Fix NH-2850 - Unable to use enums in NH 3.2 QueryOver checked comparison

Author: FlukeFan

src/NHibernate.Test/Criteria/Lambda/ExpressionProcessorFixture.cs

@@ -231,6 +231,28 @@ public void TestEvaluateEnumeration()
 			Assert.AreEqual(before.ToString(), after.ToString());
 		}
 
+		[Test]
+		public void TestUnaryConversionChecked()
+		{
+			checked
+			{
+				ICriterion before = Restrictions.Eq("Gender", PersonGender.Female);
+				ICriterion after = ExpressionProcessor.ProcessExpression<Person>(p => p.Gender == PersonGender.Female);
+				Assert.AreEqual(before.ToString(), after.ToString());
+			}
+		}
+
+		[Test]
+		public void TestUnaryConversionUnchecked()
+		{
+			unchecked
+			{
+				ICriterion before = Restrictions.Eq("Gender", PersonGender.Female);
+				ICriterion after = ExpressionProcessor.ProcessExpression<Person>(p => p.Gender == PersonGender.Female);
+				Assert.AreEqual(before.ToString(), after.ToString());
+			}
+		}
+
 		[Test]
 		public void TestEvaluateSubclass()
 		{

src/NHibernate/Impl/ExpressionProcessor.cs

@@ -170,7 +170,7 @@ public static IProjection FindMemberProjection(Expression expression)
 			{
 				UnaryExpression unaryExpression = (UnaryExpression)expression;
 
-				if (unaryExpression.NodeType != ExpressionType.Convert)
+				if (!IsConversion(unaryExpression.NodeType))
 					throw new Exception("Cannot interpret member from " + expression.ToString());
 
 				return FindMemberProjection(unaryExpression.Operand);
@@ -212,7 +212,7 @@ public static string FindMemberExpression(Expression expression)
 
 					return FindMemberExpression(memberExpression.Expression) + "." + memberExpression.Member.Name;
 				}
-				else if (memberExpression.Expression.NodeType == ExpressionType.Convert)
+				else if (IsConversion(memberExpression.Expression.NodeType))
 				{
 					return (FindMemberExpression(memberExpression.Expression) + "." + memberExpression.Member.Name).TrimStart('.');
 				}
@@ -226,7 +226,7 @@ public static string FindMemberExpression(Expression expression)
 			{
 				UnaryExpression unaryExpression = (UnaryExpression)expression;
 
-				if (unaryExpression.NodeType != ExpressionType.Convert)
+				if (!IsConversion(unaryExpression.NodeType))
 					throw new Exception("Cannot interpret member from " + expression.ToString());
 
 				return FindMemberExpression(unaryExpression.Operand);
@@ -302,7 +302,7 @@ private static System.Type FindMemberType(Expression expression)
 			{
 				UnaryExpression unaryExpression = (UnaryExpression)expression;
 
-				if (unaryExpression.NodeType != ExpressionType.Convert)
+				if (!IsConversion(unaryExpression.NodeType))
 					throw new Exception("Cannot interpret member from " + expression.ToString());
 
 				return FindMemberType(unaryExpression.Operand);
@@ -340,7 +340,7 @@ private static bool IsMemberExpression(Expression expression)
 			{
 				UnaryExpression unaryExpression = (UnaryExpression)expression;
 
-				if (unaryExpression.NodeType != ExpressionType.Convert)
+				if (!IsConversion(unaryExpression.NodeType))
 					throw new Exception("Cannot interpret member from " + expression.ToString());
 
 				return IsMemberExpression(unaryExpression.Operand);
@@ -375,6 +375,11 @@ private static bool IsMemberExpression(Expression expression)
 			return false;
 		}
 
+		private static bool IsConversion(ExpressionType expressionType)
+		{
+			return (expressionType == ExpressionType.Convert || expressionType == ExpressionType.ConvertChecked);
+		}
+
 		private static object ConvertType(object value, System.Type type)
 		{
 			if (value == null)