Attempt a fix

Author: fredericDelaporte

src/NHibernate.Test/Async/NHSpecificTest/GH3609/Fixture.cs

@@ -31,6 +31,7 @@ protected override void OnSetUp()
 			};
 			session.Save(order);
 			session.Save(new LineItem { Order = order, ItemName = "Bananas", Amount = 5 });
+			session.Save(new CleanLineItem { Order = order, ItemName = "Bananas", Amount = 5 });
 
 			order = new Order
 			{
@@ -39,6 +40,7 @@ protected override void OnSetUp()
 			};
 			session.Save(order);
 			session.Save(new LineItem { Order = order, ItemName = "Apples", Amount = 10 });
+			session.Save(new CleanLineItem { Order = order, ItemName = "Apples", Amount = 10 });
 
 			transaction.Commit();
 		}
@@ -48,6 +50,7 @@ protected override void OnTearDown()
 			using var session = OpenSession();
 			using var transaction = session.BeginTransaction();
 
+			session.CreateQuery("delete from CleanLineItem").ExecuteUpdate();
 			session.CreateQuery("delete from System.Object").ExecuteUpdate();
 
 			transaction.Commit();
@@ -63,10 +66,24 @@ public async Task QueryWithAnyAsync()
 			// sort of Linq that we were using in our app.  It seems to occur when we force an EXISTS( ... ) subquery.
 			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
 			var orderCount = await (session.Query<LineItem>().CountAsync(x => validOrders.Any(y => y == x.Order)));
-        
+
+			Assert.That(orderCount, Is.EqualTo(1));
+		}
+
+		[Test]
+		public async Task QueryWithAnyOnCleanLinesAsync()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+
+			// This form of query is how we first discovered the issue.  This is a simplified reproduction of the
+			// sort of Linq that we were using in our app.  It seems to occur when we force an EXISTS( ... ) subquery.
+			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
+			var orderCount = await (session.Query<CleanLineItem>().CountAsync(x => validOrders.Any(y => y == x.Order)));
+
 			Assert.That(orderCount, Is.EqualTo(1));
 		}
-    
+
 		[Test]
 		public async Task QueryWithContainsAsync()
 		{
@@ -75,10 +92,10 @@ public async Task QueryWithContainsAsync()
 
 			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
 			var orderCount = await (session.Query<LineItem>().CountAsync(x => validOrders.Contains(x.Order)));
-        
+
 			Assert.That(orderCount, Is.EqualTo(1));
 		}
-    
+
 		[Test]
 		public async Task SimpleQueryForDataWhichWasInsertedViaAdoShouldProvideExpectedResultsAsync()
 		{

src/NHibernate.Test/NHSpecificTest/GH3609/Entities.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 
 namespace NHibernate.Test.NHSpecificTest.GH3609
 {
@@ -21,4 +21,15 @@ public class LineItem
 
 		public virtual decimal Amount { get; set; }
 	}
+
+	public class CleanLineItem
+	{
+		public virtual long Id { get; set; }
+
+		public virtual Order Order { get; set; }
+
+		public virtual string ItemName { get; set; }
+
+		public virtual decimal Amount { get; set; }
+	}
 }

src/NHibernate.Test/NHSpecificTest/GH3609/Fixture.cs

@@ -19,6 +19,7 @@ protected override void OnSetUp()
 			};
 			session.Save(order);
 			session.Save(new LineItem { Order = order, ItemName = "Bananas", Amount = 5 });
+			session.Save(new CleanLineItem { Order = order, ItemName = "Bananas", Amount = 5 });
 
 			order = new Order
 			{
@@ -27,6 +28,7 @@ protected override void OnSetUp()
 			};
 			session.Save(order);
 			session.Save(new LineItem { Order = order, ItemName = "Apples", Amount = 10 });
+			session.Save(new CleanLineItem { Order = order, ItemName = "Apples", Amount = 10 });
 
 			transaction.Commit();
 		}
@@ -36,6 +38,7 @@ protected override void OnTearDown()
 			using var session = OpenSession();
 			using var transaction = session.BeginTransaction();
 
