equivariant functions ('in' = headconst!?)

[Bruno Medeiros]

Andrei Alexandrescu wrote:
> 
> You'll be glad then to learn that "in" means const at least in D2:
> 
> void foo(in char[] s); // same as foo(const(char)[] s)
> 

What??
Whoa, at first I thought you were mistaken, and meant 'const(char[]) s' 
instead (since that is what is the same as 'const char[] s'), but I 
fired up my editor and tried it out, and it works as you described! Even 
more surprising, it works the same way when using a class type:

class Foo { int x; }

void func(in Foo foo, const scope Foo foo2)
{
   foo = null; // Ok!
   //foo2 = null; //Compile error!
   //foo.x = 0;  // Compile error!
   pragma(msg, (typeof(foo)).stringof ~ " " ~ (typeof(foo2)).stringof);
}

Which means 'in' works exactly as headconst! Is this another easter egg, 
or a bug? It's certainly not according to the spec at least.

-- 
Bruno Medeiros - Software Developer, MSc. in CS/E graduate
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D