9 @@ namespace ts {
     }
 
     export function updatePropertyAccess(node: PropertyAccessExpression, expression: Expression, name: Identifier) {
-        Debug.assert(!(node.flags & NodeFlags.OptionalChain), "Cannot update a PropertyAccessChain using updatePropertyAccess. Use updatePropertyAccessChain instead.");
+        if (isOptionalChain(node)) {
+            return updatePropertyAccessChain(node, expression, node.questionDotToken, name);
+        }
         // Because we are updating existed propertyAccess we want to inherit its emitFlags
         // instead of using the default from createPropertyAccess
         return node.expression !== expression
@@ -1103,7 +1105,9 @@ namespace ts {
     }
 
     export function updateElementAccess(node: ElementAccessExpression, expression: Expression, argumentExpression: Expression) {
-        Debug.assert(!(node.flags & NodeFlags.OptionalChain), "Cannot update an ElementAccessChain using updateElementAccess. Use updateElementAccessChain instead.");
+        if (isOptionalChain(node)) {
+            return updateElementAccessChain(node, expression, node.questionDotToken, argumentExpression);
+        }
         return node.expression !== expression
             || node.argumentExpression !== argumentExpression
             ? updateNode(createElementAccess(expression, argumentExpression), node)
@@ -1137,7 +1141,9 @@ namespace ts {
     }
 
     export function updateCall(node: CallExpression, expression: Expression, typeArguments: readonly TypeNode[] | undefined, argumentsArray: readonly Expression[]) {
-        Debug.assert(!(node.flags & NodeFlags.OptionalChain), "Cannot update a CallChain using updateCall. Use updateCallChain instead.");
+        if (isOptionalChain(node)) {
+            return updateCallChain(node, expression, node.questionDotToken, typeArguments, argumentsArray);
+        }
         return node.expression !== expression
             || node.typeArguments !== typeArguments
             || node.arguments !== argumentsArray
@@ -1805,7 +1811,7 @@ namespace ts {
         const node = <ForOfStatement>createSynthesizedNode(SyntaxKind.ForOfStatement);
         node.awaitModifier = awaitModifier;
         node.initializer = initializer;
-        node.expression = expression;
+        node.expression = isCommaSequence(expression) ? createParen(expression) : expression;
         node.statement = asEmbeddedStatement(statement);
         return node;
     }
@@ -2974,7 +2980,10 @@ namespace ts {
                     (texts || (texts = [])).push(prependNode);
                     break;
                 case BundleFileSectionKind.Internal:
-                    if (stripInternal) break;
+                    if (stripInternal) {
+                        if (!texts) texts = [];
+                        break;
+                    }
                     // falls through
 
                 case BundleFileSectionKind.Text:
@@ -4730,7 +4739,7 @@ namespace ts {
         const conditionalPrecedence = getOperatorPrecedence(SyntaxKind.ConditionalExpression, SyntaxKind.QuestionToken);
         const emittedCondition = skipPartiallyEmittedExpressions(condition);
         const conditionPrecedence = getExpressionPrecedence(emittedCondition);
-        if (compareValues(conditionPrecedence, conditionalPrecedence) === Comparison.LessThan) {
+        if (compareValues(conditionPrecedence, conditionalPrecedence) !== Comparison.GreaterThan) {
             return createParen(condition);
         }
         return condition;

src/compiler/moduleSpecifiers.ts

@@ -317,9 +317,13 @@ namespace ts.moduleSpecifiers {
 
         // If the module could be imported by a directory name, use that directory's name
         const moduleSpecifier = packageNameOnly ? moduleFileName : getDirectoryOrExtensionlessFileName(moduleFileName);
+        const globalTypingsCacheLocation = host.getGlobalTypingsCacheLocation && host.getGlobalTypingsCacheLocation();
         // Get a path that's relative to node_modules or the importing file's path
         // if node_modules folder is in this folder or any of its parent folders, no need to keep it.
-        if (!startsWith(sourceDirectory, getCanonicalFileName(moduleSpecifier.substring(0, parts.topLevelNodeModulesIndex)))) return undefined;
+        const pathToTopLevelNodeModules = getCanonicalFileName(moduleSpecifier.substring(0, parts.topLevelNodeModulesIndex));
+        if (!(startsWith(sourceDirectory, pathToTopLevelNodeModules) || globalTypingsCacheLocation && startsWith(getCanonicalFileName(globalTypingsCacheLocation), pathToTopLevelNodeModules))) {
+            return undefined;
+        }
 
         // If the module was found in @types, get the actual Node package name
         const nodeModulesDirectoryName = moduleSpecifier.substring(parts.topLevelPackageNameIndex + 1);

src/compiler/parser.ts

@@ -1401,7 +1401,14 @@ namespace ts {
             // Only for end of file because the error gets reported incorrectly on embedded script tags.
             const reportAtCurrentPosition = token() === SyntaxKind.EndOfFileToken;
 
-            return createMissingNode<Identifier>(SyntaxKind.Identifier, reportAtCurrentPosition, diagnosticMessage || Diagnostics.Identifier_expected);
+            const isReservedWord = scanner.isReservedWord();
+            const msgArg = scanner.getTokenText();
+
+            const defaultMessage = isReservedWord ?
+                Diagnostics.Identifier_expected_0_is_a_reserved_word_that_cannot_be_used_here :
+                Diagnostics.Identifier_expected;
+
+            return createMissingNode<Identifier>(SyntaxKind.Identifier, reportAtCurrentPosition, diagnosticMessage || defaultMessage, msgArg);
         }
 
         function parseIdentifier(diagnosticMessage?: DiagnosticMessage): Identifier {

src/compiler/path.ts

@@ -0,0 +1,855 @@
+/* @internal */
+namespace ts {
+    /**
+     * Internally, we represent paths as strings with '/' as the directory separator.
+     * When we make system calls (eg: LanguageServiceHost.getDirectory()),
+     * we expect the host to correctly handle paths in our specified format.
+     */
+    export const directorySeparator = "/";
+    const altDirectorySeparator = "\\";
+    const urlSchemeSeparator = "://";
+    const backslashRegExp = /\\/g;
+
+    //// Path Tests
+
+    /**
+     * Determines whether a charCode corresponds to `/` or `\`.
+     */
+    export function isAnyDirectorySeparator(charCode: number): boolean {
+        return charCode === CharacterCodes.slash || charCode === CharacterCodes.backslash;
+    }
+
+    /**
+     * Determines whether a path starts with a URL scheme (e.g. starts with `http://`, `ftp://`, `file://`, etc.).
+     */
+    export function isUrl(path: string) {
+        return getEncodedRootLength(path) < 0;
+    }
+
+    /**
+     * Determines whether a path is an absolute disk path (e.g. starts with `/`, or a dos path
+     * like `c:`, `c:\` or `c:/`).
+     */
+    export function isRootedDiskPath(path: string) {
+        return getEncodedRootLength(path) > 0;
+    }
+
+    /**
+     * Determines whether a path consists only of a path root.
+     */
+    export function isDiskPathRoot(path: string) {
+        const rootLength = getEncodedRootLength(path);
+        return rootLength > 0 && rootLength === path.length;
+    }
+
+    /**
+     * Determines whether a path starts with an absolute path component (i.e. `/`, `c:/`, `file://`, etc.).
+     *
+     * ```ts
+     * // POSIX
+     * pathIsAbsolute("/path/to/file.ext") === true
+     * // DOS
+     * pathIsAbsolute("c:/path/to/file.ext") === true
+     * // URL
+     * pathIsAbsolute("file:///path/to/file.ext") === true
+     * // Non-absolute
+     * pathIsAbsolute("path/to/file.ext") === false
+     * pathIsAbsolute("./path/to/file.ext") === false
+     * ```
+     */
+    export function pathIsAbsolute(path: string): boolean {
+        return getEncodedRootLength(path) !== 0;
+    }
+
+    /**
+     * Determines whether a path starts with a relative path component (i.e. `.` or `..`).
+     */
+    export function pathIsRelative(path: string): boolean {
+        return /^\.\.?($|[\\/])/.test(path);
+    }
+
+    export function hasExtension(fileName: string): boolean {
+        return stringContains(getBaseFileName(fileName), ".");
+    }
+
+    export function fileExtensionIs(path: string, extension: string): boolean {
+        return path.length > extension.length && endsWith(path, extension);
+    }
+
+    export function fileExtensionIsOneOf(path: string, extensions: readonly string[]): boolean {
+        for (const extension of extensions) {
+            if (fileExtensionIs(path, extension)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Determines whether a path has a trailing separator (`/` or `\\`).
+     */
+    export function hasTrailingDirectorySeparator(path: string) {
+        return path.length > 0 && isAnyDirectorySeparator(path.charCodeAt(path.length - 1));
+    }
+
+    //// Path Parsing
+
+    function isVolumeCharacter(charCode: number) {
+        return (charCode >= CharacterCodes.a && charCode <= CharacterCodes.z) ||
+            (charCode >= CharacterCodes.A && charCode <= CharacterCodes.Z);
+    }
+
+    function getFileUrlVolumeSeparatorEnd(url: string, start: number) {
+        const ch0 = url.charCodeAt(start);
+        if (ch0 === CharacterCodes.colon) return start + 1;
+        if (ch0 === CharacterCodes.percent && url.charCodeAt(start + 1) === CharacterCodes._3) {
+            const ch2 = url.charCodeAt(start + 2);
+            if (ch2 === CharacterCodes.a || ch2 === CharacterCodes.A) return start + 3;
+        }
+        return -1;
+    }
+
+    /**
+     * Returns length of the root part of a path or URL (i.e. length of "/", "x:/", "//server/share/, file:///user/files").
+     * If the root is part of a URL, the twos-complement of the root length is returned.
+     */
+    function getEncodedRootLength(path: string): number {
+        if (!path) return 0;
+        const ch0 = path.charCodeAt(0);
+
+        // POSIX or UNC
+        if (ch0 === CharacterCodes.slash || ch0 === CharacterCodes.backslash) {
+            if (path.charCodeAt(1) !== ch0) return 1; // POSIX: "/" (or non-normalized "\")
+
+            const p1 = path.indexOf(ch0 === CharacterCodes.slash ? directorySeparator : altDirectorySeparator, 2);
+            if (p1 < 0) return path.length; // UNC: "//server" or "\\server"
+
+            return p1 + 1; // UNC: "//server/" or "\\server\"
+        }
+
+        // DOS
+        if (isVolumeCharacter(ch0) && path.charCodeAt(1) === CharacterCodes.colon) {
+            const ch2 = path.charCodeAt(2);
+            if (ch2 === CharacterCodes.slash || ch2 === CharacterCodes.backslash) return 3; // DOS: "c:/" or "c:\"
+            if (path.length === 2) return 2; // DOS: "c:" (but not "c:d")
+        }
+
+        // URL
+        const schemeEnd = path.indexOf(urlSchemeSeparator);
+        if (schemeEnd !== -1) {
+            const authorityStart = schemeEnd + urlSchemeSeparator.length;
+            const authorityEnd = path.indexOf(directorySeparator, authorityStart);
+            if (authorityEnd !== -1) { // URL: "file:///", "file://server/", "file://server/path"
+                // For local "file" URLs, include the leading DOS volume (if present).
+                // Per https://www.ietf.org/rfc/rfc1738.txt, a host of "" or "localhost" is a
+                // special case interpreted as "the machine from which the URL is being interpreted".
+                const scheme = path.slice(0, schemeEnd);
+                const authority = path.slice(authorityStart, authorityEnd);
+                if (scheme === "file" && (authority === "" || authority === "localhost") &&
+                    isVolumeCharacter(path.charCodeAt(authorityEnd + 1))) {
+                    const volumeSeparatorEnd = getFileUrlVolumeSeparatorEnd(path, authorityEnd + 2);
+                    if (volumeSeparatorEnd !== -1) {
+                        if (path.charCodeAt(volumeSeparatorEnd) === CharacterCodes.slash) {
+                            // URL: "file:///c:/", "file://localhost/c:/", "file:///c%3a/", "file://localhost/c%3a/"
+                            return ~(volumeSeparatorEnd + 1);
+                        }
+                        if (volumeSeparatorEnd === path.length) {
+                            // URL: "file:///c:", "file://localhost/c:", "file:///c$3a", "file://localhost/c%3a"
+                            // but not "file:///c:d" or "file:///c%3ad"
+                            return ~volumeSeparatorEnd;
+                        }
+                    }
+                }
+                return ~(authorityEnd + 1); // URL: "file://server/", "http://server/"
+            }
+            return ~path.length; // URL: "file://server", "http://server"
+        }
+
+        // relative
+        return 0;
+    }
+
+    /**
+     * Returns length of the root part of a path or URL (i.e. length of "/", "x:/", "//server/share/, file:///user/files").
+     *
+     * For example:
+     * ```ts
+     * getRootLength("a") === 0                   // ""
+     * getRootLength("/") === 1                   // "/"
+     * getRootLength("c:") === 2                  // "c:"
+     * getRootLength("c:d") === 0                 // ""
+     * getRootLength("c:/") === 3                 // "c:/"
+     * getRootLength("c:\\") === 3                // "c:\\"
+     * getRootLength("//server") === 7            // "//server"
+     * getRootLength("//server/share") === 8      // "//server/"
+     * getRootLength("\\\\server") === 7          // "\\\\server"
+     * getRootLength("\\\\server\\share") === 8   // "\\\\server\\"
+     * getRootLength("file:///path") === 8        // "file:///"
+     * getRootLength("file:///c:") === 10         // "file:///c:"
+     * getRootLength("file:///c:d") === 8         // "file:///"
+     * getRootLength("file:///c:/path") === 11    // "file:///c:/"
+     * getRootLength("file://server") === 13      // "file://server"
+     * getRootLength("file://server/path") === 14 // "file://server/"
+     * getRootLength("http://server") === 13      // "http://server"
+     * getRootLength("http://server/path") === 14 // "http://server/"
+     * ```
+     */
+    export function getRootLength(path: string) {
+        const rootLength = getEncodedRootLength(path);
+        return rootLength < 0 ? ~rootLength : rootLength;
+    }
+
+    /**
+     * Returns the path except for its basename. Semantics align with NodeJS's `path.dirname`
+     * except that we support URLs as well.
+     *
+     * ```ts
+     * // POSIX
+     * getDirectoryPath("/path/to/file.ext") === "/path/to"
+     * getDirectoryPath("/path/to/") === "/path"
+     * getDirectoryPath("/") === "/"
+     * // DOS
+     * getDirectoryPath("c:/path/to/file.ext") === "c:/path/to"
+     * getDirectoryPath("c:/path/to/") === "c:/path"
+     * getDirectoryPath("c:/") === "c:/"
+     * getDirectoryPath("c:") === "c:"
+     * // URL
+     * getDirectoryPath("http://typescriptlang.org/path/to/file.ext") === "http://typescriptlang.org/path/to"
+     * getDirectoryPath("http://typescriptlang.org/path/to") === "http://typescriptlang.org/path"
+     * getDirectoryPath("http://typescriptlang.org/") === "http://typescriptlang.org/"
+     * getDirectoryPath("http://typescriptlang.org") === "http://typescriptlang.org"
+     * ```
+     */
+    export function getDirectoryPath(path: Path): Path;
+    /**
+     * Returns the path except for its basename. Semantics align with NodeJS's `path.dirname`
+     * except that we support URLs as well.
+     *
+     * ```ts
+     * // POSIX
+     * getDirectoryPath("/path/to/file.ext") === "/path/to"
+     * getDirectoryPath("/path/to/") === "/path"
+     * getDirectoryPath("/") === "/"
+     * // DOS
+     * getDirectoryPath("c:/path/to/file.ext") === "c:/path/to"
+     * getDirectoryPath("c:/path/to/") === "c:/path"
+     * getDirectoryPath("c:/") === "c:/"
+     * getDirectoryPath("c:") === "c:"
+     * // URL
+     * getDirectoryPath("http://typescriptlang.org/path/to/file.ext") === "http://typescriptlang.org/path/to"
+     * getDirectoryPath("http://typescriptlang.org/path/to") === "http://typescriptlang.org/path"
+     * getDirectoryPath("http://typescriptlang.org/") === "http://typescriptlang.org/"
+     * getDirectoryPath("http://typescriptlang.org") === "http://typescriptlang.org"
+     * getDirectoryPath("file://server/path/to/file.ext") === "file://server/path/to"
+     * getDirectoryPath("file://server/path/to") === "file://server/path"
+     * getDirectoryPath("file://server/") === "file://server/"
+     * getDirectoryPath("file://server") === "file://server"
+     * getDirectoryPath("file:///path/to/file.ext") === "file:///path/to"
+     * getDirectoryPath("file:///path/to") === "file:///path"
+     * getDirectoryPath("file:///") === "file:///"
+     * getDirectoryPath("file://") === "file://"
+     * ```
+     */
+    export function getDirectoryPath(path: string): string;
+    export function getDirectoryPath(path: string): string {
+        path = normalizeSlashes(path);
+
+        // If the path provided is itself the root, then return it.
+        const rootLength = getRootLength(path);
+        if (rootLength === path.length) return path;
+
+        // return the leading portion of the path up to the last (non-terminal) directory separator
+        // but not including any trailing directory separator.
+        path = removeTrailingDirectorySeparator(path);
+        return path.slice(0, Math.max(rootLength, path.lastIndexOf(directorySeparator)));
+    }
+
+    /**
+     * Returns the path except for its containing directory name.
+     * Semantics align with NodeJS's `path.basename` except that we support URL's as well.
+     *
+     * ```ts
+     * // POSIX
+     * getBaseFileName("/path/to/file.ext") === "file.ext"
+     * getBaseFileName("/path/to/") === "to"
+     * getBaseFileName("/") === ""
+     * // DOS
+     * getBaseFileName("c:/path/to/file.ext") === "file.ext"
+     * getBaseFileName("c:/path/to/") === "to"
+     * getBaseFileName("c:/") === ""
+     * getBaseFileName("c:") === ""
+     * // URL
+     * getBaseFileName("http://typescriptlang.org/path/to/file.ext") === "file.ext"
+     * getBaseFileName("http://typescriptlang.org/path/to/") === "to"
+     * getBaseFileName("http://typescriptlang.org/") === ""
+     * getBaseFileName("http://typescriptlang.org") === ""
+     * getBaseFileName("file://server/path/to/file.ext") === "file.ext"
+     * getBaseFileName("file://server/path/to/") === "to"
+     * getBaseFileName("file://server/") === ""
+     * getBaseFileName("file://server") === ""
+     * getBaseFileName("file:///path/to/file.ext") === "file.ext"
+     * getBaseFileName("file:///path/to/") === "to"
+     * getBaseFileName("file:///") === ""
+     * getBaseFileName("file://") === ""
+     * ```
+     */
+    export function getBaseFileName(path: string): string;
+    /**
+     * Gets the portion of a path following the last (non-terminal) separator (`/`).
+     * Semantics align with NodeJS's `path.basename` except that we support URL's as well.
+     * If the base name has any one of the provided extensions, it is removed.
+     *
+     * ```ts
+     * getBaseFileName("/path/to/file.ext", ".ext", true) === "file"
+     * getBaseFileName("/path/to/file.js", ".ext", true) === "file.js"
+     * getBaseFileName("/path/to/file.js", [".ext", ".js"], true) === "file"
+     * getBaseFileName("/path/to/file.ext", ".EXT", false) === "file.ext"
+     * ```
+     */
+    export function getBaseFileName(path: string, extensions: string | readonly string[], ignoreCase: boolean): string;
+    export function getBaseFileName(path: string, extensions?: string | readonly string[], ignoreCase?: boolean) {
+        path = normalizeSlashes(path);
+
+        // if the path provided is itself the root, then it has not file name.
+        const rootLength = getRootLength(path);
+        if (rootLength === path.length) return "";
+
+        // return the trailing portion of the path starting after the last (non-terminal) directory
+        // separator but not including any trailing directory separator.
+        path = removeTrailingDirectorySeparator(path);
+        const name = path.slice(Math.max(getRootLength(path), path.lastIndexOf(directorySeparator) + 1));
+        const extension = extensions !== undefined && ignoreCase !== undefined ? getAnyExtensionFromPath(name, extensions, ignoreCase) : undefined;
+        return extension ? name.slice(0, name.length - extension.length) : name;
+    }
+
+    function tryGetExtensionFromPath(path: string, extension: string, stringEqualityComparer: (a: string, b: string) => boolean) {
+        if (!startsWith(extension, ".")) extension = "." + extension;
+        if (path.length >= extension.length && path.charCodeAt(path.length - extension.length) === CharacterCodes.dot) {
+            const pathExtension = path.slice(path.length - extension.length);
+            if (stringEqualityComparer(pathExtension, extension)) {
+                return pathExtension;
+            }
+        }
+    }
+
+    function getAnyExtensionFromPathWorker(path: string, extensions: string | readonly string[], stringEqualityComparer: (a: string, b: string) => boolean) {
+        if (typeof extensions === "string") {
+            return tryGetExtensionFromPath(path, extensions, stringEqualityComparer) || "";
+        }
+        for (const extension of extensions) {
+            const result = tryGetExtensionFromPath(path, extension, stringEqualityComparer);
+            if (result) return result;
+        }
+        return "";
+    }
+
+    /**
+     * Gets the file extension for a path.
+     *
+     * ```ts
+     * getAnyExtensionFromPath("/path/to/file.ext") === ".ext"
+     * getAnyExtensionFromPath("/path/to/file.ext/") === ".ext"
+     * getAnyExtensionFromPath("/path/to/file") === ""
+     * getAnyExtensionFromPath("/path/to.ext/file") === ""
+     * ```
+     */
+    export function getAnyExtensionFromPath(path: string): string;
+    /**
+     * Gets the file extension for a path, provided it is one of the provided extensions.
+     *
+     * ```ts
+     * getAnyExtensionFromPath("/path/to/file.ext", ".ext", true) === ".ext"
+     * getAnyExtensionFromPath("/path/to/file.js", ".ext", true) === ""
+     * getAnyExtensionFromPath("/path/to/file.js", [".ext", ".js"], true) === ".js"
+     * getAnyExtensionFromPath("/path/to/file.ext", ".EXT", false) === ""
+     */
+    export function getAnyExtensionFromPath(path: string, extensions: string | readonly string[], ignoreCase: boolean): string;
+    export function getAnyExtensionFromPath(path: string, extensions?: string | readonly string[], ignoreCase?: boolean): string {
+        // Retrieves any string from the final "." onwards from a base file name.
+        // Unlike extensionFromPath, which throws an exception on unrecognized extensions.
+        if (extensions) {
+            return getAnyExtensionFromPathWorker(removeTrailingDirectorySeparator(path), extensions, ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive);
+        }
+        const baseFileName = getBaseFileName(path);
+        const extensionIndex = baseFileName.lastIndexOf(".");
+        if (extensionIndex >= 0) {
+            return baseFileName.substring(extensionIndex);
+        }
+        return "";
+    }
+
+    function pathComponents(path: string, rootLength: number) {
+        const root = path.substring(0, rootLength);
+        const rest = path.substring(rootLength).split(directorySeparator);
+        if (rest.length && !lastOrUndefined(rest)) rest.pop();
+        return [root, ...rest];
+    }
+
+    /**
+     * Parse a path into an array containing a root component (at index 0) and zero or more path
+     * components (at indices > 0). The result is not normalized.
+     * If the path is relative, the root component is `""`.
+     * If the path is absolute, the root component includes the first path separator (`/`).
+     *
+     * ```ts
+     * // POSIX
+     * getPathComponents("/path/to/file.ext") === ["/", "path", "to", "file.ext"]
+     * getPathComponents("/path/to/") === ["/", "path", "to"]
+     * getPathComponents("/") === ["/"]
+     * // DOS
+     * getPathComponents("c:/path/to/file.ext") === ["c:/", "path", "to", "file.ext"]
+     * getPathComponents("c:/path/to/") === ["c:/", "path", "to"]
+     * getPathComponents("c:/") === ["c:/"]
+     * getPathComponents("c:") === ["c:"]
+     * // URL
+     * getPathComponents("http://typescriptlang.org/path/to/file.ext") === ["http://typescriptlang.org/", "path", "to", "file.ext"]
+     * getPathComponents("http://typescriptlang.org/path/to/") === ["http://typescriptlang.org/", "path", "to"]
+     * getPathComponents("http://typescriptlang.org/") === ["http://typescriptlang.org/"]
+     * getPathComponents("http://typescriptlang.org") === ["http://typescriptlang.org"]
+     * getPathComponents("file://server/path/to/file.ext") === ["file://server/", "path", "to", "file.ext"]
+     * getPathComponents("file://server/path/to/") === ["file://server/", "path", "to"]
+     * getPathComponents("file://server/") === ["file://server/"]
+     * getPathComponents("file://server") === ["file://server"]
+     * getPathComponents("file:///path/to/file.ext") === ["file:///", "path", "to", "file.ext"]
+     * getPathComponents("file:///path/to/") === ["file:///", "path", "to"]
+     * getPathComponents("file:///") === ["file:///"]
+     * getPathComponents("file://") === ["file://"]
+     */
+    export function getPathComponents(path: string, currentDirectory = "") {
+        path = combinePaths(currentDirectory, path);
+        return pathComponents(path, getRootLength(path));
+    }
+
+    //// Path Formatting
+
+    /**
+     * Formats a parsed path consisting of a root component (at index 0) and zero or more path
+     * segments (at indices > 0).
+     *
+     * ```ts
+     * getPathFromPathComponents(["/", "path", "to", "file.ext"]) === "/path/to/file.ext"
+     * ```
+     */
+    export function getPathFromPathComponents(pathComponents: readonly string[]) {
+        if (pathComponents.length === 0) return "";
+
+        const root = pathComponents[0] && ensureTrailingDirectorySeparator(pathComponents[0]);
+        return root + pathComponents.slice(1).join(directorySeparator);
+    }
+
+    //// Path Normalization
+
+    /**
+     * Normalize path separators, converting `\` into `/`.
+     */
+    export function normalizeSlashes(path: string): string {
+        return path.replace(backslashRegExp, directorySeparator);
+    }
+
+    /**
+     * Reduce an array of path components to a more simplified path by navigating any
+     * `"."` or `".."` entries in the path.
+     */
+    export function reducePathComponents(components: readonly string[]) {
+        if (!some(components)) return [];
+        const reduced = [components[0]];
+        for (let i = 1; i < components.length; i++) {
+            const component = components[i];
+            if (!component) continue;
+            if (component === ".") continue;
+            if (component === "..") {
+                if (reduced.length > 1) {
+                    if (reduced[reduced.length - 1] !== "..") {
+                        reduced.pop();
+                        continue;
+                    }
+                }
+                else if (reduced[0]) continue;
+            }
+            reduced.push(component);
+        }
+        return reduced;
+    }
+
+    /**
+     * Combines paths. If a path is absolute, it replaces any previous path. Relative paths are not simplified.
+     *
+     * ```ts
+     * // Non-rooted
+     * combinePaths("path", "to", "file.ext") === "path/to/file.ext"
+     * combinePaths("path", "dir", "..", "to", "file.ext") === "path/dir/../to/file.ext"
+     * // POSIX
+     * combinePaths("/path", "to", "file.ext") === "/path/to/file.ext"
+     * combinePaths("/path", "/to", "file.ext") === "/to/file.ext"
+     * // DOS
+     * combinePaths("c:/path", "to", "file.ext") === "c:/path/to/file.ext"
+     * combinePaths("c:/path", "c:/to", "file.ext") === "c:/to/file.ext"
+     * // URL
+     * combinePaths("file:///path", "to", "file.ext") === "file:///path/to/file.ext"
+     * combinePaths("file:///path", "file:///to", "file.ext") === "file:///to/file.ext"
+     * ```
+     */
+    export function combinePaths(path: string, ...paths: (string | undefined)[]): string {
+        if (path) path = normalizeSlashes(path);
+        for (let relativePath of paths) {
+            if (!relativePath) continue;
+            relativePath = normalizeSlashes(relativePath);
+            if (!path || getRootLength(relativePath) !== 0) {
+                path = relativePath;
+            }
+            else {
+                path = ensureTrailingDirectorySeparator(path) + relativePath;
+            }
+        }
+        return path;
+    }
+
+    /**
+     * Combines and resolves paths. If a path is absolute, it replaces any previous path. Any
+     * `.` and `..` path components are resolved. Trailing directory separators are preserved.
+     *
+     * ```ts
+     * resolvePath("/path", "to", "file.ext") === "path/to/file.ext"
+     * resolvePath("/path", "to", "file.ext/") === "path/to/file.ext/"
+     * resolvePath("/path", "dir", "..", "to", "file.ext") === "path/to/file.ext"
+     * ```
+     */
+    export function resolvePath(path: string, ...paths: (string | undefined)[]): string {
+        return normalizePath(some(paths) ? combinePaths(path, ...paths) : normalizeSlashes(path));
+    }
+
+    /**
+     * Parse a path into an array containing a root component (at index 0) and zero or more path
+     * components (at indices > 0). The result is normalized.
+     * If the path is relative, the root component is `""`.
+     * If the path is absolute, the root component includes the first path separator (`/`).
+     *
+     * ```ts
+     * getNormalizedPathComponents("to/dir/../file.ext", "/path/") === ["/", "path", "to", "file.ext"]
+     */
+    export function getNormalizedPathComponents(path: string, currentDirectory: string | undefined) {
+        return reducePathComponents(getPathComponents(path, currentDirectory));
+    }
+
+    export function getNormalizedAbsolutePath(fileName: string, currentDirectory: string | undefined) {
+        return getPathFromPathComponents(getNormalizedPathComponents(fileName, currentDirectory));
+    }
+
+    export function normalizePath(path: string): string {
+        path = normalizeSlashes(path);
+        const normalized = getPathFromPathComponents(reducePathComponents(getPathComponents(path)));
+        return normalized && hasTrailingDirectorySeparator(path) ? ensureTrailingDirectorySeparator(normalized) : normalized;
+    }
+
+    function getPathWithoutRoot(pathComponents: readonly string[]) {
+        if (pathComponents.length === 0) return "";
+        return pathComponents.slice(1).join(directorySeparator);
+    }
+
+    export function getNormalizedAbsolutePathWithoutRoot(fileName: string, currentDirectory: string | undefined) {
+        return getPathWithoutRoot(getNormalizedPathComponents(fileName, currentDirectory));
+    }
+
+    export function toPath(fileName: string, basePath: string | undefined, getCanonicalFileName: (path: string) => string): Path {
+        const nonCanonicalizedPath = isRootedDiskPath(fileName)
+            ? normalizePath(fileName)
+            : getNormalizedAbsolutePath(fileName, basePath);
+        return <Path>getCanonicalFileName(nonCanonicalizedPath);
+    }
+
+    export function normalizePathAndParts(path: string): { path: string, parts: string[] } {
+        path = normalizeSlashes(path);
+        const [root, ...parts] = reducePathComponents(getPathComponents(path));
+        if (parts.length) {
+            const joinedParts = root + parts.join(directorySeparator);
+            return { path: hasTrailingDirectorySeparator(path) ? ensureTrailingDirectorySeparator(joinedParts) : joinedParts, parts };
+        }
+        else {
+            return { path: root, parts };
+        }
+    }
+
+    //// Path Mutation
+
+    /**
+     * Removes a trailing directory separator from a path, if it does not already have one.
+     *
+     * ```ts
+     * removeTrailingDirectorySeparator("/path/to/file.ext") === "/path/to/file.ext"
+     * removeTrailingDirectorySeparator("/path/to/file.ext/") === "/path/to/file.ext"
+     * ```
+     */
+    export function removeTrailingDirectorySeparator(path: Path): Path;
+    export function removeTrailingDirectorySeparator(path: string): string;
+    export function removeTrailingDirectorySeparator(path: string) {
+        if (hasTrailingDirectorySeparator(path)) {
+            return path.substr(0, path.length - 1);
+        }
+
+        return path;
+    }
+
+    /**
+     * Adds a trailing directory separator to a path, if it does not already have one.
+     *
+     * ```ts
+     * ensureTrailingDirectorySeparator("/path/to/file.ext") === "/path/to/file.ext/"
+     * ensureTrailingDirectorySeparator("/path/to/file.ext/") === "/path/to/file.ext/"
+     * ```
+     */
+    export function ensureTrailingDirectorySeparator(path: Path): Path;
+    export function ensureTrailingDirectorySeparator(path: string): string;
+    export function ensureTrailingDirectorySeparator(path: string) {
+        if (!hasTrailingDirectorySeparator(path)) {
+            return path + directorySeparator;
+        }
+
+        return path;
+    }
+
+    /**
+     * Ensures a path is either absolute (prefixed with `/` or `c:`) or dot-relative (prefixed
+     * with `./` or `../`) so as not to be confused with an unprefixed module name.
+     *
+     * ```ts
+     * ensurePathIsNonModuleName("/path/to/file.ext") === "/path/to/file.ext"
+     * ensurePathIsNonModuleName("./path/to/file.ext") === "./path/to/file.ext"
+     * ensurePathIsNonModuleName("../path/to/file.ext") === "../path/to/file.ext"
+     * ensurePathIsNonModuleName("path/to/file.ext") === "./path/to/file.ext"
+     * ```
+     */
+    export function ensurePathIsNonModuleName(path: string): string {
+        return !pathIsAbsolute(path) && !pathIsRelative(path) ? "./" + path : path;
+    }
+
+    /**
+     * Changes the extension of a path to the provided extension.
+     *
+     * ```ts
+     * changeAnyExtension("/path/to/file.ext", ".js") === "/path/to/file.js"
+     * ```
+     */
+    export function changeAnyExtension(path: string, ext: string): string;
+    /**
+     * Changes the extension of a path to the provided extension if it has one of the provided extensions.
+     *
+     * ```ts
+     * changeAnyExtension("/path/to/file.ext", ".js", ".ext") === "/path/to/file.js"
+     * changeAnyExtension("/path/to/file.ext", ".js", ".ts") === "/path/to/file.ext"
+     * changeAnyExtension("/path/to/file.ext", ".js", [".ext", ".ts"]) === "/path/to/file.js"
+     * ```
+     */
+    export function changeAnyExtension(path: string, ext: string, extensions: string | readonly string[], ignoreCase: boolean): string;
+    export function changeAnyExtension(path: string, ext: string, extensions?: string | readonly string[], ignoreCase?: boolean) {
+        const pathext = extensions !== undefined && ignoreCase !== undefined ? getAnyExtensionFromPath(path, extensions, ignoreCase) : getAnyExtensionFromPath(path);
+        return pathext ? path.slice(0, path.length - pathext.length) + (startsWith(ext, ".") ? ext : "." + ext) : path;
+    }
+
+    //// Path Comparisons
+
+    // check path for these segments: '', '.'. '..'
+    const relativePathSegmentRegExp = /(^|\/)\.{0,2}($|\/)/;
+
+    function comparePathsWorker(a: string, b: string, componentComparer: (a: string, b: string) => Comparison) {
+        if (a === b) return Comparison.EqualTo;
+        if (a === undefined) return Comparison.LessThan;
+        if (b === undefined) return Comparison.GreaterThan;
+
+        // NOTE: Performance optimization - shortcut if the root segments differ as there would be no
+        //       need to perform path reduction.
+        const aRoot = a.substring(0, getRootLength(a));
+        const bRoot = b.substring(0, getRootLength(b));
+        const result = compareStringsCaseInsensitive(aRoot, bRoot);
+        if (result !== Comparison.EqualTo) {
+            return result;
+        }
+
+        // NOTE: Performance optimization - shortcut if there are no relative path segments in
+        //       the non-root portion of the path
+        const aRest = a.substring(aRoot.length);
+        const bRest = b.substring(bRoot.length);
+        if (!relativePathSegmentRegExp.test(aRest) && !relativePathSegmentRegExp.test(bRest)) {
+            return componentComparer(aRest, bRest);
+        }
+
+        // The path contains a relative path segment. Normalize the paths and perform a slower component
+        // by component comparison.
+        const aComponents = reducePathComponents(getPathComponents(a));
+        const bComponents = reducePathComponents(getPathComponents(b));
+        const sharedLength = Math.min(aComponents.length, bComponents.length);
+        for (let i = 1; i < sharedLength; i++) {
+            const result = componentComparer(aComponents[i], bComponents[i]);
+            if (result !== Comparison.EqualTo) {
+                return result;
+            }
+        }
+        return compareValues(aComponents.length, bComponents.length);
+    }
+
+    /**
+     * Performs a case-sensitive comparison of two paths. Path roots are always compared case-insensitively.
+     */
+    export function comparePathsCaseSensitive(a: string, b: string) {
+        return comparePathsWorker(a, b, compareStringsCaseSensitive);
+    }
+
+    /**
+     * Performs a case-insensitive comparison of two paths.
+     */
+    export function comparePathsCaseInsensitive(a: string, b: string) {
+        return comparePathsWorker(a, b, compareStringsCaseInsensitive);
+    }
+
+    /**
+     * Compare two paths using the provided case sensitivity.
+     */
+    export function comparePaths(a: string, b: string, ignoreCase?: boolean): Comparison;
+    export function comparePaths(a: string, b: string, currentDirectory: string, ignoreCase?: boolean): Comparison;
+    export function comparePaths(a: string, b: string, currentDirectory?: string | boolean, ignoreCase?: boolean) {
+        if (typeof currentDirectory === "string") {
+            a = combinePaths(currentDirectory, a);
+            b = combinePaths(currentDirectory, b);
+        }
+        else if (typeof currentDirectory === "boolean") {
+            ignoreCase = currentDirectory;
+        }
+        return comparePathsWorker(a, b, getStringComparer(ignoreCase));
+    }
+
+    /**
+     * Determines whether a `parent` path contains a `child` path using the provide case sensitivity.
+     */
+    export function containsPath(parent: string, child: string, ignoreCase?: boolean): boolean;
+    export function containsPath(parent: string, child: string, currentDirectory: string, ignoreCase?: boolean): boolean;
+    export function containsPath(parent: string, child: string, currentDirectory?: string | boolean, ignoreCase?: boolean) {
+        if (typeof currentDirectory === "string") {
+            parent = combinePaths(currentDirectory, parent);
+            child = combinePaths(currentDirectory, child);
+        }
+        else if (typeof currentDirectory === "boolean") {
+            ignoreCase = currentDirectory;
+        }
+        if (parent === undefined || child === undefined) return false;
+        if (parent === child) return true;
+        const parentComponents = reducePathComponents(getPathComponents(parent));
+        const childComponents = reducePathComponents(getPathComponents(child));
+        if (childComponents.length < parentComponents.length) {
+            return false;
+        }
+
+        const componentEqualityComparer = ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive;
+        for (let i = 0; i < parentComponents.length; i++) {
+            const equalityComparer = i === 0 ? equateStringsCaseInsensitive : componentEqualityComparer;
+            if (!equalityComparer(parentComponents[i], childComponents[i])) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Determines whether `fileName` starts with the specified `directoryName` using the provided path canonicalization callback.
+     * Comparison is case-sensitive between the canonical paths.
+     *
+     * @deprecated Use `containsPath` if possible.
+     */
+    export function startsWithDirectory(fileName: string, directoryName: string, getCanonicalFileName: GetCanonicalFileName): boolean {
+        const canonicalFileName = getCanonicalFileName(fileName);
+        const canonicalDirectoryName = getCanonicalFileName(directoryName);
+        return startsWith(canonicalFileName, canonicalDirectoryName + "/") || startsWith(canonicalFileName, canonicalDirectoryName + "\\");
+    }
+
+    //// Relative Paths
+
+    export function getPathComponentsRelativeTo(from: string, to: string, stringEqualityComparer: (a: string, b: string) => boolean, getCanonicalFileName: GetCanonicalFileName) {
+        const fromComponents = reducePathComponents(getPathComponents(from));
+        const toComponents = reducePathComponents(getPathComponents(to));
+
+        let start: number;
+        for (start = 0; start < fromComponents.length && start < toComponents.length; start++) {
+            const fromComponent = getCanonicalFileName(fromComponents[start]);
+            const toComponent = getCanonicalFileName(toComponents[start]);
+            const comparer = start === 0 ? equateStringsCaseInsensitive : stringEqualityComparer;
+            if (!comparer(fromComponent, toComponent)) break;
+        }
+
+        if (start === 0) {
+            return toComponents;
+        }
+
+        const components = toComponents.slice(start);
+        const relative: string[] = [];
+        for (; start < fromComponents.length; start++) {
+            relative.push("..");
+        }
+        return ["", ...relative, ...components];
+    }
+
+    /**
+     * Gets a relative path that can be used to traverse between `from` and `to`.
+     */
+    export function getRelativePathFromDirectory(from: string, to: string, ignoreCase: boolean): string;
+    /**
+     * Gets a relative path that can be used to traverse between `from` and `to`.
+     */
+    export function getRelativePathFromDirectory(fromDirectory: string, to: string, getCanonicalFileName: GetCanonicalFileName): string; // eslint-disable-line @typescript-eslint/unified-signatures
+    export function getRelativePathFromDirectory(fromDirectory: string, to: string, getCanonicalFileNameOrIgnoreCase: GetCanonicalFileName | boolean) {
+        Debug.assert((getRootLength(fromDirectory) > 0) === (getRootLength(to) > 0), "Paths must either both be absolute or both be relative");
+        const getCanonicalFileName = typeof getCanonicalFileNameOrIgnoreCase === "function" ? getCanonicalFileNameOrIgnoreCase : identity;
+        const ignoreCase = typeof getCanonicalFileNameOrIgnoreCase === "boolean" ? getCanonicalFileNameOrIgnoreCase : false;
+        const pathComponents = getPathComponentsRelativeTo(fromDirectory, to, ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive, getCanonicalFileName);
+        return getPathFromPathComponents(pathComponents);
+    }
+
+    export function convertToRelativePath(absoluteOrRelativePath: string, basePath: string, getCanonicalFileName: (path: string) => string): string {
+        return !isRootedDiskPath(absoluteOrRelativePath)
+            ? absoluteOrRelativePath
+            : getRelativePathToDirectoryOrUrl(basePath, absoluteOrRelativePath, basePath, getCanonicalFileName, /*isAbsolutePathAnUrl*/ false);
+    }
+
+    export function getRelativePathFromFile(from: string, to: string, getCanonicalFileName: GetCanonicalFileName) {
+        return ensurePathIsNonModuleName(getRelativePathFromDirectory(getDirectoryPath(from), to, getCanonicalFileName));
+    }
+
+    export function getRelativePathToDirectoryOrUrl(directoryPathOrUrl: string, relativeOrAbsolutePath: string, currentDirectory: string, getCanonicalFileName: GetCanonicalFileName, isAbsolutePathAnUrl: boolean) {
+        const pathComponents = getPathComponentsRelativeTo(
+            resolvePath(currentDirectory, directoryPathOrUrl),
+            resolvePath(currentDirectory, relativeOrAbsolutePath),
+            equateStringsCaseSensitive,
+            getCanonicalFileName
+        );
+
+        const firstComponent = pathComponents[0];
+        if (isAbsolutePathAnUrl && isRootedDiskPath(firstComponent)) {
+            const prefix = firstComponent.charAt(0) === directorySeparator ? "file://" : "file:///";
+            pathComponents[0] = prefix + firstComponent;
+        }
+
+        return getPathFromPathComponents(pathComponents);
+    }
+
+    //// Path Traversal
+
+    /**
+     * Calls `callback` on `directory` and every ancestor directory it has, returning the first defined result.
+     */
+    export function forEachAncestorDirectory<T>(directory: Path, callback: (directory: Path) => T | undefined): T | undefined;
+    export function forEachAncestorDirectory<T>(directory: string, callback: (directory: string) => T | undefined): T | undefined;
+    export function forEachAncestorDirectory<T>(directory: Path, callback: (directory: Path) => T | undefined): T | undefined {
+        while (true) {
+            const result = callback(directory);
+            if (result !== undefined) {
+                return result;
+            }
+
+            const parentPath = getDirectoryPath(directory);
+            if (parentPath === directory) {
+                return undefined;
+            }
+
+            directory = parentPath;
+        }
+    }
+}

