Use Locked constructor instead of into

[stargazing-dino]

I don't know why but when I was building this lib for my little micro controller in no_std, I was getting this error:

error[E0277]: the trait bound `RwLock<StringsInterner>: core::convert::From<StringsInterner>` is not satisfied
  --> /Users/katzen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rhai-1.19.0/src/api/mod.rs:66:68
   |
66 |             self.interned_strings = Some(StringsInterner::new(max).into());
   |                                                                    ^^^^ the trait `core::convert::From<StringsInterner>` is not implemented for `RwLock<StringsInterner>`, which is required by `StringsInterner: core::convert::Into<_>`
   |
   = note: required for `StringsInterner` to implement `core::convert::Into<RwLock<StringsInterner>>`

So I tried just pulling in the Locked type and using that instead. Seemed to fix things.

Here is my a snippet of my dependency list if it's interesting:

[dependencies]
# TODO: had to add this because rhai isn't requesting a feature it relies on.
once_cell = { version = "1.19.0", default-features = false, features = [
    "alloc",
] }
# https://rhai.rs/book/start/builds/minimal.html
rhai = { version = "1.19.0", default-features = false, features = [
    "no_std",
    "sync",
    "only_i32",
    "f32_float",
    "no_custom_syntax",
    "no_time",
] }

[schungx]

It could be that RwLock in no-std has some compatibility issues...

However we have been liberally using .into() everywhere so I wonder why it only trips up here...

BTW which microcontroller are you building for? We don't have many examples of no-std builds and I'd love if you can share some snippets.

Also the need for once_cell/alloc is for your own code, correct? Thats because it doesnt seem to require it in a normal no-std build.

[stargazing-dino]

Yeah, honestly no clue why it tripped up here. Once I get home I'll try again from scratch and see if anything changes. Might've been a temporary thing. I did make sure to update cargo/rust though and my dependencies to latest.

The once_cell thing came from #869 and I don't think it's actually needed. I removed it yesterday and it didn't have a hiccup but at one point it did fix a similar issue for me.

I am using an nrf52. Not really much code as it's all spaghetti nonsense right now but I could share with you a minimal example perhaps running on a microbit v2 later this week.

[schungx]

The once_cell thing came from #869 and I don't think it's actually needed. I removed it yesterday and it didn't have a hiccup but at one point it did fix a similar issue for me.

Yeah, I remember there were some changes since then.

BTW, appreciate if you can dig out why it failed to compile on that particular line, because I can't seem to reproduce it.

[stargazing-dino]

Tried it again with a clean compile and it went through no problem. No idea why this was erroring at first :\

Anyways, I'll close this as I don't think it's needed

[jeromegn]

I'm compiling for the x86_64-unknown-none target and getting a similar issue with sync and no_std enabled when using a once_cell::sync::Lazy:

error[E0277]: the trait bound `RwLock<StringsInterner>: core::convert::From<StringsInterner>` is not satisfied
  --> /home/jerome/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rhai-1.20.0/src/api/mod.rs:66:68
   |
66 |             self.interned_strings = Some(StringsInterner::new(max).into());
   |                                                                    ^^^^ the trait `core::convert::From<StringsInterner>` is not implemented for `RwLock<StringsInterner>`
   |
   = note: required for `StringsInterner` to implement `core::convert::Into<RwLock<StringsInterner>>`

Unfortunately, cargo clean did not fix it :)

Maybe minimal repo:

#![no_std]

use once_cell::sync::Lazy;

static ENGINE: Lazy<rhai::Engine> = Lazy::new(rhai::Engine::new_raw);

fn main() {}

[dependencies]
once_cell = { version = "1.20.2", default-features = false, features = ["critical-section"] }
rhai = { version = "1.20.0", default-features = false, features = ["no_std", "sync"] }

[profile.release]
panic = "abort"

cargo build --target x86_64-unknown-none

I am running rustc 1.84.0-nightly (b91a3a056 2024-11-07)

[schungx]

This is totally strange... I'm happy to just put in the fiz, but I fear we may be masking a deeper, more subtle bug.