+			session.CreateQuery("delete from CleanLineItem").ExecuteUpdate();
 			session.CreateQuery("delete from System.Object").ExecuteUpdate();
 
 			transaction.Commit();
@@ -51,10 +54,24 @@ public void QueryWithAny()
 			// sort of Linq that we were using in our app.  It seems to occur when we force an EXISTS( ... ) subquery.
 			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
 			var orderCount = session.Query<LineItem>().Count(x => validOrders.Any(y => y == x.Order));
-        
+
+			Assert.That(orderCount, Is.EqualTo(1));
+		}
+
+		[Test]
+		public void QueryWithAnyOnCleanLines()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+
+			// This form of query is how we first discovered the issue.  This is a simplified reproduction of the
+			// sort of Linq that we were using in our app.  It seems to occur when we force an EXISTS( ... ) subquery.
+			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
+			var orderCount = session.Query<CleanLineItem>().Count(x => validOrders.Any(y => y == x.Order));
+
 			Assert.That(orderCount, Is.EqualTo(1));
 		}
-    
+
 		[Test]
 		public void QueryWithContains()
 		{
@@ -63,10 +80,10 @@ public void QueryWithContains()
 
 			var validOrders = session.Query<Order>().Where(x => x.CreatedDate > new DateTime(2024, 9, 10));
 			var orderCount = session.Query<LineItem>().Count(x => validOrders.Contains(x.Order));
-        
+
 			Assert.That(orderCount, Is.EqualTo(1));
 		}
-    
+
 		[Test]
 		public void SimpleQueryForDataWhichWasInsertedViaAdoShouldProvideExpectedResults()
 		{

src/NHibernate.Test/NHSpecificTest/GH3609/Mappings.hbm.xml

@@ -1,13 +1,13 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test"
                    namespace="NHibernate.Test.NHSpecificTest.GH3609">
-  
+
   <class name="Order" table="TheOrder">
     <id name="Id" generator="identity" />
     <property name="CreatedDate" />
-    <property name="UniqueId" />
+    <property name="UniqueId" unique="true" />
   </class>
-  
+
   <class name="LineItem">
     <id name="Id" generator="identity" />
     <property name="ItemName" />
@@ -18,4 +18,13 @@
                  column="OrderId" />
   </class>
 
+  <class name="CleanLineItem">
+    <id name="Id" generator="identity" />
+    <property name="ItemName" />
+    <property name="Amount" />
+    <many-to-one name="Order"
+                 property-ref="UniqueId"
+                 column="OrderId" />
+  </class>
+
 </hibernate-mapping>

src/NHibernate/Hql/Ast/ANTLR/Tree/DotNode.cs

@@ -402,8 +402,11 @@ private void DereferenceEntity(EntityType entityType, bool implicitJoin, string
 			string property = _propertyName;
 			bool joinIsNeeded;
 
-			//For nullable entity comparisons we always need to add join (like not constrained one-to-one or not-found ignore associations)
-			bool comparisonWithNullableEntity = entityType.IsNullable && Walker.IsComparativeExpressionClause && !IsCorrelatedSubselect;
+			// For nullable entity comparisons we always need to add join (like not constrained one-to-one or not-found ignore associations).
+			// For property-ref associations, we also need this unless finding a way in the IdentNode for the other hand of the comparison
+			// to detect it should yield the property-ref columns instead of the primary key columns.
+			bool comparisonWithNullableEntityOrThroughPropertyRef = Walker.IsComparativeExpressionClause
+				&& (entityType.IsNullable || entityType.IsUniqueKeyReference);
 
 			if ( IsDotNode( parent ) ) 
 			{
@@ -412,7 +415,7 @@ private void DereferenceEntity(EntityType entityType, bool implicitJoin, string
 				// entity's PK (because 'our' table would know the FK).
 				parentAsDotNode = ( DotNode ) parent;
 				property = parentAsDotNode._propertyName;
-				joinIsNeeded = generateJoin && ((Walker.IsSelectStatement && comparisonWithNullableEntity) || !IsReferenceToPrimaryKey( parentAsDotNode._propertyName, entityType ));
+				joinIsNeeded = generateJoin && ((Walker.IsSelectStatement && comparisonWithNullableEntityOrThroughPropertyRef) || !IsReferenceToPrimaryKey( parentAsDotNode._propertyName, entityType ));
 			}
 			else if ( ! Walker.IsSelectStatement ) 
 			{
@@ -426,13 +429,14 @@ private void DereferenceEntity(EntityType entityType, bool implicitJoin, string
 			else
 			{
 				joinIsNeeded = generateJoin || (Walker.IsInSelect && !Walker.IsInCase) || (Walker.IsInFrom && !Walker.IsComparativeExpressionClause)
-				               || comparisonWithNullableEntity;
+				               || comparisonWithNullableEntityOrThroughPropertyRef;
 			}
 
 			if ( joinIsNeeded )
 			{
-				DereferenceEntityJoin(classAlias, entityType, implicitJoin, parent, comparisonWithNullableEntity);
-				if (comparisonWithNullableEntity)
+				var forceLeftJoin = comparisonWithNullableEntityOrThroughPropertyRef && !IsCorrelatedSubselect;
+				DereferenceEntityJoin(classAlias, entityType, implicitJoin, parent, forceLeftJoin);
+				if (comparisonWithNullableEntityOrThroughPropertyRef)
 				{
 					_columns = FromElement.GetIdentityColumns();
 				}