src/compiler/perfLogger.ts

@@ -38,6 +38,4 @@ namespace ts {
 
     /** Performance logger that will generate ETW events if possible - check for `logEvent` member, as `etwModule` will be `{}` when browserified */
     export const perfLogger: PerfLogger = etwModule && etwModule.logEvent ? etwModule : nullLogger;
-    const args = typeof process === "undefined" ? [] : process.argv;
-    perfLogger.logInfoEvent(`Starting TypeScript v${versionMajorMinor} with command line: ${JSON.stringify(args)}`);
 }

src/compiler/program.ts

@@ -545,6 +545,9 @@ namespace ts {
         return resolutions;
     }
 
+    /* @internal */
+    export const inferredTypesContainingFile = "__inferred type names__.ts";
+
     interface DiagnosticCache<T extends Diagnostic> {
         perFile?: Map<T[]>;
         allDiagnostics?: Diagnostic[];
@@ -875,7 +878,7 @@ namespace ts {
             if (typeReferences.length) {
                 // This containingFilename needs to match with the one used in managed-side
                 const containingDirectory = options.configFilePath ? getDirectoryPath(options.configFilePath) : host.getCurrentDirectory();
-                const containingFilename = combinePaths(containingDirectory, "__inferred type names__.ts");
+                const containingFilename = combinePaths(containingDirectory, inferredTypesContainingFile);
                 const resolutions = resolveTypeReferenceDirectiveNamesWorker(typeReferences, containingFilename);
                 for (let i = 0; i < typeReferences.length; i++) {
                     processTypeReferenceDirective(typeReferences[i], resolutions[i]);
@@ -2926,10 +2929,6 @@ namespace ts {
                 programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_incremental_can_only_be_specified_using_tsconfig_emitting_to_single_file_or_when_option_tsBuildInfoFile_is_specified));
             }
 
-            if (options.noEmit && isIncrementalCompilation(options)) {
-                createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_with_option_1, "noEmit", options.incremental ? "incremental" : "composite");
-            }
-
             verifyProjectReferences();
 
             // List of collected files is complete; validate exhautiveness if this is a project with a file list

src/compiler/resolutionCache.ts

@@ -669,6 +669,11 @@ namespace ts {
                         // Mark the file as needing re-evaluation of module resolution instead of using it blindly.
                         resolution.isInvalidated = true;
                         (filesWithInvalidatedResolutions || (filesWithInvalidatedResolutions = createMap<true>())).set(containingFilePath, true);
+
+                        // When its a file with inferred types resolution, invalidate type reference directive resolution
+                        if (containingFilePath.endsWith(inferredTypesContainingFile)) {
+                            resolutionHost.onChangedAutomaticTypeDirectiveNames();
+                        }
                     }
                 });
             });

src/compiler/sys.ts

@@ -682,6 +682,7 @@ namespace ts {
         /*@internal*/ bufferFrom?(input: string, encoding?: string): Buffer;
         // For testing
         /*@internal*/ now?(): Date;
+        /*@internal*/ require?(baseDir: string, moduleName: string): RequireResult;
     }
 
     export interface FileWatcher {
@@ -876,6 +877,15 @@ namespace ts {
                 bufferFrom,
                 base64decode: input => bufferFrom(input, "base64").toString("utf8"),
                 base64encode: input => bufferFrom(input).toString("base64"),
+                require: (baseDir, moduleName) => {
+                    try {
+                        const modulePath = resolveJSModule(moduleName, baseDir, nodeSystem);
+                        return { module: require(modulePath), modulePath, error: undefined };
+                    }
+                    catch (error) {
+                        return { module: undefined, modulePath: undefined, error };
+                    }
+                }
             };
             return nodeSystem;
 
@@ -1022,6 +1032,7 @@ namespace ts {
                     return watchDirectoryUsingFsWatch;
                 }
 
+                // defer watchDirectoryRecursively as it depends on `ts.createMap()` which may not be usable yet.
                 const watchDirectory = tscWatchDirectory === "RecursiveDirectoryUsingFsWatchFile" ?
                     createWatchDirectoryUsing(fsWatchFile) :
                     tscWatchDirectory === "RecursiveDirectoryUsingDynamicPriorityPolling" ?

src/compiler/transformers/classFields.ts

@@ -132,7 +132,7 @@ namespace ts {
             // Create a temporary variable to store a computed property name (if necessary).
             // If it's not inlineable, then we emit an expression after the class which assigns
             // the property name to the temporary variable.
-            const expr = getPropertyNameExpressionIfNeeded(node.name, !!node.initializer);
+            const expr = getPropertyNameExpressionIfNeeded(node.name, !!node.initializer || !!context.getCompilerOptions().useDefineForClassFields);
             if (expr && !isSimpleInlineableExpression(expr)) {
                 (pendingExpressions || (pendingExpressions = [])).push(expr);
             }
@@ -145,7 +145,7 @@ namespace ts {
             }
 
             const savedPendingExpressions = pendingExpressions;
-            pendingExpressions = undefined!;
+            pendingExpressions = undefined;
 
             const extendsClauseElement = getEffectiveBaseTypeNode(node);
             const isDerivedClass = !!(extendsClauseElement && skipOuterExpressions(extendsClauseElement.expression).kind !== SyntaxKind.NullKeyword);

src/compiler/transformers/declarations.ts

@@ -285,6 +285,7 @@ namespace ts {
             let combinedStatements: NodeArray<Statement>;
             if (isSourceFileJS(currentSourceFile)) {
                 combinedStatements = createNodeArray(transformDeclarationsForJS(node));
+                refs.forEach(referenceVisitor);
                 emittedImports = filter(combinedStatements, isAnyImportSyntax);
             }
             else {

src/compiler/tsbuild.ts

@@ -1788,31 +1788,25 @@ namespace ts {
 
         let reportQueue = true;
         let successfulProjects = 0;
-        let errorProjects = 0;
         while (true) {
             const invalidatedProject = getNextInvalidatedProject(state, buildOrder, reportQueue);
             if (!invalidatedProject) break;
             reportQueue = false;
             invalidatedProject.done(cancellationToken);
-            if (state.diagnostics.has(invalidatedProject.projectPath)) {
-                errorProjects++;
-            }
-            else {
-                successfulProjects++;
-            }
+            if (!state.diagnostics.has(invalidatedProject.projectPath)) successfulProjects++;
         }
 
         disableCache(state);
         reportErrorSummary(state, buildOrder);
         startWatching(state, buildOrder);
 
-        return isCircularBuildOrder(buildOrder) ?
-            ExitStatus.ProjectReferenceCycle_OutputsSkupped :
-            errorProjects ?
-                successfulProjects ?
-                    ExitStatus.DiagnosticsPresent_OutputsGenerated :
-                    ExitStatus.DiagnosticsPresent_OutputsSkipped :
-                ExitStatus.Success;
+        return isCircularBuildOrder(buildOrder)
+            ? ExitStatus.ProjectReferenceCycle_OutputsSkipped
+            : !buildOrder.some(p => state.diagnostics.has(toResolvedConfigFilePath(state, p)))
+                ? ExitStatus.Success
+                : successfulProjects
+                    ? ExitStatus.DiagnosticsPresent_OutputsGenerated
+                    : ExitStatus.DiagnosticsPresent_OutputsSkipped;
     }
 
     function clean(state: SolutionBuilderState, project?: string, onlyReferences?: boolean) {
@@ -1821,7 +1815,7 @@ namespace ts {
 
         if (isCircularBuildOrder(buildOrder)) {
             reportErrors(state, buildOrder.circularDiagnostics);
-            return ExitStatus.ProjectReferenceCycle_OutputsSkupped;
+            return ExitStatus.ProjectReferenceCycle_OutputsSkipped;
         }
 
         const { options, host } = state;

src/compiler/tsconfig.json

@@ -4,7 +4,9 @@
         "outFile": "../../built/local/compiler.js"
     },
 
-    "references": [],
+    "references": [
+        { "path": "../shims" },
+    ],
 
     "files": [
         "core.ts",
@@ -15,6 +17,7 @@
 
         "types.ts",
         "sys.ts",
+        "path.ts",
         "diagnosticInformationMap.generated.ts",
         "scanner.ts",
         "utilities.ts",

src/compiler/tsconfig.release.json

@@ -4,5 +4,8 @@
         "outFile": "../../built/local/compiler.release.js",
         "removeComments": true,
         "preserveConstEnums": false
-    }
+    },
+    "references": [
+        { "path": "../shims" }
+    ]
 }

src/compiler/types.ts

@@ -2250,12 +2250,14 @@ namespace ts {
         parent: CaseBlock;
         expression: Expression;
         statements: NodeArray<Statement>;
+        /* @internal */ fallthroughFlowNode?: FlowNode;
     }
 
     export interface DefaultClause extends Node {
         kind: SyntaxKind.DefaultClause;
         parent: CaseBlock;
         statements: NodeArray<Statement>;
+        /* @internal */ fallthroughFlowNode?: FlowNode;
     }
 
     export type CaseOrDefaultClause = CaseClause | DefaultClause;
@@ -2681,6 +2683,7 @@ namespace ts {
         isArrayType?: boolean;
     }
 
+    // NOTE: Ensure this is up-to-date with src/debug/debug.ts
     export const enum FlowFlags {
         Unreachable    = 1 << 0,  // Unreachable code
         Start          = 1 << 1,  // Start of flow graph
@@ -3258,6 +3261,9 @@ namespace ts {
         InvalidProject_OutputsSkipped = 3,
 
         // When build is skipped because project references form cycle
+        ProjectReferenceCycle_OutputsSkipped = 4,
+
+        /** @deprecated Use ProjectReferenceCycle_OutputsSkipped instead. */
         ProjectReferenceCycle_OutputsSkupped = 4,
     }
 
@@ -3365,8 +3371,10 @@ namespace ts {
 
         getFullyQualifiedName(symbol: Symbol): string;
         getAugmentedPropertiesOfType(type: Type): Symbol[];
+
         getRootSymbols(symbol: Symbol): readonly Symbol[];
         getContextualType(node: Expression): Type | undefined;
+        /* @internal */ getContextualType(node: Expression, contextFlags?: ContextFlags): Type | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
         /* @internal */ getContextualTypeForObjectLiteralElement(element: ObjectLiteralElementLike): Type | undefined;
         /* @internal */ getContextualTypeForArgumentAtIndex(call: CallLikeExpression, argIndex: number): Type | undefined;
         /* @internal */ getContextualTypeForJsxAttribute(attribute: JsxAttribute | JsxSpreadAttribute): Type | undefined;
@@ -3443,8 +3451,7 @@ namespace ts {
             resolvedReturnType: Type,
             typePredicate: TypePredicate | undefined,
             minArgumentCount: number,
-            hasRestParameter: boolean,
-            hasLiteralTypes: boolean,
+            flags: SignatureFlags
         ): Signature;
         /* @internal */ createSymbol(flags: SymbolFlags, name: __String): TransientSymbol;
         /* @internal */ createIndexInfo(type: Type, isReadonly: boolean, declaration?: SignatureDeclaration): IndexInfo;
@@ -3526,6 +3533,14 @@ namespace ts {
         Subtype
     }
 
+    /* @internal */
+    export const enum ContextFlags {
+        None          = 0,
+        Signature     = 1 << 0, // Obtaining contextual signature
+        NoConstraints = 1 << 1, // Don't obtain type variable constraints
+        Completion    = 1 << 2, // Obtaining constraint type for completion
+    }
+
     // NOTE: If modifying this enum, must modify `TypeFormatFlags` too!
     export const enum NodeBuilderFlags {
         None                                    = 0,
@@ -4655,7 +4670,22 @@ namespace ts {
         Construct,
     }
 
+    /* @internal */
+    export const enum SignatureFlags {
+        None = 0,
+        HasRestParameter = 1 << 0,      // Indicates last parameter is rest parameter
+        HasLiteralTypes = 1 << 1,       // Indicates signature is specialized
+        IsOptionalCall = 1 << 2,        // Indicates signature comes from a CallChain
+
+        // We do not propagate `IsOptionalCall` to instantiated signatures, as that would result in us
+        // attempting to add `| undefined` on each recursive call to `getReturnTypeOfSignature` when
+        // instantiating the return type.
+        PropagatingFlags = HasRestParameter | HasLiteralTypes,
+    }
+
     export interface Signature {
+        /* @internal */ flags: SignatureFlags;
+        /* @internal */ checker?: TypeChecker;
         declaration?: SignatureDeclaration | JSDocSignature; // Originating declaration
         typeParameters?: readonly TypeParameter[];   // Type parameters (undefined if non-generic)
         parameters: readonly Symbol[];               // Parameters
@@ -4672,10 +4702,6 @@ namespace ts {
         /* @internal */
         minArgumentCount: number;           // Number of non-optional parameters
         /* @internal */
-        hasRestParameter: boolean;          // True if last parameter is rest parameter
-        /* @internal */
-        hasLiteralTypes: boolean;           // True if specialized
-        /* @internal */
         target?: Signature;                 // Instantiation target
         /* @internal */
         mapper?: TypeMapper;                // Instantiation mapper
@@ -4686,11 +4712,11 @@ namespace ts {
         /* @internal */
         canonicalSignatureCache?: Signature; // Canonical version of signature (deferred)
         /* @internal */
+        optionalCallSignatureCache?: Signature; // Optional chained call version of signature (deferred)
+        /* @internal */
         isolatedSignatureType?: ObjectType; // A manufactured type that just contains the signature for purposes of signature comparison
         /* @internal */
         instantiations?: Map<Signature>;    // Generic signature instantiation cache
-        /* @internal */
-        isOptionalCall?: boolean;
     }
 
     export const enum IndexKind {
@@ -4935,6 +4961,7 @@ namespace ts {
         lib?: string[];
         /*@internal*/listEmittedFiles?: boolean;
         /*@internal*/listFiles?: boolean;
+        /*@internal*/listFilesOnly?: boolean;
         locale?: string;
         mapRoot?: string;
         maxNodeModuleJsDepth?: number;
@@ -5123,6 +5150,11 @@ namespace ts {
         /* @internal */ spec: ConfigFileSpecs;
     }
 
+    /* @internal */
+    export type RequireResult<T = {}> =
+        | { module: T, modulePath?: string, error: undefined }
+        | { module: undefined, modulePath?: undefined, error: { stack?: string, message?: string } };
+
     export interface CreateProgramOptions {
         rootNames: readonly string[];
         options: CompilerOptions;
@@ -6149,6 +6181,8 @@ namespace ts {
         readFile?(path: string): string | undefined;
         /* @internal */
         getProbableSymlinks?(files: readonly SourceFile[]): ReadonlyMap<string>;
+        /* @internal */
+        getGlobalTypingsCacheLocation?(): string | undefined;
     }
 
     // Note: this used to be deprecated in our public API, but is still used internally
@@ -6418,6 +6452,7 @@ namespace ts {
         readonly disableSuggestions?: boolean;
         readonly quotePreference?: "auto" | "double" | "single";
         readonly includeCompletionsForModuleExports?: boolean;
+        readonly includeAutomaticOptionalChainCompletions?: boolean;
         readonly includeCompletionsWithInsertText?: boolean;
         readonly importModuleSpecifierPreference?: "relative" | "non-relative";
         /** Determines whether we import `foo/index.ts` as "foo", "foo/index", or "foo/index.js" */

src/compiler/utilities.ts

@@ -36,7 +36,7 @@ namespace ts {
 
     /** Create a new escaped identifier map. */
     export function createUnderscoreEscapedMap<T>(): UnderscoreEscapedMap<T> {
-        return new MapCtr<T>() as UnderscoreEscapedMap<T>;
+        return new Map<T>() as UnderscoreEscapedMap<T>;
     }
 
     export function hasEntries(map: ReadonlyUnderscoreEscapedMap<any> | undefined): map is ReadonlyUnderscoreEscapedMap<any> {
@@ -94,13 +94,6 @@ namespace ts {
         };
     }
 
-    export function toPath(fileName: string, basePath: string | undefined, getCanonicalFileName: (path: string) => string): Path {
-        const nonCanonicalizedPath = isRootedDiskPath(fileName)
-            ? normalizePath(fileName)
-            : getNormalizedAbsolutePath(fileName, basePath);
-        return <Path>getCanonicalFileName(nonCanonicalizedPath);
-    }
-
     export function changesAffectModuleResolution(oldOptions: CompilerOptions, newOptions: CompilerOptions): boolean {
         return oldOptions.configFilePath !== newOptions.configFilePath ||
             optionsHaveModuleResolutionChanges(oldOptions, newOptions);
@@ -968,6 +961,11 @@ namespace ts {
                 break;
             case SyntaxKind.ArrowFunction:
                 return getErrorSpanForArrowFunction(sourceFile, <ArrowFunction>node);
+            case SyntaxKind.CaseClause:
+            case SyntaxKind.DefaultClause:
+                const start = skipTrivia(sourceFile.text, (<CaseOrDefaultClause>node).pos);
+                const end = (<CaseOrDefaultClause>node).statements.length > 0 ? (<CaseOrDefaultClause>node).statements[0].pos : (<CaseOrDefaultClause>node).end;
+                return createTextSpanFromBounds(start, end);
         }
 
         if (errorNode === undefined) {
@@ -1821,9 +1819,9 @@ namespace ts {
      * exactly one argument (of the form 'require("name")').
      * This function does not test if the node is in a JavaScript file or not.
      */
-    export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteralLike: true): callExpression is RequireOrImportCall & { expression: Identifier, arguments: [StringLiteralLike] };
-    export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteralLike: boolean): callExpression is CallExpression;
-    export function isRequireCall(callExpression: Node, checkArgumentIsStringLiteralLike: boolean): callExpression is CallExpression {
+    export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: true): callExpression is RequireOrImportCall & { expression: Identifier, arguments: [StringLiteralLike] };
+    export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: boolean): callExpression is CallExpression;
+    export function isRequireCall(callExpression: Node, requireStringLiteralLikeArgument: boolean): callExpression is CallExpression {
         if (callExpression.kind !== SyntaxKind.CallExpression) {
             return false;
         }
@@ -1837,7 +1835,7 @@ namespace ts {
             return false;
         }
         const arg = args[0];
-        return !checkArgumentIsStringLiteralLike || isStringLiteralLike(arg);
+        return !requireStringLiteralLikeArgument || isStringLiteralLike(arg);
     }
 
     export function isSingleOrDoubleQuote(charCode: number) {
@@ -2060,7 +2058,7 @@ namespace ts {
             idText(expr.expression.expression) === "Object" &&
             idText(expr.expression.name) === "defineProperty" &&
             isStringOrNumericLiteralLike(expr.arguments[1]) &&
-            isBindableStaticNameExpression(expr.arguments[0]);
+            isBindableStaticNameExpression(expr.arguments[0], /*excludeThisKeyword*/ true);
     }
 
     export function isBindableStaticElementAccessExpression(node: Node, excludeThisKeyword?: boolean): node is BindableStaticElementAccessExpression {
@@ -2174,9 +2172,11 @@ namespace ts {
                 nextToLast = nextToLast.expression as Exclude<BindableStaticNameExpression, Identifier>;
             }
             const id = nextToLast.expression;
-            if (id.escapedText === "exports" ||
-                id.escapedText === "module" && getElementOrPropertyAccessName(nextToLast) === "exports") {
-                // exports.name = expr OR module.exports.name = expr
+            if ((id.escapedText === "exports" ||
+                id.escapedText === "module" && getElementOrPropertyAccessName(nextToLast) === "exports") &&
+                // ExportsProperty does not support binding with computed names
+                isBindableStaticAccessExpression(lhs)) {
+                // exports.name = expr OR module.exports.name = expr OR exports["name"] = expr ...
                 return AssignmentDeclarationKind.ExportsProperty;
             }
             // F.G...x = expr
@@ -4179,6 +4179,23 @@ namespace ts {
         return node.kind === SyntaxKind.Identifier || isPropertyAccessEntityNameExpression(node);
     }
 
+    export function getFirstIdentifier(node: EntityNameOrEntityNameExpression): Identifier {
+        switch (node.kind) {
+            case SyntaxKind.Identifier:
+                return node;
+            case SyntaxKind.QualifiedName:
+                do {
+                    node = node.left;
+                } while (node.kind !== SyntaxKind.Identifier);
+                return node;
+            case SyntaxKind.PropertyAccessExpression:
+                do {
+                    node = node.expression;
+                } while (node.kind !== SyntaxKind.Identifier);
+                return node;
+        }
+    }
+
     export function isDottedName(node: Expression): boolean {
         return node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.ThisKeyword ||
             node.kind === SyntaxKind.PropertyAccessExpression && isDottedName((<PropertyAccessExpression>node).expression) ||
@@ -4733,25 +4750,6 @@ namespace ts {
         });
     }
 
-    /** Calls `callback` on `directory` and every ancestor directory it has, returning the first defined result. */
-    export function forEachAncestorDirectory<T>(directory: Path, callback: (directory: Path) => T | undefined): T | undefined;
-    export function forEachAncestorDirectory<T>(directory: string, callback: (directory: string) => T | undefined): T | undefined;
-    export function forEachAncestorDirectory<T>(directory: Path, callback: (directory: Path) => T | undefined): T | undefined {
-        while (true) {
-            const result = callback(directory);
-            if (result !== undefined) {
-                return result;
-            }
-
-            const parentPath = getDirectoryPath(directory);
-            if (parentPath === directory) {
-                return undefined;
-            }
-
-            directory = parentPath;
-        }
-    }
-
     // Return true if the given type is the constructor type for an abstract class
     export function isAbstractConstructorType(type: Type): boolean {
         return !!(getObjectFlags(type) & ObjectFlags.Anonymous) && !!type.symbol && isAbstractConstructorSymbol(type.symbol);
@@ -5906,9 +5904,19 @@ namespace ts {
     }
 
     export function isOptionalChain(node: Node): node is PropertyAccessChain | ElementAccessChain | CallChain {
-        return isPropertyAccessChain(node)
-            || isElementAccessChain(node)
-            || isCallChain(node);
+        const kind = node.kind;
+        return !!(node.flags & NodeFlags.OptionalChain) &&
+            (kind === SyntaxKind.PropertyAccessExpression
+                || kind === SyntaxKind.ElementAccessExpression
+                || kind === SyntaxKind.CallExpression);
+    }
+
+    /**
+     * Determines whether a node is the expression preceding an optional chain (i.e. `a` in `a?.b`).
+     */
+    /* @internal */
+    export function isExpressionOfOptionalChainRoot(node: Node): node is Expression & { parent: OptionalChainRoot } {
+        return isOptionalChainRoot(node.parent) && node.parent.expression === node;
     }
 
     export function isNewExpression(node: Node): node is NewExpression {
@@ -7310,7 +7318,7 @@ namespace ts {
         getSourceFileConstructor(): new (kind: SyntaxKind.SourceFile, pos?: number, end?: number) => SourceFile;
         getSymbolConstructor(): new (flags: SymbolFlags, name: __String) => Symbol;
         getTypeConstructor(): new (checker: TypeChecker, flags: TypeFlags) => Type;
-        getSignatureConstructor(): new (checker: TypeChecker) => Signature;
+        getSignatureConstructor(): new (checker: TypeChecker, flags: SignatureFlags) => Signature;
         getSourceMapSourceConstructor(): new (fileName: string, text: string, skipTrivia?: (pos: number) => number) => SourceMapSource;
     }
 
@@ -7331,7 +7339,12 @@ namespace ts {
         }
     }
 
-    function Signature() {}
+    function Signature(this: Signature, checker: TypeChecker, flags: SignatureFlags) {
+        this.flags = flags;
+        if (Debug.isDebugging) {
+            this.checker = checker;
+        }
+    }
 
     function Node(this: Node, kind: SyntaxKind, pos: number, end: number) {
         this.pos = pos;
@@ -7635,294 +7648,6 @@ namespace ts {
         return true;
     }
 
-    /**
-     * Internally, we represent paths as strings with '/' as the directory separator.
-     * When we make system calls (eg: LanguageServiceHost.getDirectory()),
-     * we expect the host to correctly handle paths in our specified format.
-     */
-    export const directorySeparator = "/";
-    const altDirectorySeparator = "\\";
-    const urlSchemeSeparator = "://";
-    const backslashRegExp = /\\/g;
-
-    /**
-     * Normalize path separators.
-     */
-    export function normalizeSlashes(path: string): string {
-        return path.replace(backslashRegExp, directorySeparator);
-    }
-
-    function isVolumeCharacter(charCode: number) {
-        return (charCode >= CharacterCodes.a && charCode <= CharacterCodes.z) ||
-            (charCode >= CharacterCodes.A && charCode <= CharacterCodes.Z);
-    }
-
-    function getFileUrlVolumeSeparatorEnd(url: string, start: number) {
-        const ch0 = url.charCodeAt(start);
-        if (ch0 === CharacterCodes.colon) return start + 1;
-        if (ch0 === CharacterCodes.percent && url.charCodeAt(start + 1) === CharacterCodes._3) {
-            const ch2 = url.charCodeAt(start + 2);
-            if (ch2 === CharacterCodes.a || ch2 === CharacterCodes.A) return start + 3;
-        }
-        return -1;
-    }
-
-    /**
-     * Returns length of the root part of a path or URL (i.e. length of "/", "x:/", "//server/share/, file:///user/files").
-     * If the root is part of a URL, the twos-complement of the root length is returned.
-     */
-    function getEncodedRootLength(path: string): number {
-        if (!path) return 0;
-        const ch0 = path.charCodeAt(0);
-
-        // POSIX or UNC
-        if (ch0 === CharacterCodes.slash || ch0 === CharacterCodes.backslash) {
-            if (path.charCodeAt(1) !== ch0) return 1; // POSIX: "/" (or non-normalized "\")
-
-            const p1 = path.indexOf(ch0 === CharacterCodes.slash ? directorySeparator : altDirectorySeparator, 2);
-            if (p1 < 0) return path.length; // UNC: "//server" or "\\server"
-
-            return p1 + 1; // UNC: "//server/" or "\\server\"
-        }
-
-        // DOS
-        if (isVolumeCharacter(ch0) && path.charCodeAt(1) === CharacterCodes.colon) {
-            const ch2 = path.charCodeAt(2);
-            if (ch2 === CharacterCodes.slash || ch2 === CharacterCodes.backslash) return 3; // DOS: "c:/" or "c:\"
-            if (path.length === 2) return 2; // DOS: "c:" (but not "c:d")
-        }
-
-        // URL
-        const schemeEnd = path.indexOf(urlSchemeSeparator);
-        if (schemeEnd !== -1) {
-            const authorityStart = schemeEnd + urlSchemeSeparator.length;
-            const authorityEnd = path.indexOf(directorySeparator, authorityStart);
-            if (authorityEnd !== -1) { // URL: "file:///", "file://server/", "file://server/path"
-                // For local "file" URLs, include the leading DOS volume (if present).
-                // Per https://www.ietf.org/rfc/rfc1738.txt, a host of "" or "localhost" is a
-                // special case interpreted as "the machine from which the URL is being interpreted".
-                const scheme = path.slice(0, schemeEnd);
-                const authority = path.slice(authorityStart, authorityEnd);
-                if (scheme === "file" && (authority === "" || authority === "localhost") &&
-                    isVolumeCharacter(path.charCodeAt(authorityEnd + 1))) {
-                    const volumeSeparatorEnd = getFileUrlVolumeSeparatorEnd(path, authorityEnd + 2);
-                    if (volumeSeparatorEnd !== -1) {
-                        if (path.charCodeAt(volumeSeparatorEnd) === CharacterCodes.slash) {
-                            // URL: "file:///c:/", "file://localhost/c:/", "file:///c%3a/", "file://localhost/c%3a/"
-                            return ~(volumeSeparatorEnd + 1);
-                        }
-                        if (volumeSeparatorEnd === path.length) {
-                            // URL: "file:///c:", "file://localhost/c:", "file:///c$3a", "file://localhost/c%3a"
-                            // but not "file:///c:d" or "file:///c%3ad"
-                            return ~volumeSeparatorEnd;
-                        }
-                    }
-                }
-                return ~(authorityEnd + 1); // URL: "file://server/", "http://server/"
-            }
-            return ~path.length; // URL: "file://server", "http://server"
-        }
-
-        // relative
-        return 0;
-    }
-
-    /**
-     * Returns length of the root part of a path or URL (i.e. length of "/", "x:/", "//server/share/, file:///user/files").
-     *
-     * For example:
-     * ```ts
-     * getRootLength("a") === 0                   // ""
-     * getRootLength("/") === 1                   // "/"
-     * getRootLength("c:") === 2                  // "c:"
-     * getRootLength("c:d") === 0                 // ""
-     * getRootLength("c:/") === 3                 // "c:/"
-     * getRootLength("c:\\") === 3                // "c:\\"
-     * getRootLength("//server") === 7            // "//server"
-     * getRootLength("//server/share") === 8      // "//server/"
-     * getRootLength("\\\\server") === 7          // "\\\\server"
-     * getRootLength("\\\\server\\share") === 8   // "\\\\server\\"
-     * getRootLength("file:///path") === 8        // "file:///"
-     * getRootLength("file:///c:") === 10         // "file:///c:"
-     * getRootLength("file:///c:d") === 8         // "file:///"
-     * getRootLength("file:///c:/path") === 11    // "file:///c:/"
-     * getRootLength("file://server") === 13      // "file://server"
-     * getRootLength("file://server/path") === 14 // "file://server/"
-     * getRootLength("http://server") === 13      // "http://server"
-     * getRootLength("http://server/path") === 14 // "http://server/"
-     * ```
-     */
-    export function getRootLength(path: string) {
-        const rootLength = getEncodedRootLength(path);
-        return rootLength < 0 ? ~rootLength : rootLength;
-    }
-
-    // TODO(rbuckton): replace references with `resolvePath`
-    export function normalizePath(path: string): string {
-        return resolvePath(path);
-    }
-
-    export function normalizePathAndParts(path: string): { path: string, parts: string[] } {
-        path = normalizeSlashes(path);
-        const [root, ...parts] = reducePathComponents(getPathComponents(path));
-        if (parts.length) {
-            const joinedParts = root + parts.join(directorySeparator);
-            return { path: hasTrailingDirectorySeparator(path) ? ensureTrailingDirectorySeparator(joinedParts) : joinedParts, parts };
-        }
-        else {
-            return { path: root, parts };
-        }
-    }
-
-    /**
-     * Returns the path except for its basename. Semantics align with NodeJS's `path.dirname`
-     * except that we support URLs as well.
-     *
-     * ```ts
-     * getDirectoryPath("/path/to/file.ext") === "/path/to"
-     * getDirectoryPath("/path/to/") === "/path"
-     * getDirectoryPath("/") === "/"
-     * ```
-     */
-    export function getDirectoryPath(path: Path): Path;
-    /**
-     * Returns the path except for its basename. Semantics align with NodeJS's `path.dirname`
-     * except that we support URLs as well.
-     *
-     * ```ts
-     * getDirectoryPath("/path/to/file.ext") === "/path/to"
-     * getDirectoryPath("/path/to/") === "/path"
-     * getDirectoryPath("/") === "/"
-     * ```
-     */
-    export function getDirectoryPath(path: string): string;
-    export function getDirectoryPath(path: string): string {
-        path = normalizeSlashes(path);
-
-        // If the path provided is itself the root, then return it.
-        const rootLength = getRootLength(path);
-        if (rootLength === path.length) return path;
-
-        // return the leading portion of the path up to the last (non-terminal) directory separator
-        // but not including any trailing directory separator.
-        path = removeTrailingDirectorySeparator(path);
-        return path.slice(0, Math.max(rootLength, path.lastIndexOf(directorySeparator)));
-    }
-
-    export function startsWithDirectory(fileName: string, directoryName: string, getCanonicalFileName: GetCanonicalFileName): boolean {
-        const canonicalFileName = getCanonicalFileName(fileName);
-        const canonicalDirectoryName = getCanonicalFileName(directoryName);
-        return startsWith(canonicalFileName, canonicalDirectoryName + "/") || startsWith(canonicalFileName, canonicalDirectoryName + "\\");
-    }
-
-    export function isUrl(path: string) {
-        return getEncodedRootLength(path) < 0;
-    }
-
-    export function pathIsRelative(path: string): boolean {
-        return /^\.\.?($|[\\/])/.test(path);
-    }
-
-    /**
-     * Determines whether a path is an absolute path (e.g. starts with `/`, or a dos path
-     * like `c:`, `c:\` or `c:/`).
-     */
-    export function isRootedDiskPath(path: string) {
-        return getEncodedRootLength(path) > 0;
-    }
-
-    /**
-     * Determines whether a path consists only of a path root.
-     */
-    export function isDiskPathRoot(path: string) {
-        const rootLength = getEncodedRootLength(path);
-        return rootLength > 0 && rootLength === path.length;
-    }
-
-    export function convertToRelativePath(absoluteOrRelativePath: string, basePath: string, getCanonicalFileName: (path: string) => string): string {
-        return !isRootedDiskPath(absoluteOrRelativePath)
-            ? absoluteOrRelativePath
-            : getRelativePathToDirectoryOrUrl(basePath, absoluteOrRelativePath, basePath, getCanonicalFileName, /*isAbsolutePathAnUrl*/ false);
-    }
-
-    function pathComponents(path: string, rootLength: number) {
-        const root = path.substring(0, rootLength);
-        const rest = path.substring(rootLength).split(directorySeparator);
-        if (rest.length && !lastOrUndefined(rest)) rest.pop();
-        return [root, ...rest];
-    }
-
-    /**
-     * Parse a path into an array containing a root component (at index 0) and zero or more path
-     * components (at indices > 0). The result is not normalized.
-     * If the path is relative, the root component is `""`.
-     * If the path is absolute, the root component includes the first path separator (`/`).
-     */
-    export function getPathComponents(path: string, currentDirectory = "") {
-        path = combinePaths(currentDirectory, path);
-        const rootLength = getRootLength(path);
-        return pathComponents(path, rootLength);
-    }
-
-    /**
-     * Reduce an array of path components to a more simplified path by navigating any
-     * `"."` or `".."` entries in the path.
-     */
-    export function reducePathComponents(components: readonly string[]) {
-        if (!some(components)) return [];
-        const reduced = [components[0]];
-        for (let i = 1; i < components.length; i++) {
-            const component = components[i];
-            if (!component) continue;
-            if (component === ".") continue;
-            if (component === "..") {
-                if (reduced.length > 1) {
-                    if (reduced[reduced.length - 1] !== "..") {
-                        reduced.pop();
-                        continue;
-                    }
-                }
-                else if (reduced[0]) continue;
-            }
-            reduced.push(component);
-        }
-        return reduced;
-    }
-
-    /**
-     * Parse a path into an array containing a root component (at index 0) and zero or more path
-     * components (at indices > 0). The result is normalized.
-     * If the path is relative, the root component is `""`.
-     * If the path is absolute, the root component includes the first path separator (`/`).
-     */
-    export function getNormalizedPathComponents(path: string, currentDirectory: string | undefined) {
-        return reducePathComponents(getPathComponents(path, currentDirectory));
-    }
-
-    export function getNormalizedAbsolutePath(fileName: string, currentDirectory: string | undefined) {
-        return getPathFromPathComponents(getNormalizedPathComponents(fileName, currentDirectory));
-    }
-
-    /**
-     * Formats a parsed path consisting of a root component (at index 0) and zero or more path
-     * segments (at indices > 0).
-     */
-    export function getPathFromPathComponents(pathComponents: readonly string[]) {
-        if (pathComponents.length === 0) return "";
-
-        const root = pathComponents[0] && ensureTrailingDirectorySeparator(pathComponents[0]);
-        return root + pathComponents.slice(1).join(directorySeparator);
-    }
-
-    export function getNormalizedAbsolutePathWithoutRoot(fileName: string, currentDirectory: string | undefined) {
-        return getPathWithoutRoot(getNormalizedPathComponents(fileName, currentDirectory));
-    }
-
-    function getPathWithoutRoot(pathComponents: readonly string[]) {
-        if (pathComponents.length === 0) return "";
-        return pathComponents.slice(1).join(directorySeparator);
-    }
-
     export function discoverProbableSymlinks(files: readonly SourceFile[], getCanonicalFileName: GetCanonicalFileName, cwd: string): ReadonlyMap<string> {
         const result = createMap<string>();
         const symlinks = flatten<readonly [string, string]>(mapDefined(files, sf =>
@@ -7956,278 +7681,8 @@ namespace ts {
 
