Merge pull request #11759 from webpack/fix-external-this-concatenation

Make external modules of type 'this' work with module concatenation

lib/ExternalModule.js

@@ -293,7 +293,7 @@ class ExternalModule extends Module {
 			exportsType: undefined
 		};
 		this.buildInfo = {
-			strict: true
+			strict: this.externalType !== "this"
 		};
 		this.buildMeta.exportsType = "dynamic";
 		let canMangle = false;
@@ -412,18 +412,19 @@ class ExternalModule extends Module {
 			chunkGraph
 		);
 
-		let sourceString;
+		let sourceString = sourceData.expression;
+		if (sourceData.iife)
+			sourceString = `(function() { return ${sourceString}; }())`;
 		if (concatenationScope) {
 			sourceString = `${runtimeTemplate.supportsConst() ? "const" : "var"} ${
 				ConcatenationScope.NAMESPACE_OBJECT_EXPORT
-			} = ${sourceData.expression};`;
+			} = ${sourceString};`;
 			concatenationScope.registerNamespaceExport(
 				ConcatenationScope.NAMESPACE_OBJECT_EXPORT
 			);
 		} else {
-			sourceString = `module.exports = ${sourceData.expression};`;
+			sourceString = `module.exports = ${sourceString};`;
 		}
-		if (sourceData.iife) sourceString = `(function() { ${sourceString} })();`;
 		if (sourceData.init) sourceString = `${sourceData.init}\n${sourceString}`;
 
 		const sources = new Map();

test/configCases/externals/this/index.js

@@ -0,0 +1,11 @@
+afterEach(done => {
+	(function() { delete this.EXTERNAL_TEST_GLOBAL; })();
+	done();
+});
+
+it("should import an external value assigned to global this", function() {
+	(function() { this.EXTERNAL_TEST_GLOBAL = 42; })();
+	// eslint-disable-next-line node/no-missing-require
+	const result = require("external");
+	expect(result).toBe(42);
+});

test/configCases/externals/this/webpack.config.js

@@ -0,0 +1,9 @@
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	optimization: {
+		concatenateModules: true
+	},
+	externals: {
+		external: "this EXTERNAL_TEST_GLOBAL"
+	}
+};