Message Title

It appears that the problem is that the root does not have an alias (yet) when the JQL is generated. So then PathTypeExpression.render() invokes Root.getPathIdentifier() which returns getAlias(), which is null at that time.

select case when type(null) in (:param0)
    then treat(generatedAlias0 as org.hibernate.bugs.Dog).numSpots
    else 0 end
from Animal as generatedAlias0

Note the type(null), which causes the problem. This, even though later we have Animal as generatedAlias0.

iff --git a/orm/hibernate-orm-5/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java b/orm/hibernate-orm-5/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java
index b30891f..06c285c 100644
--- a/orm/hibernate-orm-5/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java
+++ b/orm/hibernate-orm-5/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java
@@ -47,6 +47,7 @@ public class JPAUnitTestCase {
 
                final CriteriaQuery<Integer> query = cb.createQuery(Integer.class);
                final Root<Animal> animal = query.from(Animal.class);
+               animal.alias("a");
 
                final Expression<Boolean> isDog = JPAUtil.instanceOf(entityManager, animal, Dog.class);
                final Expression<Integer> numSpots = cb.<Integer>selectCase()