Resolve factoryBeanClass if necessary

Update `AbstractAutowireCapableBeanFactory.getTypeForFactoryBean` to
use fallback to `determineTargetType` if the factory bean definition
does not have a resolved class.

This is required for the case where a `@Configuration` class is picked
up via component scanning and has a bean type that has not yet been
resolved.

Closes gh-23338

Author: philwebb

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

@@ -858,9 +858,16 @@ protected ResolvableType getTypeForFactoryBean(String beanName,
 				// Try to obtain the FactoryBean's object type from its factory method
 				// declaration without instantiating the containing bean at all.
 				BeanDefinition factoryBeanDefinition = getBeanDefinition(factoryBeanName);
-				if (factoryBeanDefinition instanceof AbstractBeanDefinition &&
-						((AbstractBeanDefinition) factoryBeanDefinition).hasBeanClass()) {
-					Class<?> factoryBeanClass = ((AbstractBeanDefinition) factoryBeanDefinition).getBeanClass();
+				Class<?> factoryBeanClass = null;
+				if (factoryBeanDefinition instanceof AbstractBeanDefinition
+						&& ((AbstractBeanDefinition) factoryBeanDefinition).hasBeanClass()) {
+					factoryBeanClass = ((AbstractBeanDefinition) factoryBeanDefinition).getBeanClass();
+				}
+				else {
+					RootBeanDefinition fbmbd = getMergedBeanDefinition(factoryBeanName, factoryBeanDefinition);
+					factoryBeanClass = determineTargetType(factoryBeanName, fbmbd, new Class<?>[] { Object.class });
+				}
+				if (factoryBeanClass != null) {
 					result = getTypeForFactoryBeanFromMethod(factoryBeanClass, factoryMethodName);
 					if (result.resolve() != null) {
 						return result;

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

@@ -28,6 +28,8 @@
 import org.springframework.beans.factory.support.AbstractBeanFactory;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.beans.factory.support.GenericBeanDefinition;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.type.AnnotationMetadata;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -80,6 +82,32 @@ public void postFreezeAttribute() {
 		assertPostFreeze(AttributeClassConfiguration.class);
 	}
 
+	@Test
+	public void preFreezeUnresolvedGenericFactoryBean() {
+		// Covers the case where a @Configuration is picked up via component scanning
+		// and its bean definition only has a String bean class. In such cases
+		// beanDefinition.hasBeanClass() returns false so we need to actually
+		// call determineTargetType ourselves
+		GenericBeanDefinition factoryBeanDefinition = new GenericBeanDefinition();
+		factoryBeanDefinition.setBeanClassName(GenericClassConfiguration.class.getName());
+		GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
+		beanDefinition.setBeanClass(FactoryBean.class);
+		beanDefinition.setFactoryBeanName("factoryBean");
+		beanDefinition.setFactoryMethodName("myBean");
+		GenericApplicationContext context = new GenericApplicationContext();
+		try {
+			context.registerBeanDefinition("factoryBean", factoryBeanDefinition);
+			context.registerBeanDefinition("myBean", beanDefinition);
+			NameCollectingBeanFactoryPostProcessor postProcessor = new NameCollectingBeanFactoryPostProcessor();
+			context.addBeanFactoryPostProcessor(postProcessor);
+			context.refresh();
+			assertContainsMyBeanName(postProcessor.getNames());
+		}
+		finally {
+			context.close();
+		}
+	}
+
 	private void assertPostFreeze(Class<?> configurationClass) {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
 				configurationClass);
@@ -90,11 +118,16 @@ private void assertPreFreeze(Class<?> configurationClass,
 			BeanFactoryPostProcessor... postProcessors) {
 		NameCollectingBeanFactoryPostProcessor postProcessor = new NameCollectingBeanFactoryPostProcessor();
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
-		Arrays.stream(postProcessors).forEach(context::addBeanFactoryPostProcessor);
-		context.addBeanFactoryPostProcessor(postProcessor);
-		context.register(configurationClass);
-		context.refresh();
-		assertContainsMyBeanName(postProcessor.getNames());
+		try {
+			Arrays.stream(postProcessors).forEach(context::addBeanFactoryPostProcessor);
+			context.addBeanFactoryPostProcessor(postProcessor);
+			context.register(configurationClass);
+			context.refresh();
+			assertContainsMyBeanName(postProcessor.getNames());
+		}
+		finally {
+			context.close();
+		}
 	}
 
 	private void assertContainsMyBeanName(AnnotationConfigApplicationContext context) {