Prevent global CallError tracker from growing indefinitely

[Bromeon]

Implements a ring buffer to limit the number of simultaneously available CallError instances. Hands out IDs and guarantees that IDs become invalid once the slot is overwritten.

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-798

[lilizoey]

Just been going back through PRs i didnt get a chance to look at but just fyi you can do this now:

[const { None }; N]

[Bromeon]

Oh, this is great to know, thanks! I was looking for alternative patterns but couldn't find this, maybe too recent 🙂

Will introduce as a drive-by-commit somewhere 👍

[Bromeon]

Unfortunately with vec![...] it doesn't work:

error: no rules expected the token `const`
  --> godot-core/src/private.rs:53:31
   |
53 |             ring_buffer: vec![const { None }; Self::MAX_ENTRIES as usize],
   |                               ^^^^^ no rules expected this token in macro call
   |
   = note: while trying to match end of macro

And directly None caused the original error:

error[E0277]: the trait bound `Option<call_error::CallError>: Clone` is not satisfied
    --> godot-core/src/private.rs:53:32
     |
53   |             ring_buffer: vec![ None; Self::MAX_ENTRIES as usize],
     |                          ------^^^^-----------------------------
     |                          |     |
     |                          |     the trait `Clone` is not implemented for `Option<call_error::CallError>`
     |                          required by a bound introduced by this call
     |
     = note: required for `Option<call_error::CallError>` to implement `Clone`

---

What does work is this, but then again that's not really better than the current code:

            ring_buffer: [const { None }; Self::MAX_ENTRIES as usize]
                .into_iter()
                .collect(),

[lilizoey]

can't you just do .into()?

[Bromeon]

I thought I tried that, but probably made a mistake. That works, thanks! 🙂