[vala] Support nullable error types in VAPI files

[Jürg Billeter <juergbi src gnome org>]

commit 8cfa1ac483108240ee119605ebd2bb96301d8e8f
Author: Jürg Billeter <j bitron ch>
Date:   Thu Feb 18 23:02:27 2010 +0100

    Support nullable error types in VAPI files

 vala/valaerrortype.vala |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)
---
diff --git a/vala/valaerrortype.vala b/vala/valaerrortype.vala
index d0992e8..a21a323 100644
--- a/vala/valaerrortype.vala
+++ b/vala/valaerrortype.vala
@@ -1,6 +1,6 @@
 /* valaerrortype.vala
  *
- * Copyright (C) 2008  Jürg Billeter
+ * Copyright (C) 2008-2010  Jürg Billeter
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -77,11 +77,19 @@ public class Vala.ErrorType : ReferenceType {
 	}
 
 	public override string to_qualified_string (Scope? scope) {
+		string result;
+
 		if (error_domain == null) {
-			return "GLib.Error";
+			result = "GLib.Error";
 		} else {
-			return error_domain.get_full_name ();
+			result = error_domain.get_full_name ();
+		}
+
+		if (nullable) {
+			result += "?";
 		}
+
+		return result;
 	}
 
 	public override DataType copy () {