Code review changes

Author: maca88

src/NHibernate.DomainModel/Northwind/Entities/Animal.cs

@@ -12,7 +12,9 @@ public class Animal
         public virtual Animal Father { get; set; }
         public virtual IList<Animal> Children { get; set; }
         public virtual string SerialNumber { get; set; }
-    }
+
+		public virtual Animal FatherOrMother => Father ?? Mother;
+	}
 
     public abstract class Reptile : Animal
     {
@@ -30,4 +32,4 @@ public abstract class Mammal : Animal
     public class Dog : Mammal { }
 
     public class Cat : Mammal { }
-}
+}

src/NHibernate.Test/Async/Linq/SelectionTests.cs

@@ -289,6 +289,14 @@ public async Task CanSelectFirstElementFromChildCollectionAsync()
 			}
 		}
 
+		[Test]
+		public async Task CanSelectNotMappedEntityPropertyAsync()
+		{
+			var list = await (db.Animals.Where(o => o.Mother != null).Select(o => o.FatherOrMother.SerialNumber).ToListAsync());
+
+			Assert.That(list, Has.Count.GreaterThan(0));
+		}
+
 		[Test]
 		public async Task CanProjectWithCastAsync()
 		{

src/NHibernate.Test/Linq/SelectionTests.cs

@@ -328,6 +328,14 @@ public void CanSelectWrappedType()
 			Assert.IsTrue(query.ToArray().Length > 0);
 		}
 
+		[Test]
+		public void CanSelectNotMappedEntityProperty()
+		{
+			var list = db.Animals.Where(o => o.Mother != null).Select(o => o.FatherOrMother.SerialNumber).ToList();
+
+			Assert.That(list, Has.Count.GreaterThan(0));
+		}
+
 		[Test]
 		public void CanProjectWithCast()
 		{

src/NHibernate/Linq/ReWriters/AddJoinsReWriter.cs

@@ -27,8 +27,8 @@ private AddJoinsReWriter(ISessionFactoryImplementor sessionFactory, QueryModel q
 		{
 			_sessionFactory = sessionFactory;
 			var joiner = new Joiner(queryModel, AddJoin);
-			_memberExpressionJoinDetector = new MemberExpressionJoinDetector(this, joiner, _sessionFactory);
-			_whereJoinDetector = new WhereJoinDetector(this, joiner, _sessionFactory);
+			_memberExpressionJoinDetector = new MemberExpressionJoinDetector(this, joiner);
+			_whereJoinDetector = new WhereJoinDetector(this, joiner);
 		}
 
 		public static void ReWrite(QueryModel queryModel, VisitorParameters parameters)

src/NHibernate/Linq/Visitors/MemberExpressionJoinDetector.cs

@@ -19,21 +19,16 @@ internal class MemberExpressionJoinDetector : RelinqExpressionVisitor
 	{
 		private readonly IIsEntityDecider _isEntityDecider;
 		private readonly IJoiner _joiner;
-		private readonly ISessionFactoryImplementor _sessionFactory;
 
 		private bool _requiresJoinForNonIdentifier;
 		private bool _preventJoinsInConditionalTest;
 		private bool _hasIdentifier;
 		private int _memberExpressionDepth;
 
-		public MemberExpressionJoinDetector(
-			IIsEntityDecider isEntityDecider,
-			IJoiner joiner,
-			ISessionFactoryImplementor sessionFactory)
+		public MemberExpressionJoinDetector(IIsEntityDecider isEntityDecider, IJoiner joiner)
 		{
 			_isEntityDecider = isEntityDecider;
 			_joiner = joiner;
-			_sessionFactory = sessionFactory;
 		}
 
 		protected override Expression VisitMember(MemberExpression expression)

src/NHibernate/Linq/Visitors/SelectClauseNominator.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
+using NHibernate.Engine;
 using NHibernate.Linq.Functions;
 using NHibernate.Linq.Expressions;
 using NHibernate.Util;
@@ -15,6 +16,7 @@ namespace NHibernate.Linq.Visitors
 	class SelectClauseHqlNominator : RelinqExpressionVisitor
 	{
 		private readonly ILinqToHqlGeneratorsRegistry _functionRegistry;
+		private readonly ISessionFactoryImplementor _sessionFactory;
 
 		/// <summary>
 		/// The expression parts that can be converted to pure HQL.
@@ -35,6 +37,7 @@ class SelectClauseHqlNominator : RelinqExpressionVisitor
 		public SelectClauseHqlNominator(VisitorParameters parameters)
 		{
 			_functionRegistry = parameters.SessionFactory.Settings.LinqToHqlGeneratorsRegistry;
+			_sessionFactory = parameters.SessionFactory;
 		}
 
 		internal Expression Nominate(Expression expression)
@@ -168,8 +171,10 @@ private bool CanBeEvaluatedInHqlSelectStatement(Expression expression, bool proj
 				return projectConstantsInHql;
 			}
 
-			// Assume all is good
-			return true;
+			return !(expression is MemberExpression memberExpression) || // Assume all is good
+			       // Evaluate only expressions that represent a mapped property
+			       ExpressionsHelper.TryGetMappedType(_sessionFactory, expression, out _, out _, out _, out _) ||
+			       _functionRegistry.TryGetGenerator(memberExpression.Member, out _);
 		}
 
 		private static bool CanBeEvaluatedInHqlStatementShortcut(Expression expression)

src/NHibernate/Linq/Visitors/WhereJoinDetector.cs

@@ -62,7 +62,6 @@ internal class WhereJoinDetector : RelinqExpressionVisitor
 		// TODO: There are a number of types of expressions that we didn't handle here due to time constraints.  For example, the ?: operator could be checked easily.
 		private readonly IIsEntityDecider _isEntityDecider;
 		private readonly IJoiner _joiner;
-		private readonly ISessionFactoryImplementor _sessionFactory;
 
 		private readonly Stack<bool> _handled = new Stack<bool>();
 
@@ -72,14 +71,10 @@ internal class WhereJoinDetector : RelinqExpressionVisitor
 		// The following is used for member expressions traversal.
 		private int _memberExpressionDepth;
 
-		internal WhereJoinDetector(
-			IIsEntityDecider isEntityDecider,
-			IJoiner joiner,
-			ISessionFactoryImplementor sessionFactory)
+		internal WhereJoinDetector(IIsEntityDecider isEntityDecider, IJoiner joiner)
 		{
 			_isEntityDecider = isEntityDecider;
 			_joiner = joiner;
-			_sessionFactory = sessionFactory;
 		}
 
 		public Expression Transform(Expression expression)