Not sure .. is this a bug?

[Downs]

import std.stdio;

class foo { int e; abstract const void bar(); }

class bug: foo { void bar() { writefln("I NOW CHANGEZ TEH OBJECTS"); e=5; } }

void main() {
  const(bug) okay=new bug;
  // okay.bar; fails as expected
  const(foo) Bug=cast(foo)okay;
  Bug.bar; // interestingly works.
}

>From my POV, the Bug.bar is modifying data it shouldn't be able to modify, but then again, I'm rather new to the whole constness thing. So, is this a bug?
 -- downs