--moduleResolution bundler (formerly known as hybrid)

src/compiler/binder.ts

@@ -82,6 +82,7 @@ import {
     getContainingClass,
     getEffectiveContainerForJSDocTemplateTag,
     getElementOrPropertyAccessName,
+    getEmitModuleResolutionKind,
     getEmitScriptTarget,
     getEnclosingBlockScopeContainer,
     getErrorSpanForNode,
@@ -227,6 +228,7 @@ import {
     ModifierFlags,
     ModuleBlock,
     ModuleDeclaration,
+    ModuleResolutionKind,
     Mutable,
     NamespaceExportDeclaration,
     Node,
@@ -3583,6 +3585,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
         if (!isBindingPattern(node.name)) {
             const possibleVariableDecl = node.kind === SyntaxKind.VariableDeclaration ? node : node.parent.parent;
             if (isInJSFile(node) &&
+                getEmitModuleResolutionKind(options) !== ModuleResolutionKind.Hybrid &&
                 isVariableDeclarationInitializedToBareOrAccessedRequire(possibleVariableDecl) &&
                 !getJSDocTypeTag(node) &&
                 !(getCombinedModifierFlags(node) & ModifierFlags.Export)

src/compiler/checker.ts

@@ -133,6 +133,7 @@ import {
     ElementFlags,
     EmitFlags,
     EmitHint,
+    emitModuleKindIsNonNodeESM,
     EmitResolver,
     EmitTextWriter,
     emptyArray,
@@ -309,6 +310,7 @@ import {
     getResolutionModeOverrideForClause,
     getResolvedExternalModuleName,
     getResolvedModule,
+    getResolveJsonModule,
     getRestParameterElementType,
     getRootDeclaration,
     getScriptTargetFeatures,
@@ -338,8 +340,8 @@ import {
     hasAccessorModifier,
     hasAmbientModifier,
     hasContextSensitiveParameters,
-    HasDecorators,
     hasDecorators,
+    HasDecorators,
     hasDynamicName,
     hasEffectiveModifier,
     hasEffectiveModifiers,
@@ -348,8 +350,8 @@ import {
     hasExtension,
     HasIllegalDecorators,
     HasIllegalModifiers,
-    HasInitializer,
     hasInitializer,
+    HasInitializer,
     hasJSDocNodes,
     hasJSDocParameterTags,
     hasJsonModuleEmitEnabled,
@@ -449,6 +451,7 @@ import {
     isConstructorTypeNode,
     isConstTypeReference,
     isDeclaration,
+    isDeclarationFileName,
     isDeclarationName,
     isDeclarationReadonly,
     isDecorator,
@@ -884,6 +887,7 @@ import {
     setTextRangePosEnd,
     setValueDeclaration,
     ShorthandPropertyAssignment,
+    shouldAllowImportingTsExtension,
     shouldPreserveConstEnums,
     Signature,
     SignatureDeclaration,
@@ -4509,6 +4513,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (
                 namespace.valueDeclaration &&
                 isInJSFile(namespace.valueDeclaration) &&
+                getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Hybrid &&
                 isVariableDeclaration(namespace.valueDeclaration) &&
                 namespace.valueDeclaration.initializer &&
                 isCommonJsRequire(namespace.valueDeclaration.initializer)
@@ -4693,6 +4698,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name ||
                 (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal;
         const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat;
+        const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
         const resolvedModule = getResolvedModule(currentSourceFile, moduleReference, mode);
         const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule);
         const sourceFile = resolvedModule
@@ -4703,11 +4709,28 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (resolutionDiagnostic) {
                 error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName);
             }
+
+            if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) {
+                const importOrExport =
+                    findAncestor(location, isImportDeclaration)?.importClause ||
+                    findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration));
+                if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) {
+                    error(
+                        errorNode,
+                        Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead,
+                        getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))));
+                }
+            }
+            else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) {
+                const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference));
+                error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension);
+            }
+
             if (sourceFile.symbol) {
                 if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) {
                     errorOnImplicitAnyModule(/*isError*/ false, errorNode, resolvedModule, moduleReference);
                 }
-                if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) {
+                if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) {
                     const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration);
                     const overrideClauseHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined;
                     const overrideClause = overrideClauseHost && isImportTypeNode(overrideClauseHost) ? overrideClauseHost.assertions?.assertClause : overrideClauseHost?.assertClause;
@@ -4815,25 +4838,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             else {
                 const tsExtension = tryExtractTSExtension(moduleReference);
                 const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference);
-                const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
                 const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 ||
                     moduleResolutionKind === ModuleResolutionKind.NodeNext;
                 if (tsExtension) {
-                    const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
-                    const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
-                    let replacedImportSource = importSourceWithoutExtension;
-                    /**
-                     * Direct users to import source with .js extension if outputting an ES module.
-                     * @see https://github.com/microsoft/TypeScript/issues/42151
-                     */
-                    if (moduleKind >= ModuleKind.ES2015) {
-                        replacedImportSource += tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js";
-                    }
-                    error(errorNode, diag, tsExtension, replacedImportSource);
-                }
-                else if (!compilerOptions.resolveJsonModule &&
+                    errorOnTSExtensionImport(tsExtension);
+                }
+                else if (!getResolveJsonModule(compilerOptions) &&
                     fileExtensionIs(moduleReference, Extension.Json) &&
-                    getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic &&
+                    moduleResolutionKind !== ModuleResolutionKind.Classic &&
                     hasJsonModuleEmitEnabled(compilerOptions)) {
                     error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference);
                 }
@@ -4855,6 +4867,23 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             }
         }
         return undefined;
+
+        function errorOnTSExtensionImport(tsExtension: string) {
+            const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
+            error(errorNode, diag, tsExtension, getSuggestedImportSource(tsExtension));
+        }
+
+        function getSuggestedImportSource(tsExtension: string) {
+            const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
+            /**
+             * Direct users to import source with .js extension if outputting an ES module.
+             * @see https://github.com/microsoft/TypeScript/issues/42151
+             */
+            if (emitModuleKindIsNonNodeESM(moduleKind) || mode === ModuleKind.ESNext) {
+                return importSourceWithoutExtension + (tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js");
+            }
+            return importSourceWithoutExtension;
+        }
     }
 
