From 6e38a8471db9bf2ec4d7869d86eca3080e7fb292 Mon Sep 17 00:00:00 2001
From: Duncan M <duncan@pleasantsolutions.com>
Date: Mon, 8 Nov 2021 09:06:13 -0700
Subject: [PATCH] Fix TryGetMappedNullability for CompositeCustomType

Fixes #2937
---
 src/NHibernate.Test/Linq/TryGetMappedTests.cs | 12 ++++++++++++
 src/NHibernate/Util/ExpressionsHelper.cs      |  6 +++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/NHibernate.Test/Linq/TryGetMappedTests.cs b/src/NHibernate.Test/Linq/TryGetMappedTests.cs
index 964072efdc2..44839dccf96 100644
--- a/src/NHibernate.Test/Linq/TryGetMappedTests.cs
+++ b/src/NHibernate.Test/Linq/TryGetMappedTests.cs
@@ -272,6 +272,18 @@ public void NestedComponentPropertyCastTest()
 				o => o?.Name == "component[OtherProperty1]");
 		}
 
+		[Test]
+		public void CompositePropertyTest()
+		{
+			var query = session.Query<Glarch>().Select(o => o.Multiple.count);
+			AssertSupported(
+				query,
+				typeof(Glarch).FullName,
+				"Multiple.count",
+				o => o is Int32Type,
+				o => o?.Name == typeof(MultiplicityType).FullName);
+		}
+
 		[Test]
 		public void ManyToOneTest()
 		{
diff --git a/src/NHibernate/Util/ExpressionsHelper.cs b/src/NHibernate/Util/ExpressionsHelper.cs
index 050a4d2ed22..29d9f73d53c 100644
--- a/src/NHibernate/Util/ExpressionsHelper.cs
+++ b/src/NHibernate/Util/ExpressionsHelper.cs
@@ -158,7 +158,11 @@ internal static bool TryGetMappedNullability(
 			}
 
 			int index;
-			if (componentType != null)
+			if (componentType is CompositeCustomType cct)
+			{
+				memberPath = memberPath.Remove(memberPath.LastIndexOf('.'));
+			}
+			else if (componentType != null)
 			{
 				index = Array.IndexOf(
 					componentType.PropertyNames,