Inject @Configuration BeanFactory before autowire

Add EnhancedConfigurationBeanPostProcessor to inject the BeanFactory
into EnhancedConfiguration classes before the
AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues method
is called.

Prior to this commit it was possible for @Autowire in a @Configuration
class to invoke an enhanced configuration class method before the
BeanFactory was injected. This is due to the fact that the
AutowiredAnnotationBeanPostProcessor was called before
AbstractAutowireCapableBeanFactory.invokeAwareMethods().

Issue: SPR-10668

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

@@ -411,7 +411,8 @@ class ConfigurationClassEnhancer {
 			Field field = ReflectionUtils.findField(enhancedConfigInstance.getClass(), BEAN_FACTORY_FIELD);
 			Assert.state(field != null, "Unable to find generated bean factory field");
 			Object beanFactory = ReflectionUtils.getField(field, enhancedConfigInstance);
-			Assert.isInstanceOf(ConfigurableBeanFactory.class, beanFactory);
+			Assert.state(beanFactory != null, "The BeanFactory has not been injected into the @Configuration class");
+			Assert.state(beanFactory instanceof ConfigurableBeanFactory, "The injected BeanFactory is not a ConfigurableBeanFactory");
 			return (ConfigurableBeanFactory) beanFactory;
 		}
 	}

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

@@ -16,6 +16,7 @@
 
 package org.springframework.context.annotation;
 
+import java.beans.PropertyDescriptor;
 import java.io.IOException;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
@@ -27,15 +28,18 @@ import java.util.Stack;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeansException;
+import org.springframework.beans.PropertyValues;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
+import org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
 import org.springframework.beans.factory.config.SingletonBeanRegistry;
 import org.springframework.beans.factory.parsing.FailFastProblemReporter;
 import org.springframework.beans.factory.parsing.PassThroughSourceExtractor;
@@ -50,6 +54,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.EnvironmentAware;
 import org.springframework.context.ResourceLoaderAware;
+import org.springframework.context.annotation.ConfigurationClassEnhancer.EnhancedConfiguration;
 import org.springframework.context.annotation.ConfigurationClassParser.ImportRegistry;
 import org.springframework.core.Ordered;
 import org.springframework.core.PriorityOrdered;
@@ -96,6 +101,9 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 	private static final String IMPORT_REGISTRY_BEAN_NAME =
 			ConfigurationClassPostProcessor.class.getName() + ".importRegistry";
 
+	private static final String ENHANCED_CONFIGURATION_PROCESSOR_BEAN_NAME =
+			ConfigurationClassPostProcessor.class.getName() + ".enhancedConfigurationProcessor";
+
 
 	private final Log logger = LogFactory.getLog(getClass());
 
@@ -225,6 +233,10 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 		iabpp.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 		registry.registerBeanDefinition(IMPORT_AWARE_PROCESSOR_BEAN_NAME, iabpp);
 
+		RootBeanDefinition ecbpp = new RootBeanDefinition(EnhancedConfigurationBeanPostProcessor.class);
+		ecbpp.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
+		registry.registerBeanDefinition(ENHANCED_CONFIGURATION_PROCESSOR_BEAN_NAME, ecbpp);
+
 		int registryId = System.identityHashCode(registry);
 		if (this.registriesPostProcessed.contains(registryId)) {
 			throw new IllegalStateException(
@@ -424,4 +436,40 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 		}
 	}
 
+
+	/**
+	 * {@link InstantiationAwareBeanPostProcessorAdapter} that ensures
+	 * {@link EnhancedConfiguration} beans are injected with the {@link BeanFactory}
+	 * before the {@link AutowiredAnnotationBeanPostProcessor} runs (SPR-10668).
+	 */
+	private static class EnhancedConfigurationBeanPostProcessor extends
+			InstantiationAwareBeanPostProcessorAdapter implements PriorityOrdered,
+			BeanFactoryAware {
+
+		private BeanFactory beanFactory;
+
+		@Override
+		public int getOrder() {
+			return Ordered.HIGHEST_PRECEDENCE;
+		}
+
+		@Override
+		public PropertyValues postProcessPropertyValues(PropertyValues pvs,
+				PropertyDescriptor[] pds, Object bean, String beanName)
+				throws BeansException {
+			// Inject the BeanFactory before AutowiredAnnotationBeanPostProcessor's
+			// postProcessPropertyValues method attempts to auto-wire other configuration
+			// beans.
+			if (bean instanceof EnhancedConfiguration) {
+				((EnhancedConfiguration) bean).setBeanFactory(this.beanFactory);
+			}
+			return pvs;
+		}
+
+		@Override
+		public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
+			this.beanFactory = beanFactory;
+		}
+
+	}
 }