copying const struct

[Benjamin Thaut]

Am 14.10.2013 13:35, schrieb Jack Applegame:
> Why this doesn't compile?
>
> http://dpaste.dzfl.pl/21ef5b04
>
> class Foo {}
>
> struct Bar1 {
>      const(Foo[]) member;
> }
>
> struct Bar2 {
>      const Foo member;
> }
>
> void main() {
>      const Bar1 bar1;
>      const Bar2 bar2;
>      Bar1 b1 = bar1; // ok
>      Bar2 b2 = bar2; // cannot implicitly convert expression (bar2) of
> type const(Bar2) to Bar2
> }

Because in D const is transitive. That means if a reference is const the 
object it points to is also const. And everything that object points to 
is const, and so on.

The line "Bar2 b2 = bar2;" would remove const from "member" which does 
not happen because const is not convertible to mutable implicitly.

Kind Regards
Benjamin Thaut