--defaultIsModuleExports and --allowRequireESM

src/compiler/checker.ts

@@ -8,6 +8,7 @@ import {
     addSyntheticLeadingComment,
     AliasDeclarationNode,
     AllAccessorDeclarations,
+    AllowRequireESM,
     AmbientModuleDeclaration,
     and,
     AnonymousType,
@@ -138,6 +139,7 @@ import {
     Decorator,
     deduplicate,
     DefaultClause,
+    DefaultIsModuleExports,
     defaultMaximumTruncationLength,
     DeferredTypeReference,
     DeleteExpression,
@@ -245,6 +247,7 @@ import {
     GetAccessorDeclaration,
     getAliasDeclarationFromName,
     getAllJSDocTags,
+    getAllowRequireESM,
     getAllowSyntheticDefaultImports,
     getAncestor,
     getAssignedExpandoInitializer,
@@ -268,6 +271,7 @@ import {
     getDeclarationsOfKind,
     getDeclaredExpandoInitializer,
     getDecorators,
+    getDefaultIsModuleExports,
     getDirectoryPath,
     getEffectiveBaseTypeNode,
     getEffectiveConstraintOfTypeParameter,
@@ -3634,7 +3638,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         const usageMode = file && getEmitSyntaxForModuleSpecifierExpression(usage);
         if (file && usageMode !== undefined) {
             const targetMode = host.getImpliedNodeFormatForEmit(file);
-            if (usageMode === ModuleKind.ESNext && targetMode === ModuleKind.CommonJS && ModuleKind.Node16 <= moduleKind && moduleKind <= ModuleKind.NodeNext) {
+            const defaultIsModuleExports = getDefaultIsModuleExports(compilerOptions);
+            const usesNodeLikeInteropRules = DefaultIsModuleExports.Node16 <= defaultIsModuleExports && defaultIsModuleExports <= DefaultIsModuleExports.NodeNext;
+            if (usageMode === ModuleKind.ESNext && targetMode !== ModuleKind.ESNext && usesNodeLikeInteropRules) {
                 // In Node.js, CommonJS modules always have a synthetic default when imported into ESM
                 return true;
             }
@@ -3649,6 +3655,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
         // Declaration files (and ambient modules)
         if (!file || file.isDeclarationFile) {
+            // Unambiguously ESM files do not have a synthetic default
+            if (file && host.getImpliedNodeFormatForEmit(file) === ModuleKind.ESNext) {
+                return false;
+            }
             // Definitely cannot have a synthetic default if they have a syntactic default member specified
             const defaultExportSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, /*sourceNode*/ undefined, /*dontResolveAlias*/ true); // Dont resolve alias because we want the immediately exported symbol's declaration
             if (defaultExportSymbol && some(defaultExportSymbol.declarations, isSyntacticDefault)) {
@@ -4571,7 +4581,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         const mode = contextSpecifier && isStringLiteralLike(contextSpecifier)
             ? host.getModeForUsageLocation(currentSourceFile, contextSpecifier)
             : host.getDefaultResolutionModeForFile(currentSourceFile);
+        const importingFileIsJavaScript = isSourceFileJS(currentSourceFile);
         const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
+        const allowRequireESM = getAllowRequireESM(compilerOptions);
         const resolvedModule = host.getResolvedModule(currentSourceFile, moduleReference, mode)?.resolvedModule;
         const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule, currentSourceFile);
         const sourceFile = resolvedModule
@@ -4607,12 +4619,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) {
                     errorOnImplicitAnyModule(/*isError*/ false, errorNode, currentSourceFile, mode, resolvedModule, moduleReference);
                 }
-                if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) {
-                    const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration);
+                if (AllowRequireESM.Node16 <= allowRequireESM && allowRequireESM <= AllowRequireESM.NodeNext) {
+                    const isSyncImport = (host.getImpliedNodeFormatForEmit(currentSourceFile) === ModuleKind.CommonJS && !findAncestor(location, isImportCall))
+                        || !!findAncestor(location, n => isImportEqualsDeclaration(n) || importingFileIsJavaScript && isVariableDeclarationInitializedToBareOrAccessedRequire(n));
                     const overrideHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined;
                     // An override clause will take effect for type-only imports and import types, and allows importing the types across formats, regardless of
                     // normal mode restrictions
-                    if (isSyncImport && sourceFile.impliedNodeFormat === ModuleKind.ESNext && !hasResolutionModeOverride(overrideHost)) {
+                    if (isSyncImport && host.getImpliedNodeFormatForEmit(sourceFile) === ModuleKind.ESNext && !hasResolutionModeOverride(overrideHost)) {
                         if (findAncestor(location, isImportEqualsDeclaration)) {
                             // ImportEquals in a ESM file resolving to another ESM file
                             error(errorNode, Diagnostics.Module_0_cannot_be_imported_using_this_construct_The_specifier_only_resolves_to_an_ES_module_which_cannot_be_imported_with_require_Use_an_ECMAScript_import_instead, moduleReference);

