Fix query source naming

Author: hazzik

src/NHibernate.Test/Linq/QueryLock.cs

@@ -125,6 +125,23 @@ from o in c.Orders.WithLock(LockMode.Upgrade)
 			}
 		}
 
+		[Test]
+		public void CanSetLockOnBothJoinAndMainComplex()
+		{
+			using (session.BeginTransaction())
+			{
+				var result = (
+					from c in db.Customers.Where(x => true).WithLock(LockMode.Upgrade)
+					from o in c.Orders.Where(x => true).WithLock(LockMode.Upgrade)
+					select new {o, c}
+				).ToList();
+
+				Assert.That(result, Has.Count.EqualTo(830));
+				Assert.That(session.GetCurrentLockMode(result[0].o), Is.EqualTo(LockMode.Upgrade));
+				Assert.That(session.GetCurrentLockMode(result[0].c), Is.EqualTo(LockMode.Upgrade));
+			}
+		}
+
 		[Test]
 		public void CanSetLockOnLinqPagingQuery()
 		{

src/NHibernate/Linq/LockResultOperator.cs

@@ -9,9 +9,9 @@ namespace NHibernate.Linq
 {
 	internal class LockResultOperator : ResultOperatorBase
 	{
-		private readonly QuerySourceReferenceExpression _qsrExpression;
+		private QuerySourceReferenceExpression _qsrExpression;
 
-		public string Alias => _qsrExpression.ReferencedQuerySource.ItemName;
+		public IQuerySource QuerySource => _qsrExpression.ReferencedQuerySource;
 
 		public ConstantExpression LockMode { get; }
 
@@ -38,6 +38,7 @@ public override ResultOperatorBase Clone(CloneContext cloneContext)
 
 		public override void TransformExpressions(Func<Expression, Expression> transformation)
 		{
+			_qsrExpression = (QuerySourceReferenceExpression) transformation(_qsrExpression);
 		}
 	}
 }

src/NHibernate/Linq/Visitors/ResultOperatorProcessors/ProcessLock.cs

@@ -4,7 +4,8 @@ internal class ProcessLock : IResultOperatorProcessor<LockResultOperator>
 	{
 		public void Process(LockResultOperator resultOperator, QueryModelVisitor queryModelVisitor, IntermediateHqlTree tree)
 		{
-			tree.AddAdditionalCriteria((q, p) => q.SetLockMode(resultOperator.Alias, (LockMode) resultOperator.LockMode.Value));
+			var alias = queryModelVisitor.VisitorParameters.QuerySourceNamer.GetName(resultOperator.QuerySource);
+			tree.AddAdditionalCriteria((q, p) => q.SetLockMode(alias, (LockMode) resultOperator.LockMode.Value));
 		}
 	}
 }