[Mono-bugs] [Bug 481621] NRE thrown when trying to remove null element (not null LinkedListNode element)

[bugzilla_noreply at novell.com]

https://bugzilla.novell.com/show_bug.cgi?id=481621

User andyhume32 at yahoo.co.uk added comment
https://bugzilla.novell.com/show_bug.cgi?id=481621#c2


Andy Hume <andyhume32 at yahoo.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andyhume32 at yahoo.co.uk




--- Comment #2 from Andy Hume <andyhume32 at yahoo.co.uk>  2009-03-09 03:35:19 MST ---
But (T)null is a valid value to add, so it's a valid value to remove as well,
see test below.  So the fix should instead be something like the following. 
Are there a pile more tests needed however?

[[
--- D:\Temp\LinkedList.cs-revBASE.svn001.tmp.cs    Mon Mar  9 09:28:13 2009
+++
D:\cygwin\usr\src\mono\mcs\class\System\System.Collections.Generic\LinkedList.cs
   Mon Mar  9 09:25:59 2009
@@ -235,7 +235,7 @@
                 return null;
             do
             {
-                if ( (value == null && node.Value == null) || value.Equals
(node.Value))
+                if ( (value == null && node.Value == null) || (value != null
&& value.Equals (node.Value)))
                     return node;
                 node = node.forward;
             }
]]


[[
using System;
using System.Collections.Generic;


class LinkedListAddRemoveNull {
    static int Main()
    {
        Play();
        return Test();
    }

    static int Test()
    {
            LinkedList <object> l = new LinkedList<object> ();
            l.AddLast ((object)null);
            bool success = l.Remove ((object)null);
            Console.WriteLine (success.ToString());
            return success ? 1 : 0;
    }

    static void Play()
    {
        var li = new LinkedList<string> ();
        li.AddLast((string)null);
        li.AddLast("abcd");
        li.AddLast((string)null);
        li.AddLast("efgh");
        Dump(li);
        Console.WriteLine();
        PrintBoolean(
            li.Remove((string)null));
        Dump(li);
        Console.WriteLine();
        PrintBoolean(
            li.Remove((string)null));
        Dump(li);
        Console.WriteLine();
        PrintBoolean(
            li.Remove((string)null));
        Dump(li);
        Console.WriteLine();
    }

    static void PrintBoolean(bool value)
    {
        Console.WriteLine("bool = {0}", value);
    }

    static void Dump(System.Collections.IEnumerable eable)
    {
       foreach (object cur in eable) {
           if (cur == null)
               Console.Write("(null), ");
           else
               Console.Write("'{0}', ", cur);
       }
       Console.WriteLine();
    }
}
]]

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