Added a pretty simple diagnostic system so we can provide improved diagnostics to clients.

src/Generator/Diagnostics.cs

@@ -0,0 +1,32 @@
+using System;
+
+namespace Cxxi
+{
+    public enum DiagnosticKind
+    {
+        Message,
+        Warning,
+        Error
+    }
+
+    public struct DiagnosticInfo
+    {
+        public string Message;
+        public string File;
+        public int Line;
+        public int Column;
+    }
+
+    public interface IDiagnosticConsumer
+    {
+        void Emit(DiagnosticKind kind, DiagnosticInfo info);
+    }
+
+    public class TextDiagnosticPrinter : IDiagnosticConsumer
+    {
+        public void Emit(DiagnosticKind kind, DiagnosticInfo info)
+        {
+            Console.WriteLine(info.Message);
+        }
+    }
+}

src/Generator/Driver.cs

@@ -10,6 +10,7 @@ namespace Cxxi
     {
         private readonly Options options;
         private readonly ILibrary transform;
+        private readonly IDiagnosticConsumer diagnostics;
         private readonly TypeMapDatabase typeDatabase;
         private Library library;
 
@@ -17,6 +18,8 @@ namespace Cxxi
         {
             this.options = options;
             this.transform = transform;
+            this.diagnostics = new TextDiagnosticPrinter();
+
             typeDatabase = new TypeMapDatabase();
             typeDatabase.SetupTypeMaps();
         }