Resolve conflict with upstream/main

Author: yeomgahui

CONTRIBUTING.md

@@ -49,7 +49,7 @@ In general, things we find useful when reviewing suggestions are:
 
 ## What You'll Need
 
-0. [A bug or feature you want to work on](https://github.com/microsoft/TypeScript/labels/help%20wanted)!
+0. [A bug or feature you want to work on](https://github.com/microsoft/TypeScript/issues?q=is%3Aissue%20label%3A%22Help%20Wanted%22)!
 1. [A GitHub account](https://github.com/join).
 2. A copy of the TypeScript code. See the next steps for instructions.
 3. [Node](https://nodejs.org), which runs JavaScript locally. Current or LTS will both work.

src/compiler/checker.ts

@@ -603,6 +603,7 @@ export const moduleOptionDeclaration: CommandLineOptionOfCustomType = {
         esnext: ModuleKind.ESNext,
         node16: ModuleKind.Node16,
         node18: ModuleKind.Node18,
+        node20: ModuleKind.Node20,
         nodenext: ModuleKind.NodeNext,
         preserve: ModuleKind.Preserve,
     })),

src/compiler/commandLineParser.ts

@@ -1031,11 +1031,11 @@
         "category": "Error",
         "code": 1322
     },
-    "Dynamic imports are only supported when the '--module' flag is set to 'es2020', 'es2022', 'esnext', 'commonjs', 'amd', 'system', 'umd', 'node16', 'node18', or 'nodenext'.": {
+    "Dynamic imports are only supported when the '--module' flag is set to 'es2020', 'es2022', 'esnext', 'commonjs', 'amd', 'system', 'umd', 'node16', 'node18', 'node20', or 'nodenext'.": {
         "category": "Error",
         "code": 1323
     },
-    "Dynamic imports only support a second argument when the '--module' option is set to 'esnext', 'node16', 'node18', 'nodenext', or 'preserve'.": {
+    "Dynamic imports only support a second argument when the '--module' option is set to 'esnext', 'node16', 'node18', 'node20', 'nodenext', or 'preserve'.": {
         "category": "Error",
         "code": 1324
     },
@@ -1103,7 +1103,7 @@
         "category": "Error",
         "code": 1341
     },
-    "The 'import.meta' meta-property is only allowed when the '--module' option is 'es2020', 'es2022', 'esnext', 'system', 'node16', 'node18', or 'nodenext'.": {
+    "The 'import.meta' meta-property is only allowed when the '--module' option is 'es2020', 'es2022', 'esnext', 'system', 'node16', 'node18', 'node20', or 'nodenext'.": {
         "category": "Error",
         "code": 1343
     },
@@ -1223,7 +1223,7 @@
         "category": "Message",
         "code": 1377
     },
-    "Top-level 'await' expressions are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
+    "Top-level 'await' expressions are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'node20', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
         "category": "Error",
         "code": 1378
     },
@@ -1427,7 +1427,7 @@
         "category": "Error",
         "code": 1431
     },
-    "Top-level 'for await' loops are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
+    "Top-level 'for await' loops are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'node20', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
         "category": "Error",
         "code": 1432
     },
@@ -3799,15 +3799,15 @@
         "category": "Error",
         "code": 2820
     },
-    "Import assertions are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.": {
+    "Import assertions are only supported when the '--module' option is set to 'esnext', 'node18', 'node20', 'nodenext', or 'preserve'.": {
         "category": "Error",
         "code": 2821
     },
     "Import assertions cannot be used with type-only imports or exports.": {
         "category": "Error",
         "code": 2822
     },
-    "Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.": {
+    "Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'node20', 'nodenext', or 'preserve'.": {
         "category": "Error",
         "code": 2823
     },
@@ -3887,7 +3887,7 @@
         "category": "Error",
         "code": 2853
     },
-    "Top-level 'await using' statements are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
+    "Top-level 'await using' statements are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', 'node18', 'node20', 'nodenext', or 'preserve', and the 'target' option is set to 'es2017' or higher.": {
         "category": "Error",
         "code": 2854
     },

src/compiler/diagnosticMessages.json

@@ -8392,7 +8392,10 @@ namespace Parser {
             phaseModifier = SyntaxKind.TypeKeyword;
             identifier = isIdentifier() ? parseIdentifier() : undefined;
         }
-        else if (identifier?.escapedText === "defer" && token() !== SyntaxKind.FromKeyword) {
+        else if (
+            identifier?.escapedText === "defer" &&
+            (token() === SyntaxKind.FromKeyword ? !lookAhead(nextTokenIsStringLiteral) : token() !== SyntaxKind.CommaToken && token() !== SyntaxKind.EqualsToken)
+        ) {
             phaseModifier = SyntaxKind.DeferKeyword;
             identifier = isIdentifier() ? parseIdentifier() : undefined;
         }

src/compiler/parser.ts

@@ -4986,8 +4986,8 @@ function updateHostForUseSourceOfProjectReferenceRedirect(host: HostForUseSource
 
     function fileOrDirectoryExistsUsingSource(fileOrDirectory: string, isFile: boolean): boolean {
         const fileOrDirectoryExistsUsingSource = isFile ?
-            (file: string) => fileExistsIfProjectReferenceDts(file) :
-            (dir: string) => directoryExistsIfProjectReferenceDeclDir(dir);
+            fileExistsIfProjectReferenceDts :
+            directoryExistsIfProjectReferenceDeclDir;
         // Check current directory or file
         const result = fileOrDirectoryExistsUsingSource(fileOrDirectory);
         if (result !== undefined) return result;