 /* @internal */
 namespace ts {
-    export function getPathComponentsRelativeTo(from: string, to: string, stringEqualityComparer: (a: string, b: string) => boolean, getCanonicalFileName: GetCanonicalFileName) {
-        const fromComponents = reducePathComponents(getPathComponents(from));
-        const toComponents = reducePathComponents(getPathComponents(to));
-
-        let start: number;
-        for (start = 0; start < fromComponents.length && start < toComponents.length; start++) {
-            const fromComponent = getCanonicalFileName(fromComponents[start]);
-            const toComponent = getCanonicalFileName(toComponents[start]);
-            const comparer = start === 0 ? equateStringsCaseInsensitive : stringEqualityComparer;
-            if (!comparer(fromComponent, toComponent)) break;
-        }
-
-        if (start === 0) {
-            return toComponents;
-        }
-
-        const components = toComponents.slice(start);
-        const relative: string[] = [];
-        for (; start < fromComponents.length; start++) {
-            relative.push("..");
-        }
-        return ["", ...relative, ...components];
-    }
-
-    export function getRelativePathFromFile(from: string, to: string, getCanonicalFileName: GetCanonicalFileName) {
-        return ensurePathIsNonModuleName(getRelativePathFromDirectory(getDirectoryPath(from), to, getCanonicalFileName));
-    }
-
-    /**
-     * Gets a relative path that can be used to traverse between `from` and `to`.
-     */
-    export function getRelativePathFromDirectory(from: string, to: string, ignoreCase: boolean): string;
-    /**
-     * Gets a relative path that can be used to traverse between `from` and `to`.
-     */
-    export function getRelativePathFromDirectory(fromDirectory: string, to: string, getCanonicalFileName: GetCanonicalFileName): string; // eslint-disable-line @typescript-eslint/unified-signatures
-    export function getRelativePathFromDirectory(fromDirectory: string, to: string, getCanonicalFileNameOrIgnoreCase: GetCanonicalFileName | boolean) {
-        Debug.assert((getRootLength(fromDirectory) > 0) === (getRootLength(to) > 0), "Paths must either both be absolute or both be relative");
-        const getCanonicalFileName = typeof getCanonicalFileNameOrIgnoreCase === "function" ? getCanonicalFileNameOrIgnoreCase : identity;
-        const ignoreCase = typeof getCanonicalFileNameOrIgnoreCase === "boolean" ? getCanonicalFileNameOrIgnoreCase : false;
-        const pathComponents = getPathComponentsRelativeTo(fromDirectory, to, ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive, getCanonicalFileName);
-        return getPathFromPathComponents(pathComponents);
-    }
-
-    export function getRelativePathToDirectoryOrUrl(directoryPathOrUrl: string, relativeOrAbsolutePath: string, currentDirectory: string, getCanonicalFileName: GetCanonicalFileName, isAbsolutePathAnUrl: boolean) {
-        const pathComponents = getPathComponentsRelativeTo(
-            resolvePath(currentDirectory, directoryPathOrUrl),
-            resolvePath(currentDirectory, relativeOrAbsolutePath),
-            equateStringsCaseSensitive,
-            getCanonicalFileName
-        );
-
-        const firstComponent = pathComponents[0];
-        if (isAbsolutePathAnUrl && isRootedDiskPath(firstComponent)) {
-            const prefix = firstComponent.charAt(0) === directorySeparator ? "file://" : "file:///";
-            pathComponents[0] = prefix + firstComponent;
-        }
-
-        return getPathFromPathComponents(pathComponents);
-    }
-
-    /**
-     * Ensures a path is either absolute (prefixed with `/` or `c:`) or dot-relative (prefixed
-     * with `./` or `../`) so as not to be confused with an unprefixed module name.
-     */
-    export function ensurePathIsNonModuleName(path: string): string {
-        return getRootLength(path) === 0 && !pathIsRelative(path) ? "./" + path : path;
-    }
-
-    /**
-     * Returns the path except for its containing directory name.
-     * Semantics align with NodeJS's `path.basename` except that we support URL's as well.
-     *
-     * ```ts
-     * getBaseFileName("/path/to/file.ext") === "file.ext"
-     * getBaseFileName("/path/to/") === "to"
-     * getBaseFileName("/") === ""
-     * ```
-     */
-    export function getBaseFileName(path: string): string;
-    /**
-     * Gets the portion of a path following the last (non-terminal) separator (`/`).
-     * Semantics align with NodeJS's `path.basename` except that we support URL's as well.
-     * If the base name has any one of the provided extensions, it is removed.
-     *
-     * ```ts
-     * getBaseFileName("/path/to/file.ext", ".ext", true) === "file"
-     * getBaseFileName("/path/to/file.js", ".ext", true) === "file.js"
-     * ```
-     */
-    export function getBaseFileName(path: string, extensions: string | readonly string[], ignoreCase: boolean): string;
-    export function getBaseFileName(path: string, extensions?: string | readonly string[], ignoreCase?: boolean) {
-        path = normalizeSlashes(path);
-
-        // if the path provided is itself the root, then it has not file name.
-        const rootLength = getRootLength(path);
-        if (rootLength === path.length) return "";
-
-        // return the trailing portion of the path starting after the last (non-terminal) directory
-        // separator but not including any trailing directory separator.
-        path = removeTrailingDirectorySeparator(path);
-        const name = path.slice(Math.max(getRootLength(path), path.lastIndexOf(directorySeparator) + 1));
-        const extension = extensions !== undefined && ignoreCase !== undefined ? getAnyExtensionFromPath(name, extensions, ignoreCase) : undefined;
-        return extension ? name.slice(0, name.length - extension.length) : name;
-    }
-
-    /**
-     * Combines paths. If a path is absolute, it replaces any previous path.
-     */
-    export function combinePaths(path: string, ...paths: (string | undefined)[]): string {
-        if (path) path = normalizeSlashes(path);
-        for (let relativePath of paths) {
-            if (!relativePath) continue;
-            relativePath = normalizeSlashes(relativePath);
-            if (!path || getRootLength(relativePath) !== 0) {
-                path = relativePath;
-            }
-            else {
-                path = ensureTrailingDirectorySeparator(path) + relativePath;
-            }
-        }
-        return path;
-    }
-
-    /**
-     * Combines and resolves paths. If a path is absolute, it replaces any previous path. Any
-     * `.` and `..` path components are resolved.
-     */
-    export function resolvePath(path: string, ...paths: (string | undefined)[]): string {
-        const combined = some(paths) ? combinePaths(path, ...paths) : normalizeSlashes(path);
-        const normalized = getPathFromPathComponents(reducePathComponents(getPathComponents(combined)));
-        return normalized && hasTrailingDirectorySeparator(combined) ? ensureTrailingDirectorySeparator(normalized) : normalized;
-    }
-
-    /**
-     * Determines whether a path has a trailing separator (`/` or `\\`).
-     */
-    export function hasTrailingDirectorySeparator(path: string) {
-        if (path.length === 0) return false;
-        const ch = path.charCodeAt(path.length - 1);
-        return ch === CharacterCodes.slash || ch === CharacterCodes.backslash;
-    }
-
-    /**
-     * Removes a trailing directory separator from a path.
-     * @param path The path.
-     */
-    export function removeTrailingDirectorySeparator(path: Path): Path;
-    export function removeTrailingDirectorySeparator(path: string): string;
-    export function removeTrailingDirectorySeparator(path: string) {
-        if (hasTrailingDirectorySeparator(path)) {
-            return path.substr(0, path.length - 1);
-        }
-
-        return path;
-    }
-
-    /**
-     * Adds a trailing directory separator to a path, if it does not already have one.
-     * @param path The path.
-     */
-    export function ensureTrailingDirectorySeparator(path: Path): Path;
-    export function ensureTrailingDirectorySeparator(path: string): string;
-    export function ensureTrailingDirectorySeparator(path: string) {
-        if (!hasTrailingDirectorySeparator(path)) {
-            return path + directorySeparator;
-        }
-
-        return path;
-    }
-
-    // check path for these segments: '', '.'. '..'
-    const relativePathSegmentRegExp = /(^|\/)\.{0,2}($|\/)/;
-
-    function comparePathsWorker(a: string, b: string, componentComparer: (a: string, b: string) => Comparison) {
-        if (a === b) return Comparison.EqualTo;
-        if (a === undefined) return Comparison.LessThan;
-        if (b === undefined) return Comparison.GreaterThan;
-
-        // NOTE: Performance optimization - shortcut if the root segments differ as there would be no
-        //       need to perform path reduction.
-        const aRoot = a.substring(0, getRootLength(a));
-        const bRoot = b.substring(0, getRootLength(b));
-        const result = compareStringsCaseInsensitive(aRoot, bRoot);
-        if (result !== Comparison.EqualTo) {
-            return result;
-        }
-
-        // NOTE: Performance optimization - shortcut if there are no relative path segments in
-        //       the non-root portion of the path
-        const aRest = a.substring(aRoot.length);
-        const bRest = b.substring(bRoot.length);
-        if (!relativePathSegmentRegExp.test(aRest) && !relativePathSegmentRegExp.test(bRest)) {
-            return componentComparer(aRest, bRest);
-        }
-
-        // The path contains a relative path segment. Normalize the paths and perform a slower component
-        // by component comparison.
-        const aComponents = reducePathComponents(getPathComponents(a));
-        const bComponents = reducePathComponents(getPathComponents(b));
-        const sharedLength = Math.min(aComponents.length, bComponents.length);
-        for (let i = 1; i < sharedLength; i++) {
-            const result = componentComparer(aComponents[i], bComponents[i]);
-            if (result !== Comparison.EqualTo) {
-                return result;
-            }
-        }
-        return compareValues(aComponents.length, bComponents.length);
-    }
-
-    /**
-     * Performs a case-sensitive comparison of two paths.
-     */
-    export function comparePathsCaseSensitive(a: string, b: string) {
-        return comparePathsWorker(a, b, compareStringsCaseSensitive);
-    }
-
-    /**
-     * Performs a case-insensitive comparison of two paths.
-     */
-    export function comparePathsCaseInsensitive(a: string, b: string) {
-        return comparePathsWorker(a, b, compareStringsCaseInsensitive);
-    }
-
-    export function comparePaths(a: string, b: string, ignoreCase?: boolean): Comparison;
-    export function comparePaths(a: string, b: string, currentDirectory: string, ignoreCase?: boolean): Comparison;
-    export function comparePaths(a: string, b: string, currentDirectory?: string | boolean, ignoreCase?: boolean) {
-        if (typeof currentDirectory === "string") {
-            a = combinePaths(currentDirectory, a);
-            b = combinePaths(currentDirectory, b);
-        }
-        else if (typeof currentDirectory === "boolean") {
-            ignoreCase = currentDirectory;
-        }
-        return comparePathsWorker(a, b, getStringComparer(ignoreCase));
-    }
-
-    export function containsPath(parent: string, child: string, ignoreCase?: boolean): boolean;
-    export function containsPath(parent: string, child: string, currentDirectory: string, ignoreCase?: boolean): boolean;
-    export function containsPath(parent: string, child: string, currentDirectory?: string | boolean, ignoreCase?: boolean) {
-        if (typeof currentDirectory === "string") {
-            parent = combinePaths(currentDirectory, parent);
-            child = combinePaths(currentDirectory, child);
-        }
-        else if (typeof currentDirectory === "boolean") {
-            ignoreCase = currentDirectory;
-        }
-        if (parent === undefined || child === undefined) return false;
-        if (parent === child) return true;
-        const parentComponents = reducePathComponents(getPathComponents(parent));
-        const childComponents = reducePathComponents(getPathComponents(child));
-        if (childComponents.length < parentComponents.length) {
-            return false;
-        }
-
-        const componentEqualityComparer = ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive;
-        for (let i = 0; i < parentComponents.length; i++) {
-            const equalityComparer = i === 0 ? equateStringsCaseInsensitive : componentEqualityComparer;
-            if (!equalityComparer(parentComponents[i], childComponents[i])) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    function isDirectorySeparator(charCode: number): boolean {
-        return charCode === CharacterCodes.slash || charCode === CharacterCodes.backslash;
-    }
-
     function stripLeadingDirectorySeparator(s: string): string | undefined {
-        return isDirectorySeparator(s.charCodeAt(0)) ? s.slice(1) : undefined;
+        return isAnyDirectorySeparator(s.charCodeAt(0)) ? s.slice(1) : undefined;
     }
 
     export function tryRemoveDirectoryPrefix(path: string, dirPath: string, getCanonicalFileName: GetCanonicalFileName): string | undefined {
@@ -8250,10 +7705,6 @@ namespace ts {
 
     const wildcardCharCodes = [CharacterCodes.asterisk, CharacterCodes.question];
 
-    export function hasExtension(fileName: string): boolean {
-        return stringContains(getBaseFileName(fileName), ".");
-    }
-
     export const commonPackageFolders: readonly string[] = ["node_modules", "bower_components", "jspm_packages"];
 
     const implicitExcludePathRegexPattern = `(?!(${commonPackageFolders.join("|")})(/|$))`;
@@ -8718,13 +8169,6 @@ namespace ts {
         return <T>changeAnyExtension(path, newExtension, extensionsToRemove, /*ignoreCase*/ false);
     }
 
-    export function changeAnyExtension(path: string, ext: string): string;
-    export function changeAnyExtension(path: string, ext: string, extensions: string | readonly string[], ignoreCase: boolean): string;
-    export function changeAnyExtension(path: string, ext: string, extensions?: string | readonly string[], ignoreCase?: boolean) {
-        const pathext = extensions !== undefined && ignoreCase !== undefined ? getAnyExtensionFromPath(path, extensions, ignoreCase) : getAnyExtensionFromPath(path);
-        return pathext ? path.slice(0, path.length - pathext.length) + (startsWith(ext, ".") ? ext : "." + ext) : path;
-    }
-
     export function tryParsePattern(pattern: string): Pattern | undefined {
         // This should be verified outside of here and a proper error thrown.
         Debug.assert(hasZeroOrOneAsteriskCharacter(pattern));
@@ -8767,42 +8211,6 @@ namespace ts {
         return find<Extension>(extensionsToRemove, e => fileExtensionIs(path, e));
     }
 
-    function getAnyExtensionFromPathWorker(path: string, extensions: string | readonly string[], stringEqualityComparer: (a: string, b: string) => boolean) {
-        if (typeof extensions === "string") extensions = [extensions];
-        for (let extension of extensions) {
-            if (!startsWith(extension, ".")) extension = "." + extension;
-            if (path.length >= extension.length && path.charAt(path.length - extension.length) === ".") {
-                const pathExtension = path.slice(path.length - extension.length);
-                if (stringEqualityComparer(pathExtension, extension)) {
-                    return pathExtension;
-                }
-            }
-        }
-        return "";
-    }
-
-    /**
-     * Gets the file extension for a path.
-     */
-    export function getAnyExtensionFromPath(path: string): string;
-    /**
-     * Gets the file extension for a path, provided it is one of the provided extensions.
-     */
-    export function getAnyExtensionFromPath(path: string, extensions: string | readonly string[], ignoreCase: boolean): string;
-    export function getAnyExtensionFromPath(path: string, extensions?: string | readonly string[], ignoreCase?: boolean): string {
-        // Retrieves any string from the final "." onwards from a base file name.
-        // Unlike extensionFromPath, which throws an exception on unrecognized extensions.
-        if (extensions) {
-            return getAnyExtensionFromPathWorker(path, extensions, ignoreCase ? equateStringsCaseInsensitive : equateStringsCaseSensitive);
-        }
-        const baseFileName = getBaseFileName(path);
-        const extensionIndex = baseFileName.lastIndexOf(".");
-        if (extensionIndex >= 0) {
-            return baseFileName.substring(extensionIndex);
-        }
-        return "";
-    }
-
     export function isCheckJsEnabledForFile(sourceFile: SourceFile, compilerOptions: CompilerOptions) {
         return sourceFile.checkJsDirective ? sourceFile.checkJsDirective.enabled : compilerOptions.checkJs;
     }

src/compiler/watch.ts

@@ -91,7 +91,7 @@ namespace ts {
     /** Parses config file using System interface */
     export function parseConfigFileWithSystem(configFileName: string, optionsToExtend: CompilerOptions, system: System, reportDiagnostic: DiagnosticReporter) {
         const host: ParseConfigFileHost = <any>system;
-        host.onUnRecoverableConfigFileDiagnostic = diagnostic => reportUnrecoverableDiagnostic(sys, reportDiagnostic, diagnostic);
+        host.onUnRecoverableConfigFileDiagnostic = diagnostic => reportUnrecoverableDiagnostic(system, reportDiagnostic, diagnostic);
         const result = getParsedCommandLineOfConfigFile(configFileName, optionsToExtend, host);
         host.onUnRecoverableConfigFileDiagnostic = undefined!; // TODO: GH#18217
         return result;
@@ -129,7 +129,7 @@ namespace ts {
     }
 
     export function listFiles(program: ProgramToEmitFilesAndReportErrors, writeFileName: (s: string) => void) {
-        if (program.getCompilerOptions().listFiles) {
+        if (program.getCompilerOptions().listFiles || program.getCompilerOptions().listFilesOnly) {
             forEach(program.getSourceFiles(), file => {
                 writeFileName(file.fileName);
             });
@@ -149,6 +149,8 @@ namespace ts {
         emitOnlyDtsFiles?: boolean,
         customTransformers?: CustomTransformers
     ) {
+        const isListFilesOnly = !!program.getCompilerOptions().listFilesOnly;
+
         // First get and report any syntactic errors.
         const diagnostics = program.getConfigFileParsingDiagnostics().slice();
         const configFileParsingDiagnosticsLength = diagnostics.length;
@@ -158,15 +160,20 @@ namespace ts {
         // semantic errors.
         if (diagnostics.length === configFileParsingDiagnosticsLength) {
             addRange(diagnostics, program.getOptionsDiagnostics(cancellationToken));
-            addRange(diagnostics, program.getGlobalDiagnostics(cancellationToken));
 
-            if (diagnostics.length === configFileParsingDiagnosticsLength) {
-                addRange(diagnostics, program.getSemanticDiagnostics(/*sourceFile*/ undefined, cancellationToken));
+            if (!isListFilesOnly) {
+                addRange(diagnostics, program.getGlobalDiagnostics(cancellationToken));
+
+                if (diagnostics.length === configFileParsingDiagnosticsLength) {
+                    addRange(diagnostics, program.getSemanticDiagnostics(/*sourceFile*/ undefined, cancellationToken));
+                }
             }
         }
 
         // Emit and report any errors we ran into.
-        const emitResult = program.emit(/*targetSourceFile*/ undefined, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers);
+        const emitResult = isListFilesOnly
+            ? { emitSkipped: true, diagnostics: emptyArray }
+            : program.emit(/*targetSourceFile*/ undefined, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers);
         const { emittedFiles, diagnostics: emitDiagnostics } = emitResult;
         addRange(diagnostics, emitDiagnostics);
 

src/debug/debug.ts

@@ -0,0 +1,499 @@
+/// <reference lib="es2019" />
+
+/* @internal */
+namespace Debug {
+    interface Node {
+        kind: number;
+    }
+
+    type FunctionExpression = Node;
+    type ArrowFunction = Node;
+    type MethodDeclaration = Node;
+    type Expression = Node;
+    type SourceFile = Node;
+
+    interface SwitchStatement extends Node {
+        caseBlock: CaseBlock;
+    }
+
+    interface CaseBlock extends Node {
+        clauses: (CaseClause | DefaultClause)[];
+    }
+
+    interface CaseClause extends Node {
+        _caseclauseBrand: any;
+        expression: Expression;
+    }
+
+    interface DefaultClause extends Node {
+        _defaultClauseBrand: any;
+    }
+
+    interface TypeScriptModule {
+        readonly SyntaxKind: {
+            readonly CaseClause: number;
+            readonly DefaultClause: number;
+        };
+
+        readonly FlowFlags: {
+            readonly Unreachable: number,
+            readonly Start: number,
+            readonly BranchLabel: number,
+            readonly LoopLabel: number,
+            readonly Assignment: number,
+            readonly TrueCondition: number,
+            readonly FalseCondition: number,
+            readonly SwitchClause: number,
+            readonly ArrayMutation: number,
+            readonly Call: number,
+            readonly Referenced: number,
+            readonly Shared: number,
+            readonly PreFinally: number,
+            readonly AfterFinally: number,
+            readonly Label: number,
+            readonly Condition: number,
+        };
+
+        getSourceFileOfNode(node: Node): SourceFile;
+        getSourceTextOfNodeFromSourceFile(sourceFile: SourceFile, node: Node, includeTrivia?: boolean): string;
+        isDefaultClause(node: Node): node is DefaultClause;
+    }
+
+    type FlowNode =
+        | AfterFinallyFlow
+        | PreFinallyFlow
+        | FlowStart
+        | FlowLabel
+        | FlowAssignment
+        | FlowCall
+        | FlowCondition
+        | FlowSwitchClause
+        | FlowArrayMutation
+        ;
+
+    interface FlowNodeBase {
+        flags: FlowFlags;
+        id?: number;
+    }
+
+    interface AfterFinallyFlow extends FlowNodeBase {
+        antecedent: FlowNode;
+    }
+
+    interface PreFinallyFlow extends FlowNodeBase {
+        antecedent: FlowNode;
+    }
+
+    interface FlowStart extends FlowNodeBase {
+        node?: FunctionExpression | ArrowFunction | MethodDeclaration;
+    }
+
+    interface FlowLabel extends FlowNodeBase {
+        antecedents: FlowNode[] | undefined;
+    }
+
+    interface FlowAssignment extends FlowNodeBase {
+        node: Expression;
+        antecedent: FlowNode;
+    }
+
+    interface FlowCall extends FlowNodeBase {
+        node: Expression;
+        antecedent: FlowNode;
+    }
+
+    interface FlowCondition extends FlowNodeBase {
+        node: Expression;
+        antecedent: FlowNode;
+    }
+
+    interface FlowSwitchClause extends FlowNodeBase {
+        switchStatement: SwitchStatement;
+        clauseStart: number;
+        clauseEnd: number;
+        antecedent: FlowNode;
+    }
+
+    interface FlowArrayMutation extends FlowNodeBase {
+        node: Expression;
+        antecedent: FlowNode;
+    }
+
+    type FlowFlags = number;
+    let FlowFlags: TypeScriptModule["FlowFlags"];
+    let getSourceFileOfNode: TypeScriptModule["getSourceFileOfNode"];
+    let getSourceTextOfNodeFromSourceFile: TypeScriptModule["getSourceTextOfNodeFromSourceFile"];
+    let isDefaultClause: TypeScriptModule["isDefaultClause"];
+
+    export function init(ts: TypeScriptModule) {
+        FlowFlags = ts.FlowFlags;
+        getSourceFileOfNode = ts.getSourceFileOfNode;
+        getSourceTextOfNodeFromSourceFile = ts.getSourceTextOfNodeFromSourceFile;
+        isDefaultClause = ts.isDefaultClause;
+    }
+
+    let nextDebugFlowId = -1;
+
+    function getDebugFlowNodeId(f: FlowNode) {
+        if (!f.id) {
+            f.id = nextDebugFlowId;
+            nextDebugFlowId--;
+        }
+        return f.id;
+    }
+
+    export function formatControlFlowGraph(flowNode: FlowNode) {
+        const enum BoxCharacter {
+            lr = "─",
+            ud = "│",
+            dr = "╭",
+            dl = "╮",
+            ul = "╯",
+            ur = "╰",
+            udr = "├",
+            udl = "┤",
+            dlr = "┬",
+            ulr = "┴",
+            udlr = "╫",
+        }
+
+        const enum Connection {
+            Up = 1 << 0,
+            Down = 1 << 1,
+            Left = 1 << 2,
+            Right = 1 << 3,
+
+            UpDown = Up | Down,
+            LeftRight = Left | Right,
+            UpLeft = Up | Left,
+            UpRight = Up | Right,
+            DownLeft = Down | Left,
+            DownRight = Down | Right,
+            UpDownLeft = UpDown | Left,
+            UpDownRight = UpDown | Right,
+            UpLeftRight = Up | LeftRight,
+            DownLeftRight = Down | LeftRight,
+            UpDownLeftRight = UpDown | LeftRight,
+
+            NoChildren = 1 << 4,
+        }
+
+        interface FlowGraphNode {
+            id: number;
+            flowNode: FlowNode;
+            edges: FlowGraphEdge[];
+            text: string;
+            lane: number;
+            endLane: number;
+            level: number;
+        }
+
+        interface FlowGraphEdge {
+            source: FlowGraphNode;
+            target: FlowGraphNode;
+        }
+
+        const hasAntecedentFlags =
+            FlowFlags.Assignment |
+            FlowFlags.Condition |
+            FlowFlags.SwitchClause |
+            FlowFlags.ArrayMutation |
+            FlowFlags.Call |
+            FlowFlags.PreFinally |
+            FlowFlags.AfterFinally;
+
+        const hasNodeFlags =
+            FlowFlags.Start |
+            FlowFlags.Assignment |
+            FlowFlags.Call |
+            FlowFlags.Condition |
+            FlowFlags.ArrayMutation;
+
+        const links: Record<number, FlowGraphNode> = Object.create(/*o*/ null); // eslint-disable-line no-null/no-null
+        const nodes: FlowGraphNode[] = [];
+        const edges: FlowGraphEdge[] = [];
+        const root = buildGraphNode(flowNode);
+        for (const node of nodes) {
+            computeLevel(node);
+        }
+
+        const height = computeHeight(root);
+        const columnWidths = computeColumnWidths(height);
+        computeLanes(root, 0);
+        return renderGraph();
+
+        function isFlowSwitchClause(f: FlowNode): f is FlowSwitchClause {
+            return !!(f.flags & FlowFlags.SwitchClause);
+        }
+
+        function hasAntecedents(f: FlowNode): f is FlowLabel & { antecedents: FlowNode[] } {
+            return !!(f.flags & FlowFlags.Label) && !!(f as FlowLabel).antecedents;
+        }
+
+        function hasAntecedent(f: FlowNode): f is Extract<FlowNode, { antecedent: FlowNode }> {
+            return !!(f.flags & hasAntecedentFlags);
+        }
+
+        function hasNode(f: FlowNode): f is Extract<FlowNode, { node?: Node }> {
+            return !!(f.flags & hasNodeFlags);
+        }
+
+        function getChildren(node: FlowGraphNode) {
+            const children: FlowGraphNode[] = [];
+            for (const edge of node.edges) {
+                if (edge.source === node) {
+                    children.push(edge.target);
+                }
+            }
+            return children;
+        }
+
+        function getParents(node: FlowGraphNode) {
+            const parents: FlowGraphNode[] = [];
+            for (const edge of node.edges) {
+                if (edge.target === node) {
+                    parents.push(edge.source);
+                }
+            }
+            return parents;
+        }
+
+        function buildGraphNode(flowNode: FlowNode) {
+            const id = getDebugFlowNodeId(flowNode);
+            let graphNode = links[id];
+            if (!graphNode) {
+                links[id] = graphNode = { id, flowNode, edges: [], text: renderFlowNode(flowNode), lane: -1, endLane: -1, level: -1 };
+                nodes.push(graphNode);
+                if (!(flowNode.flags & FlowFlags.PreFinally)) {
+                    if (hasAntecedents(flowNode)) {
+
+                        for (const antecedent of flowNode.antecedents) {
+                            buildGraphEdge(graphNode, antecedent);
+                        }
+                    }
+                    else if (hasAntecedent(flowNode)) {
+                        buildGraphEdge(graphNode, flowNode.antecedent);
+                    }
+                }
+            }
+            return graphNode;
+        }
+
+        function buildGraphEdge(source: FlowGraphNode, antecedent: FlowNode) {
+            const target = buildGraphNode(antecedent);
+            const edge: FlowGraphEdge = { source, target };
+            edges.push(edge);
+            source.edges.push(edge);
+            target.edges.push(edge);
+        }
+
+        function computeLevel(node: FlowGraphNode): number {
+            if (node.level !== -1) {
+                return node.level;
+            }
+            let level = 0;
+            for (const parent of getParents(node)) {
+                level = Math.max(level, computeLevel(parent) + 1);
+            }
+            return node.level = level;
+        }
+
+        function computeHeight(node: FlowGraphNode): number {
+            let height = 0;
+            for (const child of getChildren(node)) {
+                height = Math.max(height, computeHeight(child));
+            }
+            return height + 1;
+        }
+
+        function computeColumnWidths(height: number) {
+            const columns: number[] = fill(Array(height), 0);
+            for (const node of nodes) {
+                columns[node.level] = Math.max(columns[node.level], node.text.length);
+            }
+            return columns;
+        }
+
+        function computeLanes(node: FlowGraphNode, lane: number) {
+            if (node.lane === -1) {
+                node.lane = lane;
+                node.endLane = lane;
+                const children = getChildren(node);
+                for (let i = 0; i < children.length; i++) {
+                    if (i > 0) lane++;
+                    const child = children[i];
+                    computeLanes(child, lane);
+                    if (child.endLane > node.endLane) {
+                        lane = child.endLane;
+                    }
+                }
+                node.endLane = lane;
+            }
+        }
+
+        function getHeader(flags: FlowFlags) {
+            if (flags & FlowFlags.Start) return "Start";
+            if (flags & FlowFlags.BranchLabel) return "Branch";
+            if (flags & FlowFlags.LoopLabel) return "Loop";
+            if (flags & FlowFlags.Assignment) return "Assignment";
+            if (flags & FlowFlags.TrueCondition) return "True";
+            if (flags & FlowFlags.FalseCondition) return "False";
+            if (flags & FlowFlags.SwitchClause) return "SwitchClause";
+            if (flags & FlowFlags.ArrayMutation) return "ArrayMutation";
+            if (flags & FlowFlags.Call) return "Call";
+            if (flags & FlowFlags.PreFinally) return "PreFinally";
+            if (flags & FlowFlags.AfterFinally) return "AfterFinally";
+            if (flags & FlowFlags.Unreachable) return "Unreachable";
+            throw new Error();
+        }
+
+        function getNodeText(node: Node) {
+            const sourceFile = getSourceFileOfNode(node);
+            return getSourceTextOfNodeFromSourceFile(sourceFile, node, /*includeTrivia*/ false);
+        }
+
+        function renderFlowNode(flowNode: FlowNode) {
+            let text = getHeader(flowNode.flags);
+            if (hasNode(flowNode)) {
+                if (flowNode.node) {
+                    text += ` (${getNodeText(flowNode.node)})`;
+                }
+            }
+            else if (isFlowSwitchClause(flowNode)) {
+                const clauses: string[] = [];
+                for (let i = flowNode.clauseStart; i < flowNode.clauseEnd; i++) {
+                    const clause = flowNode.switchStatement.caseBlock.clauses[i];
+                    if (isDefaultClause(clause)) {
+                        clauses.push("default");
+                    }
+                    else {
+                        clauses.push(getNodeText(clause.expression));
+                    }
+                }
+                text += ` (${clauses.join(", ")})`;
+            }
+            return text;
+        }
+
+        function renderGraph() {
+            const columnCount = columnWidths.length;
+            const laneCount = nodes.reduce((x, n) => Math.max(x, n.lane), 0) + 1;
+            const lanes: string[] = fill(Array(laneCount), "");
+            const grid: (FlowGraphNode | undefined)[][] = columnWidths.map(() => Array(laneCount));
+            const connectors: Connection[][] = columnWidths.map(() => fill(Array(laneCount), 0));
+
+            // build connectors
+            for (const node of nodes) {
+                grid[node.level][node.lane] = node;
+                const children = getChildren(node);
+                for (let i = 0; i < children.length; i++) {
+                    const child = children[i];
+                    let connector: Connection = Connection.Right;
+                    if (child.lane === node.lane) connector |= Connection.Left;
+                    if (i > 0) connector |= Connection.Up;
+                    if (i < children.length - 1) connector |= Connection.Down;
+                    connectors[node.level][child.lane] |= connector;
+                }
+                if (children.length === 0) {
+                    connectors[node.level][node.lane] |= Connection.NoChildren;
+                }
+                const parents = getParents(node);
+                for (let i = 0; i < parents.length; i++) {
+                    const parent = parents[i];
+                    let connector: Connection = Connection.Left;
+                    if (i > 0) connector |= Connection.Up;
+                    if (i < parents.length - 1) connector |= Connection.Down;
+                    connectors[node.level - 1][parent.lane] |= connector;
+                }
+            }
+
+            // fill in missing connectors
+            for (let column = 0; column < columnCount; column++) {
+                for (let lane = 0; lane < laneCount; lane++) {
+                    const left = column > 0 ? connectors[column - 1][lane] : 0;
+                    const above = lane > 0 ? connectors[column][lane - 1] : 0;
+                    let connector = connectors[column][lane];
+                    if (!connector) {
+                        if (left & Connection.Right) connector |= Connection.LeftRight;
+                        if (above & Connection.Down) connector |= Connection.UpDown;
+                        connectors[column][lane] = connector;
+                    }
+                }
+            }
+
+            for (let column = 0; column < columnCount; column++) {
+                for (let lane = 0; lane < lanes.length; lane++) {
+                    const connector = connectors[column][lane];
+                    const fill = connector & Connection.Left ? BoxCharacter.lr : " ";
+                    const node = grid[column][lane];
+                    if (!node) {
+                        if (column < columnCount - 1) {
+                            writeLane(lane, repeat(fill, columnWidths[column] + 1));
+                        }
+                    }
+                    else {
+                        writeLane(lane, node.text);
+                        if (column < columnCount - 1) {
+                            writeLane(lane, " ");
+                            writeLane(lane, repeat(fill, columnWidths[column] - node.text.length));
+                        }
+                    }
+                    writeLane(lane, getBoxCharacter(connector));
+                    writeLane(lane, connector & Connection.Right && column < columnCount - 1 && !grid[column + 1][lane] ? BoxCharacter.lr : " ");
+                }
+            }
+
+            return `\n${lanes.join("\n")}\n`;
+
+            function writeLane(lane: number, text: string) {
+                lanes[lane] += text;
+            }
+        }
+
+        function getBoxCharacter(connector: Connection) {
+            switch (connector) {
+                case Connection.UpDown: return BoxCharacter.ud;
+                case Connection.LeftRight: return BoxCharacter.lr;
+                case Connection.UpLeft: return BoxCharacter.ul;
+                case Connection.UpRight: return BoxCharacter.ur;
+                case Connection.DownLeft: return BoxCharacter.dl;
+                case Connection.DownRight: return BoxCharacter.dr;
+                case Connection.UpDownLeft: return BoxCharacter.udl;
+                case Connection.UpDownRight: return BoxCharacter.udr;
+                case Connection.UpLeftRight: return BoxCharacter.ulr;
+                case Connection.DownLeftRight: return BoxCharacter.dlr;
+                case Connection.UpDownLeftRight: return BoxCharacter.udlr;
+            }
+            return " ";
+        }
+
+        function fill<T>(array: T[], value: T) {
+            if (array.fill) {
+                array.fill(value);
+            }
+            else {
+                for (let i = 0; i < array.length; i++) {
+                    array[i] = value;
+                }
+            }
+            return array;
+        }
+
+        function repeat(ch: string, length: number) {
+            if (ch.repeat) {
+                return length > 0 ? ch.repeat(length) : "";
+            }
+            let s = "";
+            while (s.length < length) {
+                s += ch;
+            }
+            return s;
+        }
+    }
+
+    // Export as a module. NOTE: Can't use module exports as this is built using --outFile
+    declare const module: { exports: {} };
+    if (typeof module !== "undefined" && module.exports) {
+        module.exports = Debug;
+    }
+}

src/debug/tsconfig.json

@@ -0,0 +1,13 @@
+{
+    "extends": "../tsconfig-library-base",
+    "compilerOptions": {
+        "target": "es2019",
+        "lib": ["es2019"],
+        "outFile": "../../built/local/compiler-debug.js",
+        "declaration": false,
+        "sourceMap": true
+    },
+    "files": [
+        "debug.ts"
+    ]
+}

src/harness/client.ts

@@ -290,7 +290,7 @@ namespace ts.server {
             const args: protocol.FileLocationRequestArgs = this.createFileLocationRequestArgs(fileName, position);
 
             const request = this.processRequest<protocol.DefinitionRequest>(CommandNames.DefinitionAndBoundSpan, args);
-            const response = this.processResponse<protocol.DefinitionInfoAndBoundSpanReponse>(request);
+            const response = this.processResponse<protocol.DefinitionInfoAndBoundSpanResponse>(request);
             const body = Debug.assertDefined(response.body); // TODO: GH#18217
 
             return {

src/harness/fakes.ts

@@ -524,7 +524,7 @@ ${indentText}${text}`;
 
     export const version = "FakeTSVersion";
 
-    export function patchSolutionBuilderHost(host: ts.SolutionBuilderHost<ts.BuilderProgram>, sys: System) {
+    export function patchHostForBuildInfoReadWrite(host: ts.CompilerHost | ts.SolutionBuilderHost<ts.BuilderProgram>) {
         const originalReadFile = host.readFile;
         host.readFile = (path, encoding) => {
             const value = originalReadFile.call(host, path, encoding);
@@ -537,7 +537,7 @@ ${indentText}${text}`;
 
         if (host.writeFile) {
             const originalWriteFile = host.writeFile;
-            host.writeFile = (fileName, content, writeByteOrderMark) => {
+            host.writeFile = (fileName: string, content: string, writeByteOrderMark: boolean) => {
                 if (!ts.isBuildInfoFile(fileName)) return originalWriteFile.call(host, fileName, content, writeByteOrderMark);
                 const buildInfo = ts.getBuildInfo(content);
                 sanitizeBuildInfoProgram(buildInfo);
@@ -545,6 +545,10 @@ ${indentText}${text}`;
                 originalWriteFile.call(host, fileName, ts.getBuildInfoText(buildInfo), writeByteOrderMark);
             };
         }
+    }
+
+    export function patchSolutionBuilderHost(host: ts.SolutionBuilderHost<ts.BuilderProgram>, sys: System) {
+        patchHostForBuildInfoReadWrite(host);
 
         ts.Debug.assert(host.now === undefined);
         host.now = () => new Date(sys.vfs.time());

src/harness/fourslash.ts

@@ -775,7 +775,9 @@ namespace FourSlash {
         private verifyCompletionsWorker(options: FourSlashInterface.VerifyCompletionsOptions): void {
             const actualCompletions = this.getCompletionListAtCaret({ ...options.preferences, triggerCharacter: options.triggerCharacter })!;
             if (!actualCompletions) {
-                if (ts.hasProperty(options, "exact") && options.exact === undefined) return;
+                if (ts.hasProperty(options, "exact") && (options.exact === undefined || ts.isArray(options.exact) && !options.exact.length)) {
+                    return;
+                }
                 this.raiseError(`No completions at position '${this.currentCaretPosition}'.`);
             }
 
