Generate binding without tokio dependency

[dikatok]

Hi @fzyzcjy, if I only have synchronous-only apis in rust, is it possible to remove tokio dependency from the generated binding?

[fzyzcjy]

Sure, I think so. Maybe try remove that feature and see whether it works

[dikatok]

@fzyzcjy sorry for the late reply, I was not able to continue further because frb_generated.rs is still importing Lockable and few others with me excluding rust-async feature and having no opaque and async methods.

[fzyzcjy]

Hmm, it seems I use tokio to implement the opaque feature. If this is also not needed, maybe try to gate the code either at generation time or with rust features.

btw curious why do you not want tokio dependency? If it is (almost) not used, then I think rust will remove almost all of its code at compile time.

[dikatok]

@fzyzcjy I have already feature gated frb as follow, that is why the compiler complains as I omitted rust-async.

flutter_rust_bridge = { version = "=2.10.0", default-features = false, features = [
	"anyhow",
	"dart-opaque",
	"log",
	"portable-atomic",
	"thread-pool",
	"user-utils",
	"wasm-start",
] }

I am just investigating if it is possible to remove, since the plan of the library maintainer I am creating binding for is not to depend on crate that has possibility to have security issues and instead to rely on the host language to have async feature.

Does rust compiler perform tree-shaking like javascript bundler?

[dikatok]

@fzyzcjy

Currently I fix this by having rust-async enbled 
and declaring a custom FLUTTER_RUST_BRIDGE_HANDLER that has no async executor. 
Thats fine, but I believe that this should be fixed here.

#2723 (comment)

is this a viable option?

[fzyzcjy]

Yes I think #2723 is a way to solve it, feel free to PR!