src/compiler/commandLineParser.ts

@@ -1,4 +1,5 @@
 import {
+    AllowRequireESM,
     AlternateModeDiagnostics,
     append,
     arrayFrom,
@@ -23,6 +24,7 @@ import {
     createDiagnosticForNodeInSourceFile,
     createGetCanonicalFileName,
     Debug,
+    DefaultIsModuleExports,
     Diagnostic,
     DiagnosticArguments,
     DiagnosticMessage,
@@ -1196,6 +1198,33 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
         category: Diagnostics.Modules,
         description: Diagnostics.Conditions_to_set_in_addition_to_the_resolver_specific_defaults_when_resolving_imports,
     },
+    {
+        name: "defaultIsModuleExports",
+        type: new Map(Object.entries({
+            auto: DefaultIsModuleExports.Auto,
+            node16: DefaultIsModuleExports.Node16,
+            nodenext: DefaultIsModuleExports.NodeNext,
+        })),
+        affectsSemanticDiagnostics: true,
+        affectsBuildInfo: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Specify_the_target_runtime_s_rules_for_default_imports_targeting_CommonJS_modules,
+        defaultValueDescription: Diagnostics.node16_when_module_is_node16_nodenext_when_module_is_nodenext_auto_otherwise,
+    },
+    {
+        name: "allowRequireESM",
+        type: new Map(Object.entries({
+            never: AllowRequireESM.Never,
+            always: AllowRequireESM.Always,
+            node16: AllowRequireESM.Node16,
+            nodenext: AllowRequireESM.NodeNext,
+        })),
+        affectsSemanticDiagnostics: true,
+        affectsBuildInfo: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Specify_the_target_runtime_s_rules_for_CommonJS_require_calls_targeting_ECMAScript_modules,
+        defaultValueDescription: Diagnostics.node16_when_module_is_node16_nodenext_when_module_is_nodenext_always_otherwise,
+    },
 
     // Source Maps
     {

src/compiler/diagnosticMessages.json

@@ -6392,6 +6392,14 @@
         "category": "Message",
         "code": 6805
     },
+    "Specify the target runtime's rules for default imports targeting CommonJS modules.": {
+        "category": "Message",
+        "code": 6806
+    },
+    "Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules.": {
+        "category": "Message",
+        "code": 6807
+    },
 
     "one of:": {
         "category": "Message",
@@ -6521,6 +6529,14 @@
         "category": "Error",
         "code": 6931
     },
+    "'node16' when 'module' is 'node16'; 'nodenext' when 'module' is 'nodenext'; 'auto' otherwise.": {
+        "category": "Message",
+        "code": 6932
+    },
+    "'node16' when 'module' is 'node16'; 'nodenext' when 'module' is 'nodenext'; 'always' otherwise.": {
+        "category": "Message",
+        "code": 6933
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",

src/compiler/types.ts

@@ -7227,6 +7227,7 @@ export interface CompilerOptions {
     allowJs?: boolean;
     /** @internal */ allowNonTsExtensions?: boolean;
     allowArbitraryExtensions?: boolean;
+    allowRequireESM?: AllowRequireESM;
     allowSyntheticDefaultImports?: boolean;
     allowUmdGlobalAccess?: boolean;
     allowUnreachableCode?: boolean;
@@ -7254,6 +7255,7 @@ export interface CompilerOptions {
     declarationMap?: boolean;
     emitDeclarationOnly?: boolean;
     declarationDir?: string;
+    defaultIsModuleExports?: DefaultIsModuleExports;
     /** @internal */ diagnostics?: boolean;
     /** @internal */ extendedDiagnostics?: boolean;
     disableSizeLimit?: boolean;
@@ -7423,6 +7425,19 @@ export enum ModuleKind {
     Preserve = 200,
 }
 
+export enum DefaultIsModuleExports {
+    Auto = 1,
+    Node16 = 100,
+    NodeNext = 199,
+}
+
+export enum AllowRequireESM {
+    Never = 0,
+    Always = 1,
+    Node16 = 100,
+    NodeNext = 199,
+}
+
 export const enum JsxEmit {
     None = 0,
     Preserve = 1,

