Explicit error message for bean name clash with containing configuration class

Issue: SPR-15775

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

@@ -198,6 +198,11 @@ class ConfigurationClassBeanDefinitionReader {
 
 		// Has this effectively been overridden before (e.g. via XML)?
 		if (isOverriddenByExistingDefinition(beanMethod, beanName)) {
+			if (beanName.equals(beanMethod.getConfigurationClass().getBeanName())) {
+				throw new BeanDefinitionStoreException(beanMethod.getConfigurationClass().getResource().getDescription(),
+						beanName, "Bean name derived from @Bean method '" + beanMethod.getMetadata().getMethodName() +
+						"' clashes with bean name for containing configuration class; please make those names unique!");
+			}
 			return;
 		}
 

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

@@ -800,6 +800,12 @@ public class ConfigurationClassPostProcessorTests {
 		assertSame(ctx.getBean(TestBean.class), bean.getTestBean());
 	}
 
+	@Test(expected = BeanDefinitionStoreException.class)
+	public void testNameClashBetweenConfigurationClassAndBean() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(MyTestBean.class);
+		ctx.getBean("myTestBean", TestBean.class);
+	}
+
 
 	// -------------------------------------------------------------------------
 

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

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2002-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.annotation;
+
+/**
+ * @author Juergen Hoeller
+ */
+@Configuration
+class MyTestBean {
+
+	@Bean
+	public org.springframework.tests.sample.beans.TestBean myTestBean() {
+		return new org.springframework.tests.sample.beans.TestBean();
+	}
+
+}