@@ -0,0 +1,5 @@
+---
+"webpack": patch
+---
+
+Fix loss of export definitions in the module library under cache.
@@ -12,7 +12,7 @@
 /** @import Dependency from "./Dependency" */
 /** @import DependencyTemplates from "./DependencyTemplates" */
 /** @import { GenerateContext } from "./Generator" */
-/** @import Module, { RuntimeRequirements } from "./Module" */
+/** @import Module, { CodeGenerationResultData, RuntimeRequirements } from "./Module" */
 /** @import ModuleGraph from "./ModuleGraph" */
 /** @import RuntimeTemplate from "./RuntimeTemplate" */
 /** @import { RuntimeSpec } from "./util/runtime" */
@@ -37,6 +37,7 @@
  * @property {ConcatenationScope=} concatenationScope when in a concatenated module, information about other concatenated modules
  * @property {CodeGenerationResults} codeGenerationResults the code generation results
  * @property {InitFragment<GenerateContext>[]} chunkInitFragments chunkInitFragments
+ * @property {(() => CodeGenerationResultData)=} getData get access to the code generation data
  */
 
 /**
 
@@ -129,6 +129,9 @@ const makeSerializable = require("./util/makeSerializable");
  * @property {Set<string>} freeNames free identifier names in the rendered source for javascript modules
  * @property {InitFragment<EXPECTED_ANY>[]} chunkInitFragments chunk init fragments for javascript modules
  * @property {string} externalReexport native external reexport source and attributes
+ * @property {string} exportsSource export definitions left out of a javascript module's source on demand (see `KnownMeta.onDemandExports`), to be placed before its body where it is wrapped
+ * @property {string} exportsBindingSource export definitions left out on demand that read the module's own declarations, to be placed after its body where it is wrapped
+ * @property {Record<string, string>} exportsFinalName final name of each used export of a concatenated module whose definitions were left out on demand
  * @property {{ javascript?: string, ["asset-url"]?: string }} url url for asset modules
  * @property {string} filename a filename for asset modules
  * @property {AssetInfo} assetInfo an asset info for asset modules
@@ -182,9 +185,6 @@ const makeSerializable = require("./util/makeSerializable");
  * @property {(false | "redirect" | "redirect-warn")=} defaultObject
  * @property {boolean=} async
  * @property {boolean=} sideEffectFree
- * @property {Map<string, Record<string, string>>=} exportsFinalNameByRuntime using in ModuleLibraryPlugin
- * @property {Map<string, string>=} exportsSourceByRuntime using in ModuleLibraryPlugin
- * @property {Map<string, string>=} exportsBindingSourceByRuntime export definitions `ModuleLibraryPlugin` took over, re-emitted only where the module is wrapped
  */
 
 /**
 
@@ -143,6 +143,7 @@ class ModuleGraphModule {
  * @typedef {object} KnownMeta
  * @property {Map<Module, string>=} importVarMap
  * @property {Map<Module, string>=} deferredImportVarMap
+ * @property {boolean=} onDemandExports generate export definitions on demand
  */
 
 /** @typedef {KnownMeta & Record<CommonJsExportRequireDependencyIDsSymbol | HarmonyImportSpecifierDependencyIDsSymbol | HarmonyExportImportedSpecifierDependencyIDsSymbol, string[]> & Record<string, EXPECTED_ANY>} Meta */
 
@@ -13,11 +13,8 @@ const makeSerializable = require("../util/makeSerializable");
 const memoize = require("../util/memoize");
 const NullDependency = require("./NullDependency");
 
-// Required here rather than at the top: the plugin reaches back into the dependencies.
-const getJavascriptModulesPlugin = memoize(() =>
-	require("../javascript/JavascriptModulesPlugin")
-);
-// Same reason: the deferred-namespace runtime imports dependencies from here.
+// Required here rather than at the top: the deferred-namespace runtime imports
+// dependencies from here.
 const getDeferredCycleHelpers = memoize(() =>
 	require("../runtime/MakeDeferredNamespaceObjectRuntime")
 );
@@ -99,7 +96,8 @@ HarmonyCompatibilityDependency.Template = class HarmonyExportDependencyTemplate
 			initFragments,
 			runtimeRequirements,
 			runtime,
-			concatenationScope
+			concatenationScope,
+			getData
 		}
 	) {
 		// a wrapped module has a real exports object that still needs `__esModule`
@@ -113,20 +111,13 @@ HarmonyCompatibilityDependency.Template = class HarmonyExportDependencyTemplate
 				exportsArgument: module.exportsArgument,
 				runtimeRequirements
 			});
-			// A library exporting the same bindings natively never reads the marker back
-			// off the exports object, so it takes the call over and emits it where wrapped.
-			const hooks = getJavascriptModulesPlugin().getCompilationHooks(
-				runtimeTemplate.compilation
-			);
-			const takenOver =
-				hooks.onDemandExportsGeneration.isUsed() &&
-				hooks.onDemandExportsGeneration.call(
-					module,
-					runtime,
-					content,
-					false
-				) === true;
-			if (!takenOver) {
+
+			const meta = moduleGraph.getMetaIfExisting(module);
+			if (!concatenationScope && meta && meta.onDemandExports && getData) {
+				const data = getData();
+				const before = data.get("exportsSource");
+				data.set("exportsSource", before ? `${before}${content}` : content);
+			} else {
 				initFragments.push(
 					new InitFragment(
 						content,
 
