c# - What does "DisplayClass" name mean when calling lambda?

Question

According to this answer when code uses local variables from inside lambda methods the compiler will generate extra classes that can have name such as c__DisplayClass1. For example the following (completely useless) code:

class Program
{
    static void Main()
    {
        try {
            implMain();
        } catch (Exception e) {
            Console.WriteLine(e.ToString());
        }
    }

    static void implMain()
    {
        for (int i = 0; i < 10; i++) {
            invoke(() => {
                Console.WriteLine(i);
                throw new InvalidOperationException();
            });
        }
    }
    static void invoke(Action what)
    {
        what();
    }
}

outputs the following call stack:

System.InvalidOperationException
at ConsoleApplication1.Program.<>c__DisplayClass2.<implMain>b__0()
at ConsoleApplication1.Program.invoke(Action what)
at ConsoleApplication1.Program.implMain()
at ConsoleApplication1.Program.Main()

Note that there's c__DisplayClass2 in there which is a name of a class generated by the compiler to hold the loop variable.

According to this answer c__DisplayClass "means"

c --> anonymous method closure class ("DisplayClass")

Okay, but what does "DisplayClass" mean here?

What does this generated class "display"? In other words why is it not "MagicClass" or "GeneratedClass" or any other name?

Answer 1

From an answer to a related question by Eric Lippert:

The reason that a closure class is called "DisplayClass" is a bit unfortunate: this is jargon used by the debugger team to describe a class that has special behaviours when displayed in the debugger. Obviously we do not want to display "x" as a field of an impossibly-named class when you are debugging your code; rather, you want it to look like any other local variable. There is special gear in the debugger to handle doing so for this kind of display class. It probably should have been called "ClosureClass" instead, to make it easier to read disassembly.