Add support for nullable types and fix c# 3.0 compatibility bug.

Dapper/SqlMapper.cs

@@ -1520,13 +1520,10 @@ static List<FieldInfo> GetSettableFields(Type t)
                     int i = 0;
                     for (; i < ctorParameters.Length; i++)
                     {
-                        if (!String.Equals(ctorParameters[i].Name, names[i], StringComparison.OrdinalIgnoreCase)
-                            || (types[i] != ctorParameters[i].ParameterType
-#if CSHARP30
-                            ))
-#else
-                                && !(ctorParameters[i].ParameterType.IsEnum && ctorParameters[i].ParameterType.GetEnumUnderlyingType() == types[i])))
-#endif
+                        if (!String.Equals(ctorParameters[i].Name, names[i], StringComparison.OrdinalIgnoreCase))
+                            break;
+                        var unboxedType = Nullable.GetUnderlyingType(ctorParameters[i].ParameterType) ?? ctorParameters[i].ParameterType;
+                        if (unboxedType != types[i] && !(unboxedType.IsEnum && Enum.GetUnderlyingType(unboxedType) == types[i]))
                             break;
                     }
                     if (i == ctorParameters.Length)

Tests/Tests.cs

@@ -35,23 +35,29 @@ public class ConcreteOrder : Order
 
         class NoDefaultConstructor
         {
-            public NoDefaultConstructor(int a, float f, ShortEnum e)
+            public NoDefaultConstructor(int a, int? b, float f, ShortEnum e, ShortEnum? n)
             {
                 A = a;
+                B = b;
                 F = f;
                 E = e;
+                N = n;
             }
             public int A { get; set; }
+            public int? B { get; set; }
             public float F { get; set; }
             public ShortEnum E { get; set; }
+            public ShortEnum? N { get; set; }
         }
 
         public void TestNoDefaultConstructor()
         {
-            NoDefaultConstructor nodef = connection.Query<NoDefaultConstructor>("select CAST(NULL AS integer) A, CAST(NULL AS real) f, cast(2 as smallint) E").First();
+            NoDefaultConstructor nodef = connection.Query<NoDefaultConstructor>("select CAST(NULL AS integer) A,  CAST(NULL AS integer) b, CAST(NULL AS real) f, cast(2 as smallint) E, cast(null as smallint) n").First();
             nodef.A.IsEqualTo(0);
+            nodef.B.IsEqualTo(null);
             nodef.F.IsEqualTo(0);
             nodef.E.IsEqualTo(ShortEnum.Two);
+            nodef.N.IsEqualTo(null);
         }
 
         // http://stackoverflow.com/q/8593871