fix: collisions in ESM library

lib/esm/ModuleChunkFormatPlugin.js

@@ -56,15 +56,19 @@ class ModuleChunkFormatPlugin {
 								"HMR is not implemented for module chunk format yet"
 							);
 						} else {
-							source.add(`export const id = ${JSON.stringify(chunk.id)};\n`);
-							source.add(`export const ids = ${JSON.stringify(chunk.ids)};\n`);
-							source.add("export const modules = ");
+							source.add(
+								`export const __webpack_id__ = ${JSON.stringify(chunk.id)};\n`
+							);
+							source.add(
+								`export const __webpack_ids__ = ${JSON.stringify(chunk.ids)};\n`
+							);
+							source.add("export const __webpack_modules__ = ");
 							source.add(modules);
 							source.add(";\n");
 							const runtimeModules =
 								chunkGraph.getChunkRuntimeModulesInOrder(chunk);
 							if (runtimeModules.length > 0) {
-								source.add("export const runtime =\n");
+								source.add("export const __webpack_runtime__ =\n");
 								source.add(
 									Template.renderChunkRuntimeModules(
 										runtimeModules,

lib/esm/ModuleChunkLoadingRuntimeModule.js

@@ -161,29 +161,29 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 			withLoading || withExternalInstallChunk
 				? `var installChunk = ${runtimeTemplate.basicFunction("data", [
 						runtimeTemplate.destructureObject(
-							["ids", "modules", "runtime"],
+							["__webpack_ids__", "__webpack_modules__", "__webpack_runtime__"],
 							"data"
 						),
 						'// add "modules" to the modules object,',
 						'// then flag all "ids" as loaded and fire callback',
 						"var moduleId, chunkId, i = 0;",
-						"for(moduleId in modules) {",
+						"for(moduleId in __webpack_modules__) {",
 						Template.indent([
-							`if(${RuntimeGlobals.hasOwnProperty}(modules, moduleId)) {`,
+							`if(${RuntimeGlobals.hasOwnProperty}(__webpack_modules__, moduleId)) {`,
 							Template.indent(
-								`${RuntimeGlobals.moduleFactories}[moduleId] = modules[moduleId];`
+								`${RuntimeGlobals.moduleFactories}[moduleId] = __webpack_modules__[moduleId];`
 							),
 							"}"
 						]),
 						"}",
-						`if(runtime) runtime(${RuntimeGlobals.require});`,
-						"for(;i < ids.length; i++) {",
+						`if(__webpack_runtime__) __webpack_runtime__(${RuntimeGlobals.require});`,
+						"for(;i < __webpack_ids__.length; i++) {",
 						Template.indent([
-							"chunkId = ids[i];",
+							"chunkId = __webpack_ids__[i];",
 							`if(${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) && installedChunks[chunkId]) {`,
 							Template.indent("installedChunks[chunkId][0]();"),
 							"}",
-							"installedChunks[ids[i]] = 0;"
+							"installedChunks[__webpack_ids__[i]] = 0;"
 						]),
 						"}",
 						withOnChunkLoad ? `${RuntimeGlobals.onChunksLoaded}();` : ""

test/configCases/library/issue-18951/index.js

@@ -0,0 +1,7 @@
+it("should don't have variable name conflict", function() {
+	expect(true).toBe(true);
+});
+
+export const id = "collision";
+export const ids = ["collision"];
+export const modules = { "collision": true };

test/configCases/library/issue-18951/test.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+	findBundle: function (i, options) {
+		return ["main.mjs"];
+	}
+};

test/configCases/library/issue-18951/webpack.config.js

@@ -0,0 +1,11 @@
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	experiments: { outputModule: true },
+	output: {
+		filename: "[name].mjs",
+		library: { type: "module" }
+	},
+	optimization: {
+		runtimeChunk: "single" // any value other than `false`
+	}
+};