PhobosWatch: manifest => enum

[Walter Bright]

Janice Caron wrote:
> On 12/28/07, Walter Bright <newshound1 at digitalmars.com> wrote:
>> Janice Caron wrote:
>>> y is a /copy/ of x, and clearly it should be possible to make a copy
>>> of a const thing and have the copy be mutable.
>> That doesn't work for structs or classes.
> 
> It doesn't? For structs
> 
>     struct S {}
>     const S x;
>     auto y = x;

Imagine you have:
	struct S { int* p; }
Because const is transitive, const(S) implies that now p points to 
const. But if you strip off the const in the assignment, you've lost the 
const-ness of p, and now you have a gaping hole in the const-correctness.

> Isn't
> 
>     class C {}
>     enum { C x; }
>     auto y = x;
> 
> exactly the same problem?

No, because y will be of type C and will have the value null.

>> Just for fun, how would we define a tail const member function?
> 
> Yeah, I agreed, it wouldn't work for classes. Still don't see any
> problem for structs though.

You'd need tail const member functions for structs, too.