src/compiler/program.ts

@@ -87,6 +87,7 @@ function getModuleTransformer(moduleKind: ModuleKind): TransformerFactory<Source
         case ModuleKind.ES2015:
         case ModuleKind.Node16:
         case ModuleKind.Node18:
+        case ModuleKind.Node20:
         case ModuleKind.NodeNext:
         case ModuleKind.CommonJS:
             // Wraps `transformModule` and `transformECMAScriptModule` and

src/compiler/transformer.ts

@@ -6539,7 +6539,7 @@ export const enum ObjectFlags {
     CouldContainTypeVariablesComputed = 1 << 19, // CouldContainTypeVariables flag has been computed
     /** @internal */
     CouldContainTypeVariables = 1 << 20, // Type could contain a type variable
-
+    SingleSignatureType = 1 << 27, // A single signature type extracted from a potentially broader type
     ClassOrInterface = Class | Interface,
     /** @internal */
     RequiresWidening = ContainsWideningType | ContainsObjectOrArrayLiteral,
@@ -6555,7 +6555,6 @@ export const enum ObjectFlags {
     ContainsSpread   = 1 << 21,  // Object literal contains spread operation
     ObjectRestType   = 1 << 22,  // Originates in object rest declaration
     InstantiationExpressionType = 1 << 23,  // Originates in instantiation expression
-    SingleSignatureType = 1 << 27,  // A single signature type extracted from a potentially broader type
     /** @internal */
     IsClassInstanceClone = 1 << 24, // Type is a clone of a class instance type
     // Flags that require TypeFlags.Object and ObjectFlags.Reference
@@ -6770,12 +6769,6 @@ export interface AnonymousType extends ObjectType {
     instantiations?: Map<string, Type>; // Instantiations of generic type alias (undefined if non-generic)
 }
 
-/** @internal */
-// A SingleSignatureType may have bespoke outer type parameters to handle free type variable inferences
-export interface SingleSignatureType extends AnonymousType {
-    outerTypeParameters?: TypeParameter[];
-}
-
 /** @internal */
 export interface InstantiationExpressionType extends AnonymousType {
     node: NodeWithTypeArguments;
@@ -7061,8 +7054,6 @@ export interface Signature {
     isolatedSignatureType?: ObjectType; // A manufactured type that just contains the signature for purposes of signature comparison
     /** @internal */
     instantiations?: Map<string, Signature>;    // Generic signature instantiation cache
-    /** @internal */
-    implementationSignatureCache?: Signature;  // Copy of the signature with fresh type parameters to use in checking the body of a potentially self-referential generic function (deferred)
 }
 
 export const enum IndexKind {
@@ -7170,6 +7161,7 @@ export interface InferenceContext {
     mapper: TypeMapper;                           // Mapper that fixes inferences
     nonFixingMapper: TypeMapper;                  // Mapper that doesn't fix inferences
     returnMapper?: TypeMapper;                    // Type mapper for inferences from return types (if any)
+    outerReturnMapper?: TypeMapper;               // Type mapper for inferences from return types of outer function (if any)
     inferredTypeParameters?: readonly TypeParameter[]; // Inferred type parameters for function result
     intraExpressionInferenceSites?: IntraExpressionInferenceSite[];
 }
@@ -7606,6 +7598,7 @@ export enum ModuleKind {
     // Node16+ is an amalgam of commonjs (albeit updated) and es2022+, and represents a distinct module system from es2020/esnext
     Node16 = 100,
     Node18 = 101,
+    Node20 = 102,
     NodeNext = 199,
 
     // Emit as written

src/compiler/types.ts

@@ -8964,6 +8964,7 @@ const _computedOptions = createComputedCompilerOptions({
             return target ??
                 ((compilerOptions.module === ModuleKind.Node16 && ScriptTarget.ES2022) ||
                     (compilerOptions.module === ModuleKind.Node18 && ScriptTarget.ES2022) ||
+                    (compilerOptions.module === ModuleKind.Node20 && ScriptTarget.ES2023) ||
                     (compilerOptions.module === ModuleKind.NodeNext && ScriptTarget.ESNext) ||
                     ScriptTarget.ES5);
         },
@@ -8987,6 +8988,7 @@ const _computedOptions = createComputedCompilerOptions({
                         break;
                     case ModuleKind.Node16:
                     case ModuleKind.Node18:
+                    case ModuleKind.Node20:
                         moduleResolution = ModuleResolutionKind.Node16;
                         break;
                     case ModuleKind.NodeNext:
@@ -9030,6 +9032,7 @@ const _computedOptions = createComputedCompilerOptions({
             switch (_computedOptions.module.computeValue(compilerOptions)) {
                 case ModuleKind.Node16:
                 case ModuleKind.Node18:
+                case ModuleKind.Node20:
                 case ModuleKind.NodeNext:
                 case ModuleKind.Preserve:
                     return true;
@@ -9092,6 +9095,14 @@ const _computedOptions = createComputedCompilerOptions({
             if (compilerOptions.resolveJsonModule !== undefined) {
                 return compilerOptions.resolveJsonModule;
             }
+            switch (_computedOptions.module.computeValue(compilerOptions)) {
+                // TODO in 6.0: uncomment
+                // case ModuleKind.Node16:
+                // case ModuleKind.Node18:
+                case ModuleKind.Node20:
+                case ModuleKind.NodeNext:
+                    return true;
+            }
             return _computedOptions.moduleResolution.computeValue(compilerOptions) === ModuleResolutionKind.Bundler;
         },
     },