typedef, implicit cast, bug or feature?

[Anders Runesson]

I'm not sure if this is me missing something, or if it's a bug:

********
import std.stdio;

class BaseClass {
        int BaseProp() { return 1; }
}

typedef BaseClass ClassTypedef;

void testfunc(ClassTypedef t) {    writefln(t.BaseProp());   }
*************

this gives the compiler message:

test.d(9): this for BaseProp needs to be type BaseClass not type
ClassTypedef

The docs say that typedefs can be implicitly cast to their underlying
type, so why can't t be used as a BaseClass reference? Seems like a bug
to me.
/Anders