dispose code generation results after sealing the compilation

lib/CodeGenerationResults.js

@@ -27,6 +27,7 @@ class CodeGenerationResults {
 	 * @returns {CodeGenerationResult} the CodeGenerationResult
 	 */
 	get(module, runtime) {
+		this._verifyAlive();
 		const entry = this.map.get(module);
 		if (entry === undefined) {
 			throw new Error(
@@ -72,6 +73,7 @@ Caller might not support runtime-dependent code generation (opt-out via optimiza
 	 * @returns {boolean} true, when we have data for this
 	 */
 	has(module, runtime) {
+		this._verifyAlive();
 		const entry = this.map.get(module);
 		if (entry === undefined) {
 			return false;
@@ -142,9 +144,23 @@ Caller might not support runtime-dependent code generation (opt-out via optimiza
 	 * @returns {void}
 	 */
 	add(module, runtime, result) {
+		this._verifyAlive();
 		const map = provide(this.map, module, () => new RuntimeSpecMap());
 		map.set(runtime, result);
 	}
+
+	_verifyAlive() {
+		if (this.map === undefined) {
+			throw new Error(
+				"CodeGenerationResults has been accessed after its lifetime. They are no longer available after sealing the compilation."
+			);
+		}
+	}
+
+	dispose() {
+		this.map.clear();
+		this.map = undefined;
+	}
 }
 
 module.exports = CodeGenerationResults;

lib/Compilation.js

@@ -2132,6 +2132,7 @@ BREAKING CHANGE: Asset processing hooks in Compilation has been merged into a si
 		this.assets = {};
 		this.assetsInfo.clear();
 		this.moduleGraph.removeAllModuleAttributes();
+		this.codeGenerationResults = undefined;
 	}
 
 	/**
@@ -2418,6 +2419,7 @@ Or do you want to use the entrypoints '${name}' and '${runtime}' independently o
 										this.unseal();
 										return this.seal(callback);
 									}
+									this.codeGenerationResults.dispose();
 									return this.hooks.afterSeal.callAsync(err => {
 										if (err) {
 											return callback(

lib/Compiler.js

@@ -359,12 +359,13 @@ class Compiler {
 	// e.g. move compilation specific info from Modules into ModuleGraph
 	_cleanupLastCompilation() {
 		if (this._lastCompilation !== undefined) {
-			for (const module of this._lastCompilation.modules) {
+			const c = this._lastCompilation;
+			for (const module of c.modules) {
 				ChunkGraph.clearChunkGraphForModule(module);
 				ModuleGraph.clearModuleGraphForModule(module);
 				module.cleanupForCache();
 			}
-			for (const chunk of this._lastCompilation.chunks) {
+			for (const chunk of c.chunks) {
 				ChunkGraph.clearChunkGraphForChunk(chunk);
 			}
 			this._lastCompilation = undefined;

types.d.ts

@@ -1174,6 +1174,7 @@ declare abstract class CodeGenerationResults {
 	getData(module: Module, runtime: RuntimeSpec, key: string): any;
 	getHash(module: Module, runtime: RuntimeSpec): any;
 	add(module: Module, runtime: RuntimeSpec, result: CodeGenerationResult): void;
+	dispose(): void;
 }
 type CodeValue =
 	| undefined