HHH-7216 'java.lang.IllegalStateException: No supertype found' thrown on query with COUNT aggregate function

hibernate-entitymanager/src/main/java/org/hibernate/jpa/criteria/expression/function/AggregationFunction.java

@@ -115,7 +115,7 @@ public class AggregationFunction<T>
         	        Expression argExpr = argExprs.get(0);
         	        if (argExpr instanceof Root<?>) {
         	            Root<?> root = (Root<?>)argExpr;
-        	            if (root.getModel().getIdType() != null) {
+        	            if (!root.getModel().hasSingleIdAttribute()) {
         	                buffer.append('*');
         	                return;
         	            }

hibernate-entitymanager/src/test/java/org/hibernate/jpa/test/criteria/idclass/IdClassPredicateTest.java

@@ -28,6 +28,7 @@ import java.util.List;
 import javax.persistence.EntityManager;
 import javax.persistence.criteria.CriteriaBuilder;
 import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Expression;
 import javax.persistence.criteria.Predicate;
 import javax.persistence.criteria.Root;
 
@@ -143,6 +144,37 @@ public class IdClassPredicateTest extends AbstractMetamodelSpecificTest {
 		em.close();
 	}
 
+	@Test
+	public void testCountIdClassAttributes(){
+		EntityManager em = getOrCreateEntityManager();
+		em.getTransaction().begin();
+		CriteriaBuilder cb = em.getCriteriaBuilder();
+		CriteriaQuery<Long> cq = cb.createQuery(Long.class);
+		Root<Widget> path = cq.from(Widget.class);
+		Expression<Long> countSelection = cb.count(path);
+		cq.select(countSelection);
+		Long count = em.createQuery(cq).getSingleResult();
+//		// Packaging arguments for use in query.
+//		List<String> divisions = new ArrayList<String>( );
+//		divisions.add( "NA" );
+//		divisions.add( "EU" );
+//
+//		// Building the query.
+//		CriteriaBuilder criteria = em.getCriteriaBuilder( );
+//		CriteriaQuery<Widget> query = criteria.createQuery( Widget.class );
+//		Root<Widget> root = query.from( Widget.class );
+//
+//		Predicate predicate = root.get( "division" ).in( divisions );
+//		query.where( predicate );
+//
+//		// Retrieving query.;
+//		List<Widget> widgets = em.createQuery( query ).getResultList( );
+//		Assert.assertEquals( 4, widgets.size() );
+
+		em.getTransaction().commit();
+		em.close();
+	}
+
 
 	@Test
 	public void testDeclaredIdClassAttributes( ) {