@@ -4894,12 +4896,14 @@ namespace FourSlashInterface {
             "declare",
             "keyof",
             "module",
+            "namespace",
             "never",
             "readonly",
             "number",
             "object",
             "string",
             "symbol",
+            "type",
             "unique",
             "unknown",
             "bigint",
@@ -5091,12 +5095,14 @@ namespace FourSlashInterface {
             "declare",
             "keyof",
             "module",
+            "namespace",
             "never",
             "readonly",
             "number",
             "object",
             "string",
             "symbol",
+            "type",
             "unique",
             "unknown",
             "bigint",

src/harness/harnessLanguageService.ts

@@ -220,6 +220,10 @@ namespace Harness.LanguageService {
             return !!this.typesRegistry && this.typesRegistry.has(name);
         }
 
+        getGlobalTypingsCacheLocation() {
+            return "/Library/Caches/typescript";
+        }
+
         installPackage = ts.notImplemented;
 
         getCompilationSettings() { return this.settings; }
@@ -796,7 +800,7 @@ namespace Harness.LanguageService {
             return mockHash(s);
         }
 
-        require(_initialDir: string, _moduleName: string): ts.server.RequireResult {
+        require(_initialDir: string, _moduleName: string): ts.RequireResult {
             switch (_moduleName) {
                 // Adds to the Quick Info a fixed string and a string from the config file
                 // and replaces the first display part

src/harness/virtualFileSystemWithWatch.ts

@@ -341,7 +341,7 @@ interface Array<T> { length: number; [n: number]: T; }`
         private readonly currentDirectory: string;
         private readonly customWatchFile: HostWatchFile | undefined;
         private readonly customRecursiveWatchDirectory: HostWatchDirectory | undefined;
-        public require: ((initialPath: string, moduleName: string) => server.RequireResult) | undefined;
+        public require: ((initialPath: string, moduleName: string) => RequireResult) | undefined;
 
         constructor(
             public withSafeList: boolean,

src/lib/dom.generated.d.ts

@@ -9762,7 +9762,7 @@ interface ImageData {
 declare var ImageData: {
     prototype: ImageData;
     new(width: number, height: number): ImageData;
-    new(array: Uint8ClampedArray, width: number, height: number): ImageData;
+    new(array: Uint8ClampedArray, width: number, height?: number): ImageData;
 };
 
 interface InnerHTML {
@@ -19083,7 +19083,7 @@ declare namespace WebAssembly {
     
     var Instance: {
         prototype: Instance;
-        new(module: Module, importObject?: any): Instance;
+        new(module: Module, importObject?: Imports): Instance;
     };
     
     interface LinkError {

src/lib/es5.d.ts

@@ -682,8 +682,8 @@ interface Math {
     /** Returns a pseudorandom number between 0 and 1. */
     random(): number;
     /**
-     * Returns a supplied numeric expression rounded to the nearest number.
-     * @param x The value to be rounded to the nearest number.
+     * Returns a supplied numeric expression rounded to the nearest integer.
+     * @param x The value to be rounded to the nearest integer.
      */
     round(x: number): number;
     /**
@@ -873,12 +873,12 @@ interface DateConstructor {
     /**
      * Returns the number of milliseconds between midnight, January 1, 1970 Universal Coordinated Time (UTC) (or GMT) and the specified date.
      * @param year The full year designation is required for cross-century date accuracy. If year is between 0 and 99 is used, then year is assumed to be 1900 + year.
-     * @param month The month as an number between 0 and 11 (January to December).
-     * @param date The date as an number between 1 and 31.
-     * @param hours Must be supplied if minutes is supplied. An number from 0 to 23 (midnight to 11pm) that specifies the hour.
-     * @param minutes Must be supplied if seconds is supplied. An number from 0 to 59 that specifies the minutes.
-     * @param seconds Must be supplied if milliseconds is supplied. An number from 0 to 59 that specifies the seconds.
-     * @param ms An number from 0 to 999 that specifies the milliseconds.
+     * @param month The month as a number between 0 and 11 (January to December).
+     * @param date The date as a number between 1 and 31.
+     * @param hours Must be supplied if minutes is supplied. A number from 0 to 23 (midnight to 11pm) that specifies the hour.
+     * @param minutes Must be supplied if seconds is supplied. A number from 0 to 59 that specifies the minutes.
+     * @param seconds Must be supplied if milliseconds is supplied. A number from 0 to 59 that specifies the seconds.
+     * @param ms A number from 0 to 999 that specifies the milliseconds.
      */
     UTC(year: number, month: number, date?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): number;
     now(): number;

src/lib/webworker.generated.d.ts

@@ -2202,7 +2202,7 @@ interface ImageData {
 declare var ImageData: {
     prototype: ImageData;
     new(width: number, height: number): ImageData;
-    new(array: Uint8ClampedArray, width: number, height: number): ImageData;
+    new(array: Uint8ClampedArray, width: number, height?: number): ImageData;
 };
 
 /** This Channel Messaging API interface allows us to create a new message channel and send data through it via its two MessagePort properties. */
@@ -5609,7 +5609,7 @@ declare namespace WebAssembly {
     
     var Instance: {
         prototype: Instance;
-        new(module: Module, importObject?: any): Instance;
+        new(module: Module, importObject?: Imports): Instance;
     };
     
     interface Memory {

src/loc/lcl/chs/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -4087,7 +4087,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Function lacks ending return statement and return type does not include 'undefined'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[函数缺少结束返回语句，返回类型不包括 "undefined"。]]></Val>
+            <Val><![CDATA[函数缺少结束 return 语句，返回类型不包括 "undefined"。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4987,7 +4987,7 @@
         <Str Cat="Text">
           <Val><![CDATA[JSX fragment is not supported when using an inline JSX factory pragma]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[使用内联 JSX 工厂杂注时，不支持 JSX 片段]]></Val>
+            <Val><![CDATA[使用内联 JSX 工厂 pragma 时，不支持 JSX 片段]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/cht/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -25,7 +25,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A '{0}' modifier cannot be used with an import declaration.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 修飾詞無法與匯入宣告並用。]]></Val>
+            <Val><![CDATA['{0}' 修飾元無法與匯入宣告並用。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -34,7 +34,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A '{0}' modifier cannot be used with an interface declaration.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 修飾詞無法與介面宣告並用。]]></Val>
+            <Val><![CDATA['{0}' 修飾元無法與介面宣告並用。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -88,7 +88,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A class declaration without the 'default' modifier must have a name.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[不具 'default' 修飾詞的類別宣告必須要有名稱。]]></Val>
+            <Val><![CDATA[不具 'default' 修飾元的類別宣告必須要有名稱。]]></Val>
           </Tgt>
           <Prev Cat="Text">
             <Val><![CDATA[A class declaration without the 'default' modifier must have a name]]></Val>
@@ -265,7 +265,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A 'declare' modifier cannot be used in an already ambient context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[不得在現有環境內容中使用 'declare' 修飾詞。]]></Val>
+            <Val><![CDATA[不得在現有環境內容中使用 'declare' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -274,7 +274,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A 'declare' modifier is required for a top level declaration in a .d.ts file.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[.d.ts 檔案中的最上層宣告需要 'declare' 修飾詞。]]></Val>
+            <Val><![CDATA[.d.ts 檔案中的最上層宣告需要 'declare' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -886,7 +886,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Accessibility modifier already seen.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[已有存取範圍修飾詞。]]></Val>
+            <Val><![CDATA[已有存取範圍修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -934,7 +934,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Add all missing 'async' modifiers]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[新增缺少的所有 'async' 修飾詞]]></Val>
+            <Val><![CDATA[新增缺少的所有 'async' 修飾元]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -961,7 +961,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Add async modifier to containing function]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[將 async 修飾詞新增至包含的函式]]></Val>
+            <Val><![CDATA[將 async 修飾元新增至包含的函式]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1129,7 +1129,7 @@
         <Str Cat="Text">
           <Val><![CDATA[All declarations of '{0}' must have identical modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 的所有宣告都必須有相同修飾詞。]]></Val>
+            <Val><![CDATA['{0}' 的所有宣告都必須有相同修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1363,7 +1363,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot have modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[匯出指派不得有修飾詞。]]></Val>
+            <Val><![CDATA[匯出指派不得有修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1381,7 +1381,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export declaration cannot have modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[匯出宣告不得有修飾詞。]]></Val>
+            <Val><![CDATA[匯出宣告不得有修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1417,7 +1417,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An import declaration cannot have modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[匯入宣告不得有修飾詞。]]></Val>
+            <Val><![CDATA[匯入宣告不得有修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1480,7 +1480,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An index signature parameter cannot have an accessibility modifier.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[索引簽章參數不得有存取範圍修飾詞。]]></Val>
+            <Val><![CDATA[索引簽章參數不得有存取範圍修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1708,7 +1708,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Augmentations for the global scope should have 'declare' modifier unless they appear in already ambient context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[除非全域範圍的增強指定已顯示在環境內容中，否則應含有 'declare' 修飾詞。]]></Val>
+            <Val><![CDATA[除非全域範圍的增強指定已顯示在環境內容中，否則應含有 'declare' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4087,7 +4087,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Function lacks ending return statement and return type does not include 'undefined'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[函式缺少結束傳回陳述式，且傳回類型不包括 'undefined'。]]></Val>
+            <Val><![CDATA[函式缺少結束 return 陳述式，且傳回類型不包括 'undefined'。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -5260,7 +5260,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Modifiers cannot appear here.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[此處不得出現修飾詞。]]></Val>
+            <Val><![CDATA[此處不得出現修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9325,7 +9325,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier already seen.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[已有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[已有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9334,7 +9334,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a class element.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[類別項目不得有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[類別項目不得有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9343,7 +9343,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a constructor declaration.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[建構函式宣告不得有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[建構函式宣告不得有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9352,7 +9352,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a data property.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[資料屬性不得有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[資料屬性不得有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9361,7 +9361,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a module or namespace element.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[模組或命名空間元素不能有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[模組或命名空間元素不能有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9370,7 +9370,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a parameter.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[參數不得有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[參數不得有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9379,7 +9379,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on a type member.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[類型成員不能有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[類型成員不能有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9388,7 +9388,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot appear on an index signature.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[索引簽章不能有 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[索引簽章不能有 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9397,7 +9397,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot be used here.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[無法在此處使用 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[無法在此處使用 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9406,7 +9406,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot be used in an ambient context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[無法在環境內容中使用 '{0}' 修飾詞。]]></Val>
+            <Val><![CDATA[無法在環境內容中使用 '{0}' 修飾元。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9415,7 +9415,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot be used with '{1}' modifier.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 修飾詞無法與 '{1}' 修飾詞並用。]]></Val>
+            <Val><![CDATA['{0}' 修飾元無法與 '{1}' 修飾元並用。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9424,7 +9424,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier cannot be used with a class declaration.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 修飾詞無法與類別宣告並用。]]></Val>
+            <Val><![CDATA['{0}' 修飾元無法與類別宣告並用。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9433,7 +9433,7 @@
         <Str Cat="Text">
           <Val><![CDATA['{0}' modifier must precede '{1}' modifier.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['{0}' 修飾詞必須在 '{1}' 修飾詞之前。]]></Val>
+            <Val><![CDATA['{0}' 修飾元必須在 '{1}' 修飾元之前。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9496,7 +9496,7 @@
         <Str Cat="Text">
           <Val><![CDATA['abstract' modifier can only appear on a class, method, or property declaration.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['abstract' 修飾詞只能出現在類別宣告、方法宣告或屬性宣告。]]></Val>
+            <Val><![CDATA['abstract' 修飾元只能出現在類別宣告、方法宣告或屬性宣告。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9649,7 +9649,7 @@
         <Str Cat="Text">
           <Val><![CDATA['export' modifier cannot be applied to ambient modules and module augmentations since they are always visible.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['export' 修飾詞無法套用至環境模組或模組增強指定，原因是這二者永遠會顯示。]]></Val>
+            <Val><![CDATA['export' 修飾元無法套用至環境模組或模組增強指定，原因是這二者永遠會顯示。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9874,7 +9874,7 @@
         <Str Cat="Text">
           <Val><![CDATA['readonly' modifier can only appear on a property declaration or index signature.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['readonly' 修飾詞只能出現在屬性宣告或索引簽章。]]></Val>
+            <Val><![CDATA['readonly' 修飾元只能出現在屬性宣告或索引簽章。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/csy/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <LCX SchemaVersion="6.0" Name="f:\ddSetup\sources\typescript\localization\compiler2.resx" PsrId="306" FileType="1" SrcCul="en-US" TgtCul="cs-CZ" xmlns="http://schemas.microsoft.com/locstudio/2006/6/lcx">
   <Props>
     <Str Name="CustomName1" Val="Custom 1" />
@@ -4096,7 +4096,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Function lacks ending return statement and return type does not include 'undefined'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Ve funkci chybí koncový návratový příkaz a návratový typ neobsahuje undefined.]]></Val>
+            <Val><![CDATA[Ve funkci chybí koncový příkaz return a návratový typ neobsahuje undefined.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/fra/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <LCX SchemaVersion="6.0" Name="f:\ddSetup\sources\typescript\localization\compiler2.resx" PsrId="306" FileType="1" SrcCul="en-US" TgtCul="fr-FR" xmlns="http://schemas.microsoft.com/locstudio/2006/6/lcx">
   <Props>
     <Str Name="CustomName1" Val="Custom 1" />
@@ -1348,7 +1348,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment can only be used in a module.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Une attribution d'exportation peut uniquement être utilisée dans un module.]]></Val>
+            <Val><![CDATA[Une affectation d'exportation peut uniquement être utilisée dans un module.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -5539,7 +5539,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Not all code paths return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Les chemins de code ne retournent pas tous une valeur.]]></Val>
+            <Val><![CDATA[Les chemins du code ne retournent pas tous une valeur.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -6916,7 +6916,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Report error when not all code paths in function return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Signalez une erreur quand les chemins de code de la fonction ne retournent pas tous une valeur.]]></Val>
+            <Val><![CDATA[Signalez une erreur quand les chemins du code de la fonction ne retournent pas tous une valeur.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/jpn/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -1228,7 +1228,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An AMD module cannot have multiple name assignments.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[AMD モジュールに複数の名前を割り当てることはできません。]]></Val>
+            <Val><![CDATA[AMD モジュールに複数の名前を代入することはできません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1336,7 +1336,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment can only be used in a module.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートの割り当てはモジュールでのみ使用可能です。]]></Val>
+            <Val><![CDATA[エクスポートの代入はモジュールでのみ使用可能です。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1345,7 +1345,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot be used in a module with other exported elements.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートの割り当ては、エクスポートされた他の要素を含むモジュールでは使用できません。]]></Val>
+            <Val><![CDATA[エクスポートの代入は、エクスポートされた他の要素を含むモジュールでは使用できません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1354,7 +1354,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot be used in a namespace.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートの割り当ては、名前空間では使用できません。]]></Val>
+            <Val><![CDATA[エクスポートの代入は、名前空間では使用できません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1363,7 +1363,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot have modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートの割り当てに修飾子を指定することはできません。]]></Val>
+            <Val><![CDATA[エクスポートの代入に修飾子を指定することはできません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -3610,7 +3610,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Export assignment cannot be used when targeting ECMAScript modules. Consider using 'export default' or another module format instead.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[ECMAScript モジュールを対象にする場合は、エクスポート割り当てを使用できません。代わりに 'export default' または別のモジュール書式の使用をご検討ください。]]></Val>
+            <Val><![CDATA[ECMAScript モジュールを対象にする場合は、エクスポート代入を使用できません。代わりに 'export default' または別のモジュール書式の使用をご検討ください。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -3619,7 +3619,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Export assignment is not supported when '--module' flag is 'system'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[割り当てのエクスポートは、'--module' フラグが 'system' の場合にはサポートされません。]]></Val>
+            <Val><![CDATA[代入のエクスポートは、'--module' フラグが 'system' の場合にはサポートされません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -3703,7 +3703,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Exports and export assignments are not permitted in module augmentations.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートとエクスポートの割り当てはモジュールの拡張では許可されていません。]]></Val>
+            <Val><![CDATA[エクスポートとエクスポートの代入はモジュールの拡張では許可されていません。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4390,7 +4390,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Import assignment cannot be used when targeting ECMAScript modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[ECMAScript モジュールを対象にする場合は、インポート割り当てを使用できません。代わりに 'import * as ns from "mod"'、'import {a} from "mod"'、'import d from "mod"' などのモジュール書式の使用をご検討ください。]]></Val>
+            <Val><![CDATA[ECMAScript モジュールを対象にする場合は、インポート代入を使用できません。代わりに 'import * as ns from "mod"'、'import {a} from "mod"'、'import d from "mod"' などのモジュール書式の使用をご検討ください。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4987,7 +4987,7 @@
         <Str Cat="Text">
           <Val><![CDATA[JSX fragment is not supported when using an inline JSX factory pragma]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[JSX フラグメントはインライン JSX ファクトリ プラグマの使用時にサポートされていません]]></Val>
+            <Val><![CDATA[JSX フラグメントはインライン JSX ファクトリ pragma の使用時にサポートされていません]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -6622,7 +6622,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Property assignment expected.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[プロパティの割り当てが必要です。]]></Val>
+            <Val><![CDATA[プロパティの代入が必要です。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -7870,7 +7870,7 @@
         <Str Cat="Text">
           <Val><![CDATA[The expression of an export assignment must be an identifier or qualified name in an ambient context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[エクスポートの割り当ての式は、環境コンテキストの識別子または修飾名にする必要があります。]]></Val>
+            <Val><![CDATA[エクスポートの代入の式は、環境コンテキストの識別子または修飾名にする必要があります。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -8170,7 +8170,7 @@
         <Str Cat="Text">
           <Val><![CDATA[The target of an object rest assignment must be a variable or a property access.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[オブジェクトの残り部分の割り当ての対象は、変数またはプロパティ アクセスである必要があります。]]></Val>
+            <Val><![CDATA[オブジェクトの残り部分の代入の対象は、変数またはプロパティ アクセスである必要があります。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9535,7 +9535,7 @@
         <Str Cat="Text">
           <Val><![CDATA['=' can only be used in an object literal property inside a destructuring assignment.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['=' は、非構造化割り当て内のオブジェクト リテラル プロパティでのみ使用できます。]]></Val>
+            <Val><![CDATA['=' は、非構造化代入内のオブジェクト リテラル プロパティでのみ使用できます。]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9601,7 +9601,7 @@
         <Str Cat="Text">
           <Val><![CDATA['const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment or type query.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['const' 列挙型は、プロパティまたはインデックスのアクセス式、インポート宣言またはエクスポートの割り当ての右辺、型のクエリにのみ使用できます。]]></Val>
+            <Val><![CDATA['const' 列挙型は、プロパティまたはインデックスのアクセス式、インポート宣言またはエクスポートの代入の右辺、型のクエリにのみ使用できます。]]></Val>
           </Tgt>
           <Prev Cat="Text">
             <Val><![CDATA['const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment.]]></Val>

src/loc/lcl/kor/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -9856,7 +9856,7 @@
         <Str Cat="Text">
           <Val><![CDATA['parameter modifiers' can only be used in a .ts file.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA['parameter modifiers'는 .ts 파일에서만 사용할 수 있습니다.]]></Val>
+            <Val><![CDATA['매개 변수 한정자'는 .ts 파일에서만 사용할 수 있습니다.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/plk/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -303,7 +303,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A definite assignment assertion '!' is not permitted in this context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Asercja określonego przydziału „!” nie jest dozwolona w tym kontekście.]]></Val>
+            <Val><![CDATA[Asercja określonego przypisania „!” nie jest dozwolona w tym kontekście.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4077,7 +4077,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Function lacks ending return statement and return type does not include 'undefined'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Funkcja nie zawiera końcowej instrukcji „return”, a zwracany typ nie obejmuje wartości „undefined”.]]></Val>
+            <Val><![CDATA[Funkcja nie zawiera końcowej instrukcji return, a zwracany typ nie obejmuje wartości „undefined”.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -5517,7 +5517,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Not all code paths return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Nie wszystkie ścieżki kodu zwracają wartość.]]></Val>
+            <Val><![CDATA[Nie wszystkie ścieżki w kodzie zwracają wartość.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -6891,7 +6891,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Report error when not all code paths in function return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Zgłoś błąd, gdy nie wszystkie ścieżki kodu zwracają wartość.]]></Val>
+            <Val><![CDATA[Zgłoś błąd, gdy nie wszystkie ścieżki w kodzie zwracają wartość.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/loc/lcl/rus/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -309,7 +309,7 @@
         <Str Cat="Text">
           <Val><![CDATA[A definite assignment assertion '!' is not permitted in this context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Утверждение определенного присваивания "!" запрещено в этом контексте.]]></Val>
+            <Val><![CDATA[Утверждение определенного назначения "!" запрещено в этом контексте.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -978,7 +978,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Add definite assignment assertion to property '{0}']]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Добавить утверждение определенного присваивания к свойству "{0}"]]></Val>
+            <Val><![CDATA[Добавить утверждение определенного назначения к свойству "{0}"]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -987,7 +987,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Add definite assignment assertions to all uninitialized properties]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Добавить утверждения определенного присваивания ко всем неинициализированным свойствам]]></Val>
+            <Val><![CDATA[Добавить утверждения определенного назначения ко всем неинициализированным свойствам]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1227,7 +1227,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An AMD module cannot have multiple name assignments.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Модуль AMD не может иметь несколько присваиваний имен.]]></Val>
+            <Val><![CDATA[Модуль AMD не может иметь несколько назначений имен.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1335,7 +1335,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment can only be used in a module.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Присваивание экспорта может быть использовано только в модуле.]]></Val>
+            <Val><![CDATA[Назначение экспорта может быть использовано только в модуле.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1344,7 +1344,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot be used in a module with other exported elements.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Присваивание экспорта нельзя использовать в модуле с другими экспортированными элементами.]]></Val>
+            <Val><![CDATA[Назначение экспорта нельзя использовать в модуле с другими экспортированными элементами.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1353,7 +1353,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot be used in a namespace.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Присваивание экспорта нельзя использовать в пространстве имен.]]></Val>
+            <Val><![CDATA[Назначение экспорта нельзя использовать в пространстве имен.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -1362,7 +1362,7 @@
         <Str Cat="Text">
           <Val><![CDATA[An export assignment cannot have modifiers.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Присваивание экспорта не может иметь модификаторы.]]></Val>
+            <Val><![CDATA[Назначение экспорта не может иметь модификаторы.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -3618,7 +3618,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Export assignment is not supported when '--module' flag is 'system'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Присваивание экспорта не поддерживается, если флаг "--module" имеет значение "system".]]></Val>
+            <Val><![CDATA[Назначение экспорта не поддерживается, если флаг "--module" имеет значение "system".]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -4086,7 +4086,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Function lacks ending return statement and return type does not include 'undefined'.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[В функции отсутствует завершающий оператор возвращаемого значения, а тип возвращаемого значения не включает undefined.]]></Val>
+            <Val><![CDATA[В функции отсутствует завершающий оператор return, а тип возвращаемого значения не включает "undefined".]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -5526,7 +5526,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Not all code paths return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Не все пути кода возвращают значение.]]></Val>
+            <Val><![CDATA[Не все пути к коду возвращают значение.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -6621,7 +6621,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Property assignment expected.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Ожидалось присваивание свойства.]]></Val>
+            <Val><![CDATA[Ожидалось назначение свойства.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -6903,7 +6903,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Report error when not all code paths in function return a value.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Сообщать об ошибке, если не все пути кода в функции возвращают значение.]]></Val>
+            <Val><![CDATA[Сообщать об ошибке, если не все пути к коду в функции возвращают значение.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -7869,7 +7869,7 @@
         <Str Cat="Text">
           <Val><![CDATA[The expression of an export assignment must be an identifier or qualified name in an ambient context.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Выражение присваивания экспорта должно представлять собой идентификатор или полное имя в окружающем контексте.]]></Val>
+            <Val><![CDATA[Выражение назначения экспорта должно представлять собой идентификатор или полное имя в окружающем контексте.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />
@@ -9600,7 +9600,7 @@
         <Str Cat="Text">
           <Val><![CDATA['const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment or type query.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Перечисления const можно использовать только в выражениях доступа к свойству или индексу, а также в правой части объявления импорта, присваивания экспорта или запроса типа.]]></Val>
+            <Val><![CDATA[Перечисления const можно использовать только в выражениях доступа к свойству или индексу, а также в правой части объявления импорта, назначения экспорта или запроса типа.]]></Val>
           </Tgt>
           <Prev Cat="Text">
             <Val><![CDATA['const' enums can only be used in property or index access expressions or the right hand side of an import declaration or export assignment.]]></Val>

src/loc/lcl/trk/diagnosticMessages/diagnosticMessages.generated.json.lcl

@@ -4188,7 +4188,7 @@
         <Str Cat="Text">
           <Val><![CDATA[Generic type instantiation is excessively deep and possibly infinite.]]></Val>
           <Tgt Cat="Text" Stat="Loc" Orig="New">
-            <Val><![CDATA[Genel tür oluşturma işlemi, fazla ayrıntılı ve büyük olasılıkla sınırsız.]]></Val>
+            <Val><![CDATA[Genel tür örneği oluşturma işlemi, fazla ayrıntılı ve büyük olasılıkla sınırsız.]]></Val>
           </Tgt>
         </Str>
         <Disp Icon="Str" />

src/server/editorServices.ts

@@ -1533,6 +1533,14 @@ namespace ts.server {
             return undefined;
         }
 
+        /*@internal*/
+        findDefaultConfiguredProject(info: ScriptInfo) {
+            if (!info.isScriptOpen()) return undefined;
+            const configFileName = this.getConfigFileNameForFile(info);
+            return configFileName &&
+                this.findConfiguredProjectByProjectName(configFileName);
+        }
+
         /**
          * This function tries to search for a tsconfig.json for the given file.
          * This is different from the method the compiler uses because

src/server/project.ts

@@ -307,6 +307,11 @@ namespace ts.server {
             return this.typingsCache.installPackage({ ...options, projectName: this.projectName, projectRootPath: this.toPath(this.currentDirectory) });
         }
 
+        /*@internal*/
+        getGlobalTypingsCacheLocation() {
+            return this.getGlobalCache();
+        }
+
         private get typingsCache(): TypingsCache {
             return this.projectService.typingsCache;
         }

src/server/protocol.ts

@@ -918,10 +918,13 @@ namespace ts.server.protocol {
         body?: FileSpanWithContext[];
     }
 
-    export interface DefinitionInfoAndBoundSpanReponse extends Response {
+    export interface DefinitionInfoAndBoundSpanResponse extends Response {
         body?: DefinitionInfoAndBoundSpan;
     }
 
+    /** @deprecated Use `DefinitionInfoAndBoundSpanResponse` instead. */
+    export type DefinitionInfoAndBoundSpanReponse = DefinitionInfoAndBoundSpanResponse;
+
     /**
      * Definition response message.  Gives text range for definition.
      */
@@ -3004,6 +3007,12 @@ namespace ts.server.protocol {
          * For those entries, The `insertText` and `replacementSpan` properties will be set to change from `.x` property access to `["x"]`.
          */
         readonly includeCompletionsWithInsertText?: boolean;
+        /**
+         * Unless this option is `false`, or `includeCompletionsWithInsertText` is not enabled,
+         * member completion lists triggered with `.` will include entries on potentially-null and potentially-undefined
+         * values, with insertion text to replace preceding `.` tokens with `?.`.
+         */
+        readonly includeAutomaticOptionalChainCompletions?: boolean;
         readonly importModuleSpecifierPreference?: "relative" | "non-relative";
         readonly allowTextChangesInNewFiles?: boolean;
         readonly lazyConfiguredProjectsFromExternalProject?: boolean;

src/server/scriptInfo.ts

@@ -491,21 +491,40 @@ namespace ts.server {
                 case 1:
                     return this.containingProjects[0];
                 default:
-                    // if this file belongs to multiple projects, the first configured project should be
-                    // the default project; if no configured projects, the first external project should
-                    // be the default project; otherwise the first inferred project should be the default.
+                    // If this file belongs to multiple projects, below is the order in which default project is used
+                    // - for open script info, its default configured project during opening is default if info is part of it
+                    // - first configured project of which script info is not a source of project reference redirect
+                    // - first configured project
+                    // - first external project
+                    // - first inferred project
                     let firstExternalProject;
                     let firstConfiguredProject;
-                    for (const project of this.containingProjects) {
+                    let firstNonSourceOfProjectReferenceRedirect;
+                    let defaultConfiguredProject: ConfiguredProject | false | undefined;
+                    for (let index = 0; index < this.containingProjects.length; index++) {
+                        const project = this.containingProjects[index];
                         if (project.projectKind === ProjectKind.Configured) {
-                            if (!project.isSourceOfProjectReferenceRedirect(this.fileName)) return project;
+                            if (!project.isSourceOfProjectReferenceRedirect(this.fileName)) {
+                                // If we havent found default configuredProject and
+                                // its not the last one, find it and use that one if there
+                                if (defaultConfiguredProject === undefined &&
+                                    index !== this.containingProjects.length - 1) {
+                                    defaultConfiguredProject = project.projectService.findDefaultConfiguredProject(this) || false;
+                                }
+                                if (defaultConfiguredProject === project) return project;
+                                if (!firstNonSourceOfProjectReferenceRedirect) firstNonSourceOfProjectReferenceRedirect = project;
+                            }
                             if (!firstConfiguredProject) firstConfiguredProject = project;
                         }
                         else if (project.projectKind === ProjectKind.External && !firstExternalProject) {
                             firstExternalProject = project;
                         }
                     }
-                    return firstConfiguredProject || firstExternalProject || this.containingProjects[0];
+                    return defaultConfiguredProject ||
+                        firstNonSourceOfProjectReferenceRedirect ||
+                        firstConfiguredProject ||
+                        firstExternalProject ||
+                        this.containingProjects[0];
             }
         }
 

src/services/classifier.ts

@@ -499,8 +499,10 @@ namespace ts {
         return { spans, endOfLineState: EndOfLineState.None };
 
         function pushClassification(start: number, end: number, type: ClassificationType): void {
+            const length = end - start;
+            Debug.assert(length > 0, `Classification had non-positive length of ${length}`);
             spans.push(start);
-            spans.push(end - start);
+            spans.push(length);
             spans.push(type);
         }
     }
@@ -985,8 +987,7 @@ namespace ts {
                 return ClassificationType.bigintLiteral;
             }
             else if (tokenKind === SyntaxKind.StringLiteral) {
-                // TODO: GH#18217
-                return token!.parent.kind === SyntaxKind.JsxAttribute ? ClassificationType.jsxAttributeStringLiteralValue : ClassificationType.stringLiteral;
+                return token && token.parent.kind === SyntaxKind.JsxAttribute ? ClassificationType.jsxAttributeStringLiteralValue : ClassificationType.stringLiteral;
             }
             else if (tokenKind === SyntaxKind.RegularExpressionLiteral) {
                 // TODO: we should get another classification type for these literals.

src/services/codefixes/helpers.ts

@@ -233,14 +233,14 @@ namespace ts.codefix {
         let someSigHasRestParameter = false;
         for (const sig of signatures) {
             minArgumentCount = Math.min(sig.minArgumentCount, minArgumentCount);
-            if (sig.hasRestParameter) {
+            if (signatureHasRestParameter(sig)) {
                 someSigHasRestParameter = true;
             }
-            if (sig.parameters.length >= maxArgsSignature.parameters.length && (!sig.hasRestParameter || maxArgsSignature.hasRestParameter)) {
+            if (sig.parameters.length >= maxArgsSignature.parameters.length && (!signatureHasRestParameter(sig) || signatureHasRestParameter(maxArgsSignature))) {
                 maxArgsSignature = sig;
             }
         }
-        const maxNonRestArgs = maxArgsSignature.parameters.length - (maxArgsSignature.hasRestParameter ? 1 : 0);
+        const maxNonRestArgs = maxArgsSignature.parameters.length - (signatureHasRestParameter(maxArgsSignature) ? 1 : 0);
         const maxArgsParameterSymbolNames = maxArgsSignature.parameters.map(symbol => symbol.name);
 
         const parameters = createDummyParameters(maxNonRestArgs, maxArgsParameterSymbolNames, /* types */ undefined, minArgumentCount, /*inJs*/ false);

src/services/codefixes/importFixes.ts

@@ -631,6 +631,7 @@ namespace ts.codefix {
         let filteredCount = 0;
         const packageJson = filterByPackageJson && createAutoImportFilter(from, program, host);
         const allSourceFiles = program.getSourceFiles();
+        const globalTypingsCache = host.getGlobalTypingsCacheLocation && host.getGlobalTypingsCacheLocation();
         forEachExternalModule(program.getTypeChecker(), allSourceFiles, (module, sourceFile) => {
             if (sourceFile === undefined) {
                 if (!packageJson || packageJson.allowsImportingAmbientModule(module, allSourceFiles)) {
@@ -640,7 +641,10 @@ namespace ts.codefix {
                     filteredCount++;
                 }
             }
-            else if (sourceFile && sourceFile !== from && isImportablePath(from.fileName, sourceFile.fileName)) {
+            else if (sourceFile &&
+                sourceFile !== from &&
+                isImportablePath(from.fileName, sourceFile.fileName, hostGetCanonicalFileName(host), globalTypingsCache)
+            ) {
                 if (!packageJson || packageJson.allowsImportingSourceFile(sourceFile, allSourceFiles)) {
                     cb(module);
                 }
@@ -669,10 +673,13 @@ namespace ts.codefix {
      * Don't include something from a `node_modules` that isn't actually reachable by a global import.
      * A relative import to node_modules is usually a bad idea.
      */
-    function isImportablePath(fromPath: string, toPath: string): boolean {
+    function isImportablePath(fromPath: string, toPath: string, getCanonicalFileName: GetCanonicalFileName, globalCachePath?: string): boolean {
         // If it's in a `node_modules` but is not reachable from here via a global import, don't bother.
         const toNodeModules = forEachAncestorDirectory(toPath, ancestor => getBaseFileName(ancestor) === "node_modules" ? ancestor : undefined);
-        return toNodeModules === undefined || startsWith(fromPath, getDirectoryPath(toNodeModules));
+        const toNodeModulesParent = toNodeModules && getDirectoryPath(getCanonicalFileName(toNodeModules));
+        return toNodeModulesParent === undefined
+            || startsWith(getCanonicalFileName(fromPath), toNodeModulesParent)
+            || (!!globalCachePath && startsWith(getCanonicalFileName(globalCachePath), toNodeModulesParent));
     }
 
     export function moduleSymbolToValidIdentifier(moduleSymbol: Symbol, target: ScriptTarget): string {
@@ -718,6 +725,7 @@ namespace ts.codefix {
             readFile: maybeBind(host, host.readFile),
             useCaseSensitiveFileNames: maybeBind(host, host.useCaseSensitiveFileNames),
             getProbableSymlinks: maybeBind(host, host.getProbableSymlinks) || program.getProbableSymlinks,
+            getGlobalTypingsCacheLocation: maybeBind(host, host.getGlobalTypingsCacheLocation),
         };
 
         let usesNodeCoreModules: boolean | undefined;

src/services/codefixes/inferFromUsage.ts

@@ -49,21 +49,21 @@ namespace ts.codefix {
     registerCodeFix({
         errorCodes,
         getCodeActions(context) {
-            const { sourceFile, program, span: { start }, errorCode, cancellationToken, host } = context;
+            const { sourceFile, program, span: { start }, errorCode, cancellationToken, host, formatContext, preferences } = context;
 
             const token = getTokenAtPosition(sourceFile, start);
             let declaration!: Declaration | undefined;
-            const changes = textChanges.ChangeTracker.with(context, changes => { declaration = doChange(changes, sourceFile, token, errorCode, program, cancellationToken, /*markSeen*/ returnTrue, host); });
+            const changes = textChanges.ChangeTracker.with(context, changes => { declaration = doChange(changes, sourceFile, token, errorCode, program, cancellationToken, /*markSeen*/ returnTrue, host, formatContext, preferences); });
             const name = declaration && getNameOfDeclaration(declaration);
             return !name || changes.length === 0 ? undefined
                 : [createCodeFixAction(fixId, changes, [getDiagnostic(errorCode, token), name.getText(sourceFile)], fixId, Diagnostics.Infer_all_types_from_usage)];
         },
         fixIds: [fixId],
         getAllCodeActions(context) {
-            const { sourceFile, program, cancellationToken, host } = context;
+            const { sourceFile, program, cancellationToken, host, formatContext, preferences } = context;
             const markSeen = nodeSeenTracker();
             return codeFixAll(context, errorCodes, (changes, err) => {
-                doChange(changes, sourceFile, getTokenAtPosition(err.file, err.start), err.code, program, cancellationToken, markSeen, host);
+                doChange(changes, sourceFile, getTokenAtPosition(err.file, err.start), err.code, program, cancellationToken, markSeen, host, formatContext, preferences);
             });
         },
     });
@@ -106,7 +106,7 @@ namespace ts.codefix {
         return errorCode;
     }
 
-    function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, token: Node, errorCode: number, program: Program, cancellationToken: CancellationToken, markSeen: NodeSeenTracker, host: LanguageServiceHost): Declaration | undefined {
+    function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, token: Node, errorCode: number, program: Program, cancellationToken: CancellationToken, markSeen: NodeSeenTracker, host: LanguageServiceHost, formatContext: formatting.FormatContext, preferences: UserPreferences): Declaration | undefined {
         if (!isParameterPropertyModifier(token.kind) && token.kind !== SyntaxKind.Identifier && token.kind !== SyntaxKind.DotDotDotToken && token.kind !== SyntaxKind.ThisKeyword) {
             return undefined;
         }
@@ -118,7 +118,7 @@ namespace ts.codefix {
             case Diagnostics.Member_0_implicitly_has_an_1_type.code:
             case Diagnostics.Variable_0_implicitly_has_type_1_in_some_locations_where_its_type_cannot_be_determined.code:
                 if ((isVariableDeclaration(parent) && markSeen(parent)) || isPropertyDeclaration(parent) || isPropertySignature(parent)) { // handle bad location
-                    annotateVariableDeclaration(changes, sourceFile, parent, program, host, cancellationToken);
+                    annotateVariableDeclaration(changes, sourceFile, parent, program, host, cancellationToken, formatContext, preferences);
                     return parent;
                 }
                 if (isPropertyAccessExpression(parent)) {
@@ -136,7 +136,7 @@ namespace ts.codefix {
             case Diagnostics.Variable_0_implicitly_has_an_1_type.code: {
                 const symbol = program.getTypeChecker().getSymbolAtLocation(token);
                 if (symbol && symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration) && markSeen(symbol.valueDeclaration)) {
-                    annotateVariableDeclaration(changes, sourceFile, symbol.valueDeclaration, program, host, cancellationToken);
+                    annotateVariableDeclaration(changes, sourceFile, symbol.valueDeclaration, program, host, cancellationToken, formatContext, preferences);
                     return symbol.valueDeclaration;
                 }
                 return undefined;
@@ -152,14 +152,14 @@ namespace ts.codefix {
             // Parameter declarations
             case Diagnostics.Parameter_0_implicitly_has_an_1_type.code:
                 if (isSetAccessorDeclaration(containingFunction)) {
-                    annotateSetAccessor(changes, sourceFile, containingFunction, program, host, cancellationToken);
+                    annotateSetAccessor(changes, sourceFile, containingFunction, program, host, cancellationToken, formatContext, preferences);
                     return containingFunction;
                 }
                 // falls through
             case Diagnostics.Rest_parameter_0_implicitly_has_an_any_type.code:
                 if (markSeen(containingFunction)) {
                     const param = cast(parent, isParameter);
-                    annotateParameters(changes, sourceFile, param, containingFunction, program, host, cancellationToken);
+                    annotateParameters(changes, sourceFile, param, containingFunction, program, host, cancellationToken, formatContext, preferences);
                     return param;
                 }
                 return undefined;
@@ -168,7 +168,7 @@ namespace ts.codefix {
             case Diagnostics.Property_0_implicitly_has_type_any_because_its_get_accessor_lacks_a_return_type_annotation.code:
             case Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_return_type.code:
                 if (isGetAccessorDeclaration(containingFunction) && isIdentifier(containingFunction.name)) {
-                    annotate(changes, sourceFile, containingFunction, inferTypeForVariableFromUsage(containingFunction.name, program, cancellationToken), program, host);
+                    annotate(changes, sourceFile, containingFunction, inferTypeForVariableFromUsage(containingFunction.name, program, cancellationToken), program, host, formatContext, preferences);
                     return containingFunction;
                 }
                 return undefined;
@@ -176,7 +176,7 @@ namespace ts.codefix {
             // Set Accessor declarations
             case Diagnostics.Property_0_implicitly_has_type_any_because_its_set_accessor_lacks_a_parameter_type_annotation.code:
                 if (isSetAccessorDeclaration(containingFunction)) {
-                    annotateSetAccessor(changes, sourceFile, containingFunction, program, host, cancellationToken);
+                    annotateSetAccessor(changes, sourceFile, containingFunction, program, host, cancellationToken, formatContext, preferences);
                     return containingFunction;
                 }
                 return undefined;
@@ -194,13 +194,32 @@ namespace ts.codefix {
         }
     }
 
