fix: fix conflicts caused by multiple concatenateModules

lib/ConcatenationScope.js

@@ -10,6 +10,7 @@ const {
 	NAMESPACE_OBJECT_EXPORT
 } = require("./util/concatenate");
 
+/** @typedef {import("./Chunk")} Chunk */
 /** @typedef {import("./Module")} Module */
 /** @typedef {import("./optimize/ConcatenatedModule").ConcatenatedModuleInfo} ConcatenatedModuleInfo */
 /** @typedef {import("./optimize/ConcatenatedModule").ModuleInfo} ModuleInfo */
@@ -187,4 +188,7 @@ class ConcatenationScope {
 ConcatenationScope.DEFAULT_EXPORT = DEFAULT_EXPORT;
 ConcatenationScope.NAMESPACE_OBJECT_EXPORT = NAMESPACE_OBJECT_EXPORT;
 
+/** @type {WeakMap<Chunk, Set<string>>} */
+ConcatenationScope.chunkUsedNames = new WeakMap();
+
 module.exports = ConcatenationScope;

lib/optimize/ConcatenatedModule.js

@@ -239,6 +239,8 @@ const moveDeferToLast = (
 	return -1;
 };
 
+const INITIAL_USED_NAMES = new Set(RESERVED_NAMES);
+
 /**
  * @param {Iterable<string>} iterable iterable object
  * @returns {string} joined iterable object
@@ -1212,8 +1214,18 @@ class ConcatenatedModule extends Module {
 		/** @type {NeededNamespaceObjects} */
 		const neededNamespaceObjects = new Set();
 
-		// List of all used names to avoid conflicts
-		const allUsedNames = new Set(RESERVED_NAMES);
+		// Default disallowed names
+		const allUsedNames = new Set(INITIAL_USED_NAMES);
+		const chunks = chunkGraph.getModuleChunks(this);
+
+		// Add names already used in the current chunk scope
+		for (const chunk of chunks) {
+			if (ConcatenationScope.chunkUsedNames.has(chunk)) {
+				for (const name of ConcatenationScope.chunkUsedNames.get(chunk) || []) {
+					allUsedNames.add(name);
+				}
+			}
+		}
 
 		// Generate source code and analyse scopes
 		// Prepare a ReplaceSource for the final source
@@ -1232,6 +1244,23 @@ class ConcatenatedModule extends Module {
 			);
 		}
 
+		// Record the names registered by the current ConcatenatedModule into the chunk scope
+		if (INITIAL_USED_NAMES.size !== allUsedNames.size) {
+			for (const name of allUsedNames) {
+				if (INITIAL_USED_NAMES.has(name)) continue;
+
+				for (const chunk of chunks) {
+					if (!ConcatenationScope.chunkUsedNames.has(chunk)) {
+						ConcatenationScope.chunkUsedNames.set(chunk, new Set([name]));
+					} else {
+						/** @type {Set<string>} */ (
+							ConcatenationScope.chunkUsedNames.get(chunk)
+						).add(name);
+					}
+				}
+			}
+		}
+
 		// Updated Top level declarations are created by renaming
 		/** @type {TopLevelDeclarations} */
 		const topLevelDeclarations = new Set();

test/configCases/library/multi-concatenate-modules-named-import-externals/cjs.js

@@ -0,0 +1,2 @@
+require('./other-entry.js')
+

test/configCases/library/multi-concatenate-modules-named-import-externals/index.js

@@ -0,0 +1,6 @@
+import { readFile } from 'externals-1/foo'
+import './cjs'
+
+it('should not optimize external modules in different concatenation scope', () => {
+	expect(readFile).toBeDefined()
+})

test/configCases/library/multi-concatenate-modules-named-import-externals/other-entry.js

@@ -0,0 +1,5 @@
+import { readFile } from 'externals-2/foo'
+
+it('should not optimize external modules in different concatenation scope', () => {
+	expect(readFile).toBeDefined()
+})

test/configCases/library/multi-concatenate-modules-named-import-externals/test.config.js

@@ -0,0 +1,7 @@
+"use strict";
+
+module.exports = {
+	findBundle() {
+		return ["main.mjs"];
+	}
+};

test/configCases/library/multi-concatenate-modules-named-import-externals/webpack.config.js

@@ -0,0 +1,34 @@
+"use strict";
+
+/** @type {import("../../../../types").Configuration} */
+module.exports = {
+	cache: {
+		type: "memory" // Enable memory cache to test serialization
+	},
+	target: "node",
+	mode: "none",
+	entry: { main: "./index.js", test: "./other-entry.js" },
+	output: {
+		module: true,
+		library: {
+			type: "modern-module"
+		},
+		filename: "[name].mjs",
+		chunkFormat: "module"
+	},
+	experiments: {
+		outputModule: true
+	},
+	resolve: {
+		extensions: [".js"]
+	},
+	externalsType: "module",
+	externals: {
+		"externals-1/foo": "fs",
+		"externals-2/foo": "fs-extra"
+	},
+	optimization: {
+		concatenateModules: true,
+		usedExports: true
+	}
+};

types.d.ts

@@ -2891,6 +2891,7 @@ declare class ConcatenationScope {
 	): null | (ModuleReferenceOptions & { index: number });
 	static DEFAULT_EXPORT: string;
 	static NAMESPACE_OBJECT_EXPORT: string;
+	static chunkUsedNames: WeakMap<Chunk, Set<string>>;
 }
 
 /**