Merge branch 'main' into babel-let-const

Author: jakebailey

package-lock.json

@@ -501,6 +501,8 @@ export function bindSourceFile(file: SourceFile, options: CompilerOptions) {
 }
 
 function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
     /* eslint-disable no-var */
     var file: SourceFile;
     var options: CompilerOptions;

src/compiler/binder.ts

@@ -1378,6 +1378,8 @@ export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums
 
 /** @internal */
 export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
     /* eslint-disable no-var */
     var getPackagesMap = memoize(() => {
         // A package name maps to true when we detect it has .d.ts files.

src/compiler/checker.ts

@@ -737,15 +737,19 @@ export function getFirstProjectOutput(configFile: ParsedCommandLine, ignoreCase:
 /** @internal */
 // targetSourceFile is when users only want one file in entire project to be emitted. This is used in compileOnSave feature
 export function emitFiles(resolver: EmitResolver, host: EmitHost, targetSourceFile: SourceFile | undefined, { scriptTransformers, declarationTransformers }: EmitTransformers, emitOnly?: boolean | EmitOnly, onlyBuildInfo?: boolean, forceDtsEmit?: boolean): EmitResult {
-    const compilerOptions = host.getCompilerOptions();
-    const sourceMapDataList: SourceMapEmitResult[] | undefined = (compilerOptions.sourceMap || compilerOptions.inlineSourceMap || getAreDeclarationMapsEnabled(compilerOptions)) ? [] : undefined;
-    const emittedFilesList: string[] | undefined = compilerOptions.listEmittedFiles ? [] : undefined;
-    const emitterDiagnostics = createDiagnosticCollection();
-    const newLine = getNewLineCharacter(compilerOptions);
-    const writer = createTextWriter(newLine);
-    const { enter, exit } = performance.createTimer("printTime", "beforePrint", "afterPrint");
-    let bundleBuildInfo: BundleBuildInfo | undefined;
-    let emitSkipped = false;
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
+    /* eslint-disable no-var */
+    var compilerOptions = host.getCompilerOptions();
+    var sourceMapDataList: SourceMapEmitResult[] | undefined = (compilerOptions.sourceMap || compilerOptions.inlineSourceMap || getAreDeclarationMapsEnabled(compilerOptions)) ? [] : undefined;
+    var emittedFilesList: string[] | undefined = compilerOptions.listEmittedFiles ? [] : undefined;
+    var emitterDiagnostics = createDiagnosticCollection();
+    var newLine = getNewLineCharacter(compilerOptions);
+    var writer = createTextWriter(newLine);
+    var { enter, exit } = performance.createTimer("printTime", "beforePrint", "afterPrint");
+    var bundleBuildInfo: BundleBuildInfo | undefined;
+    var emitSkipped = false;
+    /* eslint-enable no-var */
 
     // Emit each output file
     enter();
@@ -1356,7 +1360,10 @@ export const createPrinterWithRemoveCommentsNeverAsciiEscape = /* @__PURE__ */ m
 export const createPrinterWithRemoveCommentsOmitTrailingSemicolon = /* @__PURE__ */ memoize(() => createPrinter({ removeComments: true, omitTrailingSemicolon: true }));
 
 export function createPrinter(printerOptions: PrinterOptions = {}, handlers: PrintHandlers = {}): Printer {
-    const {
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
+    /* eslint-disable no-var */
+    var {
         hasGlobalName,
         onEmitNode = noEmitNotification,
         isEmitNotificationEnabled,
@@ -1369,63 +1376,64 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
         onAfterEmitToken
     } = handlers;
 
