CSHARP-542: normalized a vb expression related to nullable comparisons.

Author: craiggwilson

Driver/Linq/Expressions/ExpressionNormalizer.cs

@@ -61,6 +61,27 @@ protected override Expression VisitBinary(BinaryExpression node)
         {
             node = EnsureConstantIsOnRight(node);
 
+            if (node.Type == typeof(Nullable<bool>))
+            {
+                switch (node.NodeType)
+                {
+                    case ExpressionType.Equal:
+                    case ExpressionType.GreaterThan:
+                    case ExpressionType.GreaterThanOrEqual:
+                    case ExpressionType.LessThan:
+                    case ExpressionType.LessThanOrEqual:
+                    case ExpressionType.NotEqual:
+                        node = Expression.MakeBinary(
+                            node.NodeType,
+                            node.Left,
+                            node.Right,
+                            false,
+                            null,
+                            null);
+                        break;
+                }
+            }
+
             Expression result = null;
             if (node.Left.NodeType == ExpressionType.Call && node.Right.NodeType == ExpressionType.Constant)
             {
@@ -118,16 +139,19 @@ protected override Expression VisitBinary(BinaryExpression node)
         /// <returns>The UnaryExpression (possibly modified).</returns>
         protected override Expression VisitUnary(UnaryExpression node)
         {
-            if (node.NodeType == ExpressionType.Convert || node.NodeType == ExpressionType.ConvertChecked)
+            var newNode = base.VisitUnary(node);
+
+            if (newNode.NodeType == ExpressionType.Convert || newNode.NodeType == ExpressionType.ConvertChecked)
             {
-                if (node.Type.IsAssignableFrom(node.Operand.Type))
+                var newUnaryNode = (UnaryExpression)newNode;
+                if (newUnaryNode.Type.IsAssignableFrom(newUnaryNode.Operand.Type))
                 {
                     // ignore the unnecessary conversion added by VB
-                    return Visit(node.Operand);
+                    newNode = newUnaryNode.Operand;
                 }
             }
 
-            return base.VisitUnary(node);
+            return newNode;
         }
 
         private BinaryExpression EnsureConstantIsOnRight(BinaryExpression node)

DriverUnitTestsVB/DriverUnitTestsVB.vbproj

@@ -67,6 +67,7 @@
     <Import Include="System.Xml.Linq" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Jira\CSharp542.vb" />
     <Compile Include="Linq\MongoQueryableTests.vb" />
     <Compile Include="Linq\MongoQueryProviderTests.vb" />
     <Compile Include="Linq\SelectDictionaryTests.vb" />

DriverUnitTestsVB/Jira/CSharp542.vb

@@ -0,0 +1,52 @@
+' Copyright 2010-2012 10gen Inc.
+'*
+'* Licensed under the Apache License, Version 2.0 (the "License");
+'* you may not use this file except in compliance with the License.
+'* You may obtain a copy of the License at
+'*
+'* http://www.apache.org/licenses/LICENSE-2.0
+'*
+'* Unless required by applicable law or agreed to in writing, software
+'* distributed under the License is distributed on an "AS IS" BASIS,
+'* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+'* See the License for the specific language governing permissions and
+'* limitations under the License.
+'
+
+
+Imports System.Collections.Generic
+Imports System.Linq
+Imports System.Text
+Imports NUnit.Framework
+
+Imports MongoDB.Bson
+Imports MongoDB.Bson.Serialization.Attributes
+Imports MongoDB.Driver
+Imports MongoDB.Driver.Linq
+
+Namespace MongoDB.DriverUnitTests.Jira
+
+    <TestFixture()>
+    Public Class CSharp542
+
+        Public Class Test
+            Public Id As ObjectId
+
+            Public MyNullableInt As Nullable(Of Integer)
+        End Class
+
+        <Test()>
+        Public Sub TestNullableComparison()
+
+            Dim server = MongoServer.Create()
+            Dim db = server.GetDatabase("test")
+            Dim col = db.GetCollection(Of Test)("foos")
+
+            Dim query = col.AsQueryable.Where(Function(p) p.MyNullableInt = 3)
+
+            Dim list = query.ToList()
+
+        End Sub
+    End Class
+
+End Namespace