On Borrow Checking

[Manu]

On Mon, 12 May 2025 at 21:10, Richard (Rikki) Andrew Cattermole via
Digitalmars-d <digitalmars-d at puremagic.com> wrote:

> On 12/05/2025 10:55 PM, Manu wrote:
> > `scope` shouldn't depend on @safe, and Walter above said it depended
> > only on -dip1000.
> > So, if it only works with @safe, I repeat again; WHY? It's not only
> > redundant annotation, but it's also a ticking bomb waiting to explode...
> > I already commented on this.
>
> @safe is the static analysis on a function that the compiler guarantees
> is memory safe.
>

`scope` has nothing to do with @safe. I want to prohibit the callee
retaining the argument; simple as that.

@trusted is the escape hatch where you have to do something that the
> compiler cannot make guarantees for.
>

This has nothing to do with @safe.

@system has no guarantees associated with it.
>
> All scope says is that this variable will not escape this function.


Exactly. Nothing to do with @safe.

It does not have any kind of ownership properties.
>

Correct.

It is not redundant information, it does serve an important purpose in
> escape analysis.
>

Incorrect.

When you see no attributes, think unknown escape behavior, it is not
> modeled. Not, this doesn't escape, or it escapes into an unknown
> location. These are all different things.
>

Okay, I'll repeat for the 3rd time or so; when `scope` is annotated to an
argument, it MUST have effect, otherwise an escape related crash is
inevitable that the user intended to prevent, and when they start debugging
and trying to track down the issue; they will see the `scope` annotation,
assume it's not that, then move on to continue looking in the wrong place
for their issue.

`scope` has nothing to do with @safe, and it MUST work in its own right,
otherwise the code is lying to the author, and it's an effective liability.
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