Code review changes

Author: maca88

src/NHibernate/Linq/Visitors/HqlGeneratorExpressionVisitor.cs

@@ -526,11 +526,14 @@ protected HqlTreeNode VisitUnaryExpression(UnaryExpression expression)
 				case ExpressionType.Convert:
 				case ExpressionType.ConvertChecked:
 				case ExpressionType.TypeAs:
-					var notCastable = _notCastableExpressions.TryGetValue(expression, out var castType);
-					castType = castType ?? expression.Type;
+					var castable = !_notCastableExpressions.TryGetValue(expression, out var castType);
+					if (castable)
+					{
+						castType = expression.Type;
+					}
 
-					return IsCastRequired(expression.Operand, castType, out var existType) && !notCastable
-						? _hqlTreeBuilder.Cast(VisitExpression(expression.Operand).AsExpression(), expression.Type)
+					return IsCastRequired(expression.Operand, castType, out var existType) && castable
+						? _hqlTreeBuilder.Cast(VisitExpression(expression.Operand).AsExpression(), castType)
 						// Make a transparent cast when an IType exists, so that it can be used to retrieve the value from the data reader
 						: existType && HqlIdent.SupportsType(castType)
 							? _hqlTreeBuilder.TransparentCast(VisitExpression(expression.Operand).AsExpression(), castType)

src/NHibernate/Linq/Visitors/NhPartialEvaluatingExpressionVisitor.cs

@@ -80,16 +80,7 @@ public override Expression Visit(Expression expression)
 			if (expression.NodeType == ExpressionType.Lambda || !_partialEvaluationInfo.IsEvaluatableExpression(expression) ||
 				#region NH additions
 				// Variables should be evaluated only when they are part of an evaluatable expression (e.g. o => string.Format("...", variable))
-				expression is UnaryExpression unaryExpression &&
-				(
-					ExpressionsHelper.IsVariable(unaryExpression.Operand, out _, out _) ||
-					// Check whether the variable is casted due to comparison with a nullable expression
-					// (e.g. o.NullableShort == shortVariable)
-					unaryExpression.Operand is UnaryExpression subUnaryExpression &&
-					unaryExpression.Type.UnwrapIfNullable() == subUnaryExpression.Type &&
-					ExpressionsHelper.IsVariable(subUnaryExpression.Operand, out _, out _)
-				)
-				)
+				ContainsVariable(expression))
 				#endregion
 				return base.Visit(expression);
 
@@ -162,8 +153,27 @@ private Expression EvaluateSubtree(Expression subtree)
 			}
 		}
 
+		#region NH additions
+
+		private bool ContainsVariable(Expression expression)
+		{
+			if (!(expression is UnaryExpression unaryExpression))
+			{
+				return false;
+			}
+
+			return ExpressionsHelper.IsVariable(unaryExpression.Operand, out _, out _) ||
+			       // Check whether the variable is casted due to comparison with a nullable expression
+			       // (e.g. o.NullableShort == shortVariable)
+			       unaryExpression.Operand is UnaryExpression subUnaryExpression &&
+			       unaryExpression.Type.UnwrapIfNullable() == subUnaryExpression.Type &&
+			       ExpressionsHelper.IsVariable(subUnaryExpression.Operand, out _, out _);
+		}
+
 		#endregion
-		
+
+		#endregion
+
 		protected override Expression VisitConstant(ConstantExpression expression)
 		{
 			if (expression.Value is Expression value)