[Mono-devel-list] mcs generates incorrect IL-code using declarations after goto

[Simon Ask Ulsnes]

Hi,

> The following simple program compiles using mcs but doesn't run, using 
> csc  this program works with .net and mono.
>
> public class Test{
>   public static void Main(){
>     goto end;
>     int a;
>   end:
>     System.Console.WriteLine("end");
>   }
> }
>
> mcs output:
> Test.cs(4) warning CS0162: Unreachable code detected
> Compilation succeeded - 1 warning(s)
>
>
> Execution:
>
> Expected result:
> end
>
> Actual result:
> ** ERROR **: Invalid IL code at IL0000 in C:Main (): IL_0000: 
> br         IL_ffffffff

Why the heck would anybody want to do that? But anyway, it only happens 
if you have actualy unreachable code. If you do a conditional goto like 
the following:

        bool b = true;
        if (b)
        {
            goto end;
        }
        else
        {
            int a = 56;
            Console.WriteLine(a);
        }
end:
        Console.WriteLine("end");

it runs fine and error-less.

I guess Mono places the unreachable code in a wrong place (while it 
should actually just delete it from the assembly generated).

Yours,
Simon