HHH-18536 - Support implicit "this" alias in HQL

Author: sebersole

hibernate-core/src/main/java/org/hibernate/query/hql/internal/SqmPathRegistryImpl.java

@@ -16,8 +16,8 @@
 import org.hibernate.jpa.spi.JpaCompliance;
 import org.hibernate.metamodel.model.domain.BasicDomainType;
 import org.hibernate.metamodel.model.domain.JpaMetamodel;
-import org.hibernate.query.criteria.JpaCrossJoin;
 import org.hibernate.query.SemanticException;
+import org.hibernate.query.criteria.JpaCrossJoin;
 import org.hibernate.query.hql.HqlLogging;
 import org.hibernate.query.hql.spi.SqmCreationProcessingState;
 import org.hibernate.query.hql.spi.SqmPathRegistry;
@@ -254,6 +254,15 @@ else if ( parentRegistered instanceof SqmEntityJoin<?,?> ) {
 			}
 		}
 
+		final boolean onlyOneFrom = sqmFromByPath.size() == 1;
+		if ( onlyOneFrom && localAlias.equals( "this" ) ) {
+			final SqmRoot<?> root = (SqmRoot<?>) sqmFromByPath.entrySet().iterator().next().getValue();
+			if (  root.getAlias() == null ) {
+				//noinspection unchecked
+				return (X) root;
+			}
+		}
+
 		return null;
 	}
 

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/thisalias/HQLThisTest.java

@@ -13,8 +13,6 @@
 
 @SessionFactory
 @DomainModel(annotatedClasses = HQLThisTest.This.class)
-@FailureExpected( jiraKey = "HHH-18536", reason = "Support implicit \"this\" alias in HQL" )
-@Jira( "https://hibernate.atlassian.net/browse/HHH-18536" )
 public class HQLThisTest {
 	@Test
 	void test(SessionFactoryScope scope) {