Tracking issue for planned features we may want to use

[lilizoey]

Some unstable or planned rust or godot features may be useful to us when they are stabilized/implemented.

Rust

• c string literals, this may simplify/optimize creation of stringy types. currently planned for stabilization in rust 1.77
• diagnostic::on_unimplemented, this would let us customize some error messages emitted by the compiler in our proc macros. currently planned for stabilization in rust 1.78.
• arbitrary self types, this would let us simplify some method calls by for instance not needing Deref for Gd<Object> to Object

Godot

• static type hints for dictionary, might allow using Dictionary more like HashMap<K,V>
• nullable builtin types, would provide a cleaner mapping of types like Option<Vector2>
• structs in godot, may provide an alternative representation of structs in godot
• trait system, we might be able to expose a rust trait to godot using this

[Bromeon]

Thanks! It seems like C string literals and on_unimplemented are happening soon enough, but arbitrary self types are nowhere and I wouldn't make anything dependent on them.

We should only track features that are planned to be implemented in the near future, to avoid unbounded and perpetually open issues. We can always create new issues, should arbitrary self types ever get into the language.

On the Godot side, I'd expect typed dictionaries and nullable types to also happen relatively soon (4.4), with structs and traits being a bit further out. But Godot has a significantly better track record on getting things done than Rust (of course also a bit lower stakes) 😉

[Bromeon]

C string literals are now stable, as of Rust 1.77.0 release.

[Bromeon]

We can probably look into typed dictionaries it for v0.5, but we need to first decide on the OutArray problem (previous attempt in #806).

Implemented diagnostic::on_unimplemented in #692 and C strings in #652. Arbitrary self types might or might not ever see the light of day, but we can add a dedicated issue once there's something actionable. Same for potential Godot features (traits, structs, nullable types) -- they should be considered on a case-by-case basis, once they're implemented upstream.