HHH-19116 Error when using fk() function on left joined many-to-one association and is null predicate

hibernate-core/src/main/java/org/hibernate/query/derived/AnonymousTupleType.java

@@ -11,6 +11,7 @@
 import java.util.List;
 import java.util.Map;
 
+import jakarta.persistence.metamodel.Bindable;
 import org.hibernate.Incubating;
 import org.hibernate.internal.util.collections.CollectionHelper;
 import org.hibernate.metamodel.UnsupportedMappingException;
@@ -31,6 +32,7 @@
 import org.hibernate.query.sqm.tree.select.SqmSubQuery;
 import org.hibernate.sql.ast.spi.FromClauseAccess;
 import org.hibernate.sql.ast.spi.SqlSelection;
+import org.hibernate.type.BasicType;
 import org.hibernate.type.descriptor.java.JavaType;
 import org.hibernate.type.descriptor.java.ObjectArrayJavaType;
 
@@ -177,20 +179,21 @@ public SqmPathSource<?> findSubPathSource(String name) {
 		final SqmSelectableNode<?> component = components[index];
 		if ( component instanceof SqmPath<?> ) {
 			final SqmPath<?> sqmPath = (SqmPath<?>) component;
-			if ( sqmPath.getNodeType() instanceof SingularPersistentAttribute<?, ?> ) {
+			final Bindable<?> model = sqmPath.getModel();
+			if ( model instanceof SingularPersistentAttribute<?, ?> ) {
 				//noinspection unchecked,rawtypes
 				return new AnonymousTupleSqmAssociationPathSource(
 						name,
 						sqmPath,
-						( (SingularPersistentAttribute<?, ?>) sqmPath.getNodeType() ).getType()
+						( (SingularPersistentAttribute<?, ?>) model ).getType()
 				);
 			}
-			else if ( sqmPath.getNodeType() instanceof PluralPersistentAttribute<?, ?, ?> ) {
+			else if ( model instanceof PluralPersistentAttribute<?, ?, ?> ) {
 				//noinspection unchecked,rawtypes
 				return new AnonymousTupleSqmAssociationPathSource(
 						name,
 						sqmPath,
-						( (PluralPersistentAttribute<?, ?, ?>) sqmPath.getNodeType() ).getElementType()
+						( (PluralPersistentAttribute<?, ?, ?>) model ).getElementType()
 				);
 			}
 			else if ( sqmPath.getNodeType() instanceof EntityDomainType<?> ) {

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

@@ -197,7 +197,7 @@ private AttributeJoinDelegate resolveAlias(String identifier, boolean isTerminal
 		if ( allowReuse ) {
 			if ( !isTerminal ) {
 				for ( SqmJoin<?, ?> sqmJoin : lhs.getSqmJoins() ) {
-					if ( sqmJoin.getAlias() == null && sqmJoin.getReferencedPathSource() == subPathSource ) {
+					if ( sqmJoin.getAlias() == null && sqmJoin.getModel() == subPathSource ) {
 						return sqmJoin;
 					}
 				}

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

@@ -427,7 +427,7 @@ public static <T, A> SqmAttributeJoin<T, A> findCompatibleFetchJoin(
 			SqmPathSource<A> pathSource,
 			SqmJoinType requestedJoinType) {
 		for ( final SqmJoin<T, ?> join : sqmFrom.getSqmJoins() ) {
-			if ( join.getReferencedPathSource() == pathSource ) {
+			if ( join.getModel() == pathSource ) {
 				final SqmAttributeJoin<T, ?> attributeJoin = (SqmAttributeJoin<T, ?>) join;
 				if ( attributeJoin.isFetched() ) {
 					final SqmJoinType joinType = join.getSqmJoinType();

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/domain/AbstractSqmAttributeJoin.java

@@ -122,7 +122,7 @@ public <X> X accept(SemanticQueryWalker<X> walker) {
 	@Override
 	public PersistentAttribute<? super O, ?> getAttribute() {
 		//noinspection unchecked
-		return (PersistentAttribute<? super O, ?>) getReferencedPathSource();
+		return (PersistentAttribute<? super O, ?>) getModel();
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/domain/SqmSingularJoin.java

@@ -14,6 +14,7 @@
 import org.hibernate.metamodel.model.domain.SingularPersistentAttribute;
 import org.hibernate.metamodel.model.domain.TreatableDomainType;
 import org.hibernate.query.sqm.SemanticQueryWalker;
+import org.hibernate.query.sqm.SqmPathSource;
 import org.hibernate.spi.NavigablePath;
 import org.hibernate.query.hql.spi.SqmCreationProcessingState;
 import org.hibernate.query.sqm.NodeBuilder;
@@ -86,6 +87,16 @@ public SqmSingularJoin<O, T> copy(SqmCopyContext context) {
 		return path;
 	}
 
+	@Override
+	public SqmPathSource<T> getNodeType() {
+		return getReferencedPathSource();
+	}
+
+	@Override
+	public SqmPathSource<T> getReferencedPathSource() {
+		return getModel().getPathSource();
+	}
+
 	@Override
 	public SingularPersistentAttribute<O, T> getModel() {
 		return (SingularPersistentAttribute<O, T>) super.getNodeType();

hibernate-core/src/test/java/org/hibernate/orm/test/query/LeftJoinNullnessPredicateQueryTest.java

@@ -9,6 +9,7 @@
 import java.util.List;
 
 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;
@@ -29,7 +30,11 @@
 @DomainModel( annotatedClasses = {
 		LeftJoinNullnessPredicateQueryTest.Author.class,
 		LeftJoinNullnessPredicateQueryTest.Book.class
-} )
+})
+@Jira( "https://hibernate.atlassian.net/browse/HHH-16505" )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17379" )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17397" )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-19116" )
 public class LeftJoinNullnessPredicateQueryTest {
 	@BeforeAll
 	public void setUp(SessionFactoryScope scope) {
@@ -80,6 +85,19 @@ public void testIsNotNull(SessionFactoryScope scope) {
 		} );
 	}
 
+	@Test
+	public void testIsNullImplicit(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final List<Book> resultList = session.createQuery(
+					"select book from Book book " +
+					"where book.author is null",
+					Book.class
+			).getResultList();
+			assertThat( resultList ).hasSize( 1 );
+			assertThat( resultList.get( 0 ).getTitle() ).isEqualTo( "Unknown Author" );
+		} );
+	}
+
 	@Test
 	public void testDereferenceIsNull(SessionFactoryScope scope) {
 		scope.inTransaction( session -> {
@@ -108,6 +126,19 @@ public void testDereferenceIsNotNull(SessionFactoryScope scope) {
 		} );
 	}
 
+	@Test
+	public void testFkImplicitIsNull(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final List<Book> resultList = session.createQuery(
+					"select book from Book book " +
+					"where fk(book.author) is null",
+					Book.class
+			).getResultList();
+			assertThat( resultList ).hasSize( 1 );
+			assertThat( resultList.get( 0 ).getTitle() ).isEqualTo( "Unknown Author" );
+		} );
+	}
+
 	@Test
 	public void testIsNotNullWithCondition(SessionFactoryScope scope) {
 		scope.inTransaction( session -> {