Consistent throwing of BeanNotOfRequiredTypeException even for existing proxy

Issue: SPR-14504

Author: jhoeller

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

@@ -52,6 +52,7 @@
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.BeanFactoryUtils;
+import org.springframework.beans.factory.BeanNotOfRequiredTypeException;
 import org.springframework.beans.factory.CannotLoadBeanClassException;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InjectionPoint;
@@ -1043,7 +1044,7 @@ public Object doResolveDependency(DependencyDescriptor descriptor, String beanNa
 			Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);
 			if (matchingBeans.isEmpty()) {
 				if (descriptor.isRequired()) {
-					raiseNoSuchBeanDefinitionException(type, descriptor.getResolvableType().toString(), descriptor);
+					raiseNoMatchingBeanFound(type, descriptor.getResolvableType().toString(), descriptor);
 				}
 				return null;
 			}
@@ -1382,17 +1383,46 @@ private boolean isSelfReference(String beanName, String candidateName) {
 	}
 
 	/**
-	 * Raise a NoSuchBeanDefinitionException for an unresolvable dependency.
+	 * Raise a NoSuchBeanDefinitionException or BeanNotOfRequiredTypeException
+	 * for an unresolvable dependency.
 	 */
-	private void raiseNoSuchBeanDefinitionException(
-			Class<?> type, String dependencyDescription, DependencyDescriptor descriptor)
-			throws NoSuchBeanDefinitionException {
+	private void raiseNoMatchingBeanFound(
+			Class<?> type, String dependencyDescription, DependencyDescriptor descriptor) throws BeansException {
+
+		checkBeanNotOfRequiredType(type, descriptor);
 
 		throw new NoSuchBeanDefinitionException(type, dependencyDescription,
 				"expected at least 1 bean which qualifies as autowire candidate for this dependency. " +
 				"Dependency annotations: " + ObjectUtils.nullSafeToString(descriptor.getAnnotations()));
 	}
 
+	/**
+	 * Raise a BeanNotOfRequiredTypeException for an unresolvable dependency, if applicable,
+	 * i.e. if the target type of the bean would match but an exposed proxy doesn't.
+	 */
+	private void checkBeanNotOfRequiredType(Class<?> type, DependencyDescriptor descriptor) {
+		for (String beanName : this.beanDefinitionNames) {
+			RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
+			Class<?> targetType = mbd.getTargetType();
+			if (targetType != null && type.isAssignableFrom(targetType) &&
+					isAutowireCandidate(beanName, mbd, descriptor, getAutowireCandidateResolver())) {
+				// Probably a poxy interfering with target type match -> throw meaningful exception.
+				Object beanInstance = getSingleton(beanName, false);
+				Class<?> beanType = (beanInstance != null ? beanInstance.getClass() : predictBeanType(beanName, mbd));
+				if (type != beanType) {
+					throw new BeanNotOfRequiredTypeException(beanName, type, beanType);
+				}
+			}
+		}
+
+		if (getParentBeanFactory() instanceof DefaultListableBeanFactory) {
+			((DefaultListableBeanFactory) getParentBeanFactory()).checkBeanNotOfRequiredType(type, descriptor);
+		}
+	}
+
+	/**
+	 * Create an {@link Optional} wrapper for the specified dependency.
+	 */
 	private Optional<?> createOptionalDependency(DependencyDescriptor descriptor, String beanName, final Object... args) {
 		DependencyDescriptor descriptorToUse = new DependencyDescriptor(descriptor) {
 			@Override

spring-context/src/test/java/org/springframework/scheduling/annotation/EnableAsyncTests.java

@@ -33,6 +33,8 @@
 import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
+import org.springframework.beans.factory.BeanNotOfRequiredTypeException;
+import org.springframework.beans.factory.UnsatisfiedDependencyException;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.annotation.AdviceMode;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -41,6 +43,7 @@
 import org.springframework.context.annotation.Lazy;
 import org.springframework.core.Ordered;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+import org.springframework.stereotype.Component;
 import org.springframework.util.ReflectionUtils;
 
 import static org.hamcrest.CoreMatchers.anyOf;
@@ -81,6 +84,36 @@ public void proxyingOccursWithMockitoStub() {
 		asyncBean.work();
 	}
 
+	@Test
+	public void properExceptionForExistingProxyDependencyMismatch() {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(AsyncConfig.class, AsyncBeanWithInterface.class, AsyncBeanUser.class);
+
+		try {
+			ctx.refresh();
+			fail("Should have thrown UnsatisfiedDependencyException");
+		}
+		catch (UnsatisfiedDependencyException ex) {
+			ex.printStackTrace();
+			assertTrue(ex.getCause() instanceof BeanNotOfRequiredTypeException);
+		}
+	}
+
+	@Test
+	public void properExceptionForResolvedProxyDependencyMismatch() {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(AsyncConfig.class, AsyncBeanUser.class, AsyncBeanWithInterface.class);
+
+		try {
+			ctx.refresh();
+			fail("Should have thrown UnsatisfiedDependencyException");
+		}
+		catch (UnsatisfiedDependencyException ex) {
+			ex.printStackTrace();
+			assertTrue(ex.getCause() instanceof BeanNotOfRequiredTypeException);
+		}
+	}
+
 	@Test
 	public void withAsyncBeanWithExecutorQualifiedByName() throws ExecutionException, InterruptedException {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
@@ -214,6 +247,15 @@ public Thread getThreadOfExecution() {
 	}
 
 
+	@Component("asyncBean")
+	static class AsyncBeanWithInterface extends AsyncBean implements Runnable {
+
+		@Override
+		public void run() {
+		}
+	}
+
+
 	static class AsyncBeanUser {
 
 		private final AsyncBean asyncBean;