Re: [PATCH v4 3/3] rust: error: Replace pr_warn by pr_warn_once

[jens . korinth]

> I would mention here the merits between `pr_warn_once` vs. `WARN_ONCE`
> and why the former was picked in this patch (especially since the
> `TODO` suggests the latter).

Tbh, I am not 100% whether this should be here at all. The bug is not here, it's
at the call site. It should probably be a `try_from` instead, to raise the error
there?

Jens