-    function annotateVariableDeclaration(changes: textChanges.ChangeTracker, sourceFile: SourceFile, declaration: VariableDeclaration | PropertyDeclaration | PropertySignature, program: Program, host: LanguageServiceHost, cancellationToken: CancellationToken): void {
+    function annotateVariableDeclaration(
+        changes: textChanges.ChangeTracker,
+        sourceFile: SourceFile,
+        declaration: VariableDeclaration | PropertyDeclaration | PropertySignature,
+        program: Program,
+        host: LanguageServiceHost,
+        cancellationToken: CancellationToken,
+        formatContext: formatting.FormatContext,
+        preferences: UserPreferences,
+    ): void {
         if (isIdentifier(declaration.name)) {
-            annotate(changes, sourceFile, declaration, inferTypeForVariableFromUsage(declaration.name, program, cancellationToken), program, host);
+            annotate(changes, sourceFile, declaration, inferTypeForVariableFromUsage(declaration.name, program, cancellationToken), program, host, formatContext, preferences);
         }
     }
 
-    function annotateParameters(changes: textChanges.ChangeTracker, sourceFile: SourceFile, parameterDeclaration: ParameterDeclaration, containingFunction: FunctionLike, program: Program, host: LanguageServiceHost, cancellationToken: CancellationToken): void {
+    function annotateParameters(
+        changes: textChanges.ChangeTracker,
+        sourceFile: SourceFile,
+        parameterDeclaration: ParameterDeclaration,
+        containingFunction: FunctionLike,
+        program: Program,
+        host: LanguageServiceHost,
+        cancellationToken: CancellationToken,
+        formatContext: formatting.FormatContext,
+        preferences: UserPreferences,
+    ): void {
         if (!isIdentifier(parameterDeclaration.name)) {
             return;
         }
@@ -216,7 +235,7 @@ namespace ts.codefix {
             if (needParens) changes.insertNodeBefore(sourceFile, first(containingFunction.parameters), createToken(SyntaxKind.OpenParenToken));
             for (const { declaration, type } of parameterInferences) {
                 if (declaration && !declaration.type && !declaration.initializer) {
-                    annotate(changes, sourceFile, declaration, type, program, host);
+                    annotate(changes, sourceFile, declaration, type, program, host, formatContext, preferences);
                 }
             }
             if (needParens) changes.insertNodeAfter(sourceFile, last(containingFunction.parameters), createToken(SyntaxKind.CloseParenToken));
@@ -248,7 +267,16 @@ namespace ts.codefix {
         ]);
     }
 
-    function annotateSetAccessor(changes: textChanges.ChangeTracker, sourceFile: SourceFile, setAccessorDeclaration: SetAccessorDeclaration, program: Program, host: LanguageServiceHost, cancellationToken: CancellationToken): void {
+    function annotateSetAccessor(
+        changes: textChanges.ChangeTracker,
+        sourceFile: SourceFile,
+        setAccessorDeclaration: SetAccessorDeclaration,
+        program: Program,
+        host: LanguageServiceHost,
+        cancellationToken: CancellationToken,
+        formatContext: formatting.FormatContext,
+        preferences: UserPreferences,
+    ): void {
         const param = firstOrUndefined(setAccessorDeclaration.parameters);
         if (param && isIdentifier(setAccessorDeclaration.name) && isIdentifier(param.name)) {
             let type = inferTypeForVariableFromUsage(setAccessorDeclaration.name, program, cancellationToken);
@@ -259,12 +287,12 @@ namespace ts.codefix {
                 annotateJSDocParameters(changes, sourceFile, [{ declaration: param, type }], program, host);
             }
             else {
-                annotate(changes, sourceFile, param, type, program, host);
+                annotate(changes, sourceFile, param, type, program, host, formatContext, preferences);
             }
         }
     }
 
-    function annotate(changes: textChanges.ChangeTracker, sourceFile: SourceFile, declaration: textChanges.TypeAnnotatable, type: Type, program: Program, host: LanguageServiceHost): void {
+    function annotate(changes: textChanges.ChangeTracker, sourceFile: SourceFile, declaration: textChanges.TypeAnnotatable, type: Type, program: Program, host: LanguageServiceHost, formatContext: formatting.FormatContext, preferences: UserPreferences): void {
         const typeNode = getTypeNodeIfAccessible(type, declaration, program, host);
         if (typeNode) {
             if (isInJSFile(sourceFile) && declaration.kind !== SyntaxKind.PropertySignature) {
@@ -276,12 +304,42 @@ namespace ts.codefix {
                 const typeTag = isGetAccessorDeclaration(declaration) ? createJSDocReturnTag(typeExpression, "") : createJSDocTypeTag(typeExpression, "");
                 addJSDocTags(changes, sourceFile, parent, [typeTag]);
             }
-            else {
+            else if (!tryReplaceImportTypeNodeWithAutoImport(typeNode, changes, sourceFile, declaration, type, program, host, formatContext, preferences)) {
                 changes.tryInsertTypeAnnotation(sourceFile, declaration, typeNode);
             }
         }
     }
 
+    function tryReplaceImportTypeNodeWithAutoImport(typeNode: TypeNode, changes: textChanges.ChangeTracker, sourceFile: SourceFile, declaration: textChanges.TypeAnnotatable, type: Type, program: Program, host: LanguageServiceHost, formatContext: formatting.FormatContext, preferences: UserPreferences): boolean {
+        if (isLiteralImportTypeNode(typeNode) && typeNode.qualifier && type.symbol) {
+            // Replace 'import("./a").SomeType' with 'SomeType' and an actual import if possible
+            const moduleSymbol = find(type.symbol.declarations, d => !!d.getSourceFile().externalModuleIndicator)?.getSourceFile().symbol;
+            // Symbol for the left-most thing after the dot
+            if (moduleSymbol) {
+                const symbol = getFirstIdentifier(typeNode.qualifier).symbol;
+                const action = getImportCompletionAction(
+                    symbol,
+                    moduleSymbol,
+                    sourceFile,
+                    symbol.name,
+                    host,
+                    program,
+                    formatContext,
+                    declaration.pos,
+                    preferences,
+                );
+                if (action.codeAction.changes.length && changes.tryInsertTypeAnnotation(sourceFile, declaration, createTypeReferenceNode(typeNode.qualifier, typeNode.typeArguments))) {
+                    for (const change of action.codeAction.changes) {
+                        const file = sourceFile.fileName === change.fileName ? sourceFile : Debug.assertDefined(program.getSourceFile(change.fileName));
+                        changes.pushRaw(file, change);
+                    }
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     function annotateJSDocParameters(changes: textChanges.ChangeTracker, sourceFile: SourceFile, parameterInferences: readonly ParameterInference[], program: Program, host: LanguageServiceHost): void {
         const signature = parameterInferences.length && parameterInferences[0].declaration.parent;
         if (!signature) {
@@ -1054,7 +1112,7 @@ namespace ts.codefix {
             }
             const returnType = combineFromUsage(combineUsages(calls.map(call => call.return_)));
             // TODO: GH#18217
-            return checker.createSignature(/*declaration*/ undefined!, /*typeParameters*/ undefined, /*thisParameter*/ undefined, parameters, returnType, /*typePredicate*/ undefined, length, /*hasRestParameter*/ false, /*hasLiteralTypes*/ false);
+            return checker.createSignature(/*declaration*/ undefined!, /*typeParameters*/ undefined, /*thisParameter*/ undefined, parameters, returnType, /*typePredicate*/ undefined, length, SignatureFlags.None);
         }
 
         function addCandidateType(usage: Usage, type: Type | undefined) {

src/services/completions.ts

@@ -338,6 +338,7 @@ namespace ts.Completions {
     ): CompletionEntry | undefined {
         let insertText: string | undefined;
         let replacementSpan: TextSpan | undefined;
+
         const insertQuestionDot = origin && originIsNullableMember(origin);
         const useBraces = origin && originIsSymbolMember(origin) || needsConvertPropertyAccess;
         if (origin && originIsThisType(origin)) {
@@ -780,7 +781,7 @@ namespace ts.Completions {
         sourceFile: SourceFile,
         isUncheckedFile: boolean,
         position: number,
-        preferences: Pick<UserPreferences, "includeCompletionsForModuleExports" | "includeCompletionsWithInsertText">,
+        preferences: Pick<UserPreferences, "includeCompletionsForModuleExports" | "includeCompletionsWithInsertText" | "includeAutomaticOptionalChainCompletions">,
         detailsEntryId: CompletionEntryIdentifier | undefined,
         host: LanguageServiceHost,
     ): CompletionData | Request | undefined {
@@ -1000,6 +1001,7 @@ namespace ts.Completions {
         let completionKind = CompletionKind.None;
         let isNewIdentifierLocation = false;
         let keywordFilters = KeywordCompletionFilters.None;
+        // This also gets mutated in nested-functions after the return
         let symbols: Symbol[] = [];
         const symbolToOriginInfoMap: SymbolOriginInfoMap = [];
         const symbolToSortTextMap: SymbolSortTextMap = [];
@@ -1115,8 +1117,17 @@ namespace ts.Completions {
                             let type = typeChecker.getTypeOfSymbolAtLocation(symbol, node).getNonOptionalType();
                             let insertQuestionDot = false;
                             if (type.isNullableType()) {
-                                insertQuestionDot = isRightOfDot && !isRightOfQuestionDot;
-                                type = type.getNonNullableType();
+                                const canCorrectToQuestionDot =
+                                isRightOfDot &&
+                                !isRightOfQuestionDot &&
+                                preferences.includeAutomaticOptionalChainCompletions !== false;
+
+                                if (canCorrectToQuestionDot || isRightOfQuestionDot) {
+                                    type = type.getNonNullableType();
+                                    if (canCorrectToQuestionDot) {
+                                        insertQuestionDot = true;
+                                    }
+                                }
                             }
                             addTypeProperties(type, !!(node.flags & NodeFlags.AwaitContext), insertQuestionDot);
                         }
@@ -1136,8 +1147,17 @@ namespace ts.Completions {
                 let type = typeChecker.getTypeAtLocation(node).getNonOptionalType();
                 let insertQuestionDot = false;
                 if (type.isNullableType()) {
-                    insertQuestionDot = isRightOfDot && !isRightOfQuestionDot;
-                    type = type.getNonNullableType();
+                    const canCorrectToQuestionDot =
+                        isRightOfDot &&
+                        !isRightOfQuestionDot &&
+                        preferences.includeAutomaticOptionalChainCompletions !== false;
+
+                    if (canCorrectToQuestionDot || isRightOfQuestionDot) {
+                        type = type.getNonNullableType();
+                        if (canCorrectToQuestionDot) {
+                            insertQuestionDot = true;
+                        }
+                    }
                 }
                 addTypeProperties(type, !!(node.flags & NodeFlags.AwaitContext), insertQuestionDot);
             }
@@ -1464,7 +1484,7 @@ namespace ts.Completions {
         }
 
         /**
-         * Gathers symbols that can be imported from other files, deduplicating along the way. Symbols can be “duplicates”
+         * Gathers symbols that can be imported from other files, de-duplicating along the way. Symbols can be "duplicates"
          * if re-exported from another module, e.g. `export { foo } from "./a"`. That syntax creates a fresh symbol, but
          * it’s just an alias to the first, and both have the same name, so we generally want to filter those aliases out,
          * if and only if the the first can be imported (it may be excluded due to package.json filtering in
@@ -1548,7 +1568,7 @@ namespace ts.Completions {
                 // Don't add another completion for `export =` of a symbol that's already global.
                 // So in `declare namespace foo {} declare module "foo" { export = foo; }`, there will just be the global completion for `foo`.
                 if (resolvedModuleSymbol !== moduleSymbol &&
-                    every(resolvedModuleSymbol.declarations, d => !!d.getSourceFile().externalModuleIndicator)) {
+                    every(resolvedModuleSymbol.declarations, d => !!d.getSourceFile().externalModuleIndicator && !findAncestor(d, isGlobalScopeAugmentation))) {
                     pushSymbol(resolvedModuleSymbol, moduleSymbol, /*skipFilter*/ true);
                 }
 
@@ -1760,7 +1780,7 @@ namespace ts.Completions {
             let existingMembers: readonly Declaration[] | undefined;
 
             if (objectLikeContainer.kind === SyntaxKind.ObjectLiteralExpression) {
-                const typeForObject = typeChecker.getContextualType(objectLikeContainer);
+                const typeForObject = typeChecker.getContextualType(objectLikeContainer, ContextFlags.Completion);
                 if (!typeForObject) return GlobalsSearch.Fail;
                 isNewIdentifierLocation = hasIndexSignature(typeForObject);
                 typeMembers = getPropertiesForObjectExpression(typeForObject, objectLikeContainer, typeChecker);
@@ -2406,6 +2426,8 @@ namespace ts.Completions {
                     return isFunctionLikeBodyKeyword(kind)
                         || kind === SyntaxKind.DeclareKeyword
                         || kind === SyntaxKind.ModuleKeyword
+                        || kind === SyntaxKind.TypeKeyword
+                        || kind === SyntaxKind.NamespaceKeyword
                         || isTypeKeyword(kind) && kind !== SyntaxKind.UndefinedKeyword;
                 case KeywordCompletionFilters.FunctionLikeBodyKeywords:
                     return isFunctionLikeBodyKeyword(kind);

src/services/findAllReferences.ts

@@ -1395,8 +1395,10 @@ namespace ts.FindAllReferences.Core {
                 || exportSpecifier.name.originalKeywordKind === SyntaxKind.DefaultKeyword;
             const exportKind = isDefaultExport ? ExportKind.Default : ExportKind.Named;
             const exportSymbol = Debug.assertDefined(exportSpecifier.symbol);
-            const exportInfo = Debug.assertDefined(getExportInfo(exportSymbol, exportKind, state.checker));
-            searchForImportsOfExport(referenceLocation, exportSymbol, exportInfo, state);
+            const exportInfo = getExportInfo(exportSymbol, exportKind, state.checker);
+            if (exportInfo) {
+                searchForImportsOfExport(referenceLocation, exportSymbol, exportInfo, state);
+            }
         }
 
         // At `export { x } from "foo"`, also search for the imported symbol `"foo".x`.

src/services/formatting/rules.ts

@@ -59,8 +59,8 @@ namespace ts.formatting {
             // in other cases there should be no space between '?' and next token
             rule("NoSpaceAfterQuestionMark", SyntaxKind.QuestionToken, anyToken, [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),
 
-            rule("NoSpaceBeforeDot", anyToken, SyntaxKind.DotToken, [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),
-            rule("NoSpaceAfterDot", SyntaxKind.DotToken, anyToken, [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),
+            rule("NoSpaceBeforeDot", anyToken, [SyntaxKind.DotToken, SyntaxKind.QuestionDotToken], [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),
+            rule("NoSpaceAfterDot", [SyntaxKind.DotToken, SyntaxKind.QuestionDotToken], anyToken, [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),
 
             rule("NoSpaceBetweenImportParenInImportType", SyntaxKind.ImportKeyword, SyntaxKind.OpenParenToken, [isNonJsxSameLineTokenContext, isImportTypeContext], RuleAction.DeleteSpace),
 

src/services/jsDoc.ts

@@ -158,25 +158,6 @@ namespace ts.JsDoc {
         }
     }
 
-    /**
-     * Iterates through 'array' by index and performs the callback on each element of array until the callback
-     * returns a truthy value, then returns that value.
-     * If no such value is found, the callback is applied to each element of array and undefined is returned.
-     */
-    function forEachUnique<T, U>(array: readonly T[] | undefined, callback: (element: T, index: number) => U): U | undefined {
-        if (array) {
-            for (let i = 0; i < array.length; i++) {
-                if (array.indexOf(array[i]) === i) {
-                    const result = callback(array[i], i);
-                    if (result) {
-                        return result;
-                    }
-                }
-            }
-        }
-        return undefined;
-    }
-
     export function getJSDocTagNameCompletions(): CompletionEntry[] {
         return jsDocTagNameCompletionEntries || (jsDocTagNameCompletionEntries = map(jsDocTagNames, tagName => {
             return {

src/services/services.ts

@@ -452,9 +452,19 @@ namespace ts {
         isClass(): this is InterfaceType {
             return !!(getObjectFlags(this) & ObjectFlags.Class);
         }
+        /**
+         * This polyfills `referenceType.typeArguments` for API consumers
+         */
+        get typeArguments() {
+            if (getObjectFlags(this) & ObjectFlags.Reference) {
+                return this.checker.getTypeArguments(this as Type as TypeReference);
+            }
+            return undefined;
+        }
     }
 
     class SignatureObject implements Signature {
+        flags: SignatureFlags;
         checker: TypeChecker;
         declaration!: SignatureDeclaration;
         typeParameters?: TypeParameter[];
@@ -464,8 +474,6 @@ namespace ts {
         resolvedTypePredicate: TypePredicate | undefined;
         minTypeArgumentCount!: number;
         minArgumentCount!: number;
-        hasRestParameter!: boolean;
-        hasLiteralTypes!: boolean;
 
         // Undefined is used to indicate the value has not been computed. If, after computing, the
         // symbol has no doc comment, then the empty array will be returned.
@@ -475,9 +483,11 @@ namespace ts {
         // symbol has no doc comment, then the empty array will be returned.
         jsDocTags?: JSDocTagInfo[];
 
-        constructor(checker: TypeChecker) {
+        constructor(checker: TypeChecker, flags: SignatureFlags) {
             this.checker = checker;
+            this.flags = flags;
         }
+
         getDeclaration(): SignatureDeclaration {
             return this.declaration;
         }
@@ -518,11 +528,11 @@ namespace ts {
 
         let doc = JsDoc.getJsDocCommentsFromDeclarations(declarations);
         if (doc.length === 0 || declarations.some(hasJSDocInheritDocTag)) {
-            for (const declaration of declarations) {
+            forEachUnique(declarations, declaration => {
                 const inheritedDocs = findInheritedJSDocComments(declaration, declaration.symbol.name, checker!); // TODO: GH#18217
                 // TODO: GH#16312 Return a ReadonlyArray, avoid copying inheritedDocs
                 if (inheritedDocs) doc = doc.length === 0 ? inheritedDocs.slice() : inheritedDocs.concat(lineBreakPart(), doc);
-            }
+            });
         }
         return doc;
     }
@@ -1629,12 +1639,12 @@ namespace ts {
             return NavigateTo.getNavigateToItems(sourceFiles, program.getTypeChecker(), cancellationToken, searchValue, maxResultCount, excludeDtsFiles);
         }
 
-        function getEmitOutput(fileName: string, emitOnlyDtsFiles = false) {
+        function getEmitOutput(fileName: string, emitOnlyDtsFiles?: boolean, forceDtsEmit?: boolean) {
             synchronizeHostData();
 
             const sourceFile = getValidSourceFile(fileName);
             const customTransformers = host.getCustomTransformers && host.getCustomTransformers();
-            return getFileEmitOutput(program, sourceFile, emitOnlyDtsFiles, cancellationToken, customTransformers);
+            return getFileEmitOutput(program, sourceFile, !!emitOnlyDtsFiles, cancellationToken, customTransformers, forceDtsEmit);
         }
 
         // Signature help

src/services/stringCompletions.ts

@@ -204,7 +204,7 @@ namespace ts.Completions.StringCompletions {
         const candidates: Signature[] = [];
         checker.getResolvedSignature(argumentInfo.invocation, candidates, argumentInfo.argumentCount);
         const types = flatMap(candidates, candidate => {
-            if (!candidate.hasRestParameter && argumentInfo.argumentCount > candidate.parameters.length) return;
+            if (!signatureHasRestParameter(candidate) && argumentInfo.argumentCount > candidate.parameters.length) return;
             const type = checker.getParameterType(candidate, argumentInfo.argumentIndex);
             isNewIdentifier = isNewIdentifier || !!(type.flags & TypeFlags.String);
             return getStringLiteralTypes(type, uniques);

src/services/symbolDisplay.ts

@@ -237,7 +237,7 @@ namespace ts.SymbolDisplay {
                 // get the signature from the declaration and write it
                 const functionDeclaration = <FunctionLike>location.parent;
                 // Use function declaration to write the signatures only if the symbol corresponding to this declaration
-                const locationIsSymbolDeclaration = find(symbol.declarations, declaration =>
+                const locationIsSymbolDeclaration = symbol.declarations && find(symbol.declarations, declaration =>
                     declaration === (location.kind === SyntaxKind.ConstructorKeyword ? functionDeclaration.parent : functionDeclaration));
 
                 if (locationIsSymbolDeclaration) {

src/services/textChanges.ts

@@ -248,6 +248,18 @@ namespace ts.textChanges {
         /** Public for tests only. Other callers should use `ChangeTracker.with`. */
         constructor(private readonly newLineCharacter: string, private readonly formatContext: formatting.FormatContext) {}
 
+        public pushRaw(sourceFile: SourceFile, change: FileTextChanges) {
+            Debug.assertEqual(sourceFile.fileName, change.fileName);
+            for (const c of change.textChanges) {
+                this.changes.push({
+                    kind: ChangeKind.Text,
+                    sourceFile,
+                    text: c.newText,
+                    range: createTextRangeFromSpan(c.span),
+                });
+            }
+        }
+
         public deleteRange(sourceFile: SourceFile, range: TextRange): void {
             this.changes.push({ kind: ChangeKind.Remove, sourceFile, range });
         }
@@ -383,12 +395,12 @@ namespace ts.textChanges {
         }
 
         /** Prefer this over replacing a node with another that has a type annotation, as it avoids reformatting the other parts of the node. */
-        public tryInsertTypeAnnotation(sourceFile: SourceFile, node: TypeAnnotatable, type: TypeNode): void {
+        public tryInsertTypeAnnotation(sourceFile: SourceFile, node: TypeAnnotatable, type: TypeNode): boolean {
             let endNode: Node | undefined;
             if (isFunctionLike(node)) {
                 endNode = findChildOfKind(node, SyntaxKind.CloseParenToken, sourceFile);
                 if (!endNode) {
-                    if (!isArrowFunction(node)) return; // Function missing parentheses, give up
+                    if (!isArrowFunction(node)) return false; // Function missing parentheses, give up
                     // If no `)`, is an arrow function `x => x`, so use the end of the first parameter
                     endNode = first(node.parameters);
                 }
@@ -398,6 +410,7 @@ namespace ts.textChanges {
             }
 
             this.insertNodeAt(sourceFile, endNode.end, type, { prefix: ": " });
+            return true;
         }
 
         public tryInsertThisTypeAnnotation(sourceFile: SourceFile, node: ThisTypeAnnotatable, type: TypeNode): void {

src/services/tsconfig.json

@@ -4,6 +4,7 @@
         "outFile": "../../built/local/services.js"
     },
     "references": [
+        { "path": "../shims" },
         { "path": "../compiler" },
         { "path": "../jsTyping" }
     ],

src/services/types.ts

@@ -68,6 +68,10 @@ namespace ts {
         isClass(): this is InterfaceType;
     }
 
+    export interface TypeReference {
+        typeArguments?: readonly Type[];
+    }
+
     export interface Signature {
         getDeclaration(): SignatureDeclaration;
         getTypeParameters(): TypeParameter[] | undefined;
@@ -239,6 +243,8 @@ namespace ts {
         resolveTypeReferenceDirectives?(typeDirectiveNames: string[], containingFile: string, redirectedReference: ResolvedProjectReference | undefined, options: CompilerOptions): (ResolvedTypeReferenceDirective | undefined)[];
         /* @internal */ hasInvalidatedResolution?: HasInvalidatedResolution;
         /* @internal */ hasChangedAutomaticTypeDirectiveNames?: boolean;
+        /* @internal */
+        getGlobalTypingsCacheLocation?(): string | undefined;
 
         /*
          * Required for full import and type reference completions.
@@ -387,7 +393,7 @@ namespace ts {
         organizeImports(scope: OrganizeImportsScope, formatOptions: FormatCodeSettings, preferences: UserPreferences | undefined): readonly FileTextChanges[];
         getEditsForFileRename(oldFilePath: string, newFilePath: string, formatOptions: FormatCodeSettings, preferences: UserPreferences | undefined): readonly FileTextChanges[];
 
-        getEmitOutput(fileName: string, emitOnlyDtsFiles?: boolean): EmitOutput;
+        getEmitOutput(fileName: string, emitOnlyDtsFiles?: boolean, forceDtsEmit?: boolean): EmitOutput;
 
         getProgram(): Program | undefined;
 
@@ -534,7 +540,7 @@ namespace ts {
 
     export interface FileTextChanges {
         fileName: string;
-        textChanges: TextChange[];
+        textChanges: readonly TextChange[];
         isNewFile?: boolean;
     }
 

src/services/utilities.ts

@@ -1458,6 +1458,25 @@ namespace ts {
     export function documentSpansEqual(a: DocumentSpan, b: DocumentSpan): boolean {
         return a.fileName === b.fileName && textSpansEqual(a.textSpan, b.textSpan);
     }
+
+    /**
+     * Iterates through 'array' by index and performs the callback on each element of array until the callback
+     * returns a truthy value, then returns that value.
+     * If no such value is found, the callback is applied to each element of array and undefined is returned.
+     */
+    export function forEachUnique<T, U>(array: readonly T[] | undefined, callback: (element: T, index: number) => U): U | undefined {
+        if (array) {
+            for (let i = 0; i < array.length; i++) {
+                if (array.indexOf(array[i]) === i) {
+                    const result = callback(array[i], i);
+                    if (result) {
+                        return result;
+                    }
+                }
+            }
+        }
+        return undefined;
+    }
 }
 
 // Display-part writer helpers

src/shims/mapShim.ts

@@ -0,0 +1,212 @@
+/* @internal */
+namespace ts {
+    // NOTE: Due to how the project-reference merging ends up working, `T` isn't considered referenced until `Map` merges with the definition
+    // in src/compiler/core.ts
+    // @ts-ignore
+    export interface Map<T> {
+        // full type defined in ~/src/compiler/core.ts
+    }
+
+    export function createMapShim(): new <T>() => Map<T> {
+        /** Create a MapLike with good performance. */
+        function createDictionaryObject<T>(): Record<string, T> {
+            const map = Object.create(/*prototype*/ null); // eslint-disable-line no-null/no-null
+
+            // Using 'delete' on an object causes V8 to put the object in dictionary mode.
+            // This disables creation of hidden classes, which are expensive when an object is
+            // constantly changing shape.
+            map.__ = undefined;
+            delete map.__;
+
+            return map;
+        }
+
+        interface MapEntry<T> {
+            readonly key?: string;
+            value?: T;
+
+            // Linked list references for iterators.
+            nextEntry?: MapEntry<T>;
+            previousEntry?: MapEntry<T>;
+
+            /**
+             * Specifies if iterators should skip the next entry.
+             * This will be set when an entry is deleted.
+             * See https://github.com/Microsoft/TypeScript/pull/27292 for more information.
+             */
+            skipNext?: boolean;
+        }
+
+        class MapIterator<T, U extends (string | T | [string, T])> {
+            private currentEntry?: MapEntry<T>;
+            private selector: (key: string, value: T) => U;
+
+            constructor(currentEntry: MapEntry<T>, selector: (key: string, value: T) => U) {
+                this.currentEntry = currentEntry;
+                this.selector = selector;
+            }
+
+            public next(): { value: U, done: false } | { value: never, done: true } {
+                // Navigate to the next entry.
+                while (this.currentEntry) {
+                    const skipNext = !!this.currentEntry.skipNext;
+                    this.currentEntry = this.currentEntry.nextEntry;
+
+                    if (!skipNext) {
+                        break;
+                    }
+                }
+
+                if (this.currentEntry) {
+                    return { value: this.selector(this.currentEntry.key!, this.currentEntry.value!), done: false };
+                }
+                else {
+                    return { value: undefined as never, done: true };
+                }
+            }
+        }
+
+        return class <T> implements Map<T> {
+            private data = createDictionaryObject<MapEntry<T>>();
+            public size = 0;
+
+            // Linked list references for iterators.
+            // See https://github.com/Microsoft/TypeScript/pull/27292
+            // for more information.
+
+            /**
+             * The first entry in the linked list.
+             * Note that this is only a stub that serves as starting point
+             * for iterators and doesn't contain a key and a value.
+             */
+            private readonly firstEntry: MapEntry<T>;
+            private lastEntry: MapEntry<T>;
+
+            constructor() {
+                // Create a first (stub) map entry that will not contain a key
+                // and value but serves as starting point for iterators.
+                this.firstEntry = {};
+                // When the map is empty, the last entry is the same as the
+                // first one.
+                this.lastEntry = this.firstEntry;
+            }
+
+            get(key: string): T | undefined {
+                const entry = this.data[key] as MapEntry<T> | undefined;
+                return entry && entry.value!;
+            }
+
+            set(key: string, value: T): this {
+                if (!this.has(key)) {
+                    this.size++;
+
+                    // Create a new entry that will be appended at the
+                    // end of the linked list.
+                    const newEntry: MapEntry<T> = {
+                        key,
+                        value
+                    };
+                    this.data[key] = newEntry;
+
+                    // Adjust the references.
+                    const previousLastEntry = this.lastEntry;
+                    previousLastEntry.nextEntry = newEntry;
+                    newEntry.previousEntry = previousLastEntry;
+                    this.lastEntry = newEntry;
+                }
+                else {
+                    this.data[key].value = value;
+                }
+
+                return this;
+            }
+
+            has(key: string): boolean {
+                // eslint-disable-next-line no-in-operator
+                return key in this.data;
+            }
+
+            delete(key: string): boolean {
+                if (this.has(key)) {
+                    this.size--;
+                    const entry = this.data[key];
+                    delete this.data[key];
+
+                    // Adjust the linked list references of the neighbor entries.
+                    const previousEntry = entry.previousEntry!;
+                    previousEntry.nextEntry = entry.nextEntry;
+                    if (entry.nextEntry) {
+                        entry.nextEntry.previousEntry = previousEntry;
+                    }
+
+                    // When the deleted entry was the last one, we need to
+                    // adjust the lastEntry reference.
+                    if (this.lastEntry === entry) {
+                        this.lastEntry = previousEntry;
+                    }
+
+                    // Adjust the forward reference of the deleted entry
+                    // in case an iterator still references it. This allows us
+                    // to throw away the entry, but when an active iterator
+                    // (which points to the current entry) continues, it will
+                    // navigate to the entry that originally came before the
+                    // current one and skip it.
+                    entry.previousEntry = undefined;
+                    entry.nextEntry = previousEntry;
+                    entry.skipNext = true;
+
+                    return true;
+                }
+                return false;
+            }
+
+            clear(): void {
+                this.data = createDictionaryObject<MapEntry<T>>();
+                this.size = 0;
+
+                // Reset the linked list. Note that we must adjust the forward
+                // references of the deleted entries to ensure iterators stuck
+                // in the middle of the list don't continue with deleted entries,
+                // but can continue with new entries added after the clear()
+                // operation.
+                const firstEntry = this.firstEntry;
+                let currentEntry = firstEntry.nextEntry;
+                while (currentEntry) {
+                    const nextEntry = currentEntry.nextEntry;
+                    currentEntry.previousEntry = undefined;
+                    currentEntry.nextEntry = firstEntry;
+                    currentEntry.skipNext = true;
+
+                    currentEntry = nextEntry;
+                }
+                firstEntry.nextEntry = undefined;
+                this.lastEntry = firstEntry;
+            }
+
+            keys(): Iterator<string> {
+                return new MapIterator(this.firstEntry, key => key);
+            }
+
+            values(): Iterator<T> {
+                return new MapIterator(this.firstEntry, (_key, value) => value);
+            }
+
+            entries(): Iterator<[string, T]> {
+                return new MapIterator(this.firstEntry, (key, value) => [key, value] as [string, T]);
+            }
+
+            forEach(action: (value: T, key: string) => void): void {
+                const iterator = this.entries();
+                while (true) {
+                    const iterResult = iterator.next();
+                    if (iterResult.done) {
+                        break;
+                    }
+
+                    const [key, value] = iterResult.value;
+                    action(value, key);
+                }
+            }
+        };
+    }
+}

src/shims/tsconfig.json

@@ -0,0 +1,9 @@
+{
+    "extends": "../tsconfig-base",
+    "compilerOptions": {
+        "outFile": "../../built/local/shims.js"
+    },
+    "files": [
+        "mapShim.ts"
+    ]
+}

src/testRunner/parallel/host.ts

@@ -147,7 +147,7 @@ namespace Harness.Parallel.Host {
                 }
 
                 cursor.hide();
-                readline.moveCursor(process.stdout, -process.stdout.columns!, -this._lineCount);
+                readline.moveCursor(process.stdout, -process.stdout.columns, -this._lineCount);
                 let lineCount = 0;
                 const numProgressBars = this._progressBars.length;
                 for (let i = 0; i < numProgressBars; i++) {
@@ -156,7 +156,7 @@ namespace Harness.Parallel.Host {
                         process.stdout.write(this._progressBars[i].text + os.EOL);
                     }
                     else {
-                        readline.moveCursor(process.stdout, -process.stdout.columns!, +1);
+                        readline.moveCursor(process.stdout, -process.stdout.columns, +1);
                     }
 
                     lineCount++;

src/testRunner/tsconfig.json

@@ -14,6 +14,7 @@
         ]
     },
     "references": [
+        { "path": "../shims", "prepend": true },
         { "path": "../compiler", "prepend": true },
         { "path": "../services", "prepend": true },
         { "path": "../jsTyping", "prepend": true },
@@ -38,6 +39,7 @@
 
         "unittests/services/extract/helpers.ts",
         "unittests/tsbuild/helpers.ts",
+        "../tsc/executeCommandLine.ts",
         "unittests/tsc/helpers.ts",
         "unittests/tscWatch/helpers.ts",
         "unittests/tsserver/helpers.ts",
@@ -60,7 +62,7 @@
         "unittests/publicApi.ts",
         "unittests/reuseProgramStructure.ts",
         "unittests/semver.ts",
-        "unittests/shimMap.ts",
+        "unittests/createMapShim.ts",
         "unittests/transform.ts",
         "unittests/config/commandLineParsing.ts",
         "unittests/config/configurationExtension.ts",
@@ -98,6 +100,7 @@
         "unittests/tsbuild/demo.ts",
         "unittests/tsbuild/emitDeclarationOnly.ts",
         "unittests/tsbuild/emptyFiles.ts",
+        "unittests/tsbuild/exitCodeOnBogusFile.ts",
         "unittests/tsbuild/graphOrdering.ts",
         "unittests/tsbuild/inferredTypeFromTransitiveModule.ts",
         "unittests/tsbuild/javascriptProjectEmit.ts",
@@ -112,6 +115,8 @@
         "unittests/tsbuild/watchEnvironment.ts",
         "unittests/tsbuild/watchMode.ts",
         "unittests/tsc/declarationEmit.ts",
+        "unittests/tsc/incremental.ts",
+        "unittests/tsc/listFilesOnly.ts",
         "unittests/tscWatch/consoleClearing.ts",
         "unittests/tscWatch/emit.ts",
         "unittests/tscWatch/emitAndErrorUpdates.ts",

src/testRunner/unittests/config/commandLineParsing.ts

@@ -446,6 +446,23 @@ namespace ts {
                 });
         });
 
+        it("parse build with listFilesOnly ", () => {
+            // --lib es6 0.ts
+            assertParseResult(["--listFilesOnly"],
+                {
+                    errors: [{
+                        messageText:"Unknown build option '--listFilesOnly'.",
+                        category: Diagnostics.Unknown_build_option_0.category,
+                        code: Diagnostics.Unknown_build_option_0.code,
+                        file: undefined,
+                        start: undefined,
+                        length: undefined,
+                    }],
+                    projects: ["."],
+                    buildOptions: {}
+                });
+        });
+
         it("Parse multiple flags with input projects at the end", () => {
             // --lib es5,es2015.symbol.wellknown --target es5 0.ts
             assertParseResult(["--force", "--verbose", "src", "tests"],

src/testRunner/unittests/createMapShim.ts

@@ -1,5 +1,5 @@
 namespace ts {
-    describe("unittests:: shimMap", () => {
+    describe("unittests:: createMapShim", () => {
 
         function testMapIterationAddedValues(map: Map<string>, useForEach: boolean): string {
             let resultString = "";
@@ -93,15 +93,15 @@ namespace ts {
             const nativeMapIteratorResult = testMapIterationAddedValues(nativeMap, /* useForEach */ false);
             assert.equal(nativeMapIteratorResult, expectedResult, "nativeMap-iterator");
 
-            // Then, test the shimMap.
-            let localShimMap = new (shimMap())<string>();
+            // Then, test the map shim.
+            const MapShim = createMapShim(); // tslint:disable-line variable-name
+            let localShimMap = new MapShim<string>();
             const shimMapForEachResult = testMapIterationAddedValues(localShimMap, /* useForEach */ true);
             assert.equal(shimMapForEachResult, expectedResult, "shimMap-forEach");
 
