Discussion Thread: DIP 1035-- at system Variables--Community Review Round 2

[Paul Backus]

On Tuesday, 2 March 2021 at 20:46:17 UTC, Atila Neves wrote:
> Pointer types *can* be unsafe, if the values came from @system 
> code. Otherwise they're perfectly safe. Slices (dynamic arrays) 
> are slightly different because of the necessity of bounds 
> checks. But deferencing a pointer is fine in @safe code - the 
> possibilities are:
>
> * it came from the GC.
> * is the address of a module-level variable.
> * is a scoped address on the stack.
> * is null.
>
> Am I missing a case?

You are conflating types and values. Pointer *values* can be 
either safe or unsafe, depending on what they point to. Pointer 
*types* are always unsafe, because they include both safe and 
unsafe values.