HHH-19116 Return actual path source for singular attribute joins

This fixes the check for `fk()` function argument type

Author: mbellade

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();