-    const extendedDiagnostics = !!printerOptions.extendedDiagnostics;
-    const newLine = getNewLineCharacter(printerOptions);
-    const moduleKind = getEmitModuleKind(printerOptions);
-    const bundledHelpers = new Map<string, boolean>();
-
-    let currentSourceFile: SourceFile | undefined;
-    let nodeIdToGeneratedName: string[]; // Map of generated names for specific nodes.
-    let nodeIdToGeneratedPrivateName: string[]; // Map of generated names for specific nodes.
-    let autoGeneratedIdToGeneratedName: string[]; // Map of generated names for temp and loop variables.
-    let generatedNames: Set<string>; // Set of names generated by the NameGenerator.
-    let formattedNameTempFlagsStack: (Map<string, TempFlags> | undefined)[];
-    let formattedNameTempFlags: Map<string, TempFlags> | undefined;
-    let privateNameTempFlagsStack: TempFlags[]; // Stack of enclosing name generation scopes.
-    let privateNameTempFlags: TempFlags; // TempFlags for the current name generation scope.
-    let tempFlagsStack: TempFlags[]; // Stack of enclosing name generation scopes.
-    let tempFlags: TempFlags; // TempFlags for the current name generation scope.
-    let reservedNamesStack: (Set<string> | undefined)[]; // Stack of reserved names in enclosing name generation scopes.
-    let reservedNames: Set<string> | undefined; // Names reserved in nested name generation scopes.
-    let reservedPrivateNamesStack: (Set<string> | undefined)[]; // Stack of reserved member names in enclosing name generation scopes.
-    let reservedPrivateNames: Set<string> | undefined; // Member names reserved in nested name generation scopes.
-    let preserveSourceNewlines = printerOptions.preserveSourceNewlines; // Can be overridden inside nodes with the `IgnoreSourceNewlines` emit flag.
-    let nextListElementPos: number | undefined; // See comment in `getLeadingLineTerminatorCount`.
-
-    let writer: EmitTextWriter;
-    let ownWriter: EmitTextWriter; // Reusable `EmitTextWriter` for basic printing.
-    let write = writeBase;
-    let isOwnFileEmit: boolean;
-    const bundleFileInfo = printerOptions.writeBundleFileInfo ? { sections: [] } as BundleFileInfo : undefined;
-    const relativeToBuildInfo = bundleFileInfo ? Debug.checkDefined(printerOptions.relativeToBuildInfo) : undefined;
-    const recordInternalSection = printerOptions.recordInternalSection;
-    let sourceFileTextPos = 0;
-    let sourceFileTextKind: BundleFileTextLikeKind = BundleFileSectionKind.Text;
+    var extendedDiagnostics = !!printerOptions.extendedDiagnostics;
+    var newLine = getNewLineCharacter(printerOptions);
+    var moduleKind = getEmitModuleKind(printerOptions);
+    var bundledHelpers = new Map<string, boolean>();
+
+    var currentSourceFile: SourceFile | undefined;
+    var nodeIdToGeneratedName: string[]; // Map of generated names for specific nodes.
+    var nodeIdToGeneratedPrivateName: string[]; // Map of generated names for specific nodes.
+    var autoGeneratedIdToGeneratedName: string[]; // Map of generated names for temp and loop variables.
+    var generatedNames: Set<string>; // Set of names generated by the NameGenerator.
+    var formattedNameTempFlagsStack: (Map<string, TempFlags> | undefined)[];
+    var formattedNameTempFlags: Map<string, TempFlags> | undefined;
+    var privateNameTempFlagsStack: TempFlags[]; // Stack of enclosing name generation scopes.
+    var privateNameTempFlags: TempFlags; // TempFlags for the current name generation scope.
+    var tempFlagsStack: TempFlags[]; // Stack of enclosing name generation scopes.
+    var tempFlags: TempFlags; // TempFlags for the current name generation scope.
+    var reservedNamesStack: (Set<string> | undefined)[]; // Stack of reserved names in enclosing name generation scopes.
+    var reservedNames: Set<string> | undefined; // Names reserved in nested name generation scopes.
+    var reservedPrivateNamesStack: (Set<string> | undefined)[]; // Stack of reserved member names in enclosing name generation scopes.
+    var reservedPrivateNames: Set<string> | undefined; // Member names reserved in nested name generation scopes.
+    var preserveSourceNewlines = printerOptions.preserveSourceNewlines; // Can be overridden inside nodes with the `IgnoreSourceNewlines` emit flag.
+    var nextListElementPos: number | undefined; // See comment in `getLeadingLineTerminatorCount`.
+
+    var writer: EmitTextWriter;
+    var ownWriter: EmitTextWriter; // Reusable `EmitTextWriter` for basic printing.
+    var write = writeBase;
+    var isOwnFileEmit: boolean;
+    var bundleFileInfo = printerOptions.writeBundleFileInfo ? { sections: [] } as BundleFileInfo : undefined;
+    var relativeToBuildInfo = bundleFileInfo ? Debug.checkDefined(printerOptions.relativeToBuildInfo) : undefined;
+    var recordInternalSection = printerOptions.recordInternalSection;
+    var sourceFileTextPos = 0;
+    var sourceFileTextKind: BundleFileTextLikeKind = BundleFileSectionKind.Text;
 
