Reject method name mismatch in case of bean name overloading

Closes gh-33330

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

@@ -298,16 +298,12 @@ protected boolean isOverriddenByExistingDefinition(BeanMethod beanMethod, String
 		}
 		BeanDefinition existingBeanDef = this.registry.getBeanDefinition(beanName);
 
-		// Is the existing bean definition one that was created from a configuration class?
-		// -> allow the current bean method to override, since both are at second-pass level.
-		// However, if the bean method is an overloaded case on the same configuration class,
-		// preserve the existing bean definition.
+		// If the bean method is an overloaded case on the same configuration class,
+		// preserve the existing bean definition and mark it as overloaded.
 		if (existingBeanDef instanceof ConfigurationClassBeanDefinition ccbd) {
-			if (ccbd.getMetadata().getClassName().equals(
-					beanMethod.getConfigurationClass().getMetadata().getClassName())) {
-				if (ccbd.getFactoryMethodMetadata().getMethodName().equals(ccbd.getFactoryMethodName())) {
-					ccbd.setNonUniqueFactoryMethodName(ccbd.getFactoryMethodMetadata().getMethodName());
-				}
+			if (ccbd.getMetadata().getClassName().equals(beanMethod.getConfigurationClass().getMetadata().getClassName()) &&
+					ccbd.getFactoryMethodMetadata().getMethodName().equals(beanMethod.getMetadata().getMethodName())) {
+				ccbd.setNonUniqueFactoryMethodName(ccbd.getFactoryMethodMetadata().getMethodName());
 				return true;
 			}
 			else {

spring-context/src/test/java/org/springframework/context/annotation/configuration/ConfigurationClassProcessingTests.java

@@ -41,6 +41,7 @@
 import org.springframework.beans.factory.config.DependencyDescriptor;
 import org.springframework.beans.factory.config.ListFactoryBean;
 import org.springframework.beans.factory.parsing.BeanDefinitionParsingException;
+import org.springframework.beans.factory.support.BeanDefinitionOverrideException;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.testfixture.beans.ITestBean;
@@ -219,6 +220,12 @@ void configurationWithNullReference() {
 		assertThat(foo.getSpouse()).isNull();
 	}
 
+	@Test  // gh-33330
+	void configurationWithMethodNameMismatch() {
+		assertThatExceptionOfType(BeanDefinitionOverrideException.class)
+				.isThrownBy(() -> initBeanFactory(ConfigWithMethodNameMismatch.class));
+	}
+
 	@Test
 	void configurationWithAdaptivePrototypes() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
@@ -352,6 +359,7 @@ private DefaultListableBeanFactory initBeanFactory(Class<?>... configClasses) {
 			String configBeanName = configClass.getName();
 			factory.registerBeanDefinition(configBeanName, new RootBeanDefinition(configClass));
 		}
+		factory.setAllowBeanDefinitionOverriding(false);
 		ConfigurationClassPostProcessor ccpp = new ConfigurationClassPostProcessor();
 		ccpp.postProcessBeanDefinitionRegistry(factory);
 		ccpp.postProcessBeanFactory(factory);
@@ -526,6 +534,19 @@ public TestBean bar() {
 	}
 
 
+	@Configuration
+	static class ConfigWithMethodNameMismatch {
+
+		@Bean(name = "foo") public TestBean foo() {
+			return new SpousyTestBean("foo");
+		}
+
+		@Bean(name = "foo") public TestBean fooX() {
+			return new SpousyTestBean("fooX");
+		}
+	}
+
+
 	@Scope("prototype")
 	static class AdaptiveInjectionPoints {