src/compiler/utilities.ts

@@ -6,6 +6,7 @@ import {
     affectsDeclarationPathOptionDeclarations,
     affectsEmitOptionDeclarations,
     AllAccessorDeclarations,
+    AllowRequireESM,
     AmbientModuleDeclaration,
     AmpersandAmpersandEqualsToken,
     AnyImportOrBareOrAccessedRequire,
@@ -90,6 +91,7 @@ import {
     DeclarationWithTypeParameters,
     Decorator,
     DefaultClause,
+    DefaultIsModuleExports,
     DestructuringAssignment,
     Diagnostic,
     DiagnosticArguments,
@@ -8852,6 +8854,30 @@ export const computedOptions = createComputedCompilerOptions({
                         computedOptions.module.computeValue(compilerOptions) === ModuleKind.NodeNext ? ModuleDetectionKind.Force : ModuleDetectionKind.Auto);
         },
     },
+    defaultIsModuleExports: {
+        dependencies: ["module", "target"],
+        computeValue: (compilerOptions): DefaultIsModuleExports => {
+            if (compilerOptions.defaultIsModuleExports !== undefined) {
+                return compilerOptions.defaultIsModuleExports;
+            }
+            const moduleKind = computedOptions.module.computeValue(compilerOptions);
+            return moduleKind === ModuleKind.Node16 ? DefaultIsModuleExports.Node16 :
+                moduleKind === ModuleKind.NodeNext ? DefaultIsModuleExports.NodeNext :
+                DefaultIsModuleExports.Auto;
+        },
+    },
+    allowRequireESM: {
+        dependencies: ["module", "target"],
+        computeValue: (compilerOptions): AllowRequireESM => {
+            if (compilerOptions.allowRequireESM !== undefined) {
+                return compilerOptions.allowRequireESM;
+            }
+            const moduleKind = computedOptions.module.computeValue(compilerOptions);
+            return moduleKind === ModuleKind.Node16 ? AllowRequireESM.Node16 :
+                moduleKind === ModuleKind.NodeNext ? AllowRequireESM.NodeNext :
+                AllowRequireESM.Always;
+        },
+    },
     isolatedModules: {
         dependencies: ["verbatimModuleSyntax"],
         computeValue: compilerOptions => {
@@ -9028,6 +9054,10 @@ export const getEmitModuleResolutionKind = computedOptions.moduleResolution.comp
 /** @internal */
 export const getEmitModuleDetectionKind = computedOptions.moduleDetection.computeValue;
 /** @internal */
+export const getDefaultIsModuleExports = computedOptions.defaultIsModuleExports.computeValue;
+/** @internal */
+export const getAllowRequireESM = computedOptions.allowRequireESM.computeValue;
+/** @internal */
 export const getIsolatedModules = computedOptions.isolatedModules.computeValue;
 /** @internal */
 export const getESModuleInterop = computedOptions.esModuleInterop.computeValue;

src/testRunner/compilerRunner.ts

@@ -129,8 +129,10 @@ class CompilerTest {
     private static varyBy: readonly string[] = [
         "allowArbitraryExtensions",
         "allowImportingTsExtensions",
+        "allowRequireESM",
         "allowSyntheticDefaultImports",
         "alwaysStrict",
+        "defaultIsModuleExports",
         "downlevelIteration",
         "experimentalDecorators",
         "emitDecoratorMetadata",

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

@@ -6902,6 +6902,7 @@ declare namespace ts {
         allowImportingTsExtensions?: boolean;
         allowJs?: boolean;
         allowArbitraryExtensions?: boolean;
+        allowRequireESM?: AllowRequireESM;
         allowSyntheticDefaultImports?: boolean;
         allowUmdGlobalAccess?: boolean;
         allowUnreachableCode?: boolean;
@@ -6916,6 +6917,7 @@ declare namespace ts {
         declarationMap?: boolean;
         emitDeclarationOnly?: boolean;
         declarationDir?: string;
+        defaultIsModuleExports?: DefaultIsModuleExports;
         disableSizeLimit?: boolean;
         disableSourceOfProjectReferenceRedirect?: boolean;
         disableSolutionSearching?: boolean;
@@ -7044,6 +7046,17 @@ declare namespace ts {
         NodeNext = 199,
         Preserve = 200,
     }
+    enum DefaultIsModuleExports {
+        Auto = 1,
+        Node16 = 100,
+        NodeNext = 199,
+    }
+    enum AllowRequireESM {
+        Never = 0,
+        Always = 1,
+        Node16 = 100,
+        NodeNext = 199,
+    }
     enum JsxEmit {
         None = 0,
         Preserve = 1,

tests/baselines/reference/config/initTSConfig/Default initialized TSConfig/tsconfig.json

@@ -39,6 +39,8 @@
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "defaultIsModuleExports": "auto",                 /* Specify the target runtime's rules for default imports targeting CommonJS modules. */
+    // "allowRequireESM": "never",                       /* Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --help/tsconfig.json

@@ -39,6 +39,8 @@
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "defaultIsModuleExports": "auto",                 /* Specify the target runtime's rules for default imports targeting CommonJS modules. */
+    // "allowRequireESM": "never",                       /* Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --watch/tsconfig.json

@@ -39,6 +39,8 @@
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "defaultIsModuleExports": "auto",                 /* Specify the target runtime's rules for default imports targeting CommonJS modules. */
+    // "allowRequireESM": "never",                       /* Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with advanced options/tsconfig.json

@@ -39,6 +39,8 @@
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "defaultIsModuleExports": "auto",                 /* Specify the target runtime's rules for default imports targeting CommonJS modules. */
+    // "allowRequireESM": "never",                       /* Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json

@@ -39,6 +39,8 @@
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "defaultIsModuleExports": "auto",                 /* Specify the target runtime's rules for default imports targeting CommonJS modules. */
+    // "allowRequireESM": "never",                       /* Specify the target runtime's rules for CommonJS 'require' calls targeting ECMAScript modules. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */