Final merged bean definition clearing in freezeConfiguration

Instead of individual last-minute clearing in markBeanAsCreated, the factory clears all merged bean definitions in freezeConfiguration, retaining the changes of merged bean definition post-processing after that point (in particular in refreshForAotProcessing).

Closes gh-28948

spring-beans/src/main/java/org/springframework/beans/factory/config/ConfigurableListableBeanFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -137,7 +137,10 @@ public interface ConfigurableListableBeanFactory
 	/**
 	 * Freeze all bean definitions, signalling that the registered bean definitions
 	 * will not be modified or post-processed any further.
-	 * <p>This allows the factory to aggressively cache bean definition metadata.
+	 * <p>This allows the factory to aggressively cache bean definition metadata
+	 * going forward, after clearing the initial temporary metadata cache.
+	 * @see #clearMetadataCache()
+	 * @see #isConfigurationFrozen()
 	 */
 	void freezeConfiguration();
 
@@ -145,6 +148,7 @@ public interface ConfigurableListableBeanFactory
 	 * Return whether this factory's bean definitions are frozen,
 	 * i.e. are not supposed to be modified or post-processed any further.
 	 * @return {@code true} if the factory's configuration is considered frozen
+	 * @see #freezeConfiguration()
 	 */
 	boolean isConfigurationFrozen();
 

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -576,7 +576,7 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 					throw new BeanCreationException(mbd.getResourceDescription(), beanName,
 							"Post-processing of merged bean definition failed", ex);
 				}
-				mbd.postProcessed = true;
+				mbd.markAsPostProcessed();
 			}
 		}
 

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java

@@ -1700,12 +1700,12 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 	protected void markBeanAsCreated(String beanName) {
 		if (!this.alreadyCreated.contains(beanName)) {
 			synchronized (this.mergedBeanDefinitions) {
-				if (!this.alreadyCreated.contains(beanName)) {
+				if (!isBeanEligibleForMetadataCaching(beanName)) {
 					// Let the bean definition get re-merged now that we're actually creating
 					// the bean... just in case some of its metadata changed in the meantime.
 					clearMergedBeanDefinition(beanName);
-					this.alreadyCreated.add(beanName);
 				}
+				this.alreadyCreated.add(beanName);
 			}
 		}
 	}

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultListableBeanFactory.java

@@ -887,6 +887,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 
 	@Override
 	public void freezeConfiguration() {
+		clearMetadataCache();
 		this.configurationFrozen = true;
 		this.frozenBeanDefinitionNames = StringUtils.toStringArray(this.beanDefinitionNames);
 	}

spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java

@@ -439,6 +439,17 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 		}
 	}
 
+	/**
+	 * Mark this bean definition as post-processed,
+	 * i.e. processed by {@link MergedBeanDefinitionPostProcessor}.
+	 * @since 6.0
+	 */
+	public void markAsPostProcessed() {
+		synchronized (this.postProcessingLock) {
+			this.postProcessed = true;
+		}
+	}
+
 	/**
 	 * Register an externally managed configuration method or field.
 	 */

spring-beans/src/test/java/org/springframework/beans/factory/DefaultListableBeanFactoryTests.java

@@ -772,6 +772,29 @@ class DefaultListableBeanFactoryTests {
 		assertThat(factory.getType("child")).isEqualTo(DerivedTestBean.class);
 	}
 
+	@Test
+	void mergedBeanDefinitionChangesRetainedAfterFreezeConfiguration() {
+		RootBeanDefinition parentDefinition = new RootBeanDefinition(Object.class);
+		ChildBeanDefinition childDefinition = new ChildBeanDefinition("parent");
+
+		DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
+		factory.registerBeanDefinition("parent", parentDefinition);
+		factory.registerBeanDefinition("child", childDefinition);
+
+		assertThat(factory.getType("parent")).isEqualTo(Object.class);
+		assertThat(factory.getType("child")).isEqualTo(Object.class);
+		((RootBeanDefinition) factory.getBeanDefinition("parent")).setBeanClass(TestBean.class);
+
+		factory.freezeConfiguration();
+
+		assertThat(factory.getType("parent")).isEqualTo(TestBean.class);
+		assertThat(factory.getType("child")).isEqualTo(TestBean.class);
+		((RootBeanDefinition) factory.getMergedBeanDefinition("child")).setBeanClass(DerivedTestBean.class);
+
+		assertThat(factory.getBean("parent")).isInstanceOf(TestBean.class);
+		assertThat(factory.getBean("child")).isInstanceOf(DerivedTestBean.class);
+	}
+
 	@Test
 	void nameAlreadyBound() {
 		Properties p = new Properties();

spring-context/src/main/java/org/springframework/context/support/PostProcessorRegistrationDelegate.java

@@ -423,6 +423,7 @@ final class PostProcessorRegistrationDelegate {
 		}
 	}
 
+
 	private static final class MergedBeanDefinitionPostProcessorInvoker {
 
 		private final DefaultListableBeanFactory beanFactory;
@@ -438,12 +439,14 @@ final class PostProcessorRegistrationDelegate {
 				RootBeanDefinition bd = (RootBeanDefinition) this.beanFactory.getMergedBeanDefinition(beanName);
 				Class<?> beanType = resolveBeanType(bd);
 				postProcessRootBeanDefinition(postProcessors, beanName, beanType, bd);
+				bd.markAsPostProcessed();
 			}
 			registerBeanPostProcessors(this.beanFactory, postProcessors);
 		}
 
 		private void postProcessRootBeanDefinition(List<MergedBeanDefinitionPostProcessor> postProcessors,
 				String beanName, Class<?> beanType, RootBeanDefinition bd) {
+
 			BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this.beanFactory, beanName, bd);
 			postProcessors.forEach(postProcessor -> postProcessor.postProcessMergedBeanDefinition(bd, beanType, beanName));
 			for (PropertyValue propertyValue : bd.getPropertyValues().getPropertyValueList()) {
@@ -466,6 +469,7 @@ final class PostProcessorRegistrationDelegate {
 
 		private void resolveInnerBeanDefinition(BeanDefinitionValueResolver valueResolver, BeanDefinition innerBeanDefinition,
 				BiConsumer<String, RootBeanDefinition> resolver) {
+
 			valueResolver.resolveInnerBean(null, innerBeanDefinition, (name, rbd) -> {
 				resolver.accept(name, rbd);
 				return Void.class;