-            localShimMap = new (shimMap())<string>();
+            localShimMap = new MapShim<string>();
             const shimMapIteratorResult = testMapIterationAddedValues(localShimMap, /* useForEach */ false);
             assert.equal(shimMapIteratorResult, expectedResult, "shimMap-iterator");
-
         });
     });
 }

src/testRunner/unittests/services/languageService.ts

@@ -15,10 +15,9 @@ class Carousel<T> extends Vue {
             "vue-class-component.d.ts": `import Vue from "./vue";
 export function Component(x: Config): any;`
         };
-        // Regression test for GH #18245 - bug in single line comment writer caused a debug assertion when attempting
-        //  to write an alias to a module's default export was referrenced across files and had no default export
-        it("should be able to create a language service which can respond to deinition requests without throwing", () => {
-            const languageService = createLanguageService({
+
+        function createLanguageService() {
+            return ts.createLanguageService({
                 getCompilationSettings() {
                     return {};
                 },
@@ -39,8 +38,45 @@ export function Component(x: Config): any;`
                     return getDefaultLibFilePath(options);
                 },
             });
+        }
+        // Regression test for GH #18245 - bug in single line comment writer caused a debug assertion when attempting
+        //  to write an alias to a module's default export was referrenced across files and had no default export
+        it("should be able to create a language service which can respond to deinition requests without throwing", () => {
+            const languageService = createLanguageService();
             const definitions = languageService.getDefinitionAtPosition("foo.ts", 160); // 160 is the latter `vueTemplateHtml` position
             expect(definitions).to.exist; // eslint-disable-line no-unused-expressions
         });
+
+        it("getEmitOutput on language service has way to force dts emit", () => {
+            const languageService = createLanguageService();
+            assert.deepEqual(
+                languageService.getEmitOutput(
+                    "foo.ts",
+                    /*emitOnlyDtsFiles*/ true
+                ),
+                {
+                    emitSkipped: true,
+                    outputFiles: emptyArray,
+                    exportedModulesFromDeclarationEmit: undefined
+                }
+            );
+
+            assert.deepEqual(
+                languageService.getEmitOutput(
+                    "foo.ts",
+                    /*emitOnlyDtsFiles*/ true,
+                    /*forceDtsEmit*/ true
+                ),
+                {
+                    emitSkipped: false,
+                    outputFiles: [{
+                        name: "foo.d.ts",
+                        text: "export {};\r\n",
+                        writeByteOrderMark: false
+                    }],
+                    exportedModulesFromDeclarationEmit: undefined
+                }
+            );
+        });
     });
 }

src/testRunner/unittests/tsbuild/containerOnlyReferenced.ts

@@ -9,40 +9,12 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
-        function outputs(folder: string) {
-            return [
-                `${folder}/index.js`,
-                `${folder}/index.d.ts`,
-                `${folder}/tsconfig.tsbuildinfo`
-            ];
-        }
-
-        it("verify that subsequent builds after initial build doesnt build anything", () => {
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            createSolutionBuilder(host, ["/src"], { verbose: true }).build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild("src/src/folder/tsconfig.json", "src/src/folder2/tsconfig.json", "src/src/tsconfig.json", "src/tests/tsconfig.json", "src/tsconfig.json"),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/folder/tsconfig.json", "src/src/folder/index.js"],
-                [Diagnostics.Building_project_0, "/src/src/folder/tsconfig.json"],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/folder2/tsconfig.json", "src/src/folder2/index.js"],
-                [Diagnostics.Building_project_0, "/src/src/folder2/tsconfig.json"],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/tests/tsconfig.json", "src/tests/index.js"],
-                [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"],
-            );
-            verifyOutputsPresent(fs, [
-                ...outputs("/src/src/folder"),
-                ...outputs("/src/src/folder2"),
-                ...outputs("/src/tests"),
-            ]);
-            host.clearDiagnostics();
-            createSolutionBuilder(host, ["/src"], { verbose: true }).build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild("src/src/folder/tsconfig.json", "src/src/folder2/tsconfig.json", "src/src/tsconfig.json", "src/tests/tsconfig.json", "src/tsconfig.json"),
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/src/folder/tsconfig.json", "src/src/folder/index.ts", "src/src/folder/index.js"],
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/src/folder2/tsconfig.json", "src/src/folder2/index.ts", "src/src/folder2/index.js"],
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/tests/tsconfig.json", "src/tests/index.ts", "src/tests/index.js"],
-            );
+        verifyTscIncrementalEdits({
+            scenario: "containerOnlyReferenced",
+            subScenario: "verify that subsequent builds after initial build doesnt build anything",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src", "--verbose"],
+            incrementalScenarios: [noChangeRun]
         });
     });
 }

src/testRunner/unittests/tsbuild/demo.ts

@@ -9,152 +9,41 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
-        function coreOutputs(): string[] {
-            return [
-                "/src/lib/core/utilities.js",
-                "/src/lib/core/utilities.d.ts",
-                "/src/lib/core/tsconfig.tsbuildinfo"
-            ];
-        }
-
-        function animalOutputs(): string[] {
-            return [
-                "/src/lib/animals/animal.js",
-                "/src/lib/animals/animal.d.ts",
-                "/src/lib/animals/index.js",
-                "/src/lib/animals/index.d.ts",
-                "/src/lib/animals/dog.js",
-                "/src/lib/animals/dog.d.ts",
-                "/src/lib/animals/tsconfig.tsbuildinfo"
-            ];
-        }
-
-        function zooOutputs(): string[] {
-            return [
-                "/src/lib/zoo/zoo.js",
-                "/src/lib/zoo/zoo.d.ts",
-                "/src/lib/zoo/tsconfig.tsbuildinfo"
-            ];
-        }
-
-        interface VerifyBuild {
-            modifyDiskLayout: (fs: vfs.FileSystem) => void;
-            expectedExitStatus: ExitStatus;
-            expectedDiagnostics: (fs: vfs.FileSystem) => fakes.ExpectedDiagnostic[];
-            expectedOutputs: readonly string[];
-            notExpectedOutputs: readonly string[];
-        }
-
-        function verifyBuild({ modifyDiskLayout, expectedExitStatus, expectedDiagnostics, expectedOutputs, notExpectedOutputs }: VerifyBuild) {
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            modifyDiskLayout(fs);
-            const builder = createSolutionBuilder(host, ["/src/tsconfig.json"], { verbose: true });
-            const exitStatus = builder.build();
-            assert.equal(exitStatus, expectedExitStatus);
-            host.assertDiagnosticMessages(...expectedDiagnostics(fs));
-            verifyOutputsPresent(fs, expectedOutputs);
-            verifyOutputsAbsent(fs, notExpectedOutputs);
-        }
-
-        it("in master branch with everything setup correctly, reports no error", () => {
-            verifyBuild({
-                modifyDiskLayout: noop,
-                expectedExitStatus: ExitStatus.Success,
-                expectedDiagnostics: () => [
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/animals/tsconfig.json", "src/zoo/tsconfig.json", "src/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/lib/core/utilities.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/animals/tsconfig.json", "src/lib/animals/animal.js"],
-                    [Diagnostics.Building_project_0, "/src/animals/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/zoo/tsconfig.json", "src/lib/zoo/zoo.js"],
-                    [Diagnostics.Building_project_0, "/src/zoo/tsconfig.json"]
-                ],
-                expectedOutputs: [...coreOutputs(), ...animalOutputs(), ...zooOutputs()],
-                notExpectedOutputs: emptyArray
-            });
+        verifyTsc({
+            scenario: "demo",
+            subScenario: "in master branch with everything setup correctly and reports no error",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.json", "--verbose"]
         });
 
-        it("in circular branch reports the error about it by stopping build", () => {
-            verifyBuild({
-                modifyDiskLayout: fs => replaceText(
-                    fs,
-                    "/src/core/tsconfig.json",
-                    "}",
-                    `},
+        verifyTsc({
+            scenario: "demo",
+            subScenario: "in circular branch reports the error about it by stopping build",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.json", "--verbose"],
+            modifyFs: fs => replaceText(
+                fs,
+                "/src/core/tsconfig.json",
+                "}",
+                `},
   "references": [
     {
       "path": "../zoo"
     }
   ]`
-                ),
-                expectedExitStatus: ExitStatus.ProjectReferenceCycle_OutputsSkupped,
-                expectedDiagnostics: () => [
-                    getExpectedDiagnosticForProjectsInBuild("src/animals/tsconfig.json", "src/zoo/tsconfig.json", "src/core/tsconfig.json", "src/tsconfig.json"),
-                    errorDiagnostic([
-                        Diagnostics.Project_references_may_not_form_a_circular_graph_Cycle_detected_Colon_0,
-                        [
-                            "/src/tsconfig.json",
-                            "/src/core/tsconfig.json",
-                            "/src/zoo/tsconfig.json",
-                            "/src/animals/tsconfig.json"
-                        ].join("\r\n")
-                    ])
-                ],
-                expectedOutputs: emptyArray,
-                notExpectedOutputs: [...coreOutputs(), ...animalOutputs(), ...zooOutputs()]
-            });
+            )
         });
-
-        it("in bad-ref branch reports the error about files not in rootDir at the import location", () => {
-            verifyBuild({
-                modifyDiskLayout: fs => prependText(
-                    fs,
-                    "/src/core/utilities.ts",
-                    `import * as A from '../animals';
+        verifyTsc({
+            scenario: "demo",
+            subScenario: "in bad-ref branch reports the error about files not in rootDir at the import location",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.json", "--verbose"],
+            modifyFs: fs => prependText(
+                fs,
+                "/src/core/utilities.ts",
+                `import * as A from '../animals';
 `
-                ),
-                expectedExitStatus: ExitStatus.DiagnosticsPresent_OutputsSkipped,
-                expectedDiagnostics: fs => [
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/animals/tsconfig.json", "src/zoo/tsconfig.json", "src/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/lib/core/utilities.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    {
-                        message: [Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, "/src/animals/animal.ts", "/src/core"],
-                        location: expectedLocationIndexOf(fs, "/src/animals/index.ts", `'./animal'`),
-                    },
-                    {
-                        message: [Diagnostics.File_0_is_not_listed_within_the_file_list_of_project_1_Projects_must_list_all_files_or_use_an_include_pattern, "/src/animals/animal.ts", "/src/core/tsconfig.json"],
-                        location: expectedLocationIndexOf(fs, "/src/animals/index.ts", `'./animal'`),
-                    },
-                    {
-                        message: [Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, "/src/animals/dog.ts", "/src/core"],
-                        location: expectedLocationIndexOf(fs, "/src/animals/index.ts", `'./dog'`),
-                    },
-                    {
-                        message: [Diagnostics.File_0_is_not_listed_within_the_file_list_of_project_1_Projects_must_list_all_files_or_use_an_include_pattern, "/src/animals/dog.ts", "/src/core/tsconfig.json"],
-                        location: expectedLocationIndexOf(fs, "/src/animals/index.ts", `'./dog'`),
-                    },
-                    {
-                        message: [Diagnostics._0_is_declared_but_its_value_is_never_read, "A"],
-                        location: expectedLocationIndexOf(fs, "/src/core/utilities.ts", `import * as A from '../animals';`),
-                    },
-                    {
-                        message: [Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, "/src/animals/index.ts", "/src/core"],
-                        location: expectedLocationIndexOf(fs, "/src/core/utilities.ts", `'../animals'`),
-                    },
-                    {
-                        message: [Diagnostics.File_0_is_not_listed_within_the_file_list_of_project_1_Projects_must_list_all_files_or_use_an_include_pattern, "/src/animals/index.ts", "/src/core/tsconfig.json"],
-                        location: expectedLocationIndexOf(fs, "/src/core/utilities.ts", `'../animals'`),
-                    },
-                    [Diagnostics.Project_0_can_t_be_built_because_its_dependency_1_has_errors, "src/animals/tsconfig.json", "src/core"],
-                    [Diagnostics.Skipping_build_of_project_0_because_its_dependency_1_has_errors, "/src/animals/tsconfig.json", "/src/core"],
-                    [Diagnostics.Project_0_can_t_be_built_because_its_dependency_1_was_not_built, "src/zoo/tsconfig.json", "src/animals"],
-                    [Diagnostics.Skipping_build_of_project_0_because_its_dependency_1_was_not_built, "/src/zoo/tsconfig.json", "/src/animals"],
-                ],
-                expectedOutputs: emptyArray,
-                notExpectedOutputs: [...coreOutputs(), ...animalOutputs(), ...zooOutputs()]
-            });
+            )
         });
     });
 }

src/testRunner/unittests/tsbuild/emptyFiles.ts

@@ -1,40 +1,25 @@
 namespace ts {
-    const projFs = loadProjectFromDisk("tests/projects/empty-files");
-
-    const allExpectedOutputs = [
-        "/src/core/index.js",
-        "/src/core/index.d.ts",
-        "/src/core/index.d.ts.map",
-    ];
-
     describe("unittests:: tsbuild - empty files option in tsconfig", () => {
-        it("has empty files diagnostic when files is empty and no references are provided", () => {
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/no-references"], { dry: false, force: false, verbose: false });
-
-            host.clearDiagnostics();
-            builder.build();
-            host.assertDiagnosticMessages({
-                message: [Diagnostics.The_files_list_in_config_file_0_is_empty, "/src/no-references/tsconfig.json"],
-                location: expectedLocationLastIndexOf(fs, "/src/no-references/tsconfig.json", "[]"),
-            });
-
-            // Check for outputs to not be written.
-            verifyOutputsAbsent(fs, allExpectedOutputs);
+        let projFs: vfs.FileSystem;
+        before(() => {
+            projFs = loadProjectFromDisk("tests/projects/empty-files");
+        });
+        after(() => {
+            projFs = undefined!;
         });
 
-        it("does not have empty files diagnostic when files is empty and references are provided", () => {
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/with-references"], { dry: false, force: false, verbose: false });
+        verifyTsc({
+            scenario: "emptyFiles",
+            subScenario: "has empty files diagnostic when files is empty and no references are provided",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/no-references"],
+        });
 
-            host.clearDiagnostics();
-            builder.build();
-            host.assertDiagnosticMessages(/*empty*/);
-
-            // Check for outputs to be written.
-            verifyOutputsPresent(fs, allExpectedOutputs);
+        verifyTsc({
+            scenario: "emptyFiles",
+            subScenario: "does not have empty files diagnostic when files is empty and references are provided",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/with-references"],
         });
     });
 }

src/testRunner/unittests/tsbuild/exitCodeOnBogusFile.ts

@@ -0,0 +1,11 @@
+namespace ts {
+    // https://github.com/microsoft/TypeScript/issues/33849
+    describe("unittests:: tsbuild:: exitCodeOnBogusFile:: test exit code", () => {
+        verifyTsc({
+            scenario: "exitCodeOnBogusFile",
+            subScenario: `test exit code`,
+            fs: () => loadProjectFromFiles({}, symbolLibContent),
+            commandLineArgs: ["-b", "bogus.json"]
+        });
+    });
+}

src/testRunner/unittests/tsbuild/helpers.ts

@@ -228,7 +228,7 @@ interface Symbol {
             if (section.kind !== BundleFileSectionKind.Prepend) {
                 writeTextOfSection(section.pos, section.end);
             }
-            else {
+            else if (section.texts.length > 0) {
                 Debug.assert(section.pos === first(section.texts).pos);
                 Debug.assert(section.end === last(section.texts).end);
                 for (const text of section.texts) {
@@ -237,6 +237,9 @@ interface Symbol {
                     writeTextOfSection(text.pos, text.end);
                 }
             }
+            else {
+                Debug.assert(section.pos === section.end);
+            }
         }
         baselineRecorder.WriteLine("======================================================================");
 
@@ -276,6 +279,7 @@ interface Symbol {
         buildKind: BuildKind;
         modifyFs: (fs: vfs.FileSystem) => void;
         subScenario?: string;
+        commandLineArgs?: readonly string[];
     }
 
     export interface VerifyTsBuildInput extends TscCompile {
@@ -287,7 +291,7 @@ interface Symbol {
         baselineSourceMap, modifyFs, baselineReadFileCalls,
         incrementalScenarios
     }: VerifyTsBuildInput) {
-        describe(`tsc --b ${scenario}:: ${subScenario}`, () => {
+        describe(`tsc ${commandLineArgs.join(" ")} ${scenario}:: ${subScenario}`, () => {
             let tick: () => void;
             let sys: TscCompileSystem;
             before(() => {
@@ -315,7 +319,12 @@ interface Symbol {
                 verifyTscBaseline(() => sys);
             });
 
-            for (const { buildKind, modifyFs, subScenario: incrementalSubScenario } of incrementalScenarios) {
+            for (const {
+                buildKind,
+                modifyFs,
+                subScenario: incrementalSubScenario,
+                commandLineArgs: incrementalCommandLineArgs
+            } of incrementalScenarios) {
                 describe(incrementalSubScenario || buildKind, () => {
                     let newSys: TscCompileSystem;
                     before(() => {
@@ -326,7 +335,7 @@ interface Symbol {
                             subScenario: incrementalSubScenario || subScenario,
                             buildKind,
                             fs: () => sys.vfs,
-                            commandLineArgs,
+                            commandLineArgs: incrementalCommandLineArgs || commandLineArgs,
                             modifyFs: fs => {
                                 tick();
                                 modifyFs(fs);

src/testRunner/unittests/tsbuild/missingExtendedFile.ts

@@ -1,17 +1,17 @@
 namespace ts {
     describe("unittests:: tsbuild:: when tsconfig extends the missing file", () => {
-        it("unittests:: tsbuild - when tsconfig extends the missing file", () => {
-            const projFs = loadProjectFromDisk("tests/projects/missingExtendedConfig");
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/tsconfig.json"], {});
-            builder.build();
-            host.assertDiagnosticMessages(
-                errorDiagnostic([Diagnostics.The_specified_path_does_not_exist_Colon_0, "/src/foobar.json"]),
-                errorDiagnostic([Diagnostics.No_inputs_were_found_in_config_file_0_Specified_include_paths_were_1_and_exclude_paths_were_2, "/src/tsconfig.first.json", "[\"**/*\"]", "[]"]),
-                errorDiagnostic([Diagnostics.The_specified_path_does_not_exist_Colon_0, "/src/foobar.json"]),
-                errorDiagnostic([Diagnostics.No_inputs_were_found_in_config_file_0_Specified_include_paths_were_1_and_exclude_paths_were_2, "/src/tsconfig.second.json", "[\"**/*\"]", "[]"])
-            );
+        let projFs: vfs.FileSystem;
+        before(() => {
+            projFs = loadProjectFromDisk("tests/projects/missingExtendedConfig");
+        });
+        after(() => {
+            projFs = undefined!;
+        });
+        verifyTsc({
+            scenario: "missingExtendedConfig",
+            subScenario: "when tsconfig extends the missing file",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.json"],
         });
     });
 }

src/testRunner/unittests/tsbuild/outFile.ts

@@ -56,11 +56,6 @@ namespace ts {
             ]
         ];
         const relSources = sources.map(([config, sources]) => [relName(config), sources.map(relName)]) as any as [Sources, Sources, Sources];
-        let expectedOutputFiles = [
-            ...outputFiles[project.first],
-            ...outputFiles[project.second],
-            ...outputFiles[project.third]
-        ];
         let initialExpectedDiagnostics: readonly fakes.ExpectedDiagnostic[] = [
             getExpectedDiagnosticForProjectsInBuild(relSources[project.first][source.config], relSources[project.second][source.config], relSources[project.third][source.config]),
             [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, relSources[project.first][source.config], relOutputFiles[project.first][ext.js]],
@@ -75,7 +70,6 @@ namespace ts {
         });
         after(() => {
             outFileFs = undefined!;
-            expectedOutputFiles = undefined!;
             initialExpectedDiagnostics = undefined!;
         });
 
@@ -166,71 +160,37 @@ namespace ts {
             baselineOnly: true
         });
 
-        it("clean projects", () => {
+        function getOutFileFsAfterBuild() {
             const fs = outFileFs.shadow();
-            const expectedOutputs = [
-                ...outputFiles[project.first],
-                ...outputFiles[project.second],
-                ...outputFiles[project.third]
-            ];
             const host = fakes.SolutionBuilderHost.create(fs);
             const builder = createSolutionBuilder(host);
             builder.build();
-            host.assertDiagnosticMessages(...initialExpectedDiagnostics);
-            // Verify they exist
-            verifyOutputsPresent(fs, expectedOutputs);
-            host.clearDiagnostics();
-            builder.clean();
-            host.assertDiagnosticMessages(/*none*/);
-            // Verify they are gone
-            verifyOutputsAbsent(fs, expectedOutputs);
-            // Subsequent clean shouldn't throw / etc
-            builder.clean();
+            fs.makeReadonly();
+            return fs;
+        }
+
+        verifyTscIncrementalEdits({
+            scenario: "outFile",
+            subScenario: "clean projects",
+            fs: getOutFileFsAfterBuild,
+            commandLineArgs: ["--b", "/src/third", "--clean"],
+            incrementalScenarios: [noChangeRun]
         });
 
-        it("verify buildInfo absence results in new build", () => {
-            const { fs, tick } = getFsWithTime(outFileFs);
-            const expectedOutputs = [
-                ...outputFiles[project.first],
-                ...outputFiles[project.second],
-                ...outputFiles[project.third]
-            ];
-            const host = fakes.SolutionBuilderHost.create(fs);
-            let builder = createSolutionBuilder(host);
-            builder.build();
-            host.assertDiagnosticMessages(...initialExpectedDiagnostics);
-            // Verify they exist
-            verifyOutputsPresent(fs, expectedOutputs);
-            // Delete bundle info
-            host.clearDiagnostics();
-
-            tick();
-            host.deleteFile(outputFiles[project.first][ext.buildinfo]);
-            tick();
-
-            builder = createSolutionBuilder(host);
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(relSources[project.first][source.config], relSources[project.second][source.config], relSources[project.third][source.config]),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, relSources[project.first][source.config], relOutputFiles[project.first][ext.buildinfo]],
-                [Diagnostics.Building_project_0, sources[project.first][source.config]],
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, relSources[project.second][source.config], relSources[project.second][source.ts][part.one], relOutputFiles[project.second][ext.js]],
-                [Diagnostics.Project_0_is_out_of_date_because_output_of_its_dependency_1_has_changed, relSources[project.third][source.config], "src/first"],
-                [Diagnostics.Updating_output_of_project_0, sources[project.third][source.config]],
-                [Diagnostics.Updating_unchanged_output_timestamps_of_project_0, sources[project.third][source.config]],
-            );
+        verifyTsc({
+            scenario: "outFile",
+            subScenario: "verify buildInfo absence results in new build",
+            fs: getOutFileFsAfterBuild,
+            commandLineArgs: ["--b", "/src/third", "--verbose"],
+            modifyFs: fs => fs.unlinkSync(outputFiles[project.first][ext.buildinfo]),
         });
 
-        it("verify that if incremental is set to false, tsbuildinfo is not generated", () => {
-            const fs = outFileFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            replaceText(fs, sources[project.third][source.config], `"composite": true,`, "");
-            const builder = createSolutionBuilder(host);
-            builder.build();
-            host.assertDiagnosticMessages(...initialExpectedDiagnostics);
-            // Verify they exist - without tsbuildinfo for third project
-            verifyOutputsPresent(fs, expectedOutputFiles.slice(0, expectedOutputFiles.length - 2));
-            verifyOutputsAbsent(fs, [outputFiles[project.third][ext.buildinfo]]);
+        verifyTsc({
+            scenario: "outFile",
+            subScenario: "tsbuildinfo is not generated when incremental is set to false",
+            fs: () => outFileFs,
+            commandLineArgs: ["--b", "/src/third", "--verbose"],
+            modifyFs: fs => replaceText(fs, sources[project.third][source.config], `"composite": true,`, ""),
         });
 
         it("rebuilds completely when version in tsbuildinfo doesnt match ts version", () => {
@@ -682,6 +642,40 @@ ${internal} enum internalEnum { a, b, c }`);
                     ignoreDtsUnchanged: true,
                     baselineOnly: true
                 });
+
+                verifyOutFileScenario({
+                    subScenario: "stripInternal when prepend is completely internal",
+                    baselineOnly: true,
+                    ignoreDtsChanged: true,
+                    ignoreDtsUnchanged: true,
+                    modifyFs: fs => {
+                        fs.writeFileSync(sources[project.first][source.ts][part.one], "/* @internal */ const A = 1;");
+                        fs.writeFileSync(sources[project.third][source.ts][part.one], "const B = 2;");
+                        fs.writeFileSync(sources[project.first][source.config], JSON.stringify({
+                            compilerOptions: {
+                                composite: true,
+                                declaration: true,
+                                declarationMap: true,
+                                skipDefaultLibCheck: true,
+                                sourceMap: true,
+                                outFile: "./bin/first-output.js"
+                            },
+                            files: [sources[project.first][source.ts][part.one]]
+                        }));
+                        fs.writeFileSync(sources[project.third][source.config], JSON.stringify({
+                            compilerOptions: {
+                                composite: true,
+                                declaration: true,
+                                declarationMap: false,
+                                stripInternal: true,
+                                sourceMap: true,
+                                outFile: "./thirdjs/output/third-output.js"
+                            },
+                            references: [{ path: "../first", prepend: true }],
+                            files: [sources[project.third][source.ts][part.one]]
+                        }));
+                    }
+                });
             });
 
             describe("empty source files", () => {
@@ -713,44 +707,26 @@ ${internal} enum internalEnum { a, b, c }`);
             });
         });
 
-        it("non module projects without prepend", () => {
-            const fs = outFileFs.shadow();
-            // No prepend
-            replaceText(fs, sources[project.third][source.config], `{ "path": "../first", "prepend": true }`, `{ "path": "../first" }`);
-            replaceText(fs, sources[project.third][source.config], `{ "path": "../second", "prepend": true }`, `{ "path": "../second" }`);
+        verifyTsc({
+            scenario: "outFile",
+            subScenario: "non module projects without prepend",
+            fs: () => outFileFs,
+            commandLineArgs: ["--b", "/src/third", "--verbose"],
+            modifyFs: fs => {
+                // No prepend
+                replaceText(fs, sources[project.third][source.config], `{ "path": "../first", "prepend": true }`, `{ "path": "../first" }`);
+                replaceText(fs, sources[project.third][source.config], `{ "path": "../second", "prepend": true }`, `{ "path": "../second" }`);
 
-            // Non Modules
-            replaceText(fs, sources[project.first][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
-            replaceText(fs, sources[project.second][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
-            replaceText(fs, sources[project.third][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
+                // Non Modules
+                replaceText(fs, sources[project.first][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
+                replaceText(fs, sources[project.second][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
+                replaceText(fs, sources[project.third][source.config], `"composite": true,`, `"composite": true, "module": "none",`);
 
-            // Own file emit
-            replaceText(fs, sources[project.first][source.config], `"outFile": "./bin/first-output.js",`, "");
-            replaceText(fs, sources[project.second][source.config], `"outFile": "../2/second-output.js",`, "");
-            replaceText(fs, sources[project.third][source.config], `"outFile": "./thirdjs/output/third-output.js",`, "");
-
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host);
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(relSources[project.first][source.config], relSources[project.second][source.config], relSources[project.third][source.config]),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, relSources[project.first][source.config], "src/first/first_PART1.js"],
-                [Diagnostics.Building_project_0, sources[project.first][source.config]],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, relSources[project.second][source.config], "src/second/second_part1.js"],
-                [Diagnostics.Building_project_0, sources[project.second][source.config]],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, relSources[project.third][source.config], "src/third/third_part1.js"],
-                [Diagnostics.Building_project_0, sources[project.third][source.config]]
-            );
-            const expectedOutputFiles = flatMap(sources, ([config, ts]) => [
-                removeFileExtension(config) + Extension.TsBuildInfo,
-                ...flatMap(ts, f => [
-                    removeFileExtension(f) + Extension.Js,
-                    removeFileExtension(f) + Extension.Js + ".map",
-                    removeFileExtension(f) + Extension.Dts,
-                    removeFileExtension(f) + Extension.Dts + ".map",
-                ])
-            ]);
-            verifyOutputsPresent(fs, expectedOutputFiles);
+                // Own file emit
+                replaceText(fs, sources[project.first][source.config], `"outFile": "./bin/first-output.js",`, "");
+                replaceText(fs, sources[project.second][source.config], `"outFile": "../2/second-output.js",`, "");
+                replaceText(fs, sources[project.third][source.config], `"outFile": "./thirdjs/output/third-output.js",`, "");
+            },
         });
     });
 }

src/testRunner/unittests/tsbuild/referencesWithRootDirInParent.ts

@@ -9,113 +9,53 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
-        it("verify that it builds correctly", () => {
-            const allExpectedOutputs = [
-                "/src/dist/other/other.js", "/src/dist/other/other.d.ts",
-                "/src/dist/main/a.js", "/src/dist/main/a.d.ts",
-                "/src/dist/main/b.js", "/src/dist/main/b.d.ts"
-            ];
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/src/main", "/src/src/other"], {});
-            builder.build();
-            host.assertDiagnosticMessages(/*empty*/);
-            verifyOutputsPresent(fs, allExpectedOutputs);
+        verifyTsc({
+            scenario: "projectReferenceWithRootDirInParent",
+            subScenario: "builds correctly",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/src/main", "/src/src/other"],
         });
 
-        it("verify that it reports error for same .tsbuildinfo file because no rootDir in the base", () => {
-            const allExpectedOutputs = [
-                "/src/dist/other.js", "/src/dist/other.d.ts",
-                "/src/dist/tsconfig.tsbuildinfo"
-            ];
-            const missingOutputs = [
-                "/src/dist/a.js", "/src/dist/a.d.ts",
-                "/src/dist/b.js", "/src/dist/b.d.ts"
-            ];
-            const fs = projFs.shadow();
-            replaceText(fs, "/src/tsconfig.base.json", `"rootDir": "./src/",`, "");
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/src/main"], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild("src/src/other/tsconfig.json", "src/src/main/tsconfig.json"),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/other/tsconfig.json", "src/dist/other.js"],
-                [Diagnostics.Building_project_0, "/src/src/other/tsconfig.json"],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/main/tsconfig.json", "src/dist/a.js"],
-                [Diagnostics.Building_project_0, "/src/src/main/tsconfig.json"],
-                {
-                    message: [Diagnostics.Cannot_write_file_0_because_it_will_overwrite_tsbuildinfo_file_generated_by_referenced_project_1, "/src/dist/tsconfig.tsbuildinfo", "/src/src/other"],
-                    location: expectedLocationIndexOf(fs, "/src/src/main/tsconfig.json", `{ "path": "../other" }`),
-                }
-            );
-            verifyOutputsPresent(fs, allExpectedOutputs);
-            verifyOutputsAbsent(fs, missingOutputs);
+        verifyTsc({
+            scenario: "projectReferenceWithRootDirInParent",
+            subScenario: "reports error for same tsbuildinfo file because no rootDir in the base",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/src/main", "--verbose"],
+            modifyFs: fs => replaceText(fs, "/src/tsconfig.base.json", `"rootDir": "./src/",`, ""),
         });
 
-        it("verify that it reports error for same .tsbuildinfo file", () => {
-            const allExpectedOutputs = [
-                "/src/dist/other.js", "/src/dist/other.d.ts",
-                "/src/dist/tsconfig.tsbuildinfo"
-            ];
-            const missingOutputs = [
-                "/src/dist/a.js", "/src/dist/a.d.ts",
-                "/src/dist/b.js", "/src/dist/b.d.ts"
-            ];
-            const fs = projFs.shadow();
-            fs.writeFileSync("/src/src/main/tsconfig.json", JSON.stringify({
-                compilerOptions: { composite: true, outDir: "../../dist/" },
-                references: [{ path: "../other" }]
-            }));
-            fs.writeFileSync("/src/src/other/tsconfig.json", JSON.stringify({
-                compilerOptions: { composite: true, outDir: "../../dist/" },
-            }));
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/src/main"], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild("src/src/other/tsconfig.json", "src/src/main/tsconfig.json"),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/other/tsconfig.json", "src/dist/other.js"],
-                [Diagnostics.Building_project_0, "/src/src/other/tsconfig.json"],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/main/tsconfig.json", "src/dist/a.js"],
-                [Diagnostics.Building_project_0, "/src/src/main/tsconfig.json"],
-                {
-                    message: [Diagnostics.Cannot_write_file_0_because_it_will_overwrite_tsbuildinfo_file_generated_by_referenced_project_1, "/src/dist/tsconfig.tsbuildinfo", "/src/src/other"],
-                    location: expectedLocationIndexOf(fs, "/src/src/main/tsconfig.json", `{"path":"../other"}`),
-                }
-            );
-            verifyOutputsPresent(fs, allExpectedOutputs);
-            verifyOutputsAbsent(fs, missingOutputs);
+        verifyTsc({
+            scenario: "projectReferenceWithRootDirInParent",
+            subScenario: "reports error for same tsbuildinfo file",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/src/main", "--verbose"],
+            modifyFs: fs => {
+                fs.writeFileSync("/src/src/main/tsconfig.json", JSON.stringify({
+                    compilerOptions: { composite: true, outDir: "../../dist/" },
+                    references: [{ path: "../other" }]
+                }));
+                fs.writeFileSync("/src/src/other/tsconfig.json", JSON.stringify({
+                    compilerOptions: { composite: true, outDir: "../../dist/" },
+                }));
+            },
         });
 
-        it("verify that it reports no error when .tsbuildinfo differ", () => {
-            const allExpectedOutputs = [
-                "/src/dist/other.js", "/src/dist/other.d.ts",
-                "/src/dist/tsconfig.main.tsbuildinfo",
-                "/src/dist/a.js", "/src/dist/a.d.ts",
-                "/src/dist/b.js", "/src/dist/b.d.ts",
-                "/src/dist/tsconfig.other.tsbuildinfo"
-            ];
-            const fs = projFs.shadow();
-            fs.renameSync("/src/src/main/tsconfig.json", "/src/src/main/tsconfig.main.json");
-            fs.renameSync("/src/src/other/tsconfig.json", "/src/src/other/tsconfig.other.json");
-            fs.writeFileSync("/src/src/main/tsconfig.main.json", JSON.stringify({
-                compilerOptions: { composite: true, outDir: "../../dist/" },
-                references: [{ path: "../other/tsconfig.other.json" }]
-            }));
-            fs.writeFileSync("/src/src/other/tsconfig.other.json", JSON.stringify({
-                compilerOptions: { composite: true, outDir: "../../dist/" },
-            }));
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, ["/src/src/main/tsconfig.main.json"], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild("src/src/other/tsconfig.other.json", "src/src/main/tsconfig.main.json"),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/other/tsconfig.other.json", "src/dist/other.js"],
-                [Diagnostics.Building_project_0, "/src/src/other/tsconfig.other.json"],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/src/main/tsconfig.main.json", "src/dist/a.js"],
-                [Diagnostics.Building_project_0, "/src/src/main/tsconfig.main.json"]
-            );
-            verifyOutputsPresent(fs, allExpectedOutputs);
+        verifyTsc({
+            scenario: "projectReferenceWithRootDirInParent",
+            subScenario: "reports no error when tsbuildinfo differ",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/src/main/tsconfig.main.json", "--verbose"],
+            modifyFs: fs => {
+                fs.renameSync("/src/src/main/tsconfig.json", "/src/src/main/tsconfig.main.json");
+                fs.renameSync("/src/src/other/tsconfig.json", "/src/src/other/tsconfig.other.json");
+                fs.writeFileSync("/src/src/main/tsconfig.main.json", JSON.stringify({
+                    compilerOptions: { composite: true, outDir: "../../dist/" },
+                    references: [{ path: "../other/tsconfig.other.json" }]
+                }));
+                fs.writeFileSync("/src/src/other/tsconfig.other.json", JSON.stringify({
+                    compilerOptions: { composite: true, outDir: "../../dist/" },
+                }));
+            },
         });
     });
 }

src/testRunner/unittests/tsbuild/resolveJsonModule.ts

@@ -1,7 +1,6 @@
 namespace ts {
     describe("unittests:: tsbuild:: with resolveJsonModule option on project resolveJsonModuleAndComposite", () => {
         let projFs: vfs.FileSystem;
-        const allExpectedOutputs = ["/src/dist/src/index.js", "/src/dist/src/index.d.ts", "/src/dist/src/hello.json"];
         before(() => {
             projFs = loadProjectFromDisk("tests/projects/resolveJsonModuleAndComposite");
         });
@@ -10,108 +9,64 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
-        function verifyProjectWithResolveJsonModule(configFile: string, ...expectedDiagnosticMessages: fakes.ExpectedDiagnostic[]) {
-            const fs = projFs.shadow();
-            verifyProjectWithResolveJsonModuleWithFs(fs, configFile, allExpectedOutputs, ...expectedDiagnosticMessages);
-        }
-
-        function verifyProjectWithResolveJsonModuleWithFs(fs: vfs.FileSystem, configFile: string, allExpectedOutputs: readonly string[], ...expectedDiagnosticMessages: fakes.ExpectedDiagnostic[]) {
-            const host = fakes.SolutionBuilderHost.create(fs);
-            const builder = createSolutionBuilder(host, [configFile], { dry: false, force: false, verbose: false });
-            builder.build();
-            host.assertDiagnosticMessages(...expectedDiagnosticMessages);
-            if (!expectedDiagnosticMessages.length) {
-                // Check for outputs. Not an exhaustive list
-                verifyOutputsPresent(fs, allExpectedOutputs);
-            }
-        }
-
-        it("with resolveJsonModule and include only", () => {
-            verifyProjectWithResolveJsonModule(
-                "/src/tsconfig_withInclude.json",
-                {
-                    message: [
-                        Diagnostics.File_0_is_not_listed_within_the_file_list_of_project_1_Projects_must_list_all_files_or_use_an_include_pattern,
-                        "/src/src/hello.json",
-                        "/src/tsconfig_withInclude.json"
-                    ],
-                    location: expectedLocationIndexOf(projFs, "/src/src/index.ts", `"./hello.json"`)
-                }
-            );
+        verifyTsc({
+            scenario: "resolveJsonModule",
+            subScenario: "include only",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig_withInclude.json"],
         });
 
-        it("with resolveJsonModule and include of *.json along with other include", () => {
-            verifyProjectWithResolveJsonModule("/src/tsconfig_withIncludeOfJson.json");
+        verifyTsc({
+            scenario: "resolveJsonModule",
+            subScenario: "include of json along with other include",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig_withIncludeOfJson.json"],
         });
 
-        it("with resolveJsonModule and include of *.json along with other include and file name matches ts file", () => {
-            const fs = projFs.shadow();
-            fs.rimrafSync("/src/src/hello.json");
-            fs.writeFileSync("/src/src/index.json", JSON.stringify({ hello: "world" }));
-            fs.writeFileSync("/src/src/index.ts", `import hello from "./index.json"
+        verifyTsc({
+            scenario: "resolveJsonModule",
+            subScenario: "include of json along with other include and file name matches ts file",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig_withIncludeOfJson.json"],
+            modifyFs: fs => {
+                fs.rimrafSync("/src/src/hello.json");
+                fs.writeFileSync("/src/src/index.json", JSON.stringify({ hello: "world" }));
+                fs.writeFileSync("/src/src/index.ts", `import hello from "./index.json"
 
 export default hello.hello`);
-            const allExpectedOutputs = ["/src/dist/src/index.js", "/src/dist/src/index.d.ts", "/src/dist/src/index.json"];
-            verifyProjectWithResolveJsonModuleWithFs(
-                fs,
-                "/src/tsconfig_withIncludeOfJson.json",
-                allExpectedOutputs,
-                errorDiagnostic([Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files, "/src/dist/src/index.d.ts"])
-            );
+            },
         });
 
-        it("with resolveJsonModule and files containing json file", () => {
-            verifyProjectWithResolveJsonModule("/src/tsconfig_withFiles.json");
+        verifyTsc({
+            scenario: "resolveJsonModule",
+            subScenario: "files containing json file",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig_withFiles.json"],
         });
 
-        it("with resolveJsonModule and include and files", () => {
-            verifyProjectWithResolveJsonModule("/src/tsconfig_withIncludeAndFiles.json");
+        verifyTsc({
+            scenario: "resolveJsonModule",
+            subScenario: "include and files",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig_withIncludeAndFiles.json"],
         });
 