     function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void {
@@ -33325,7 +33354,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
 
         // In JavaScript files, calls to any identifier 'require' are treated as external module imports
-        if (isInJSFile(node) && isCommonJsRequire(node)) {
+        if (isInJSFile(node) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Hybrid && isCommonJsRequire(node)) {
             return resolveExternalModuleTypeByLiteral(node.arguments![0] as StringLiteral);
         }
 
@@ -42730,6 +42759,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     // Import equals declaration is deprecated in es6 or above
                     grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead);
                 }
+                else if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Hybrid) {
+                    grammarErrorOnNode(node, Diagnostics.Import_assignment_is_not_allowed_when_moduleResolution_is_set_to_hybrid_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead);
+                }
             }
         }
     }
@@ -42952,6 +42984,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 // system modules does not support export assignment
                 grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_when_module_flag_is_system);
             }
+            else if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Hybrid) {
+                grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_moduleResolution_is_set_to_hybrid_Consider_using_export_default_or_another_module_format_instead);
+            }
         }
     }
 
@@ -44045,7 +44080,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 // 4). type A = import("./f/*gotToDefinitionHere*/oo")
                 if ((isExternalModuleImportEqualsDeclaration(node.parent.parent) && getExternalModuleImportEqualsDeclarationExpression(node.parent.parent) === node) ||
                     ((node.parent.kind === SyntaxKind.ImportDeclaration || node.parent.kind === SyntaxKind.ExportDeclaration) && (node.parent as ImportDeclaration).moduleSpecifier === node) ||
-                    ((isInJSFile(node) && isRequireCall(node.parent, /*checkArgumentIsStringLiteralLike*/ false)) || isImportCall(node.parent)) ||
+                    ((isInJSFile(node) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Hybrid && isRequireCall(node.parent, /*checkArgumentIsStringLiteralLike*/ false)) || isImportCall(node.parent)) ||
                     (isLiteralTypeNode(node.parent) && isLiteralImportTypeNode(node.parent.parent) && node.parent.parent.argument === node.parent)
                 ) {
                     return resolveExternalModuleName(node, node as LiteralExpression, ignoreErrors);

