Implicit @Safe Resources

[Paul Backus]

On Sunday, 3 September 2023 at 14:15:42 UTC, Menshikov wrote:
> Hi all.
> I'm currently doing OpenGL type binding, and I noticed one 
> assumption in the @safe code.
> @safe, scope work only with explicit reference types, if your 
> structure does not have such fields, then checks do not work.
> In opengl, and in other APIs, we work with resources not 
> through memory references, but through an integer descriptor.
>
> ```d
> @safe:
>
> struct BufferView {
>   GLuint id;
>
>   //...
>
>   void destroy() @trusted scope {
>     //...
>   }
> }
> ```

This is one of the problems [DIP 1035's][1] @system variables 
were designed to solve:

```d
struct BufferView {
     @system GLuint id

     //...
}
```

When compiling with `-preview=systemVariables`, Variables with 
the @system cannot be accessed from @safe code, and are protected 
against accidental corruption via aliasing, unions, and so on 
(like how built-in reference types are protected).

[1]: 
https://github.com/dlang/DIPs/blob/master/DIPs/accepted/DIP1035.md