Use `rustversion` crate instead of `stable` flag about leptos HOT 11 CLOSED

It actually seems like rustversion can't accommodate conditionally enabling features?

I can't get this to work
#![rustversion::attr(nightly, feature(unboxed_closures))]

as opposed to
#![cfg_attr(not(feature = "stable"), feature(unboxed_closures))]

@akesson I think you suggested this possibility — any thoughts? I may be doing it wrong.

from leptos.

But rustversion can enable/disable an arbitrary amount of code, right? So, what about this?

#[rustversion::nightly]
#![feature(unboxed_closures)]

from leptos.

The problem is that that's an outer attribute wrapping an inner attribute, which is not possible. See this issue.

from leptos.

I'm not sure what you want to achieve with:
#![rustversion::attr(nightly, feature(unboxed_closures))]

Use nightly, but only if feature unboxed_closures is not available on stable?

Wouldn't simply #[rustversion::nightly] suffice? When the feature is available on stable, the condition would have to be removed manually.

from leptos.

Actually, shouldn't it be: #[rustversion::attr(nightly, feature(unboxed_closures))], without the exclamation mark?

from leptos.

If you do #[rustversion::attr(nightly, feature(unboxed_closures))] then the compiler interprets it as an annotation of mod context rather than of the crate.

from leptos.

Here's an idea: add the required #![feature] using a build script. For all other things, use rustversion. That's hacky but at least you don't have to use a stable feature flag

from leptos.

Actually, in this case.. it's much better to enable the stable feature flag in the build script, with this, and people that depend on leptos won't have to set this flag. (or maybe it can enable feature = unboxed_closures directly?)

from leptos.

@dlight This seems like a good idea but I'll admit I don't quite know how to do this. If you could give a pointer (or even better a PR) I'd be really grateful.

from leptos.

How about using rustc_version for automatically setting the stable feature?

I did a test and it seems to work well.

I can do a PR, but probably best to wait for #44 to be merged because there will be Cargo.toml merge conflicts.

from leptos.

I think this should finally be fixed by #148. stable feature still exists but is now automatically enabled if you're on stable Rust.

from leptos.