Add message text to CS0618UsageOfObsoleteMemberIssue

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp.Refactoring/CodeIssues/Custom/CompilerErrors/CS0618UsageOfObsoleteMemberIssue.cs

@@ -72,6 +72,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				var attr = member.Attributes.FirstOrDefault(a => a.AttributeType.Name == "ObsoleteAttribute" && a.AttributeType.Namespace == "System");
 				if (attr == null)
 					return;
+				var message = attr.PositionalArguments.SingleOrDefault(arg => !arg.IsError && arg.ConstantValue is string);
+				if (message != null)
+					AddIssue(new CodeIssue(nodeToMark, string.Format(ctx.TranslateString("'{0}' is obsolete: '{1}'"), member.FullName, message.ConstantValue)));
+				else
 					AddIssue(new CodeIssue(nodeToMark, string.Format(ctx.TranslateString("'{0}' is obsolete"), member.FullName)));
 			}