HHH-12114 - Union-select aliases not injected before "clazz_" conditions in HQL query

hibernate-core/src/main/java/org/hibernate/hql/internal/ast/tree/MethodNode.java

@@ -15,7 +15,6 @@ import org.hibernate.hql.internal.ast.TypeDiscriminatorMetadata;
 import org.hibernate.hql.internal.ast.util.ASTUtil;
 import org.hibernate.hql.internal.ast.util.ColumnHelper;
 import org.hibernate.internal.CoreLogging;
-import org.hibernate.persister.collection.CollectionPropertyMapping;
 import org.hibernate.persister.collection.CollectionPropertyNames;
 import org.hibernate.persister.collection.QueryableCollection;
 import org.hibernate.type.Type;

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -330,7 +330,7 @@ public abstract class AbstractEntityPersister
 	}
 
 	public String getDiscriminatorColumnReaderTemplate() {
-		return DISCRIMINATOR_ALIAS;
+		return Template.TEMPLATE + "." + DISCRIMINATOR_ALIAS;
 	}
 
 	protected String getDiscriminatorAlias() {

hibernate-core/src/test/java/org/hibernate/test/unionsubclass3/UnionSubclassTest.java

@@ -0,0 +1,133 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.test.unionsubclass3;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+import org.hibernate.query.Query;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.Test;
+
+import java.util.List;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Inheritance;
+import javax.persistence.InheritanceType;
+import javax.persistence.ManyToOne;
+
+import org.hibernate.test.locking.A;
+
+import static org.hibernate.testing.transaction.TransactionUtil.doInHibernate;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author pholvs
+ */
+public class UnionSubclassTest extends BaseCoreFunctionalTestCase {
+	protected Class<?>[] getAnnotatedClasses() {
+		return new Class[] {Child.class, Parent.class, Father.class, Mother.class};
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-12114" )
+	public void testUnionSubclassClassResults() {
+		doInHibernate( this::sessionFactory, session -> {
+			Father father = new Father();
+			father.id = 1L;
+			father.fathersDay = "FD1";
+
+			Child child1 = new Child();
+			child1.id = 2L;
+			child1.parent = father;
+
+			Mother mother1 = new Mother();
+			mother1.id = 3L;
+			mother1.mothersDay = "MD1";
+
+			Child child2 = new Child();
+			child2.id = 4L;
+			child2.parent = mother1;
+
+			Mother mother2 = new Mother();
+			mother2.id = 5L;
+			mother2.mothersDay = "MD2";
+
+			Child child3 = new Child();
+			child3.id = 6L;
+			child3.parent = mother2;
+
+			Mother mother4 = new Mother();
+			mother4.id = 7L;
+			mother4.mothersDay = "MD3";
+
+			Child child4 = new Child();
+			child4.id = 8L;
+			child4.parent = mother4;
+
+			session.persist(father);
+			session.persist(mother1);
+			session.persist(mother2);
+			session.persist(mother4);
+
+			session.persist(child1);
+			session.persist(child2);
+			session.persist(child3);
+			session.persist(child4);
+		} );
+
+		doInHibernate( this::sessionFactory, session -> {
+			List results = session.createQuery(
+				"select c " +
+				"from Child c"
+				+ " left join c.parent p1 "
+				+ " left join c.parent p2 "
+				+ " where " +
+				"		(TYPE(p1) = Father and p1.fathersDay = 'FD1') " +
+				"	or "
+				+ "  	(TYPE(p2) = Mother and p2.mothersDay = 'MD1')")
+			.getResultList();
+			assertEquals(2, results.size());
+		} );
+	}
+
+	@Entity(name = "Child")
+	public static class Child
+	{
+		@Id
+		Long id;
+
+		@ManyToOne
+		Parent parent;
+
+	}
+
+	@Entity(name = "Father")
+	public static class Father extends Parent {
+		
+		@Column
+		String fathersDay;
+	}
+
+	@Entity(name = "Mother")
+	public static class Mother extends Parent {
+		
+		@Column
+		String mothersDay;
+	}
+
+	@Entity(name = "Parent")
+	@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
+	public abstract static class Parent {
+		@Id
+		public Long id;
+	}
+}
+