c# - Bug in the string comparing of the .NET Framework

Question

It's a requirement for any comparison sort to work that the underlying order operator is transitive and antisymmetric.

In .NET, that's not true for some strings:

static void CompareBug()
{
  string x = "u002Du30A2";  // or just "-ア" if charset allows
  string y = "u3042";        // or just "あ" if charset allows

  Console.WriteLine(x.CompareTo(y));  // positive one
  Console.WriteLine(y.CompareTo(x));  // positive one
  Console.WriteLine(StringComparer.InvariantCulture.Compare(x, y));  // positive one
  Console.WriteLine(StringComparer.InvariantCulture.Compare(y, x));  // positive one

  var ja = StringComparer.Create(new CultureInfo("ja-JP", false), false);
  Console.WriteLine(ja.Compare(x, y));  // positive one
  Console.WriteLine(ja.Compare(y, x));  // positive one
}

You see that x is strictly greater than y, and y is strictly greater than x.

Because x.CompareTo(x) and so on all give zero (0), it is clear that this is not an order. Not surprisingly, I get unpredictable results when I Sort arrays or lists containing strings like x and y. Though I haven't tested this, I'm sure SortedDictionary<string, WhatEver> will have problems keeping itself in sorted order and/or locating items if strings like x and y are used for keys.

Is this bug well-known? What versions of the framework are affected (I'm trying this with .NET 4.0)?

EDIT:

Here's an example where the sign is negative either way:

x = "u4E00u30A0";         // equiv: "一?"
y = "u4E00u002Du0041";   // equiv: "一-A"

question from:https://stackoverflow.com/questions/13254153/bug-in-the-string-comparing-of-the-net-framework