Add BinaryOperatorType.IsBitwise extension.

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -694,8 +694,7 @@ namespace ICSharpCode.Decompiler.CSharp
 				}
 			}
 
-			if ((op == BinaryOperatorType.BitwiseAnd || op == BinaryOperatorType.BitwiseOr || op == BinaryOperatorType.ExclusiveOr)
-				&& (left.Type.Kind == TypeKind.Enum || right.Type.Kind == TypeKind.Enum)) {
+			if (op.IsBitwise() && (left.Type.Kind == TypeKind.Enum || right.Type.Kind == TypeKind.Enum)) {
 				left = AdjustConstantExpressionToType(left, right.Type);
 				right = AdjustConstantExpressionToType(right, left.Type);
 			}

ICSharpCode.Decompiler/CSharp/NRefactoryExtensions.cs

@@ -99,5 +99,15 @@ namespace ICSharpCode.Decompiler.CSharp
 			var simpleType = type as SimpleType;
 			return simpleType != null && simpleType.Identifier == "__arglist";
 		}
+
+		/// <summary>
+		/// Returns true if <paramref name="operatorType"/> is bitwise and, bitwise or, or exclusive or.
+		/// </summary>
+		public static bool IsBitwise(this BinaryOperatorType operatorType)
+		{
+			return operatorType == BinaryOperatorType.BitwiseAnd
+				|| operatorType == BinaryOperatorType.BitwiseOr
+				|| operatorType == BinaryOperatorType.ExclusiveOr;
+		}
 	}
 }