HHH-18450 Inconsistent "SELECT 1" versus "SELECT ?1" with result type Object[]

hibernate-core/src/main/java/org/hibernate/query/sqm/internal/SqmSelectionQueryImpl.java

@@ -63,6 +63,7 @@
 import org.hibernate.sql.results.internal.TupleMetadata;
 import org.hibernate.sql.results.spi.ResultsConsumer;
 import org.hibernate.sql.results.spi.SingleResultConsumer;
+import org.hibernate.type.descriptor.java.JavaType;
 
 import static org.hibernate.jpa.HibernateHints.HINT_CACHEABLE;
 import static org.hibernate.jpa.HibernateHints.HINT_CACHE_MODE;
@@ -276,15 +277,15 @@ private static Class<?> determineResultType(SqmSelectStatement<?> sqm, Class<?>
 				return Object[].class;
 			}
 			else {
-				final SqmSelection<?> selection = selections.get(0);
+				final SqmSelection<?> selection = selections.get( 0 );
 				if ( isSelectionAssignableToResultType( selection, expectedResultType ) ) {
-					return selection.getNodeJavaType().getJavaTypeClass();
-				}
-				else {
-					// let's assume there's some
-					// way to instantiate it
-					return expectedResultType;
+					final JavaType<?> nodeJavaType = selection.getNodeJavaType();
+					if ( nodeJavaType != null ) {
+						return nodeJavaType.getJavaTypeClass();
+					}
 				}
+				// let's assume there's some way to instantiate it
+				return expectedResultType;
 			}
 		}
 		else if ( expectedResultType != null ) {

hibernate-core/src/main/java/org/hibernate/query/sqm/internal/SqmUtil.java

@@ -43,6 +43,7 @@
 import org.hibernate.metamodel.model.domain.SingularPersistentAttribute;
 import org.hibernate.metamodel.model.domain.internal.EntitySqmPathSource;
 import org.hibernate.persister.entity.EntityPersister;
+import org.hibernate.query.BindableType;
 import org.hibernate.query.IllegalQueryOperationException;
 import org.hibernate.query.IllegalSelectQueryException;
 import org.hibernate.query.Order;
@@ -827,10 +828,15 @@ static JpaOrder sortSpecification(SqmSelectStatement<?> sqm, Order<?> order) {
 	}
 
 	public static boolean isSelectionAssignableToResultType(SqmSelection<?> selection, Class<?> expectedResultType) {
-		if ( expectedResultType == null
-				|| selection != null && selection.getSelectableNode() instanceof SqmParameter ) {
+		if ( expectedResultType == null ) {
 			return true;
 		}
+		else if ( selection != null && selection.getSelectableNode() instanceof SqmParameter<?> sqmParameter ) {
+			final Class<?> anticipatedClass = sqmParameter.getAnticipatedType() != null ?
+					sqmParameter.getAnticipatedType().getBindableJavaType() :
+					null;
+			return anticipatedClass != null && expectedResultType.isAssignableFrom( anticipatedClass );
+		}
 		else if ( selection == null
 				|| !isHqlTuple( selection ) && selection.getSelectableNode().isCompoundSelection() ) {
 			return false;

hibernate-core/src/test/java/org/hibernate/orm/test/hql/SingleSelectionArrayResultTest.java

@@ -0,0 +1,94 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.hql;
+
+import org.hibernate.testing.orm.domain.gambit.BasicEntity;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel( annotatedClasses = BasicEntity.class )
+@SessionFactory
+@Jira( "https://hibernate.atlassian.net/browse/HHH-18450" )
+public class SingleSelectionArrayResultTest {
+	@Test
+	public void testArrayResult(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			assertThat( session.createQuery(
+					"select 1",
+					Object[].class
+			).getSingleResult() ).containsExactly( 1 );
+			assertThat( session.createQuery(
+					"select cast(1 as integer)",
+					Object[].class
+			).getSingleResult() ).containsExactly( 1 );
+			assertThat( session.createSelectionQuery(
+					"select id from BasicEntity",
+					Object[].class
+			).getSingleResult() ).containsExactly( 1 );
+			assertThat( session.createSelectionQuery(
+					"select cast(id as integer) from BasicEntity",
+					Object[].class
+			).getSingleResult() ).containsExactly( 1 );
+			assertThat( session.createSelectionQuery(
+					"select ?1",
+					Object[].class
+			).setParameter( 1, 1 ).getSingleResult() ).containsExactly( 1 );
+			assertThat( session.createQuery(
+					"select cast(:p1 as integer)",
+					Object[].class
+			).setParameter( "p1", 1 ).getSingleResult() ).containsExactly( 1 );
+		} );
+	}
+
+	@Test
+	public void testNormalResult(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			assertThat( session.createQuery(
+					"select 1",
+					Object.class
+			).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+			assertThat( session.createQuery(
+					"select cast(1 as integer)",
+					Object.class
+			).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+			assertThat( session.createSelectionQuery(
+					"select id from BasicEntity",
+					Object.class
+			).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+			assertThat( session.createSelectionQuery(
+					"select cast(id as integer) from BasicEntity",
+					Object.class
+			).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+			assertThat( session.createSelectionQuery(
+					"select ?1",
+					Object.class
+			).setParameter( 1, 1 ).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+			assertThat( session.createQuery(
+					"select cast(:p1 as integer)",
+					Object.class
+			).setParameter( "p1", 1 ).getSingleResult() ).isInstanceOf( Integer.class ).isEqualTo( 1 );
+		} );
+	}
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> session.persist( new BasicEntity( 1, "entity_1" ) ) );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.getSessionFactory().getSchemaManager().truncateMappedObjects();
+	}
+}