-        it("with resolveJsonModule and sourceMap", () => {
-            const { fs, tick } = getFsWithTime(projFs);
-            const configFile = "src/tsconfig_withFiles.json";
-            replaceText(fs, configFile, `"composite": true,`, `"composite": true, "sourceMap": true,`);
-            const host = fakes.SolutionBuilderHost.create(fs);
-            let builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(configFile),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, configFile, "src/dist/src/index.js"],
-                [Diagnostics.Building_project_0, `/${configFile}`]
-            );
-            verifyOutputsPresent(fs, [...allExpectedOutputs, "/src/dist/src/index.js.map"]);
-            host.clearDiagnostics();
-            builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            tick();
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(configFile),
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, configFile, "src/src/index.ts", "src/dist/src/index.js"]
-            );
+        verifyTscIncrementalEdits({
+            scenario: "resolveJsonModule",
+            subScenario: "sourcemap",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "src/tsconfig_withFiles.json", "--verbose"],
+            modifyFs: fs => replaceText(fs, "src/tsconfig_withFiles.json", `"composite": true,`, `"composite": true, "sourceMap": true,`),
+            incrementalScenarios: [noChangeRun]
         });
 
-        it("with resolveJsonModule and without outDir", () => {
-            const { fs, tick } = getFsWithTime(projFs);
-            const configFile = "src/tsconfig_withFiles.json";
-            replaceText(fs, configFile, `"outDir": "dist",`, "");
-            const host = fakes.SolutionBuilderHost.create(fs);
-            let builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(configFile),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, configFile, "src/src/index.js"],
-                [Diagnostics.Building_project_0, `/${configFile}`]
-            );
-            verifyOutputsPresent(fs, ["/src/src/index.js", "/src/src/index.d.ts"]);
-            host.clearDiagnostics();
-            builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            tick();
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(configFile),
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, configFile, "src/src/index.ts", "src/src/index.js"]
-            );
+        verifyTscIncrementalEdits({
+            scenario: "resolveJsonModule",
+            subScenario: "without outDir",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "src/tsconfig_withFiles.json", "--verbose"],
+            modifyFs: fs => replaceText(fs, "src/tsconfig_withFiles.json", `"outDir": "dist",`, ""),
+            incrementalScenarios: [noChangeRun]
         });
     });
 
@@ -125,32 +80,12 @@ export default hello.hello`);
             projFs = undefined!; // Release the contents
         });
 
-        it("when importing json module from project reference", () => {
-            const expectedOutput = "/src/main/index.js";
-            const { fs, tick } = getFsWithTime(projFs);
-            const configFile = "src/tsconfig.json";
-            const stringsConfigFile = "src/strings/tsconfig.json";
-            const mainConfigFile = "src/main/tsconfig.json";
-            const host = fakes.SolutionBuilderHost.create(fs);
-            let builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(stringsConfigFile, mainConfigFile, configFile),
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, stringsConfigFile, "src/strings/tsconfig.tsbuildinfo"],
-                [Diagnostics.Building_project_0, `/${stringsConfigFile}`],
-                [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, mainConfigFile, "src/main/index.js"],
-                [Diagnostics.Building_project_0, `/${mainConfigFile}`],
-            );
-            verifyOutputsPresent(fs, [expectedOutput]);
-            host.clearDiagnostics();
-            builder = createSolutionBuilder(host, [configFile], { verbose: true });
-            tick();
-            builder.build();
-            host.assertDiagnosticMessages(
-                getExpectedDiagnosticForProjectsInBuild(stringsConfigFile, mainConfigFile, configFile),
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, stringsConfigFile, "src/strings/foo.json", "src/strings/tsconfig.tsbuildinfo"],
-                [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, mainConfigFile, "src/main/index.ts", "src/main/index.js"],
-            );
+        verifyTscIncrementalEdits({
+            scenario: "resolveJsonModule",
+            subScenario: "importing json module from project reference",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "src/tsconfig.json", "--verbose"],
+            incrementalScenarios: [noChangeRun]
         });
     });
 }

src/testRunner/unittests/tsbuild/sample.ts

@@ -14,123 +14,63 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
+        function getSampleFsAfterBuild() {
+            const fs = projFs.shadow();
+            const host = fakes.SolutionBuilderHost.create(fs);
+            const builder = createSolutionBuilder(host, ["/src/tests"], {});
+            builder.build();
+            fs.makeReadonly();
+            return fs;
+        }
+
         describe("sanity check of clean build of 'sample1' project", () => {
-            it("can build the sample project 'sample1' without error", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: false, verbose: false });
-
-                host.clearDiagnostics();
-                builder.build();
-                host.assertDiagnosticMessages(/*empty*/);
-
-                // Check for outputs. Not an exhaustive list
-                verifyOutputsPresent(fs, allExpectedOutputs);
-            });
-
-            it("builds correctly when outDir is specified", () => {
-                const fs = projFs.shadow();
-                fs.writeFileSync("/src/logic/tsconfig.json", JSON.stringify({
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "builds correctly when outDir is specified",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests"],
+                modifyFs: fs => fs.writeFileSync("/src/logic/tsconfig.json", JSON.stringify({
                     compilerOptions: { composite: true, declaration: true, sourceMap: true, outDir: "outDir" },
                     references: [{ path: "../core" }]
-                }));
-
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], {});
-                builder.build();
-                host.assertDiagnosticMessages(/*empty*/);
-                const expectedOutputs = allExpectedOutputs.map(f => f.replace("/logic/", "/logic/outDir/"));
-                // Check for outputs. Not an exhaustive list
-                verifyOutputsPresent(fs, expectedOutputs);
+                })),
             });
 
-            it("builds correctly when declarationDir is specified", () => {
-                const fs = projFs.shadow();
-                fs.writeFileSync("/src/logic/tsconfig.json", JSON.stringify({
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "builds correctly when declarationDir is specified",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests"],
+                modifyFs: fs => fs.writeFileSync("/src/logic/tsconfig.json", JSON.stringify({
                     compilerOptions: { composite: true, declaration: true, sourceMap: true, declarationDir: "out/decls" },
                     references: [{ path: "../core" }]
-                }));
-
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], {});
-                builder.build();
-                host.assertDiagnosticMessages(/*empty*/);
-                const expectedOutputs = allExpectedOutputs.map(f => f.replace("/logic/index.d.ts", "/logic/out/decls/index.d.ts"));
-                // Check for outputs. Not an exhaustive list
-                verifyOutputsPresent(fs, expectedOutputs);
+                })),
             });
 
-            it("builds correctly when project is not composite or doesnt have any references", () => {
-                const fs = projFs.shadow();
-                replaceText(fs, "/src/core/tsconfig.json", `"composite": true,`, "");
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/core"], { verbose: true });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/core/anotherModule.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"]
-                );
-                verifyOutputsPresent(fs, ["/src/core/index.js", "/src/core/index.d.ts", "/src/core/index.d.ts.map"]);
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "builds correctly when project is not composite or doesnt have any references",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/core", "--verbose"],
+                modifyFs: fs => replaceText(fs, "/src/core/tsconfig.json", `"composite": true,`, ""),
             });
         });
 
         describe("dry builds", () => {
-            it("doesn't write any files in a dry build", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { dry: true, force: false, verbose: false });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    [Diagnostics.A_non_dry_build_would_build_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.A_non_dry_build_would_build_project_0, "/src/logic/tsconfig.json"],
-                    [Diagnostics.A_non_dry_build_would_build_project_0, "/src/tests/tsconfig.json"]
-                );
-
-                // Check for outputs to not be written. Not an exhaustive list
-                verifyOutputsAbsent(fs, allExpectedOutputs);
-            });
-
-            it("indicates that it would skip builds during a dry build", () => {
-                const { fs, tick } = getFsWithTime(projFs);
-                const host = fakes.SolutionBuilderHost.create(fs);
-
-                let builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: false, verbose: false });
-                builder.build();
-                tick();
-
-                host.clearDiagnostics();
-                builder = createSolutionBuilder(host, ["/src/tests"], { dry: true, force: false, verbose: false });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    [Diagnostics.Project_0_is_up_to_date, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date, "/src/logic/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date, "/src/tests/tsconfig.json"]
-                );
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "does not write any files in a dry build",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--dry"],
             });
         });
 
         describe("clean builds", () => {
-            it("removes all files it built", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-
-                const builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: false, verbose: false });
-                builder.build();
-                // Verify they exist
-                verifyOutputsPresent(fs, allExpectedOutputs);
-
-                builder.clean();
-                // Verify they are gone
-                verifyOutputsAbsent(fs, allExpectedOutputs);
-
-                // Subsequent clean shouldn't throw / etc
-                builder.clean();
-                verifyOutputsAbsent(fs, allExpectedOutputs);
-
-                builder.build();
-                // Verify they exist
-                verifyOutputsPresent(fs, allExpectedOutputs);
+            verifyTscIncrementalEdits({
+                scenario: "sample1",
+                subScenario: "removes all files it built",
+                fs: getSampleFsAfterBuild,
+                commandLineArgs: ["--b", "/src/tests", "--clean"],
+                incrementalScenarios: [noChangeRun]
             });
 
             it("cleans till project specified", () => {
@@ -158,29 +98,12 @@ namespace ts {
         });
 
         describe("force builds", () => {
-            it("always builds under --force", () => {
-                const { fs, time, tick } = getFsWithTime(projFs);
-                const host = fakes.SolutionBuilderHost.create(fs);
-
-                let builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: true, verbose: false });
-                builder.build();
-                let currentTime = time();
-                checkOutputTimestamps(currentTime);
-
-                tick();
-                Debug.assert(time() !== currentTime, "Time moves on");
-                currentTime = time();
-                builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: true, verbose: false });
-                builder.build();
-                checkOutputTimestamps(currentTime);
-
-                function checkOutputTimestamps(expected: number) {
-                    // Check timestamps
-                    for (const output of allExpectedOutputs) {
-                        const actual = fs.statSync(output).mtimeMs;
-                        assert(actual === expected, `File ${output} has timestamp ${actual}, expected ${expected}`);
-                    }
-                }
+            verifyTscIncrementalEdits({
+                scenario: "sample1",
+                subScenario: "always builds under with force option",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--force"],
+                incrementalScenarios: [noChangeRun]
             });
         });
 
@@ -196,64 +119,42 @@ namespace ts {
                 return { fs, host, builder };
             }
 
-            it("Builds the project", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { verbose: true });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/core/anotherModule.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/logic/tsconfig.json", "src/logic/index.js"],
-                    [Diagnostics.Building_project_0, "/src/logic/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/tests/tsconfig.json", "src/tests/index.js"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"]
-                );
-            });
-
-            // All three projects are up to date
-            it("Detects that all projects are up to date", () => {
-                const { host, builder } = initializeWithBuild();
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/logic/tsconfig.json", "src/logic/index.ts", "src/logic/index.js"],
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/tests/tsconfig.json", "src/tests/index.ts", "src/tests/index.js"]
-                );
-            });
-
-            // Update a file in the leaf node (tests), only it should rebuild the last one
-            it("Only builds the leaf node project", () => {
-                const { fs, host, builder } = initializeWithBuild();
-                fs.writeFileSync("/src/tests/index.ts", "const m = 10;");
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/logic/tsconfig.json", "src/logic/index.ts", "src/logic/index.js"],
-                    [Diagnostics.Project_0_is_out_of_date_because_oldest_output_1_is_older_than_newest_input_2, "src/tests/tsconfig.json", "src/tests/index.js", "src/tests/index.ts"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"]
-                );
-            });
-
-            // Update a file in the parent (without affecting types), should get fast downstream builds
-            it("Detects type-only changes in upstream projects", () => {
-                const { fs, host, builder } = initializeWithBuild();
-                replaceText(fs, "/src/core/index.ts", "HELLO WORLD", "WELCOME PLANET");
-                builder.build();
-
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_oldest_output_1_is_older_than_newest_input_2, "src/core/tsconfig.json", "src/core/anotherModule.js", "src/core/index.ts"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Updating_unchanged_output_timestamps_of_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date_with_d_ts_files_from_its_dependencies, "src/logic/tsconfig.json"],
-                    [Diagnostics.Updating_output_timestamps_of_project_0, "/src/logic/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date_with_d_ts_files_from_its_dependencies, "src/tests/tsconfig.json"],
-                    [Diagnostics.Updating_output_timestamps_of_project_0, "/src/tests/tsconfig.json"]
-                );
+            verifyTscIncrementalEdits({
+                scenario: "sample1",
+                subScenario: "can detect when and what to rebuild",
+                fs: getSampleFsAfterBuild,
+                commandLineArgs: ["--b", "/src/tests", "--verbose"],
+                incrementalScenarios: [
+                    // Update a file in the leaf node (tests), only it should rebuild the last one
+                    {
+                        subScenario: "Only builds the leaf node project",
+                        buildKind: BuildKind.IncrementalDtsUnchanged,
+                        modifyFs: fs => fs.writeFileSync("/src/tests/index.ts", "const m = 10;"),
+                    },
+                    // Update a file in the parent (without affecting types), should get fast downstream builds
+                    {
+                        subScenario: "Detects type-only changes in upstream projects",
+                        buildKind: BuildKind.IncrementalDtsChange,
+                        modifyFs: fs => replaceText(fs, "/src/core/index.ts", "HELLO WORLD", "WELCOME PLANET"),
+                    },
+                    {
+                        subScenario: "indicates that it would skip builds during a dry build",
+                        buildKind: BuildKind.IncrementalDtsUnchanged,
+                        modifyFs: noop,
+                        commandLineArgs: ["--b", "/src/tests", "--dry"],
+                    },
+                    {
+                        subScenario: "rebuilds from start if force option is set",
+                        buildKind: BuildKind.IncrementalDtsChange,
+                        modifyFs: noop,
+                        commandLineArgs: ["--b", "/src/tests", "--verbose", "--force"],
+                    },
+                    {
+                        subScenario: "rebuilds when tsconfig changes",
+                        buildKind: BuildKind.IncrementalDtsChange,
+                        modifyFs: fs => replaceText(fs, "/src/tests/tsconfig.json", `"composite": true`, `"composite": true, "target": "es3"`),
+                    },
+                ]
             });
 
             it("rebuilds completely when version in tsbuildinfo doesnt match ts version", () => {
@@ -300,61 +201,19 @@ namespace ts {
                 );
             });
 
-            it("rebuilds from start if --f is passed", () => {
-                const { host, builder } = initializeWithBuild({ force: true });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date_with_d_ts_files_from_its_dependencies, "src/logic/tsconfig.json"],
-                    [Diagnostics.Building_project_0, "/src/logic/tsconfig.json"],
-                    [Diagnostics.Project_0_is_up_to_date_with_d_ts_files_from_its_dependencies, "src/tests/tsconfig.json"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"]
-                );
-            });
-
-            it("rebuilds when tsconfig changes", () => {
-                const { fs, host, builder } = initializeWithBuild();
-                replaceText(fs, "/src/tests/tsconfig.json", `"composite": true`, `"composite": true, "target": "es3"`);
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/logic/tsconfig.json", "src/logic/index.ts", "src/logic/index.js"],
-                    [Diagnostics.Project_0_is_out_of_date_because_oldest_output_1_is_older_than_newest_input_2, "src/tests/tsconfig.json", "src/tests/index.js", "src/tests/tsconfig.json"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"],
-                );
-            });
-
-            it("rebuilds when extended config file changes", () => {
-                const { fs, tick } = getFsWithTime(projFs);
-                fs.writeFileSync("/src/tests/tsconfig.base.json", JSON.stringify({ compilerOptions: { target: "es3" } }));
-                replaceText(fs, "/src/tests/tsconfig.json", `"references": [`, `"extends": "./tsconfig.base.json", "references": [`);
-                const host = fakes.SolutionBuilderHost.create(fs);
-                let builder = createSolutionBuilder(host, ["/src/tests"], { verbose: true });
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/core/anotherModule.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/logic/tsconfig.json", "src/logic/index.js"],
-                    [Diagnostics.Building_project_0, "/src/logic/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/tests/tsconfig.json", "src/tests/index.js"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"]
-                );
-                host.clearDiagnostics();
-                tick();
-                builder = createSolutionBuilder(host, ["/src/tests"], { verbose: true });
-                fs.writeFileSync("/src/tests/tsconfig.base.json", JSON.stringify({ compilerOptions: {} }));
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
-                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/logic/tsconfig.json", "src/logic/index.ts", "src/logic/index.js"],
-                    [Diagnostics.Project_0_is_out_of_date_because_oldest_output_1_is_older_than_newest_input_2, "src/tests/tsconfig.json", "src/tests/index.js", "src/tests/tsconfig.base.json"],
-                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"]
-                );
+            verifyTscIncrementalEdits({
+                scenario: "sample1",
+                subScenario: "rebuilds when extended config file changes",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--verbose"],
+                modifyFs: fs => {
+                    fs.writeFileSync("/src/tests/tsconfig.base.json", JSON.stringify({ compilerOptions: { target: "es3" } }));
+                    replaceText(fs, "/src/tests/tsconfig.json", `"references": [`, `"extends": "./tsconfig.base.json", "references": [`);
+                },
+                incrementalScenarios: [{
+                    buildKind: BuildKind.IncrementalDtsChange,
+                    modifyFs: fs => fs.writeFileSync("/src/tests/tsconfig.base.json", JSON.stringify({ compilerOptions: {} }))
+                }]
             });
 
             it("builds till project specified", () => {
@@ -435,27 +294,12 @@ namespace ts {
         });
 
         describe("downstream-blocked compilations", () => {
-            it("won't build downstream projects if upstream projects have errors", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { dry: false, force: false, verbose: true });
-
-                // Induce an error in the middle project
-                replaceText(fs, "/src/logic/index.ts", "c.multiply(10, 15)", `c.muitply()`);
-                builder.build();
-                host.assertDiagnosticMessages(
-                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/core/tsconfig.json", "src/core/anotherModule.js"],
-                    [Diagnostics.Building_project_0, "/src/core/tsconfig.json"],
-                    [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/logic/tsconfig.json", "src/logic/index.js"],
-                    [Diagnostics.Building_project_0, "/src/logic/tsconfig.json"],
-                    {
-                        message: [Diagnostics.Property_0_does_not_exist_on_type_1, "muitply", `typeof import("/src/core/index")`],
-                        location: expectedLocationIndexOf(fs, "/src/logic/index.ts", "muitply"),
-                    },
-                    [Diagnostics.Project_0_can_t_be_built_because_its_dependency_1_has_errors, "src/tests/tsconfig.json", "src/logic"],
-                    [Diagnostics.Skipping_build_of_project_0_because_its_dependency_1_has_errors, "/src/tests/tsconfig.json", "/src/logic"]
-                );
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "does not build downstream projects if upstream projects have errors",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--verbose"],
+                modifyFs: fs => replaceText(fs, "/src/logic/index.ts", "c.multiply(10, 15)", `c.muitply()`)
             });
         });
 
@@ -515,54 +359,17 @@ export class cNew {}`);
         });
 
         describe("lists files", () => {
-            it("listFiles", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { listFiles: true });
-                builder.build();
-                assert.deepEqual(host.traces, [
-                    "/lib/lib.d.ts",
-                    "/src/core/anotherModule.ts",
-                    "/src/core/index.ts",
-                    "/src/core/some_decl.d.ts",
-                    "/lib/lib.d.ts",
-                    ...getCoreOutputs(),
-                    "/src/logic/index.ts",
-                    "/lib/lib.d.ts",
-                    ...getCoreOutputs(),
-                    "/src/logic/index.d.ts",
-                    "/src/tests/index.ts"
-                ]);
-
-                function getCoreOutputs() {
-                    return [
-                        "/src/core/index.d.ts",
-                        "/src/core/anotherModule.d.ts"
-                    ];
-                }
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "listFiles",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--listFiles"],
             });
-
-            it("listEmittedFiles", () => {
-                const fs = projFs.shadow();
-                const host = fakes.SolutionBuilderHost.create(fs);
-                const builder = createSolutionBuilder(host, ["/src/tests"], { listEmittedFiles: true });
-                builder.build();
-                assert.deepEqual(host.traces, [
-                    "TSFILE: /src/core/anotherModule.js",
-                    "TSFILE: /src/core/anotherModule.d.ts.map",
-                    "TSFILE: /src/core/anotherModule.d.ts",
-                    "TSFILE: /src/core/index.js",
-                    "TSFILE: /src/core/index.d.ts.map",
-                    "TSFILE: /src/core/index.d.ts",
-                    "TSFILE: /src/core/tsconfig.tsbuildinfo",
-                    "TSFILE: /src/logic/index.js.map",
-                    "TSFILE: /src/logic/index.js",
-                    "TSFILE: /src/logic/index.d.ts",
-                    "TSFILE: /src/logic/tsconfig.tsbuildinfo",
-                    "TSFILE: /src/tests/index.js",
-                    "TSFILE: /src/tests/index.d.ts",
-                    "TSFILE: /src/tests/tsconfig.tsbuildinfo",
-                ]);
+            verifyTsc({
+                scenario: "sample1",
+                subScenario: "listEmittedFiles",
+                fs: () => projFs,
+                commandLineArgs: ["--b", "/src/tests", "--listEmittedFiles"],
             });
         });
 
@@ -590,7 +397,8 @@ class someClass { }`),
                         buildKind: BuildKind.IncrementalDtsChange,
                         modifyFs: fs => replaceText(fs, "/src/logic/tsconfig.json", `"declaration": true,`, `"declaration": true,
         "declarationDir": "decls",`),
-                    }
+                    },
+                    noChangeRun,
                 ],
             });
 

src/testRunner/unittests/tsbuild/transitiveReferences.ts

@@ -1,23 +1,6 @@
 namespace ts {
     describe("unittests:: tsbuild:: when project reference is referenced transitively", () => {
         let projFs: vfs.FileSystem;
-        const allExpectedOutputs = [
-            "/src/a.js", "/src/a.d.ts",
-            "/src/b.js", "/src/b.d.ts",
-            "/src/c.js"
-        ];
-        const expectedFileTraces = [
-            "/lib/lib.d.ts",
-            "/src/a.ts",
-            "/lib/lib.d.ts",
-            "/src/a.d.ts",
-            "/src/b.ts",
-            "/lib/lib.d.ts",
-            "/src/a.d.ts",
-            "/src/b.d.ts",
-            "/src/refs/a.d.ts",
-            "/src/c.ts"
-        ];
         before(() => {
             projFs = loadProjectFromDisk("tests/projects/transitiveReferences");
         });
@@ -25,17 +8,6 @@ namespace ts {
             projFs = undefined!; // Release the contents
         });
 
-        function verifyBuild(modifyDiskLayout: (fs: vfs.FileSystem) => void, allExpectedOutputs: readonly string[], expectedFileTraces: readonly string[], ...expectedDiagnostics: fakes.ExpectedDiagnostic[]) {
-            const fs = projFs.shadow();
-            const host = fakes.SolutionBuilderHost.create(fs);
-            modifyDiskLayout(fs);
-            const builder = createSolutionBuilder(host, ["/src/tsconfig.c.json"], { listFiles: true });
-            builder.build();
-            host.assertDiagnosticMessages(...expectedDiagnostics);
-            verifyOutputsPresent(fs, allExpectedOutputs);
-            assert.deepEqual(host.traces, expectedFileTraces);
-        }
-
         function modifyFsBTsToNonRelativeImport(fs: vfs.FileSystem, moduleResolution: "node" | "classic") {
             fs.writeFileSync("/src/b.ts", `import {A} from 'a';
 export const b = new A();`);
@@ -49,35 +21,27 @@ export const b = new A();`);
             }));
         }
 
-        it("verify that it builds correctly", () => {
-            verifyBuild(noop, allExpectedOutputs, expectedFileTraces);
+        verifyTsc({
+            scenario: "transitiveReferences",
+            subScenario: "builds correctly",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.c.json", "--listFiles"],
         });
 
-        it("verify that it builds correctly when the referenced project uses different module resolution", () => {
-            verifyBuild(fs => modifyFsBTsToNonRelativeImport(fs, "classic"), allExpectedOutputs, expectedFileTraces);
+        verifyTsc({
+            scenario: "transitiveReferences",
+            subScenario: "builds correctly when the referenced project uses different module resolution",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.c.json", "--listFiles"],
+            modifyFs: fs => modifyFsBTsToNonRelativeImport(fs, "classic"),
         });
 
-        it("verify that it build reports error about module not found with node resolution with external module name", () => {
-            // Error in b build only a
-            const allExpectedOutputs = ["/src/a.js", "/src/a.d.ts"];
-            const expectedFileTraces = [
-                "/lib/lib.d.ts",
-                "/src/a.ts",
-                "/lib/lib.d.ts",
-                "/src/b.ts"
-            ];
-            verifyBuild(fs => modifyFsBTsToNonRelativeImport(fs, "node"),
-                allExpectedOutputs,
-                expectedFileTraces,
-                {
-                    message: [Diagnostics.Cannot_find_module_0, "a"],
-                    location: {
-                        file: "/src/b.ts",
-                        start: `import {A} from 'a';`.indexOf(`'a'`),
-                        length: `'a'`.length
-                    }
-                },
-            );
+        verifyTsc({
+            scenario: "transitiveReferences",
+            subScenario: "reports error about module not found with node resolution with external module name",
+            fs: () => projFs,
+            commandLineArgs: ["--b", "/src/tsconfig.c.json", "--listFiles"],
+            modifyFs: fs => modifyFsBTsToNonRelativeImport(fs, "node"),
         });
     });
 }

src/testRunner/unittests/tsc/helpers.ts

@@ -3,158 +3,20 @@ namespace ts {
         writtenFiles: Map<true>;
         baseLine(): void;
     };
-    function executeCommandLine(sys: TscCompileSystem, commandLineArgs: readonly string[]) {
-        if (isBuild(commandLineArgs)) {
-            return performBuild(sys, commandLineArgs.slice(1));
-        }
-
-        const reportDiagnostic = createDiagnosticReporter(sys);
-        const commandLine = parseCommandLine(commandLineArgs, path => sys.readFile(path));
-        if (commandLine.options.build) {
-            reportDiagnostic(createCompilerDiagnostic(Diagnostics.Option_build_must_be_the_first_command_line_argument));
-            return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-        }
-
-        if (commandLine.errors.length > 0) {
-            commandLine.errors.forEach(reportDiagnostic);
-            return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-        }
-
-        let configFileName: string | undefined;
-        if (commandLine.options.project) {
-            if (commandLine.fileNames.length !== 0) {
-                reportDiagnostic(createCompilerDiagnostic(Diagnostics.Option_project_cannot_be_mixed_with_source_files_on_a_command_line));
-                return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-            }
-
-            const fileOrDirectory = normalizePath(commandLine.options.project);
-            if (!fileOrDirectory /* current directory "." */ || sys.directoryExists(fileOrDirectory)) {
-                configFileName = combinePaths(fileOrDirectory, "tsconfig.json");
-                if (!sys.fileExists(configFileName)) {
-                    reportDiagnostic(createCompilerDiagnostic(Diagnostics.Cannot_find_a_tsconfig_json_file_at_the_specified_directory_Colon_0, commandLine.options.project));
-                    return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-                }
-            }
-            else {
-                configFileName = fileOrDirectory;
-                if (!sys.fileExists(configFileName)) {
-                    reportDiagnostic(createCompilerDiagnostic(Diagnostics.The_specified_path_does_not_exist_Colon_0, commandLine.options.project));
-                    return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-                }
-            }
-        }
-        else if (commandLine.fileNames.length === 0) {
-            const searchPath = normalizePath(sys.getCurrentDirectory());
-            configFileName = findConfigFile(searchPath, sys.fileExists);
-        }
-
-        Debug.assert(commandLine.fileNames.length !== 0 || !!configFileName);
-
-        if (configFileName) {
-            const configParseResult = Debug.assertDefined(parseConfigFileWithSystem(configFileName, commandLine.options, sys, reportDiagnostic));
-            if (isIncrementalCompilation(configParseResult.options)) {
-                performIncrementalCompilation(sys, configParseResult);
-            }
-            else {
-                performCompilation(sys, configParseResult);
-            }
-        }
-        else {
-            if (isIncrementalCompilation(commandLine.options)) {
-                performIncrementalCompilation(sys, commandLine);
-            }
-            else {
-                performCompilation(sys, commandLine);
-            }
-        }
-    }
-
-    function createReportErrorSummary(sys: TscCompileSystem, options: CompilerOptions): ReportEmitErrorSummary | undefined {
-        return options.pretty ?
-            errorCount => sys.write(getErrorSummaryText(errorCount, sys.newLine)) :
-            undefined;
-    }
-
-    function performCompilation(sys: TscCompileSystem, config: ParsedCommandLine) {
-        const { fileNames, options, projectReferences } = config;
-        const reportDiagnostic = createDiagnosticReporter(sys, options.pretty);
-        const host = createCompilerHostWorker(options, /*setParentPos*/ undefined, sys);
-        const currentDirectory = host.getCurrentDirectory();
-        const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames());
-        changeCompilerHostLikeToUseCache(host, fileName => toPath(fileName, currentDirectory, getCanonicalFileName));
-        const program = createProgram({
-            rootNames: fileNames,
-            options,
-            projectReferences,
-            host,
-            configFileParsingDiagnostics: getConfigFileParsingDiagnostics(config)
-        });
-        const exitStatus = emitFilesAndReportErrorsAndGetExitStatus(
-            program,
-            reportDiagnostic,
-            s => sys.write(s + sys.newLine),
-            createReportErrorSummary(sys, options)
-        );
-        baselineBuildInfo([config], sys.vfs, sys.writtenFiles);
-        return sys.exit(exitStatus);
-    }
-
-    function performIncrementalCompilation(sys: TscCompileSystem, config: ParsedCommandLine) {
-        const reportDiagnostic = createDiagnosticReporter(sys, config.options.pretty);
-        const { options, fileNames, projectReferences } = config;
-        const exitCode = ts.performIncrementalCompilation({
-            system: sys,
-            rootNames: fileNames,
-            options,
-            configFileParsingDiagnostics: getConfigFileParsingDiagnostics(config),
-            projectReferences,
-            reportDiagnostic,
-            reportErrorSummary: createReportErrorSummary(sys, options),
-        });
-        baselineBuildInfo([config], sys.vfs, sys.writtenFiles);
-        return sys.exit(exitCode);
-    }
-
-    function performBuild(sys: TscCompileSystem, args: string[]) {
-        const { buildOptions, projects, errors } = parseBuildCommand(args);
-        const reportDiagnostic = createDiagnosticReporter(sys, buildOptions.pretty);
-
-        if (errors.length > 0) {
-            errors.forEach(reportDiagnostic);
-            return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
-        }
-
-        Debug.assert(projects.length !== 0);
-
-        const buildHost = createSolutionBuilderHost(
-            sys,
-            /*createProgram*/ undefined,
-            reportDiagnostic,
-            createBuilderStatusReporter(sys, buildOptions.pretty),
-            createReportErrorSummary(sys, buildOptions)
-        );
-        fakes.patchSolutionBuilderHost(buildHost, sys);
-        const builder = createSolutionBuilder(buildHost, projects, buildOptions);
-        const exitCode = buildOptions.clean ? builder.clean() : builder.build();
-        baselineBuildInfo(builder.getAllParsedConfigs(), sys.vfs, sys.writtenFiles);
-        return sys.exit(exitCode);
-    }
-
-    function isBuild(commandLineArgs: readonly string[]) {
-        if (commandLineArgs.length > 0 && commandLineArgs[0].charCodeAt(0) === CharacterCodes.minus) {
-            const firstOption = commandLineArgs[0].slice(commandLineArgs[0].charCodeAt(1) === CharacterCodes.minus ? 2 : 1).toLowerCase();
-            return firstOption === "build" || firstOption === "b";
-        }
-        return false;
-    }
 
     export enum BuildKind {
         Initial = "initial-build",
         IncrementalDtsChange = "incremental-declaration-changes",
         IncrementalDtsUnchanged = "incremental-declaration-doesnt-change",
-        IncrementalHeadersChange = "incremental-headers-change-without-dts-changes"
+        IncrementalHeadersChange = "incremental-headers-change-without-dts-changes",
+        NoChangeRun ="no-change-run"
     }
 
+    export const noChangeRun: TscIncremental = {
+        buildKind: BuildKind.NoChangeRun,
+        modifyFs: noop
+    };
+
     export interface TscCompile {
         scenario: string;
         subScenario: string;
@@ -198,8 +60,17 @@ namespace ts {
 
         sys.write(`${sys.getExecutingFilePath()} ${commandLineArgs.join(" ")}\n`);
         sys.exit = exitCode => sys.exitCode = exitCode;
-        executeCommandLine(sys, commandLineArgs);
-        sys.write(`exitCode:: ${sys.exitCode}\n`);
+        executeCommandLine(
+            sys,
+            {
+                onCompilerHostCreate: host => fakes.patchHostForBuildInfoReadWrite(host),
+                onCompilationComplete: config => baselineBuildInfo([config], sys.vfs, sys.writtenFiles),
+                onSolutionBuilderHostCreate: host => fakes.patchSolutionBuilderHost(host, sys),
+                onSolutionBuildComplete: configs => baselineBuildInfo(configs, sys.vfs, sys.writtenFiles),
+            },
+            commandLineArgs,
+        );
+        sys.write(`exitCode:: ExitStatus.${ExitStatus[sys.exitCode as ExitStatus]}\n`);
         if (baselineReadFileCalls) {
             sys.write(`readFiles:: ${JSON.stringify(actualReadFileMap, /*replacer*/ undefined, " ")} `);
         }

src/testRunner/unittests/tsc/incremental.ts

@@ -0,0 +1,76 @@
+namespace ts {
+    describe("unittests:: tsc:: incremental::", () => {
+        verifyTscIncrementalEdits({
+            scenario: "incremental",
+            subScenario: "when passing filename for buildinfo on commandline",
+            fs: () => loadProjectFromFiles({
+                "/src/project/src/main.ts": "export const x = 10;",
+                "/src/project/tsconfig.json": utils.dedent`
+                    {
+                        "compilerOptions": {
+                            "target": "es5",
+                            "module": "commonjs",
+                        },
+                        "include": [
+                            "src/**/*.ts"
+                        ]
+                    }`,
+            }),
+            commandLineArgs: ["--incremental", "--p", "src/project", "--tsBuildInfoFile", "src/project/.tsbuildinfo"],
+            incrementalScenarios: [noChangeRun]
+        });
+
+        verifyTscIncrementalEdits({
+            scenario: "incremental",
+            subScenario: "when passing rootDir from commandline",
+            fs: () => loadProjectFromFiles({
+                "/src/project/src/main.ts": "export const x = 10;",
+                "/src/project/tsconfig.json": utils.dedent`
+                    {
+                        "compilerOptions": {
+                            "incremental": true,
+                            "outDir": "dist",
+                        },
+                    }`,
+            }),
+            commandLineArgs: ["--p", "src/project", "--rootDir", "src/project/src"],
+            incrementalScenarios: [noChangeRun]
+        });
+
+        verifyTscIncrementalEdits({
+            scenario: "incremental",
+            subScenario: "with only dts files",
+            fs: () => loadProjectFromFiles({
+                "/src/project/src/main.d.ts": "export const x = 10;",
+                "/src/project/src/another.d.ts": "export const y = 10;",
+                "/src/project/tsconfig.json": "{}",
+            }),
+            commandLineArgs: ["--incremental", "--p", "src/project"],
+            incrementalScenarios: [
+                noChangeRun,
+                {
+                    buildKind: BuildKind.IncrementalDtsUnchanged,
+                    modifyFs: fs => appendText(fs, "/src/project/src/main.d.ts", "export const xy = 100;")
+                }
+            ]
+        });
+
+        verifyTscIncrementalEdits({
+            scenario: "incremental",
+            subScenario: "when passing rootDir is in the tsconfig",
+            fs: () => loadProjectFromFiles({
+                "/src/project/src/main.ts": "export const x = 10;",
+                "/src/project/tsconfig.json": utils.dedent`
+                    {
+                        "compilerOptions": {
+                            "incremental": true,
+                            "outDir": "./built",
+                            "rootDir": "./"
+                        },
+                    }`,
+            }),
+            commandLineArgs: ["--p", "src/project"],
+            incrementalScenarios: [noChangeRun]
+        });
+    });
+}

src/testRunner/unittests/tsc/listFilesOnly.ts

@@ -0,0 +1,23 @@
+namespace ts {
+    describe("unittests:: tsc:: listFilesOnly::", () => {
+        verifyTsc({
+            scenario: "listFilesOnly",
+            subScenario: "combined with watch",
+            fs: () => loadProjectFromFiles({
+                "/src/test.ts": utils.dedent`
+                        export const x = 1;`,
+            }),
+            commandLineArgs: ["/src/test.ts", "--watch", "--listFilesOnly"]
+        });
+
+        verifyTsc({
+            scenario: "listFilesOnly",
+            subScenario: "loose file",
+            fs: () => loadProjectFromFiles({
+                "/src/test.ts": utils.dedent`
+                        export const x = 1;`,
+            }),
+            commandLineArgs: ["/src/test.ts", "--listFilesOnly"]
+        });
+    });
+}

src/testRunner/unittests/tscWatch/emitAndErrorUpdates.ts

@@ -1,8 +1,7 @@
 namespace ts.tscWatch {
     describe("unittests:: tsc-watch:: Emit times and Error updates in builder after program changes", () => {
-        const currentDirectory = "/user/username/projects/myproject";
         const config: File = {
-            path: `${currentDirectory}/tsconfig.json`,
+            path: `${projectRoot}/tsconfig.json`,
             content: `{}`
         };
         function getOutputFileStampAndError(host: WatchedSystem, watch: Watch, file: File) {
@@ -83,7 +82,7 @@ namespace ts.tscWatch {
             const nonLibFiles = [...filesWithNewEmit, ...filesWithOnlyErrorRefresh, ...filesNotTouched];
             const files = [...nonLibFiles, configFile, libFile];
             const compilerOptions = (JSON.parse(configFile.content).compilerOptions || {}) as CompilerOptions;
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             checkProgramActualFiles(watch(), [...nonLibFiles.map(f => f.path), libFile.path]);
             checkOutputErrorsInitial(host, getInitialErrors(watch));
@@ -167,7 +166,7 @@ namespace ts.tscWatch {
 
         describe("deep import changes", () => {
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `import {B} from './b';
 declare var console: any;
 let b = new B();
@@ -203,7 +202,7 @@ console.log(b.c.d);`
 
             describe("updates errors when deep import file changes", () => {
                 const bFile: File = {
-                    path: `${currentDirectory}/b.ts`,
+                    path: `${projectRoot}/b.ts`,
                     content: `import {C} from './c';
 export class B
 {
@@ -211,7 +210,7 @@ export class B
 }`
                 };
                 const cFile: File = {
-                    path: `${currentDirectory}/c.ts`,
+                    path: `${projectRoot}/c.ts`,
                     content: `export class C
 {
     d = 1;
@@ -222,7 +221,7 @@ export class B
 
             describe("updates errors when deep import through declaration file changes", () => {
                 const bFile: File = {
-                    path: `${currentDirectory}/b.d.ts`,
+                    path: `${projectRoot}/b.d.ts`,
                     content: `import {C} from './c';
 export class B
 {
@@ -230,7 +229,7 @@ export class B
 }`
                 };
                 const cFile: File = {
-                    path: `${currentDirectory}/c.d.ts`,
+                    path: `${projectRoot}/c.d.ts`,
                     content: `export class C
 {
     d: number;
@@ -242,7 +241,7 @@ export class B
 
         describe("updates errors in file not exporting a deep multilevel import that changes", () => {
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `export interface Point {
     name: string;
     c: Coords;
@@ -253,13 +252,13 @@ export interface Coords {
 }`
             };
             const bFile: File = {
-                path: `${currentDirectory}/b.ts`,
+                path: `${projectRoot}/b.ts`,
                 content: `import { Point } from "./a";
 export interface PointWrapper extends Point {
 }`
             };
             const cFile: File = {
-                path: `${currentDirectory}/c.ts`,
+                path: `${projectRoot}/c.ts`,
                 content: `import { PointWrapper } from "./b";
 export function getPoint(): PointWrapper {
     return {
@@ -272,12 +271,12 @@ export function getPoint(): PointWrapper {
 };`
             };
             const dFile: File = {
-                path: `${currentDirectory}/d.ts`,
+                path: `${projectRoot}/d.ts`,
                 content: `import { getPoint } from "./c";
 getPoint().c.x;`
             };
             const eFile: File = {
-                path: `${currentDirectory}/e.ts`,
+                path: `${projectRoot}/e.ts`,
                 content: `import "./d";`
             };
             verifyEmitAndErrorUpdates({
@@ -301,14 +300,14 @@ getPoint().c.x;`
 
         describe("updates errors when file transitively exported file changes", () => {
             const config: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: JSON.stringify({
                     files: ["app.ts"],
                     compilerOptions: { baseUrl: "." }
                 })
             };
             const app: File = {
-                path: `${currentDirectory}/app.ts`,
+                path: `${projectRoot}/app.ts`,
                 content: `import { Data } from "lib2/public";
 export class App {
     public constructor() {
@@ -317,11 +316,11 @@ export class App {
 }`
             };
             const lib2Public: File = {
-                path: `${currentDirectory}/lib2/public.ts`,
+                path: `${projectRoot}/lib2/public.ts`,
                 content: `export * from "./data";`
             };
             const lib2Data: File = {
-                path: `${currentDirectory}/lib2/data.ts`,
+                path: `${projectRoot}/lib2/data.ts`,
                 content: `import { ITest } from "lib1/public";
 export class Data {
     public test() {
@@ -333,15 +332,15 @@ export class Data {
 }`
             };
             const lib1Public: File = {
-                path: `${currentDirectory}/lib1/public.ts`,
+                path: `${projectRoot}/lib1/public.ts`,
                 content: `export * from "./tools/public";`
             };
             const lib1ToolsPublic: File = {
-                path: `${currentDirectory}/lib1/tools/public.ts`,
+                path: `${projectRoot}/lib1/tools/public.ts`,
                 content: `export * from "./tools.interface";`
             };
             const lib1ToolsInterface: File = {
-                path: `${currentDirectory}/lib1/tools/tools.interface.ts`,
+                path: `${projectRoot}/lib1/tools/tools.interface.ts`,
                 content: `export interface ITest {
     title: string;
 }`
@@ -372,7 +371,7 @@ export class Data {
 
             describe("when there are circular import and exports", () => {
                 const lib2Data: File = {
-                    path: `${currentDirectory}/lib2/data.ts`,
+                    path: `${projectRoot}/lib2/data.ts`,
                     content: `import { ITest } from "lib1/public"; import { Data2 } from "./data2";
 export class Data {
     public dat?: Data2; public test() {
@@ -384,7 +383,7 @@ export class Data {
 }`
                 };
                 const lib2Data2: File = {
-                    path: `${currentDirectory}/lib2/data2.ts`,
+                    path: `${projectRoot}/lib2/data2.ts`,
                     content: `import { Data } from "./data";
 export class Data2 {
     public dat?: Data;

src/testRunner/unittests/tscWatch/helpers.ts

@@ -1,3 +1,7 @@
+namespace ts {
+    export const projects = `/user/username/projects`;
+    export const projectRoot = `${projects}/myproject`;
+}
 namespace ts.tscWatch {
     export import WatchedSystem = TestFSWithWatch.TestServerHost;
     export type File = TestFSWithWatch.File;

src/testRunner/unittests/tscWatch/programUpdates.ts

@@ -918,20 +918,19 @@ namespace ts.tscWatch {
 
         describe("should not trigger should not trigger recompilation because of program emit", () => {
             function verifyWithOptions(options: CompilerOptions, outputFiles: readonly string[]) {
-                const proj = "/user/username/projects/myproject";
                 const file1: File = {
-                    path: `${proj}/file1.ts`,
+                    path: `${projectRoot}/file1.ts`,
                     content: "export const c = 30;"
                 };
                 const file2: File = {
-                    path: `${proj}/src/file2.ts`,
+                    path: `${projectRoot}/src/file2.ts`,
                     content: `import {c} from "file1"; export const d = 30;`
                 };
                 const tsconfig: File = {
-                    path: `${proj}/tsconfig.json`,
+                    path: `${projectRoot}/tsconfig.json`,
                     content: generateTSConfig(options, emptyArray, "\n")
                 };
-                const host = createWatchedSystem([file1, file2, libFile, tsconfig], { currentDirectory: proj });
+                const host = createWatchedSystem([file1, file2, libFile, tsconfig], { currentDirectory: projectRoot });
                 const watch = createWatchOfConfigFile(tsconfig.path, host, /*optionsToExtend*/ undefined, /*maxNumberOfFilesToIterateForInvalidation*/1);
                 checkProgramActualFiles(watch(), [file1.path, file2.path, libFile.path]);
 
