safety model in D

[Nick Sabalausky]

"Andrei Alexandrescu" <SeeWebsiteForEmail at erdani.org> wrote in message 
news:hcqb44$1nc9$1 at digitalmars.com...
> SafeD is, unfortunately, not finished at the moment. I want to leave in 
> place a stub that won't lock our options. Here's what we currently have:
>
> module(system) calvin;
>
> This means calvin can do unsafe things.
>
> module(safe) susie;
>
> This means susie commits to extra checks and therefore only a subset of D.
>
> module hobbes;
>
> This means hobbes abides to whatever the default safety setting is.
>
> The default safety setting is up to the compiler. In dmd by default it is 
> "system", and can be overridden with "-safe".
>
> Sketch of the safe rules:
>
> \begin{itemize*}
> \item No @cast@ from a pointer type to an integral type and vice versa
> \item No @cast@ between unrelated pointer types
> \item Bounds checks on all array accesses
> \item  No  unions  that  include  a reference  type  (array,  @class@,
>   pointer, or @struct@ including such a type)
> \item No pointer arithmetic
> \item No escape of a pointer  or reference to a local variable outside
>   its scope
> \item Cross-module function calls must only go to other @safe@ modules
> \end{itemize*}
>
> So these are my thoughts so far. There is one problem though related to 
> the last \item - there's no way for a module to specify "trusted", 
> meaning: "Yeah, I do unsafe stuff inside, but safe modules can call me no 
> problem". Many modules in std fit that mold.
>
> How can we address that? Again, I'm looking for a simple, robust, 
> extensible design that doesn't lock our options.
>

module(system, trusted) calvin;
?