fix: improve `module.exports` bundle to ESM library (#19776)

lib/library/ModuleLibraryPlugin.js

@@ -8,6 +8,7 @@
 const { ConcatSource } = require("webpack-sources");
 const RuntimeGlobals = require("../RuntimeGlobals");
 const Template = require("../Template");
+const CommonJsSelfReferenceDependency = require("../dependencies/CommonJsSelfReferenceDependency");
 const ConcatenatedModule = require("../optimize/ConcatenatedModule");
 const propertyAccess = require("../util/propertyAccess");
 const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
@@ -104,6 +105,17 @@ class ModuleLibraryPlugin extends AbstractLibraryPlugin {
 		{ options, compilation }
 	) {
 		const result = new ConcatSource(source);
+
+		if (!module.buildMeta || !module.buildMeta.exportsType) {
+			for (const dependency of module.dependencies) {
+				if (dependency instanceof CommonJsSelfReferenceDependency) {
+					result.add(`export { ${RuntimeGlobals.exports} as default }`);
+					break;
+				}
+			}
+			return result;
+		}
+
 		const exportsInfo = options.export
 			? [
 					moduleGraph.getExportInfo(

test/configCases/container/track-initial-chunks/index.js

@@ -1,6 +1,5 @@
 it("should have the hoisted container references", async () => {
 	const before = __webpack_modules__;
-	debugger;
 
 	// Initialize tracker array
 	const tracker = [];
@@ -12,7 +11,6 @@ it("should have the hoisted container references", async () => {
 	await Promise.all(tracker);
 
 	const after = __webpack_modules__;
-	debugger;
 
 	// Verify that tracker contains hoisted container references
 	expect(tracker).not.toHaveLength(0);

test/configCases/library/0-create-library/webpack.config.js

@@ -802,5 +802,18 @@ module.exports = (env, { testPath }) => [
 				"external-named": "./non-external-named"
 			}
 		}
+	},
+	{
+		entry: "./class-commonjs",
+		output: {
+			filename: "commonjs-bundle-to-esm.mjs",
+			module: true,
+			library: {
+				type: "module"
+			}
+		},
+		experiments: {
+			outputModule: true
+		}
 	}
 ];

test/configCases/library/1-use-library/esm-with-bundled-commonjs.js

@@ -0,0 +1,8 @@
+import library from "library";
+
+it(
+	"should be able to import harmony exports from library (" + NAME + ")",
+	function () {
+		expect(new library().getNumber()).toBe(1);
+	}
+);

test/configCases/library/1-use-library/webpack.config.js

@@ -687,5 +687,24 @@ module.exports = (env, { testPath }) => [
 				NAME: JSON.stringify("entryC")
 			})
 		]
+	},
+	{
+		entry: "./esm-with-bundled-commonjs",
+		output: {
+			module: true
+		},
+		experiments: { outputModule: true },
+		externals: {
+			library: path.resolve(
+				testPath,
+				"../0-create-library/commonjs-bundle-to-esm.mjs"
+			)
+		},
+		externalsType: "module-import",
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("commonjs-bundle-to-esm")
+			})
+		]
 	}
 ];