HHH-8847 - Exception thrown when trying to select a treated property

(cherry picked from commit 4132a42)

Author: sebersole

hibernate-entitymanager/src/main/java/org/hibernate/jpa/criteria/path/RootImpl.java

@@ -116,12 +116,14 @@ public String getAlias() {
 
 		@Override
 		public void prepareAlias(RenderingContext renderingContext) {
-			// do nothing...
+			// NOTE : we call `original#prepareAlias` here and during render
+			//		since in some cases only one or the other will be called
+			original.prepareAlias( renderingContext );
 		}
 
 		@Override
 		public String render(RenderingContext renderingContext) {
-			original.prepareAlias(renderingContext);
+			original.prepareAlias( renderingContext );
 			return getTreatFragment();
 		}
 

hibernate-entitymanager/src/test/java/org/hibernate/jpa/test/criteria/TreatKeywordTest.java

@@ -17,8 +17,8 @@
 import org.hibernate.jpa.test.metamodel.Thing;
 import org.hibernate.jpa.test.metamodel.ThingWithQuantity;
 import org.hibernate.jpa.test.metamodel.ThingWithQuantity_;
-import org.hibernate.testing.TestForIssue;
 
+import org.hibernate.testing.TestForIssue;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -200,6 +200,17 @@ public void treatRootReturnSuperclass() {
 		em.close();
 	}
 
+	@Test
+	public void testSelectSubclassPropertyFromDowncast() {
+		EntityManager em = getOrCreateEntityManager();
+		CriteriaBuilder builder = em.getCriteriaBuilder();
+		CriteriaQuery<Integer> criteria = builder.createQuery( Integer.class );
+		Root<Thing> root = criteria.from( Thing.class );
+		Root<ThingWithQuantity> subroot = builder.treat( root, ThingWithQuantity.class );
+		criteria.select( subroot.<Integer>get( "quantity" ) );
+		em.createQuery( criteria ).getResultList();
+		em.close();
+	}
 
 
 }