HHH-17113 Fix joined inheritance and force discriminator pruning

Author: mbellade

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -3137,20 +3137,21 @@ public void applyDiscriminator(
 			assert !creationState.supportsEntityNameUsage() : "Entity name usage should have been used instead";
 			final Map<String, EntityNameUse> entityNameUseMap;
 			final Collection<EntityMappingType> subMappingTypes = getSubMappingTypes();
+			entityNameUseMap = new HashMap<>( 1 + subMappingTypes.size() + ( isInherited() ? 1 : 0 ) );
 			if ( subMappingTypes.isEmpty() ) {
-				entityNameUseMap = Collections.singletonMap( getEntityName(), EntityNameUse.TREAT );
+				entityNameUseMap.put( getEntityName(), EntityNameUse.TREAT );
 			}
 			else {
-				entityNameUseMap = new HashMap<>( 1 + subMappingTypes.size() );
 				entityNameUseMap.put( getEntityName(), EntityNameUse.TREAT );
 				// We need to register TREAT uses for all subtypes when pruning
 				for ( EntityMappingType subMappingType : subMappingTypes ) {
 					entityNameUseMap.put( subMappingType.getEntityName(), EntityNameUse.TREAT );
 				}
-				if ( isInherited() ) {
-					// Make sure the table group includes the root table when needed for TREAT
-					tableGroup.resolveTableReference( getRootTableName() );
-				}
+			}
+			if ( isInherited() ) {
+				// Make sure the table group includes the root table when needed for TREAT
+				tableGroup.resolveTableReference( getRootTableName() );
+				entityNameUseMap.put( getRootEntityName(), EntityNameUse.EXPRESSION );
 			}
 			pruneForSubclasses( tableGroup, entityNameUseMap );
 		}

hibernate-core/src/main/java/org/hibernate/persister/entity/JoinedSubclassEntityPersister.java

@@ -1379,8 +1379,8 @@ public void pruneForSubclasses(TableGroup tableGroup, Map<String, EntityNameUse>
 				// We allow multiple joined subclasses to use the same table if they define a discriminator column.
 				// In this case, we might need to add a discriminator condition to make sure we filter the correct subtype,
 				// see SingleTableEntityPersister#pruneForSubclasses for more details on this condition
-				needsTreatDiscriminator = needsTreatDiscriminator || !persister.isAbstract() &&
-						!isTypeOrSuperType( persister ) && useKind == EntityNameUse.UseKind.TREAT;
+				needsTreatDiscriminator = needsTreatDiscriminator || !persister.isAbstract()
+						&& useKind == EntityNameUse.UseKind.TREAT && ( isInherited() || !isTypeOrSuperType( persister ) );
 			}
 		}
 		// If no tables to inner join have been found, we add at least the super class tables of this persister
@@ -1411,11 +1411,13 @@ public void pruneForSubclasses(TableGroup tableGroup, Map<String, EntityNameUse>
 						entityNameUses,
 						metamodel
 				);
-				for ( int i = 0; !applied && i < tableReferenceJoins.size(); i++ ) {
+				int i = 0;
+				for ( ; !applied && i < tableReferenceJoins.size(); i++ ) {
 					final TableReferenceJoin join = tableReferenceJoins.get( i );
 					applied = applyDiscriminatorPredicate( join, join.getJoinedTableReference(), entityNameUses, metamodel );
 				}
 				assert applied : "Could not apply treat discriminator predicate to root table join";
+				assert i == 0 || retainedTableReferences.contains( tableReferenceJoins.get( i - 1 ).getJoinedTableReference() );
 			}
 		}
 		if ( tableReferenceJoins.isEmpty() ) {