Align with SmartClassLoader handling for AOP proxy classes

Closes gh-34274

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassEnhancer.java

@@ -109,8 +109,16 @@ class ConfigurationClassEnhancer {
 			}
 			return configClass;
 		}
+
 		try {
-			Class<?> enhancedClass = createClass(newEnhancer(configClass, classLoader));
+			// Use original ClassLoader if config class not locally loaded in overriding class loader
+			if (classLoader instanceof SmartClassLoader smartClassLoader &&
+					classLoader != configClass.getClassLoader()) {
+				classLoader = smartClassLoader.getOriginalClassLoader();
+			}
+			Enhancer enhancer = newEnhancer(configClass, classLoader);
+			boolean classLoaderMismatch = (classLoader != null && classLoader != configClass.getClassLoader());
+			Class<?> enhancedClass = createClass(enhancer, classLoaderMismatch);
 			if (logger.isTraceEnabled()) {
 				logger.trace(String.format("Successfully enhanced %s; enhanced class name is: %s",
 						configClass.getName(), enhancedClass.getName()));
@@ -155,8 +163,21 @@ class ConfigurationClassEnhancer {
 	 * Uses enhancer to generate a subclass of superclass,
 	 * ensuring that callbacks are registered for the new subclass.
 	 */
-	private Class<?> createClass(Enhancer enhancer) {
+	private Class<?> createClass(Enhancer enhancer, boolean fallback) {
-		Class<?> subclass = enhancer.createClass();
+		Class<?> subclass;
+		try {
+			subclass = enhancer.createClass();
+		}
+		catch (CodeGenerationException ex) {
+			if (!fallback) {
+				throw ex;
+			}
+			// Possibly a package-visible @Bean method declaration not accessible
+			// in the given ClassLoader -> retry with original ClassLoader
+			enhancer.setClassLoader(null);
+			subclass = enhancer.createClass();
+		}
+
 		// Registering callbacks statically (as opposed to thread-local)
 		// is critical for usage in an OSGi environment (SPR-5932)...
 		Enhancer.registerStaticCallbacks(subclass, CALLBACKS);

spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassEnhancerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -18,11 +18,16 @@ package org.springframework.context.annotation;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.security.ProtectionDomain;
 import java.security.SecureClassLoader;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.core.OverridingClassLoader;
 import org.springframework.core.SmartClassLoader;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -36,19 +41,108 @@ class ConfigurationClassEnhancerTests {
 	@Test
 	void enhanceReloadedClass() throws Exception {
 		ConfigurationClassEnhancer configurationClassEnhancer = new ConfigurationClassEnhancer();
+
 		ClassLoader parentClassLoader = getClass().getClassLoader();
-		CustomClassLoader classLoader = new CustomClassLoader(parentClassLoader);
+		ClassLoader classLoader = new CustomSmartClassLoader(parentClassLoader);
 		Class<?> myClass = parentClassLoader.loadClass(MyConfig.class.getName());
-		configurationClassEnhancer.enhance(myClass, parentClassLoader);
+		Class<?> enhancedClass = configurationClassEnhancer.enhance(myClass, parentClassLoader);
-		Class<?> myReloadedClass = classLoader.loadClass(MyConfig.class.getName());
+		assertThat(myClass).isAssignableFrom(enhancedClass);
-		Class<?> enhancedReloadedClass = configurationClassEnhancer.enhance(myReloadedClass, classLoader);
+
-		assertThat(enhancedReloadedClass.getClassLoader()).isEqualTo(classLoader);
+		myClass = classLoader.loadClass(MyConfig.class.getName());
+		enhancedClass = configurationClassEnhancer.enhance(myClass, classLoader);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader);
+		assertThat(myClass).isAssignableFrom(enhancedClass);
+	}
+
+	@Test
+	void withPublicClass() {
+		ConfigurationClassEnhancer configurationClassEnhancer = new ConfigurationClassEnhancer();
+
+		ClassLoader classLoader = new URLClassLoader(new URL[0], getClass().getClassLoader());
+		Class<?> enhancedClass = configurationClassEnhancer.enhance(MyConfigWithPublicClass.class, classLoader);
+		assertThat(MyConfigWithPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader);
+
+		classLoader = new OverridingClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithPublicClass.class, classLoader);
+		assertThat(MyConfigWithPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new CustomSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithPublicClass.class, classLoader);
+		assertThat(MyConfigWithPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new BasicSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithPublicClass.class, classLoader);
+		assertThat(MyConfigWithPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+	}
+
+	@Test
+	void withNonPublicClass() {
+		ConfigurationClassEnhancer configurationClassEnhancer = new ConfigurationClassEnhancer();
+
+		ClassLoader classLoader = new URLClassLoader(new URL[0], getClass().getClassLoader());
+		Class<?> enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicClass.class, classLoader);
+		assertThat(MyConfigWithNonPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new OverridingClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicClass.class, classLoader);
+		assertThat(MyConfigWithNonPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new CustomSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicClass.class, classLoader);
+		assertThat(MyConfigWithNonPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new BasicSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicClass.class, classLoader);
+		assertThat(MyConfigWithNonPublicClass.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+	}
+
+	@Test
+	void withNonPublicMethod() {
+		ConfigurationClassEnhancer configurationClassEnhancer = new ConfigurationClassEnhancer();
+
+		ClassLoader classLoader = new URLClassLoader(new URL[0], getClass().getClassLoader());
+		Class<?> enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicMethod.class, classLoader);
+		assertThat(MyConfigWithNonPublicMethod.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader);
+
+		classLoader = new OverridingClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicMethod.class, classLoader);
+		assertThat(MyConfigWithNonPublicMethod.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new CustomSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicMethod.class, classLoader);
+		assertThat(MyConfigWithNonPublicMethod.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
+
+		classLoader = new BasicSmartClassLoader(getClass().getClassLoader());
+		enhancedClass = configurationClassEnhancer.enhance(MyConfigWithNonPublicMethod.class, classLoader);
+		assertThat(MyConfigWithNonPublicMethod.class).isAssignableFrom(enhancedClass);
+		assertThat(enhancedClass.getClassLoader()).isEqualTo(classLoader.getParent());
 	}
 
 
 	@Configuration
 	static class MyConfig {
 
+		@Bean
+		String myBean() {
+			return "bean";
+		}
+	}
+
+
+	@Configuration
+	public static class MyConfigWithPublicClass {
+
 		@Bean
 		public String myBean() {
 			return "bean";
@@ -56,9 +150,29 @@ class ConfigurationClassEnhancerTests {
 	}
 
 
-	static class CustomClassLoader extends SecureClassLoader implements SmartClassLoader {
+	@Configuration
+	static class MyConfigWithNonPublicClass {
 
-		CustomClassLoader(ClassLoader parent) {
+		@Bean
+		public String myBean() {
+			return "bean";
+		}
+	}
+
+
+	@Configuration
+	public static class MyConfigWithNonPublicMethod {
+
+		@Bean
+		String myBean() {
+			return "bean";
+		}
+	}
+
+
+	static class CustomSmartClassLoader extends SecureClassLoader implements SmartClassLoader {
+
+		CustomSmartClassLoader(ClassLoader parent) {
 			super(parent);
 		}
 
@@ -82,6 +196,29 @@ class ConfigurationClassEnhancerTests {
 		public boolean isClassReloadable(Class<?> clazz) {
 			return clazz.getName().contains("MyConfig");
 		}
+
+		@Override
+		public ClassLoader getOriginalClassLoader() {
+			return getParent();
+		}
+
+		@Override
+		public Class<?> publicDefineClass(String name, byte[] b, @Nullable ProtectionDomain protectionDomain) {
+			return defineClass(name, b, 0, b.length, protectionDomain);
+		}
+	}
+
+
+	static class BasicSmartClassLoader extends SecureClassLoader implements SmartClassLoader {
+
+		BasicSmartClassLoader(ClassLoader parent) {
+			super(parent);
+		}
+
+		@Override
+		public Class<?> publicDefineClass(String name, byte[] b, @Nullable ProtectionDomain protectionDomain) {
+			return defineClass(name, b, 0, b.length, protectionDomain);
+		}
 	}
 
 }