Implicit conversion from class in parent class fails?

[Andrew Wiley]

On Sat, Jun 16, 2012 at 11:52 AM, Namespace <rswhite4 at googlemail.com> wrote:
> Why work this:
>
> [code]
> class Foo { }
> class Bar : Foo { }
> class Quatz : Bar { }
>
> void foo(Foo f) {
>
> }
>
> void main() {
>        Foo f = new Foo();
>        Foo f2;
>
>        foo(f);
>        foo(f2);
>
>        Bar b = new Bar();
>        Bar b2;
>
>        foo(b);
>        foo(b2);
>
>        Quatz q = new Quatz();
>        Quatz q2;
>
>        foo(q);
>        foo(q2);
> }
> [/code]
>
> but not:
>
> [code]
> import std.stdio;
>
> class Foo { }
> class Bar : Foo { }
> class Quatz : Bar { }
>
> void bar(Foo[] fs) {
>
> }
>
> void main() {
>        Foo[] fs = [new Foo()];
>        Foo[] fs2;
>
>        bar(fs);
>        bar(fs2);
>
>        Bar[] bs = [new Bar()];
>        Bar[] bs2;
>
>        bar(bs);
>        bar(bs2);
>
>        Quatz[] qs = [new Quatz()];
>        Quatz[] qs2;
>
>        bar(qs);
>        bar(qs2);
> }
> [/code]
>
> I think that should work also.

The problem is that this would also work:
 [code]
 import std.stdio;

 class Foo { }
 class Bar : Foo { }
 class Quatz : Bar { }

 void bar(Foo[] fs) {
    fs[0] = new Foo(); // <-- OH NOES
 }

void main() {
        Foo[] fs = [new Foo()];
        Foo[] fs2;

        bar(fs);
        bar(fs2);

        Bar[] bs = [new Bar()];
        Bar[] bs2;

        bar(bs);
        bar(bs2);

        Quatz[] qs = [new Quatz()];
        Quatz[] qs2;

        bar(qs);
        bar(qs2);
}
 [/code]