     // Source Maps
-    let sourceMapsDisabled = true;
-    let sourceMapGenerator: SourceMapGenerator | undefined;
-    let sourceMapSource: SourceMapSource;
-    let sourceMapSourceIndex = -1;
-    let mostRecentlyAddedSourceMapSource: SourceMapSource;
-    let mostRecentlyAddedSourceMapSourceIndex = -1;
+    var sourceMapsDisabled = true;
+    var sourceMapGenerator: SourceMapGenerator | undefined;
+    var sourceMapSource: SourceMapSource;
+    var sourceMapSourceIndex = -1;
+    var mostRecentlyAddedSourceMapSource: SourceMapSource;
+    var mostRecentlyAddedSourceMapSourceIndex = -1;
 
     // Comments
-    let containerPos = -1;
-    let containerEnd = -1;
-    let declarationListContainerEnd = -1;
-    let currentLineMap: readonly number[] | undefined;
-    let detachedCommentsInfo: { nodePos: number, detachedCommentEndPos: number }[] | undefined;
-    let hasWrittenComment = false;
-    let commentsDisabled = !!printerOptions.removeComments;
-    let lastSubstitution: Node | undefined;
-    let currentParenthesizerRule: ParenthesizerRule<any> | undefined;
-    const { enter: enterComment, exit: exitComment } = performance.createTimerIf(extendedDiagnostics, "commentTime", "beforeComment", "afterComment");
-    const parenthesizer = factory.parenthesizer;
-    const typeArgumentParenthesizerRuleSelector: OrdinalParentheizerRuleSelector<TypeNode> = {
+    var containerPos = -1;
+    var containerEnd = -1;
+    var declarationListContainerEnd = -1;
+    var currentLineMap: readonly number[] | undefined;
+    var detachedCommentsInfo: { nodePos: number, detachedCommentEndPos: number }[] | undefined;
+    var hasWrittenComment = false;
+    var commentsDisabled = !!printerOptions.removeComments;
+    var lastSubstitution: Node | undefined;
+    var currentParenthesizerRule: ParenthesizerRule<any> | undefined;
+    var { enter: enterComment, exit: exitComment } = performance.createTimerIf(extendedDiagnostics, "commentTime", "beforeComment", "afterComment");
+    var parenthesizer = factory.parenthesizer;
+    var typeArgumentParenthesizerRuleSelector: OrdinalParentheizerRuleSelector<TypeNode> = {
         select: index => index === 0 ? parenthesizer.parenthesizeLeadingTypeArgument : undefined
     };
-    const emitBinaryExpression = createEmitBinaryExpression();
+    var emitBinaryExpression = createEmitBinaryExpression();
+    /* eslint-enable no-var */
 
     reset();
     return {
@@ -1567,7 +1575,7 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
             writeLine();
             const pos = writer.getTextPos();
             const savedSections = bundleFileInfo && bundleFileInfo.sections;
-            if (savedSections) bundleFileInfo.sections = [];
+            if (savedSections) bundleFileInfo!.sections = [];
             print(EmitHint.Unspecified, prepend, /*sourceFile*/ undefined);
             if (bundleFileInfo) {
                 const newSections = bundleFileInfo.sections;

src/compiler/emitter.ts

@@ -58,6 +58,7 @@ import {
     ConstructorDeclaration,
     ConstructorTypeNode,
     ConstructSignatureDeclaration,
+    containsObjectRestOrSpread,
     ContinueStatement,
     createBaseNodeFactory,
     createNodeConverters,
@@ -114,7 +115,6 @@ import {
     getAllUnscopedEmitHelpers,
     getBuildInfo,
     getCommentRange,
-    getElementsOfBindingOrAssignmentPattern,
     getEmitFlags,
     getIdentifierTypeArguments,
     getJSDocTypeAliasName,
@@ -124,7 +124,6 @@ import {
     getSourceMapRange,
     getSyntheticLeadingComments,
     getSyntheticTrailingComments,
-    getTargetOfBindingOrAssignmentElement,
     getTextOfIdentifierOrLiteral,
     hasInvalidEscape,
     HasModifiers,
@@ -150,7 +149,6 @@ import {
     isArray,
     isArrayLiteralExpression,
     isArrowFunction,
-    isAssignmentPattern,
     isBinaryExpression,
     isCallChain,
     isClassDeclaration,
@@ -3326,24 +3324,7 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
     }
 