@@ -1020,9 +1019,8 @@ namespace ts.tscWatch {
         });
 
         it("updates errors correctly when declaration emit is disabled in compiler options", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `import test from './b';
 test(4, 5);`
             };
@@ -1031,11 +1029,11 @@ test(4, 5);`
 }
 export default test;`;
             const bFile: File = {
-                path: `${currentDirectory}/b.ts`,
+                path: `${projectRoot}/b.ts`,
                 content: bFileContent
             };
             const tsconfigFile: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: JSON.stringify({
                     compilerOptions: {
                         module: "commonjs",
@@ -1045,7 +1043,7 @@ export default test;`;
                 })
             };
             const files = [aFile, bFile, libFile, tsconfigFile];
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             checkOutputErrorsInitial(host, emptyArray);
 
@@ -1072,22 +1070,21 @@ export default test;`;
         });
 
         it("updates errors when strictNullChecks changes", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `declare function foo(): null | { hello: any };
 foo().hello`
             };
             const config: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: JSON.stringify({ compilerOptions: {} })
             };
             const files = [aFile, config, libFile];
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             checkProgramActualFiles(watch(), [aFile.path, libFile.path]);
             checkOutputErrorsInitial(host, emptyArray);
-            const modifiedTimeOfAJs = host.getModifiedTime(`${currentDirectory}/a.js`);
+            const modifiedTimeOfAJs = host.getModifiedTime(`${projectRoot}/a.js`);
             host.writeFile(config.path, JSON.stringify({ compilerOptions: { strictNullChecks: true } }));
             host.runQueuedTimeoutCallbacks();
             const expectedStrictNullErrors = [
@@ -1095,39 +1092,38 @@ foo().hello`
             ];
             checkOutputErrorsIncremental(host, expectedStrictNullErrors);
             // File a need not be rewritten
-            assert.equal(host.getModifiedTime(`${currentDirectory}/a.js`), modifiedTimeOfAJs);
+            assert.equal(host.getModifiedTime(`${projectRoot}/a.js`), modifiedTimeOfAJs);
             host.writeFile(config.path, JSON.stringify({ compilerOptions: { strict: true, alwaysStrict: false } })); // Avoid changing 'alwaysStrict' or must re-bind
             host.runQueuedTimeoutCallbacks();
             checkOutputErrorsIncremental(host, expectedStrictNullErrors);
             // File a need not be rewritten
-            assert.equal(host.getModifiedTime(`${currentDirectory}/a.js`), modifiedTimeOfAJs);
+            assert.equal(host.getModifiedTime(`${projectRoot}/a.js`), modifiedTimeOfAJs);
             host.writeFile(config.path, JSON.stringify({ compilerOptions: {} }));
             host.runQueuedTimeoutCallbacks();
             checkOutputErrorsIncremental(host, emptyArray);
             // File a need not be rewritten
-            assert.equal(host.getModifiedTime(`${currentDirectory}/a.js`), modifiedTimeOfAJs);
+            assert.equal(host.getModifiedTime(`${projectRoot}/a.js`), modifiedTimeOfAJs);
         });
 
         it("updates errors when ambient modules of program changes", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `declare module 'a' {
   type foo = number;
 }`
             };
             const config: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: "{}"
             };
             const files = [aFile, config, libFile];
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             checkProgramActualFiles(watch(), [aFile.path, libFile.path]);
             checkOutputErrorsInitial(host, emptyArray);
 
             // Create bts with same file contents
-            const bTsPath = `${currentDirectory}/b.ts`;
+            const bTsPath = `${projectRoot}/b.ts`;
             host.writeFile(bTsPath, aFile.content);
             host.runQueuedTimeoutCallbacks();
             checkProgramActualFiles(watch(), [aFile.path, "b.ts", libFile.path]);
@@ -1144,7 +1140,6 @@ foo().hello`
         });
 
         describe("updates errors in lib file", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const field = "fullscreen";
             const fieldWithoutReadonly = `interface Document {
     ${field}: boolean;
@@ -1166,7 +1161,7 @@ interface Document {
                 const files = [aFile, libFileWithDocument];
 
                 function verifyLibErrors(options: CompilerOptions) {
-                    const host = createWatchedSystem(files, { currentDirectory });
+                    const host = createWatchedSystem(files, { currentDirectory: projectRoot });
                     const watch = createWatchOfFilesAndCompilerOptions([aFile.path], host, options);
                     checkProgramActualFiles(watch(), [aFile.path, libFile.path]);
                     checkOutputErrorsInitial(host, getErrors());
@@ -1202,7 +1197,7 @@ interface Document {
 
             describe("when non module file changes", () => {
                 const aFile: File = {
-                    path: `${currentDirectory}/a.ts`,
+                    path: `${projectRoot}/a.ts`,
                     content: `${fieldWithoutReadonly}
 var y: number;`
                 };
@@ -1211,7 +1206,7 @@ var y: number;`
 
             describe("when module file with global definitions changes", () => {
                 const aFile: File = {
-                    path: `${currentDirectory}/a.ts`,
+                    path: `${projectRoot}/a.ts`,
                     content: `export {}
 declare global {
 ${fieldWithoutReadonly}
@@ -1223,16 +1218,15 @@ var y: number;
         });
 
         it("when skipLibCheck and skipDefaultLibCheck changes", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const field = "fullscreen";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `interface Document {
     ${field}: boolean;
 }`
             };
             const bFile: File = {
-                path: `${currentDirectory}/b.d.ts`,
+                path: `${projectRoot}/b.d.ts`,
                 content: `interface Document {
     ${field}: boolean;
 }`
@@ -1245,13 +1239,13 @@ interface Document {
 }`
             };
             const configFile: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: "{}"
             };
 
             const files = [aFile, bFile, configFile, libFileWithDocument];
 
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             verifyProgramFiles();
             checkOutputErrorsInitial(host, [
@@ -1284,18 +1278,17 @@ interface Document {
         });
 
         it("reports errors correctly with isolatedModules", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `export const a: string = "";`
             };
             const bFile: File = {
-                path: `${currentDirectory}/b.ts`,
+                path: `${projectRoot}/b.ts`,
                 content: `import { a } from "./a";
 const b: string = a;`
             };
             const configFile: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: JSON.stringify({
                     compilerOptions: {
                         isolatedModules: true
@@ -1305,20 +1298,20 @@ const b: string = a;`
 
             const files = [aFile, bFile, libFile, configFile];
 
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             verifyProgramFiles();
             checkOutputErrorsInitial(host, emptyArray);
-            assert.equal(host.readFile(`${currentDirectory}/a.js`), `"use strict";
+            assert.equal(host.readFile(`${projectRoot}/a.js`), `"use strict";
 exports.__esModule = true;
 exports.a = "";
 `, "Contents of a.js");
-            assert.equal(host.readFile(`${currentDirectory}/b.js`), `"use strict";
+            assert.equal(host.readFile(`${projectRoot}/b.js`), `"use strict";
 exports.__esModule = true;
 var a_1 = require("./a");
 var b = a_1.a;
 `, "Contents of b.js");
-            const modifiedTime = host.getModifiedTime(`${currentDirectory}/b.js`);
+            const modifiedTime = host.getModifiedTime(`${projectRoot}/b.js`);
 
             host.writeFile(aFile.path, `export const a: number = 1`);
             host.runQueuedTimeoutCallbacks();
@@ -1326,11 +1319,11 @@ var b = a_1.a;
             checkOutputErrorsIncremental(host, [
                 getDiagnosticOfFileFromProgram(watch(), bFile.path, bFile.content.indexOf("b"), 1, Diagnostics.Type_0_is_not_assignable_to_type_1, "number", "string")
             ]);
-            assert.equal(host.readFile(`${currentDirectory}/a.js`), `"use strict";
+            assert.equal(host.readFile(`${projectRoot}/a.js`), `"use strict";
 exports.__esModule = true;
 exports.a = 1;
 `, "Contents of a.js");
-            assert.equal(host.getModifiedTime(`${currentDirectory}/b.js`), modifiedTime, "Timestamp of b.js");
+            assert.equal(host.getModifiedTime(`${projectRoot}/b.js`), modifiedTime, "Timestamp of b.js");
 
             function verifyProgramFiles() {
                 checkProgramActualFiles(watch(), [aFile.path, bFile.path, libFile.path]);
@@ -1338,9 +1331,8 @@ exports.a = 1;
         });
 
         it("reports errors correctly with file not in rootDir", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const aFile: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `import { x } from "../b";`
             };
             const bFile: File = {
@@ -1348,7 +1340,7 @@ exports.a = 1;
                 content: `export const x = 10;`
             };
             const configFile: File = {
-                path: `${currentDirectory}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: JSON.stringify({
                     compilerOptions: {
                         rootDir: ".",
@@ -1359,10 +1351,10 @@ exports.a = 1;
 
             const files = [aFile, bFile, libFile, configFile];
 
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfConfigFile("tsconfig.json", host);
             checkOutputErrorsInitial(host, [
-                getDiagnosticOfFileFromProgram(watch(), aFile.path, aFile.content.indexOf(`"../b"`), `"../b"`.length, Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, bFile.path, currentDirectory)
+                getDiagnosticOfFileFromProgram(watch(), aFile.path, aFile.content.indexOf(`"../b"`), `"../b"`.length, Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, bFile.path, projectRoot)
             ]);
             const aContent = `
 
@@ -1370,7 +1362,7 @@ ${aFile.content}`;
             host.writeFile(aFile.path, aContent);
             host.runQueuedTimeoutCallbacks();
             checkOutputErrorsIncremental(host, [
-                getDiagnosticOfFileFromProgram(watch(), aFile.path, aContent.indexOf(`"../b"`), `"../b"`.length, Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, bFile.path, currentDirectory)
+                getDiagnosticOfFileFromProgram(watch(), aFile.path, aContent.indexOf(`"../b"`), `"../b"`.length, Diagnostics.File_0_is_not_under_rootDir_1_rootDir_is_expected_to_contain_all_source_files, bFile.path, projectRoot)
             ]);
         });
     });

src/testRunner/unittests/tscWatch/resolutionCache.ts

@@ -339,42 +339,40 @@ declare module "fs" {
         });
 
         it("works when renaming node_modules folder that already contains @types folder", () => {
-            const currentDirectory = "/user/username/projects/myproject";
             const file: File = {
-                path: `${currentDirectory}/a.ts`,
+                path: `${projectRoot}/a.ts`,
                 content: `import * as q from "qqq";`
             };
             const module: File = {
-                path: `${currentDirectory}/node_modules2/@types/qqq/index.d.ts`,
+                path: `${projectRoot}/node_modules2/@types/qqq/index.d.ts`,
                 content: "export {}"
             };
             const files = [file, module, libFile];
-            const host = createWatchedSystem(files, { currentDirectory });
+            const host = createWatchedSystem(files, { currentDirectory: projectRoot });
             const watch = createWatchOfFilesAndCompilerOptions([file.path], host);
 
             checkProgramActualFiles(watch(), [file.path, libFile.path]);
             checkOutputErrorsInitial(host, [getDiagnosticModuleNotFoundOfFile(watch(), file, "qqq")]);
             checkWatchedDirectories(host, emptyArray, /*recursive*/ false);
-            checkWatchedDirectories(host, [`${currentDirectory}/node_modules`, `${currentDirectory}/node_modules/@types`], /*recursive*/ true);
+            checkWatchedDirectories(host, [`${projectRoot}/node_modules`, `${projectRoot}/node_modules/@types`], /*recursive*/ true);
 
-            host.renameFolder(`${currentDirectory}/node_modules2`, `${currentDirectory}/node_modules`);
+            host.renameFolder(`${projectRoot}/node_modules2`, `${projectRoot}/node_modules`);
             host.runQueuedTimeoutCallbacks();
-            checkProgramActualFiles(watch(), [file.path, libFile.path, `${currentDirectory}/node_modules/@types/qqq/index.d.ts`]);
+            checkProgramActualFiles(watch(), [file.path, libFile.path, `${projectRoot}/node_modules/@types/qqq/index.d.ts`]);
             checkOutputErrorsIncremental(host, emptyArray);
         });
 
         describe("ignores files/folder changes in node_modules that start with '.'", () => {
-            const projectPath = "/user/username/projects/project";
             const npmCacheFile: File = {
-                path: `${projectPath}/node_modules/.cache/babel-loader/89c02171edab901b9926470ba6d5677e.ts`,
+                path: `${projectRoot}/node_modules/.cache/babel-loader/89c02171edab901b9926470ba6d5677e.ts`,
                 content: JSON.stringify({ something: 10 })
             };
             const file1: File = {
-                path: `${projectPath}/test.ts`,
+                path: `${projectRoot}/test.ts`,
                 content: `import { x } from "somemodule";`
             };
             const file2: File = {
-                path: `${projectPath}/node_modules/somemodule/index.d.ts`,
+                path: `${projectRoot}/node_modules/somemodule/index.d.ts`,
                 content: `export const x = 10;`
             };
             const files = [libFile, file1, file2];
@@ -390,7 +388,7 @@ declare module "fs" {
             });
             it("when watching node_modules as part of wild card directories in config project", () => {
                 const config: File = {
-                    path: `${projectPath}/tsconfig.json`,
+                    path: `${projectRoot}/tsconfig.json`,
                     content: "{}"
                 };
                 const host = createWatchedSystem(files.concat(config));
@@ -402,10 +400,50 @@ declare module "fs" {
                 host.checkTimeoutQueueLength(0);
             });
         });
+
+        it("when types in compiler option are global and installed at later point", () => {
+            const projectRoot = "/user/username/projects/myproject";
+            const app: File = {
+                path: `${projectRoot}/lib/app.ts`,
+                content: `myapp.component("hello");`
+            };
+            const tsconfig: File = {
+                path: `${projectRoot}/tsconfig.json`,
+                content: JSON.stringify({
+                    compilerOptions: {
+                        module: "none",
+                        types: ["@myapp/ts-types"]
+                    }
+                })
+            };
+            const host = createWatchedSystem([app, tsconfig, libFile]);
+            const watch = createWatchOfConfigFile(tsconfig.path, host);
+            checkProgramActualFiles(watch(), [app.path, libFile.path]);
+            host.checkTimeoutQueueLength(0);
+            checkOutputErrorsInitial(host, [
+                createCompilerDiagnostic(Diagnostics.Cannot_find_type_definition_file_for_0, "@myapp/ts-types")
+            ]);
+
+            host.ensureFileOrFolder({
+                path: `${projectRoot}/node_modules/@myapp/ts-types/package.json`,
+                content: JSON.stringify({
+                    version: "1.65.1",
+                    types: "types/somefile.define.d.ts"
+                })
+            });
+            host.ensureFileOrFolder({
+                path: `${projectRoot}/node_modules/@myapp/ts-types/types/somefile.define.d.ts`,
+                content: `
+declare namespace myapp {
+    function component(str: string): number;
+}`
+            });
+            host.checkTimeoutQueueLengthAndRun(1);
+            checkOutputErrorsIncremental(host, emptyArray);
+        });
     });
 
     describe("unittests:: tsc-watch:: resolutionCache:: tsc-watch with modules linked to sibling folder", () => {
-        const projectRoot = "/user/username/projects/project";
         const mainPackageRoot = `${projectRoot}/main`;
         const linkedPackageRoot = `${projectRoot}/linked-package`;
         const mainFile: File = {

src/testRunner/unittests/tscWatch/watchApi.ts

@@ -1,6 +1,5 @@
 namespace ts.tscWatch {
     describe("unittests:: tsc-watch:: watchAPI:: tsc-watch with custom module resolution", () => {
-        const projectRoot = "/user/username/projects/project";
         const configFileJson: any = {
             compilerOptions: { module: "commonjs", resolveJsonModule: true },
             files: ["index.ts"]
@@ -39,7 +38,6 @@ namespace ts.tscWatch {
     });
 
     describe("unittests:: tsc-watch:: watchAPI:: tsc-watch expose error count to watch status reporter", () => {
-        const projectRoot = "/user/username/projects/project";
         const configFileJson: any = {
             compilerOptions: { module: "commonjs" },
             files: ["index.ts"]

src/testRunner/unittests/tsserver/compileOnSave.ts

@@ -802,7 +802,6 @@ namespace ts.projectSystem {
     });
 
     describe("unittests:: tsserver:: compileOnSave:: CompileOnSaveAffectedFileListRequest with and without projectFileName in request", () => {
-        const projectRoot = "/user/username/projects/myproject";
         const core: File = {
             path: `${projectRoot}/core/core.ts`,
             content: "let z = 10;"

src/testRunner/unittests/tsserver/configuredProjects.ts

@@ -82,7 +82,6 @@ namespace ts.projectSystem {
         });
 
         it("add and then remove a config file in a folder with loose files", () => {
-            const projectRoot = "/user/username/projects/project";
             const configFile: File = {
                 path: `${projectRoot}/tsconfig.json`,
                 content: `{
@@ -440,7 +439,6 @@ namespace ts.projectSystem {
         });
 
         it("open file become a part of configured project if it is referenced from root file", () => {
-            const projectRoot = "/user/username/projects/project";
             const file1 = {
                 path: `${projectRoot}/a/b/f1.ts`,
                 content: "export let x = 5"
@@ -846,6 +844,67 @@ namespace ts.projectSystem {
             const edits = project.getLanguageService().getFormattingEditsForDocument(f1.path, options);
             assert.deepEqual(edits, [{ span: createTextSpan(/*start*/ 7, /*length*/ 3), newText: " " }]);
         });
+
+        it("when multiple projects are open, detects correct default project", () => {
+            const barConfig: File = {
+                path: `${projectRoot}/bar/tsconfig.json`,
+                content: JSON.stringify({
+                    include: ["index.ts"],
+                    compilerOptions: {
+                        lib: ["dom", "es2017"]
+                    }
+                })
+            };
+            const barIndex: File = {
+                path: `${projectRoot}/bar/index.ts`,
+                content: `
+export function bar() {
+  console.log("hello world");
+}`
+            };
+            const fooConfig: File = {
+                path: `${projectRoot}/foo/tsconfig.json`,
+                content: JSON.stringify({
+                    include: ["index.ts"],
+                    compilerOptions: {
+                        lib: ["es2017"]
+                    }
+                })
+            };
+            const fooIndex: File = {
+                path: `${projectRoot}/foo/index.ts`,
+                content: `
+import { bar } from "bar";
+bar();`
+            };
+            const barSymLink: SymLink = {
+                path: `${projectRoot}/foo/node_modules/bar`,
+                symLink: `${projectRoot}/bar`
+            };
+
+            const lib2017: File = {
+                path: `${getDirectoryPath(libFile.path)}/lib.es2017.d.ts`,
+                content: libFile.content
+            };
+            const libDom: File = {
+                path: `${getDirectoryPath(libFile.path)}/lib.dom.d.ts`,
+                content: `
+declare var console: {
+    log(...args: any[]): void;
+};`
+            };
+            const host = createServerHost([barConfig, barIndex, fooConfig, fooIndex, barSymLink, lib2017, libDom]);
+            const session = createSession(host, { canUseEvents: true, });
+            openFilesForSession([fooIndex, barIndex], session);
+            verifyGetErrRequest({
+                session,
+                host,
+                expected: [
+                    { file: barIndex, syntax: [], semantic: [], suggestion: [] },
+                    { file: fooIndex, syntax: [], semantic: [], suggestion: [] },
+                ]
+            });
+        });
     });
 
     describe("unittests:: tsserver:: ConfiguredProjects:: non-existing directories listed in config file input array", () => {
@@ -903,13 +962,12 @@ namespace ts.projectSystem {
         });
 
         it("should tolerate invalid include files that start in subDirectory", () => {
-            const projectFolder = "/user/username/projects/myproject";
             const f = {
-                path: `${projectFolder}/src/server/index.ts`,
+                path: `${projectRoot}/src/server/index.ts`,
                 content: "let x = 1"
             };
             const config = {
-                path: `${projectFolder}/src/server/tsconfig.json`,
+                path: `${projectRoot}/src/server/tsconfig.json`,
                 content: JSON.stringify({
                     compiler: {
                         module: "commonjs",

src/testRunner/unittests/tsserver/documentRegistry.ts

@@ -1,17 +1,16 @@
 namespace ts.projectSystem {
     describe("unittests:: tsserver:: document registry in project service", () => {
-        const projectRootPath = "/user/username/projects/project";
         const importModuleContent = `import {a} from "./module1"`;
         const file: File = {
-            path: `${projectRootPath}/index.ts`,
+            path: `${projectRoot}/index.ts`,
             content: importModuleContent
         };
         const moduleFile: File = {
-            path: `${projectRootPath}/module1.d.ts`,
+            path: `${projectRoot}/module1.d.ts`,
             content: "export const a: number;"
         };
         const configFile: File = {
-            path: `${projectRootPath}/tsconfig.json`,
+            path: `${projectRoot}/tsconfig.json`,
             content: JSON.stringify({ files: ["index.ts"] })
         };
 

src/testRunner/unittests/tsserver/events/largeFileReferenced.ts

@@ -1,6 +1,5 @@
 namespace ts.projectSystem {
     describe("unittests:: tsserver:: events:: LargeFileReferencedEvent with large file", () => {
-        const projectRoot = "/user/username/projects/project";
 
         function getLargeFile(useLargeTsFile: boolean) {
             return `src/large.${useLargeTsFile ? "ts" : "js"}`;

src/testRunner/unittests/tsserver/events/projectLoading.ts

@@ -1,16 +1,15 @@
 namespace ts.projectSystem {
     describe("unittests:: tsserver:: events:: ProjectLoadingStart and ProjectLoadingFinish events", () => {
-        const projectRoot = "/user/username/projects";
         const aTs: File = {
-            path: `${projectRoot}/a/a.ts`,
+            path: `${projects}/a/a.ts`,
             content: "export class A { }"
         };
         const configA: File = {
-            path: `${projectRoot}/a/tsconfig.json`,
+            path: `${projects}/a/tsconfig.json`,
             content: "{}"
         };
-        const bTsPath = `${projectRoot}/b/b.ts`;
-        const configBPath = `${projectRoot}/b/tsconfig.json`;
+        const bTsPath = `${projects}/b/b.ts`;
+        const configBPath = `${projects}/b/tsconfig.json`;
         const files = [libFile, aTs, configA];
 
         function verifyProjectLoadingStartAndFinish(createSession: (host: TestServerHost) => {
@@ -84,14 +83,14 @@ namespace ts.projectSystem {
 
                 function verify(disableSourceOfProjectReferenceRedirect?: true) {
                     const aDTs: File = {
-                        path: `${projectRoot}/a/a.d.ts`,
+                        path: `${projects}/a/a.d.ts`,
                         content: `export declare class A {
 }
 //# sourceMappingURL=a.d.ts.map
 `
                     };
                     const aDTsMap: File = {
-                        path: `${projectRoot}/a/a.d.ts.map`,
+                        path: `${projects}/a/a.d.ts.map`,
                         content: `{"version":3,"file":"a.d.ts","sourceRoot":"","sources":["./a.ts"],"names":[],"mappings":"AAAA,qBAAa,CAAC;CAAI"}`
                     };
                     const bTs: File = {
@@ -134,7 +133,7 @@ namespace ts.projectSystem {
             });
 
             describe("with external projects and config files ", () => {
-                const projectFileName = `${projectRoot}/a/project.csproj`;
+                const projectFileName = `${projects}/a/project.csproj`;
 
                 function createSession(lazyConfiguredProjectsFromExternalProject: boolean) {
                     const { session, service, verifyEvent: verifyEventWorker, getNumberOfEvents } = createSessionToVerifyEvent(files);

src/testRunner/unittests/tsserver/externalProjects.ts

@@ -824,10 +824,9 @@ namespace ts.projectSystem {
         });
 
         it("handles creation of external project with jsconfig before jsconfig creation watcher is invoked", () => {
-            const projectLocation = `/user/username/projects/WebApplication36/WebApplication36`;
-            const projectFileName = `${projectLocation}/WebApplication36.csproj`;
+            const projectFileName = `${projectRoot}/WebApplication36.csproj`;
             const tsconfig: File = {
-                path: `${projectLocation}/tsconfig.json`,
+                path: `${projectRoot}/tsconfig.json`,
                 content: "{}"
             };
             const files = [libFile, tsconfig];
@@ -845,7 +844,7 @@ namespace ts.projectSystem {
             checkProjectActualFiles(configProject, [tsconfig.path]);
 
             // write js file, open external project and open it for edit
-            const jsFilePath = `${projectLocation}/javascript.js`;
+            const jsFilePath = `${projectRoot}/javascript.js`;
             host.writeFile(jsFilePath, "");
             service.openExternalProjects([{
                 projectFileName,
@@ -860,7 +859,7 @@ namespace ts.projectSystem {
 
             // write jsconfig file
             const jsConfig: File = {
-                path: `${projectLocation}/jsconfig.json`,
+                path: `${projectRoot}/jsconfig.json`,
                 content: "{}"
             };
             // Dont invoke file creation watchers as the repro suggests

src/testRunner/unittests/tsserver/inferredProjects.ts

@@ -1,7 +1,6 @@
 namespace ts.projectSystem {
     describe("unittests:: tsserver:: Inferred projects", () => {
         it("create inferred project", () => {
-            const projectRoot = "/user/username/projects/project";
             const appFile: File = {
                 path: `${projectRoot}/app.ts`,
                 content: `
@@ -31,7 +30,6 @@ namespace ts.projectSystem {
         });
 
         it("should use only one inferred project if 'useOneInferredProject' is set", () => {
-            const projectRoot = "/user/username/projects/project";
             const file1 = {
                 path: `${projectRoot}/a/b/main.ts`,
                 content: "let x =1;"
@@ -347,7 +345,6 @@ namespace ts.projectSystem {
         });
 
         it("should still retain configured project created while opening the file", () => {
-            const projectRoot = "/user/username/projects/project";
             const appFile: File = {
                 path: `${projectRoot}/app.ts`,
                 content: `const app = 20;`

src/testRunner/unittests/tsserver/projectErrors.ts

@@ -292,42 +292,21 @@ namespace ts.projectSystem {
                 // Since this is not js project so no typings are queued
                 host.checkTimeoutQueueLength(0);
 
-                const newTimeoutId = host.getNextTimeoutId();
-                const expectedSequenceId = session.getNextSeq();
-                session.executeCommandSeq<protocol.GeterrRequest>({
-                    command: server.CommandNames.Geterr,
-                    arguments: {
-                        delay: 0,
-                        files: [untitledFile]
-                    }
-                });
-                host.checkTimeoutQueueLength(1);
-
-                // Run the last one = get error request
-                host.runQueuedTimeoutCallbacks(newTimeoutId);
-
-                assert.isFalse(hasError());
-                host.checkTimeoutQueueLength(0);
-                checkErrorMessage(session, "syntaxDiag", { file: untitledFile, diagnostics: [] });
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks();
-                assert.isFalse(hasError());
                 const errorOffset = fileContent.indexOf(refPathNotFound1) + 1;
-                checkErrorMessage(session, "semanticDiag", {
-                    file: untitledFile,
-                    diagnostics: [
-                        createDiagnostic({ line: 1, offset: errorOffset }, { line: 1, offset: errorOffset + refPathNotFound1.length }, Diagnostics.File_0_not_found, [refPathNotFound1], "error"),
-                        createDiagnostic({ line: 2, offset: errorOffset }, { line: 2, offset: errorOffset + refPathNotFound2.length }, Diagnostics.File_0_not_found, [refPathNotFound2.substr(2)], "error")
-                    ]
+                verifyGetErrRequest({
+                    session,
+                    host,
+                    expected: [{
+                        file: untitledFile,
+                        syntax: [],
+                        semantic: [
+                            createDiagnostic({ line: 1, offset: errorOffset }, { line: 1, offset: errorOffset + refPathNotFound1.length }, Diagnostics.File_0_not_found, [refPathNotFound1], "error"),
+                            createDiagnostic({ line: 2, offset: errorOffset }, { line: 2, offset: errorOffset + refPathNotFound2.length }, Diagnostics.File_0_not_found, [refPathNotFound2.substr(2)], "error")
+                        ],
+                        suggestion: []
+                    }],
+                    onErrEvent: () => assert.isFalse(hasError())
                 });
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks(1);
-                assert.isFalse(hasError());
-                checkErrorMessage(session, "suggestionDiag", { file: untitledFile, diagnostics: [] });
-                checkCompleteEvent(session, 2, expectedSequenceId);
-                session.clearMessages();
             }
 
             it("has projectRoot", () => {
@@ -371,27 +350,16 @@ namespace ts.projectSystem {
             verifyErrorsInApp();
 
             function verifyErrorsInApp() {
-                session.clearMessages();
-                const expectedSequenceId = session.getNextSeq();
-                session.executeCommandSeq<protocol.GeterrRequest>({
-                    command: server.CommandNames.Geterr,
-                    arguments: {
-                        delay: 0,
-                        files: [app.path]
-                    }
+                verifyGetErrRequest({
+                    session,
+                    host,
+                    expected: [{
+                        file: app,
+                        syntax: [],
+                        semantic: [],
+                        suggestion: []
+                    }],
                 });
-                host.checkTimeoutQueueLengthAndRun(1);
-                checkErrorMessage(session, "syntaxDiag", { file: app.path, diagnostics: [] });
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks();
-                checkErrorMessage(session, "semanticDiag", { file: app.path, diagnostics: [] });
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks(1);
-                checkErrorMessage(session, "suggestionDiag", { file: app.path, diagnostics: [] });
-                checkCompleteEvent(session, 2, expectedSequenceId);
-                session.clearMessages();
             }
         });
 
@@ -421,7 +389,6 @@ namespace ts.projectSystem {
         });
 
         it("Reports errors correctly when file referenced by inferred project root, is opened right after closing the root file", () => {
-            const projectRoot = "/user/username/projects/myproject";
             const app: File = {
                 path: `${projectRoot}/src/client/app.js`,
                 content: ""
@@ -451,32 +418,12 @@ namespace ts.projectSystem {
             checkErrors([serverUtilities.path, app.path]);
 
             function checkErrors(openFiles: [string, string]) {
-                const expectedSequenceId = session.getNextSeq();
-                session.executeCommandSeq<protocol.GeterrRequest>({
-                    command: protocol.CommandTypes.Geterr,
-                    arguments: {
-                        delay: 0,
-                        files: openFiles
-                    }
+                verifyGetErrRequest({
+                    session,
+                    host,
+                    expected: openFiles.map(file => ({ file, syntax: [], semantic: [], suggestion: [] })),
+                    existingTimeouts: 2
                 });
-
-                for (const openFile of openFiles) {
-                    session.clearMessages();
-                    host.checkTimeoutQueueLength(3);
-                    host.runQueuedTimeoutCallbacks(host.getNextTimeoutId() - 1);
-
-                    checkErrorMessage(session, "syntaxDiag", { file: openFile, diagnostics: [] });
-                    session.clearMessages();
-
-                    host.runQueuedImmediateCallbacks();
-                    checkErrorMessage(session, "semanticDiag", { file: openFile, diagnostics: [] });
-                    session.clearMessages();
-
-                    host.runQueuedImmediateCallbacks(1);
-                    checkErrorMessage(session, "suggestionDiag", { file: openFile, diagnostics: [] });
-                }
-                checkCompleteEvent(session, 2, expectedSequenceId);
-                session.clearMessages();
             }
         });
 
@@ -531,36 +478,19 @@ declare module '@custom/plugin' {
 
             function checkErrors() {
                 host.checkTimeoutQueueLength(0);
-                const expectedSequenceId = session.getNextSeq();
-                session.executeCommandSeq<protocol.GeterrRequest>({
-                    command: server.CommandNames.Geterr,
-                    arguments: {
-                        delay: 0,
-                        files: [aFile.path],
-                    }
+                verifyGetErrRequest({
+                    session,
+                    host,
+                    expected: [{
+                        file: aFile,
+                        syntax: [],
+                        semantic: [],
+                        suggestion: [
+                            createDiagnostic({ line: 1, offset: 1 }, { line: 1, offset: 44 }, Diagnostics._0_is_declared_but_its_value_is_never_read, ["myModule"], "suggestion", /*reportsUnnecessary*/ true),
+                            createDiagnostic({ line: 2, offset: 10 }, { line: 2, offset: 13 }, Diagnostics._0_is_declared_but_its_value_is_never_read, ["foo"], "suggestion", /*reportsUnnecessary*/ true)
+                        ]
+                    }]
                 });
-
-                host.checkTimeoutQueueLengthAndRun(1);
-
-                checkErrorMessage(session, "syntaxDiag", { file: aFile.path, diagnostics: [] }, /*isMostRecent*/ true);
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks(1);
-
-                checkErrorMessage(session, "semanticDiag", { file: aFile.path, diagnostics: [] });
-                session.clearMessages();
-
-                host.runQueuedImmediateCallbacks(1);
-
-                checkErrorMessage(session, "suggestionDiag", {
-                    file: aFile.path,
-                    diagnostics: [
-                        createDiagnostic({ line: 1, offset: 1 }, { line: 1, offset: 44 }, Diagnostics._0_is_declared_but_its_value_is_never_read, ["myModule"], "suggestion", /*reportsUnnecessary*/ true),
-                        createDiagnostic({ line: 2, offset: 10 }, { line: 2, offset: 13 }, Diagnostics._0_is_declared_but_its_value_is_never_read, ["foo"], "suggestion", /*reportsUnnecessary*/ true)
-                    ],
-                });
-                checkCompleteEvent(session, 2, expectedSequenceId);
-                session.clearMessages();
             }
         });
     });

src/testRunner/unittests/tsserver/projectReferenceCompileOnSave.ts

@@ -1,8 +1,7 @@
 namespace ts.projectSystem {
     describe("unittests:: tsserver:: with project references and compile on save", () => {
-        const projectLocation = "/user/username/projects/myproject";
-        const dependecyLocation = `${projectLocation}/dependency`;
-        const usageLocation = `${projectLocation}/usage`;
+        const dependecyLocation = `${projectRoot}/dependency`;
+        const usageLocation = `${projectRoot}/usage`;
         const dependencyTs: File = {
             path: `${dependecyLocation}/fns.ts`,
             content: `export function fn1() { }
@@ -294,7 +293,7 @@ exports.fn2 = fn2;
 ${appendJs}`
                     },
                     {
-                        path: `${projectLocation}/decls/fns.d.ts`,
+                        path: `${projectRoot}/decls/fns.d.ts`,
                         content: `export declare function fn1(): void;
 export declare function fn2(): void;
 ${appendDts}`