What's meaning of `<>c.<>9`? I can't find any declaration of them, where are they from?

Question

Here is an ASP.NET Core nuget package decompiled by JustDecompile, I can't understand the usage of <>c.<>9. I found that they have no declaration, it's very strange, the Nuget package name is Microsoft.Extensions.FileProviders.Physical and the class file name is PhysicalFilesWatcher.

Answer 1

This is a part of some identifier in some compiler generated code (C# does not allow developer to use < and > in identifier names, while the IL does). There are multiple language features in C# which are expanded by compiler into code, for example await's, auto-properties, yield return's, closures and others.

UPD

In this case based on my decompilation it seems that it is compiler generated code for this Action lambda:

private static readonly Action<object> _cancelTokenSource = state => ((CancellationTokenSource)state).Cancel();

Which is initialized in generated static constructor via something like this:

PhysicalFilesWatcher._cancelTokenSource = new Action<object>((object) PhysicalFilesWatcher.'<>c.<>9, __methodptr(<. cctor>b__43_0));

[CompilerGenerated]
[Serializable]
private sealed class <>c
{
  public static readonly PhysicalFilesWatcher.<>c <>9;

  static <>c()
  {
    PhysicalFilesWatcher.<>c <>9 = new PhysicalFilesWatcher.<>c();
  }

  public <>c()
  {
    base..ctor();
  }

  internal void <. cctor>b__43_0(object state)
  {
    ((CancellationTokenSource) state).Cancel();
  }
}