src/compiler/commandLineParser.ts

@@ -964,6 +964,7 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
             classic: ModuleResolutionKind.Classic,
             node16: ModuleResolutionKind.Node16,
             nodenext: ModuleResolutionKind.NodeNext,
+            hybrid: ModuleResolutionKind.Hybrid,
         })),
         affectsModuleResolution: true,
         paramType: Diagnostics.STRATEGY,
@@ -1080,6 +1081,41 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
         category: Diagnostics.Modules,
         description: Diagnostics.List_of_file_name_suffixes_to_search_when_resolving_a_module,
     },
+    {
+        name: "allowImportingTsExtensions",
+        type: "boolean",
+        affectsModuleResolution: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Allow_imports_to_include_TypeScript_file_extensions_Requires_moduleResolution_hybrid_and_either_noEmit_or_emitDeclarationOnly_to_be_set,
+        defaultValueDescription: false,
+    },
+    {
+        name: "resolvePackageJsonExports",
+        type: "boolean",
+        affectsModuleResolution: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Use_the_package_json_exports_field_when_resolving_package_imports,
+        defaultValueDescription: Diagnostics.true_when_moduleResolution_is_node16_nodenext_or_hybrid_otherwise_false,
+    },
+    {
+        name: "resolvePackageJsonImports",
+        type: "boolean",
+        affectsModuleResolution: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Use_the_package_json_imports_field_when_resolving_imports,
+        defaultValueDescription: Diagnostics.true_when_moduleResolution_is_node16_nodenext_or_hybrid_otherwise_false,
+    },
+    {
+        name: "customConditions",
+        type: "list",
+        element: {
+            name: "condition",
+            type: "string",
+        },
+        affectsModuleResolution: true,
+        category: Diagnostics.Modules,
+        description: Diagnostics.Conditions_to_set_in_addition_to_the_resolver_specific_defaults_when_resolving_imports,
+    },
 
     // Source Maps
     {

src/compiler/diagnosticMessages.json

@@ -3563,6 +3563,10 @@
         "category": "Error",
         "code": 2845
     },
+    "A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file '{0}' instead?": {
+        "category": "Error",
+        "code": 2846
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
@@ -4221,6 +4225,26 @@
         "category": "Error",
         "code": 5095
     },
+    "Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'hybrid' and either 'noEmit' or 'emitDeclarationOnly' is set.": {
+        "category": "Error",
+        "code": 5096
+    },
+    "An import path can only end with a '{0}' extension when 'allowImportingTsExtensions' is enabled.": {
+        "category": "Error",
+        "code": 5097
+    },
+    "Option '{0}' can only be used when 'moduleResolution' is set to 'node16', 'nodenext', or 'hybrid'.": {
+        "category": "Error",
+        "code": 5098
+    },
+    "Import assignment is not allowed when 'moduleResolution' is set to 'hybrid'. Consider using 'import * as ns from \"mod\"', 'import {a} from \"mod\"', 'import d from \"mod\"', or another module format instead.": {
+        "category": "Error",
+        "code": 5099
+    },
+    "Export assignment cannot be used when 'moduleResolution' is set to 'hybrid'. Consider using 'export default' or another module format instead.": {
+        "category": "Error",
+        "code": 5100
+    },
 
     "Generates a sourcemap for each corresponding '.d.ts' file.": {
         "category": "Message",
@@ -4443,10 +4467,6 @@
         "category": "Message",
         "code": 6066
     },
-    "Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6).": {
-        "category": "Message",
-        "code": 6069
-    },
     "Initializes a TypeScript project and creates a tsconfig.json file.": {
         "category": "Message",
         "code": 6070
@@ -5430,6 +5450,26 @@
         "category": "Message",
         "code": 6406
     },
+    "Allow imports to include TypeScript file extensions. Requires '--moduleResolution hybrid' and either '--noEmit' or '--emitDeclarationOnly' to be set.": {
+        "category": "Message",
+        "code": 6407
+    },
+    "Use the package.json 'exports' field when resolving package imports.": {
+        "category": "Message",
+        "code": 6408
+    },
+    "Use the package.json 'imports' field when resolving imports.": {
+        "category": "Message",
+        "code": 6409
+    },
+    "Conditions to set in addition to the resolver-specific defaults when resolving imports.": {
+        "category": "Message",
+        "code": 6410
+    },
+    "`true` when 'moduleResolution' is 'node16', 'nodenext', or 'hybrid'; otherwise `false`.": {
+        "category": "Message",
+        "code": 6411
+    },
 
     "The expected type comes from property '{0}' which is declared here on type '{1}'": {
         "category": "Message",