hm, the moment of pressing the "send" button is often enough a moment of enlightment :)
version( D_Version2 ){
mixin("invariant(T)[] _idup(T)( T[] str ){ return str.idup; }");
} else { // D1
String _idup( char[] str ){
return str.dup;
}
}
str._idup(); // compiles with D1+D2