@@ -43,12 +43,6 @@ const ExportBindingType = Object.freeze({
 /** @typedef {Map<UsedName, { value: string, type: typeof ExportBindingType.Getter | typeof ExportBindingType.Value }>} ExportMap */
 /** @typedef {Set<string>} UnusedExports */
 
-/**
- * Lets a consumer take over the rendered `d()` call at its required position.
- * End-position value bindings cannot move before the module body.
- * @typedef {(source: string, placeAtEnd: boolean) => boolean} OnDemandGeneration
- */
-
 /** @type {ExportMap} */
 const EMPTY_MAP = new Map();
 /** @type {UnusedExports} */
@@ -64,13 +58,13 @@ class HarmonyExportInitFragment extends InitFragment {
 	 * @param {string} exportsArgument the exports identifier
 	 * @param {ExportMap} exportMap mapping from used name to exposed variable name
 	 * @param {UnusedExports} unusedExports list of unused export names
-	 * @param {OnDemandGeneration=} onDemand offered the call instead of emitting it
+	 * @param {boolean} onDemand leave the call out of the source and hand it over in the code generation data (see `KnownMeta.onDemandExports`)
 	 */
 	constructor(
 		exportsArgument,
 		exportMap = EMPTY_MAP,
 		unusedExports = EMPTY_SET,
-		onDemand = undefined
+		onDemand = false
 	) {
 		super(undefined, InitFragment.STAGE_HARMONY_EXPORTS, 1, "harmony-exports");
 		/** @type {string} */
@@ -79,7 +73,7 @@ class HarmonyExportInitFragment extends InitFragment {
 		this.exportMap = exportMap;
 		/** @type {UnusedExports} */
 		this.unusedExports = unusedExports;
-		/** @type {OnDemandGeneration | undefined} */
+		/** @type {boolean} */
 		this.onDemand = onDemand;
 
 		this._generated = false;
@@ -138,8 +132,8 @@ class HarmonyExportInitFragment extends InitFragment {
 		/** @type {undefined | UnusedExports} */
 		let unusedExports;
 		let unusedExportsOwned = false;
-		/** @type {OnDemandGeneration=} */
-		let onDemand;
+		/** @type {boolean} */
+		let onDemand = false;
 
 		for (const fragment of fragments) {
 			if (fragment.exportMap.size !== 0) {
@@ -227,7 +221,7 @@ class HarmonyExportInitFragment extends InitFragment {
 	getContent(context) {
 		this._generate(context);
 
-		const { runtimeRequirements } = context;
+		const { runtimeRequirements, getData } = context;
 		const unusedPart =
 			this.unusedExports.size > 1
 				? `/* unused harmony exports ${joinIterableWithComma(
@@ -248,7 +242,13 @@ class HarmonyExportInitFragment extends InitFragment {
 			}(${this.exportsArgument}, {${this._defsGetter.join(
 				","
 			)}\n/* harmony export */ });\n`;
-			if (this.onDemand !== undefined && this.onDemand(definePart, false)) {
+			if (this.onDemand && getData !== undefined) {
+				const data = getData();
+				const before = data.get("exportsSource");
+				data.set(
+					"exportsSource",
+					before ? `${before}${definePart}` : definePart
+				);
 				definePart = "";
 			}
 		}
@@ -261,7 +261,7 @@ class HarmonyExportInitFragment extends InitFragment {
 	 * @param {GenerateContext} context context
 	 * @returns {string | Source | undefined} the source code that will be included at the end of the module
 	 */
-	getEndContent({ runtimeRequirements }) {
+	getEndContent({ runtimeRequirements, getData }) {
 		let definePart = "";
 
 		if (this._defsValue && this._defsValue.length) {
@@ -272,14 +272,21 @@ class HarmonyExportInitFragment extends InitFragment {
 			// Only this fragment emits the array form, so the runtime helper drops the
 			// branch reading it unless this asks for it.
 			runtimeRequirements.add(RuntimeGlobals.definePropertyGettersFromArray);
-			const definition = `/* harmony export */ ${
+			definePart = `/* harmony export */ ${
 				RuntimeGlobals.definePropertyGetters
 			}(${this.exportsArgument}, [${this._defsValue.join(",")}\n/* harmony export */ ]);\n`;
 