     function propagateAssignmentPatternFlags(node: AssignmentPattern): TransformFlags {
-        if (node.transformFlags & TransformFlags.ContainsObjectRestOrSpread) return TransformFlags.ContainsObjectRestOrSpread;
-        if (node.transformFlags & TransformFlags.ContainsES2018) {
-            // check for nested spread assignments, otherwise '{ x: { a, ...b } = foo } = c'
-            // will not be correctly interpreted by the ES2018 transformer
-            for (const element of getElementsOfBindingOrAssignmentPattern(node)) {
-                const target = getTargetOfBindingOrAssignmentElement(element);
-                if (target && isAssignmentPattern(target)) {
-                    if (target.transformFlags & TransformFlags.ContainsObjectRestOrSpread) {
-                        return TransformFlags.ContainsObjectRestOrSpread;
-                    }
-                    if (target.transformFlags & TransformFlags.ContainsES2018) {
-                        const flags = propagateAssignmentPatternFlags(target);
-                        if (flags) return flags;
-                    }
-                }
-            }
-        }
-        return TransformFlags.None;
+        return containsObjectRestOrSpread(node) ? TransformFlags.ContainsObjectRestOrSpread : TransformFlags.None;
     }
 
     // @api

src/compiler/factory/nodeFactory.ts

@@ -7,6 +7,7 @@ import {
     AssertionLevel,
     AssignmentExpression,
     AssignmentOperatorOrHigher,
+    AssignmentPattern,
     BinaryExpression,
     BinaryOperator,
     BinaryOperatorToken,
@@ -76,6 +77,7 @@ import {
     InternalEmitFlags,
     isAssignmentExpression,
     isAssignmentOperator,
+    isAssignmentPattern,
     isBlock,
     isCommaListExpression,
     isComputedPropertyName,
@@ -174,6 +176,7 @@ import {
     TextRange,
     ThisTypeNode,
     Token,
+    TransformFlags,
     TypeNode,
 } from "../_namespaces/ts";
 
@@ -1742,3 +1745,31 @@ export function flattenCommaList(node: Expression) {
     flattenCommaListWorker(node, expressions);
     return expressions;
 }
+
+/**
+ * Walk an AssignmentPattern to determine if it contains object rest (`...`) syntax. We cannot rely on
+ * propagation of `TransformFlags.ContainsObjectRestOrSpread` since it isn't propagated by default in
+ * ObjectLiteralExpression and ArrayLiteralExpression since we do not know whether they belong to an
+ * AssignmentPattern at the time the nodes are parsed.
+ *
+ * @internal
+ */
+export function containsObjectRestOrSpread(node: AssignmentPattern): boolean {
+    if (node.transformFlags & TransformFlags.ContainsObjectRestOrSpread) return true;
+    if (node.transformFlags & TransformFlags.ContainsES2018) {
+        // check for nested spread assignments, otherwise '{ x: { a, ...b } = foo } = c'
+        // will not be correctly interpreted by the ES2018 transformer
+        for (const element of getElementsOfBindingOrAssignmentPattern(node)) {
+            const target = getTargetOfBindingOrAssignmentElement(element);
+            if (target && isAssignmentPattern(target)) {
+                if (target.transformFlags & TransformFlags.ContainsObjectRestOrSpread) {
+                    return true;
+                }
+                if (target.transformFlags & TransformFlags.ContainsES2018) {
+                    if (containsObjectRestOrSpread(target)) return true;
+                }
+            }
+        }
+    }
+    return false;
+}

src/compiler/factory/utilities.ts

@@ -1401,6 +1401,8 @@ export function parseJSDocTypeExpressionForTests(content: string, start?: number
 // parser instances can actually be expensive enough to impact us on projects with many source
 // files.
 namespace Parser {
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
     /* eslint-disable no-var */
 
     // Share a single scanner across all calls to parse a source file.  This helps speed things
@@ -6167,7 +6169,7 @@ namespace Parser {
     }
 
     function parseTypeAssertion(): TypeAssertion {
-        Debug.assert(scriptKind === ScriptKind.TS, "Type assertions should never be parsed outside of TS; they should either be comparisons or JSX.");
+        Debug.assert(languageVariant !== LanguageVariant.JSX, "Type assertions should never be parsed in JSX; they should be parsed as comparisons or JSX elements/fragments.");
         const pos = getNodePos();
         parseExpected(SyntaxKind.LessThanToken);
         const type = parseType();

src/compiler/parser.ts

@@ -961,6 +961,8 @@ export function createScanner(languageVersion: ScriptTarget,
     start?: number,
     length?: number): Scanner {
 
+    // Why var? It avoids TDZ checks in the runtime which can be costly.
+    // See: https://github.com/microsoft/TypeScript/issues/52924
     /* eslint-disable no-var */
     var text = textInitial!;