Missing partial modifier on declaration of type 'Program'

Question

I started a project with the new console template that uses top level statements, but I wanted to add Program Main back in anyway.

However, when I add in the class like this:

// See https://aka.ms/new-console-template for more information
Console.WriteLine("Hello, World!");

public class Program
{
    public static void Main()
    {
        Console.WriteLine("Hello World");
    }
}

I get the error:

error CS0260: Missing partial modifier on declaration of type 'Program';
Another partial declaration of this type exists

Other stack overflow questions say to just add partial, but when I do that, I get the error:

warning CS7022: The entry point of the program is global code; 
ignoring 'Program.Main()' entry point

What's going on here?

Answer 1

The problem was I forgot to remove the Console.WriteLine at the top as well.

Top level statements (added in C#9) will "compile down" into their own compiler generated Program class.

You can use sharplab to inspect the following code:

Console.WriteLine("Hello World");

Which will be compiled into something that looks like this:

[CompilerGenerated]
internal class Program
{
    private static void <Main>$(string[] args)
    {
        Console.WriteLine("Hello World");
    }
}

So you have to get rid of your top level statements if you want to use Program.Main (and vice versa).

There can only be one entry point