-			definePart =
-				this.onDemand !== undefined && this.onDemand(definition, true)
-					? definePart
-					: `\n${definition}`;
+			if (this.onDemand && getData !== undefined) {
+				const data = getData();
+				const before = data.get("exportsBindingSource");
+				data.set(
+					"exportsBindingSource",
+					before ? `${before}${definePart}` : definePart
+				);
+				definePart = "";
+			} else {
+				definePart = `\n${definePart}`;
+			}
 		}
 
 		return definePart;
 
@@ -8,7 +8,6 @@
 const Dependency = require("../Dependency");
 const { InlinedUsedName } = require("../optimize/InlineExports");
 const makeSerializable = require("../util/makeSerializable");
-const memoize = require("../util/memoize");
 const HarmonyExportInitFragment = require("./HarmonyExportInitFragment");
 
 const { ExportBindingType } = HarmonyExportInitFragment;
@@ -30,11 +29,6 @@ const NullDependency = require("./NullDependency");
  * } from "../javascript/JavascriptModule"
  */
 
-// Required here rather than at the top: the plugin reaches back into the dependencies.
-const getJavascriptModulesPlugin = memoize(() =>
-	require("../javascript/JavascriptModulesPlugin")
-);
-
 class HarmonyExportSpecifierDependency extends NullDependency {
 	/**
 	 * Creates an instance of HarmonyExportSpecifierDependency.
@@ -149,14 +143,7 @@ HarmonyExportSpecifierDependency.Template = class HarmonyExportSpecifierDependen
 	apply(
 		dependency,
 		source,
-		{
-			module,
-			moduleGraph,
-			initFragments,
-			runtime,
-			runtimeTemplate,
-			concatenationScope
-		}
+		{ module, moduleGraph, initFragments, runtime, concatenationScope }
 	) {
 		const dep = /** @type {HarmonyExportSpecifierDependency} */ (dependency);
 		// a wrapped module's bindings stay inside the wrapper, not in the shared scope
@@ -187,20 +174,12 @@ HarmonyExportSpecifierDependency.Template = class HarmonyExportSpecifierDependen
 			/** @type {import("../Module").BuildInfo} */ (module.buildInfo)
 				.isCircular === false;
 
-		// A library exporting the same bindings natively reads none of them back off the
-		// exports object, so it takes the call over and emits it only where wrapped.
-		const hooks = getJavascriptModulesPlugin().getCompilationHooks(
-			runtimeTemplate.compilation
-		);
-		const onDemand = hooks.onDemandExportsGeneration.isUsed()
-			? (/** @type {string} */ definition, /** @type {boolean} */ placeAtEnd) =>
-					hooks.onDemandExportsGeneration.call(
-						module,
-						runtime,
-						definition,
-						placeAtEnd
-					) === true
-			: undefined;
+		const meta = moduleGraph.getMetaIfExisting(module);
+
+		const onDemand =
+			!concatenationScope &&
+			meta !== undefined &&
+			meta.onDemandExports === true;
 
 		/** @type {ExportMap} */
 		const map = new Map();
 
@@ -256,6 +256,7 @@ class JavascriptGenerator extends Generator {
 				/** @type {NonNullable<GenerateContext["codeGenerationResults"]>} */
 				(generateContext.codeGenerationResults),
 			initFragments,
+			getData: generateContext.getData,
 			get chunkInitFragments() {
 				if (!chunkInitFragments) {
 					const data =
 
@@ -78,7 +78,6 @@ const { releaseParserCaches } = require("./syntax");
 /** @import DependencyTemplates from "../DependencyTemplates" */
 /** @import Entrypoint from "../Entrypoint" */
 /** @import Module, { BuildInfo, CodeGenerationResultData } from "../Module" */
-/** @import { RuntimeSpec } from "../util/runtime" */
 /** @import ModuleGraph from "../ModuleGraph" */
 /** @import RuntimeTemplate from "../RuntimeTemplate" */
 /** @import WebpackError from "../errors/WebpackError" */
@@ -332,18 +331,6 @@ const createCompilationHooks = () => ({
 	 * @since 5.22.0
 	 */
 	inlineInRuntimeBailout: new SyncBailHook(["module", "renderContext"]),
-	/**
-	 * Offers a module's rendered export-definition call to a consumer that can place
-	 * it better — a library whose entry exports the same bindings natively takes it
-	 * over and emits it only where the module is wrapped. Return true to take it.
-	 * @type {SyncBailHook<[Module, RuntimeSpec, string, boolean], boolean | void>}
-	 */
-	onDemandExportsGeneration: new SyncBailHook([
-		"module",
-		"runtime",
-		"source",
-		"placeAtEnd"
-	]),
 	/**
 	 * @type {SyncBailHook<[Module, RenderContext], string | void>}
 	 * @since 5.22.0
-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"webpack": patch
 +---
++
 +Fix loss of export definitions in the module library under cache.