Don't bother trying to deal with nullables within expressions - closes …

…#1011

CodeConverter/CSharp/VisualBasicNullableExpressionsConverter.cs

@@ -47,7 +47,8 @@ public ExpressionSyntax InvokeConversionWhenNotNull(VBSyntax.ExpressionSyntax vb
 
     public ExpressionSyntax WithBinaryExpressionLogicForNullableTypes(VBSyntax.BinaryExpressionSyntax vbNode, TypeInfo lhsTypeInfo, TypeInfo rhsTypeInfo, BinaryExpressionSyntax csBinExp, ExpressionSyntax lhs, ExpressionSyntax rhs)
     {
-        if (!IsSupported(vbNode.Kind()) || 
+        if (IsWithinQuery ||
+            !IsSupported(vbNode.Kind()) || 
             !lhsTypeInfo.ConvertedType.IsNullable() ||
             !rhsTypeInfo.ConvertedType.IsNullable()) {
             return csBinExp;
@@ -255,6 +256,10 @@ private ExpressionSyntax HasValue(bool reusable, ref ExpressionSyntax csName)
 
     private bool IsSafelyReusable(VBasic.Syntax.ExpressionSyntax e)
     {
+        // In general, you can't rely on a query to safely reuse properties (e.g. it may be compiled to SQL and use it 0 times)
+        // Since the code to guarantee the same reuse would be very complex and often not useful (e.g. pulling out methods to compose expressions), we just don't guarantee it
+        // This is a trade off, see https://github.com/icsharpcode/CodeConverter/blob/master/.github/CONTRIBUTING.md#deciding-what-the-output-should-be
+        if (IsWithinQuery) return true;
         e = e.SkipIntoParens();
         if (e is VBSyntax.LiteralExpressionSyntax) return true;
         var symbolInfo = VBasic.VisualBasicExtensions.GetSymbolInfo(_semanticModel, e);

Tests/CSharp/ExpressionTests/LinqExpressionTests.cs

@@ -822,6 +822,49 @@ from x in list2
     }
 
 
+    [Fact]
+    public async Task Issue1011_LinqExpressionWithNullableCharacterizationAsync()
+    {
+        await TestConversionVisualBasicToCSharpAsync(@"Public Class ConversionTest2
+    Private Class MyEntity
+        Property FavoriteNumber As Integer?
+        Property Name As String
+    End Class
+    Private Sub BugRepro()
+
+        Dim entities As New List(Of MyEntity)
+
+        Dim result As String = (From e In entities
+                                Where e.FavoriteNumber = 123
+                                Select e.Name).Single
+
+    End Sub
+End Class
+",
+            @"using System.Collections.Generic;
+using System.Linq;
+
+public partial class ConversionTest2
+{
+    private partial class MyEntity
+    {
+        public int? FavoriteNumber { get; set; }
+        public string Name { get; set; }
+    }
+    private void BugRepro()
+    {
+
+        var entities = new List<MyEntity>();
+
+        string result = (from e in entities
+                         where e.FavoriteNumber.Value == 123
+                         select e.Name).Single();
+
+    }
+}");
+    }
+
+
     [Fact]
     public async Task AnExpressionTreeMayNotContainIsAsync()
     {

Tests/CSharp/TypeCastTests.cs

@@ -1566,7 +1566,7 @@ private static void LinqWithNullable()
     {
         var a = new List<int?>() { 1, 2, 3, default };
         var result = from x in a
-                     where x is { } arg1 && arg1 == 1
+                     where x == 1
                      select x;
     }
 }");