wasmtime / issue #5743 `bindgen!`, `async_trait` seem to ... · git-wasmtime

Stream: git-wasmtime

Topic: wasmtime / issue #5743 `bindgen!`, `async_trait` seem to ...

Wasmtime GitHub notifications bot (Feb 07 2023 at 23:33):

wasmtime::component::bindgen!({
    world: "http",
    async: true,
});

impl HttpImports for HttpState {
    async fn request(&mut self, url: String) -> anyhow::Result<String> {
        println!("url is: {}", url);
        Ok(url.clone())
    }
}

async fn eval_with_imported() -> anyhow::Result<String> {

    let mut config = Config::new();
    config.async_support(true);
    config.wasm_component_model(true);
    let engine = Engine::new(&config)?;
    let component =
        wasmtime::component::Component::from_file(&engine, "../pasm-wit/pasm-wit-component.wasm")?;

    let mut linker = wasmtime::component::Linker::new(&engine);
    Http::add_to_linker(&mut linker, |state: &mut HttpState| state)?;

    let mut store = Store::new(&engine, HttpState {});
    let (bindings, _) = Http::instantiate_async(&mut store, &component, &linker).await?;

    let res = bindings.call_mainfn(&mut store).await?;

    Ok(res)
}

fails with error:

error[E0706]: functions in traits cannot be declared `async`
  --> src/main.rs:9:1
   |
9  | / wasmtime::component::bindgen!({
10 | |     world: "http",
11 | |     async: true,
12 | | });
   | |__^ `async` because of this
   |
   = note: `async` trait functions are not currently supported
   = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

according to doc, HttpImports is supposed to have async_trait but I don't see it in cargo expand:

use wasmtime::*;
pub struct Http {
    mainfn: wasmtime::component::Func,
}
pub trait HttpImports {
    async fn request(&mut self, url: String) -> anyhow::Result<String>;
}

also posted on zulip

Wasmtime GitHub notifications bot (Feb 07 2023 at 23:33):

zarkone labeled issue #5743:

wasmtime::component::bindgen!({
    world: "http",
    async: true,
});

impl HttpImports for HttpState {
    async fn request(&mut self, url: String) -> anyhow::Result<String> {
        println!("url is: {}", url);
        Ok(url.clone())
    }
}

async fn eval_with_imported() -> anyhow::Result<String> {

    let mut config = Config::new();
    config.async_support(true);
    config.wasm_component_model(true);
    let engine = Engine::new(&config)?;
    let component =
        wasmtime::component::Component::from_file(&engine, "../pasm-wit/pasm-wit-component.wasm")?;

    let mut linker = wasmtime::component::Linker::new(&engine);
    Http::add_to_linker(&mut linker, |state: &mut HttpState| state)?;

    let mut store = Store::new(&engine, HttpState {});
    let (bindings, _) = Http::instantiate_async(&mut store, &component, &linker).await?;

    let res = bindings.call_mainfn(&mut store).await?;

    Ok(res)
}

fails with error:

error[E0706]: functions in traits cannot be declared `async`
  --> src/main.rs:9:1
   |
9  | / wasmtime::component::bindgen!({
10 | |     world: "http",
11 | |     async: true,
12 | | });
   | |__^ `async` because of this
   |
   = note: `async` trait functions are not currently supported
   = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

according to doc, HttpImports is supposed to have async_trait but I don't see it in cargo expand:

use wasmtime::*;
pub struct Http {
    mainfn: wasmtime::component::Func,
}
pub trait HttpImports {
    async fn request(&mut self, url: String) -> anyhow::Result<String>;
}

also posted on zulip

Wasmtime GitHub notifications bot (Feb 08 2023 at 17:16):

alexcrichton closed issue #5743:

wasmtime::component::bindgen!({
    world: "http",
    async: true,
});

impl HttpImports for HttpState {
    async fn request(&mut self, url: String) -> anyhow::Result<String> {
        println!("url is: {}", url);
        Ok(url.clone())
    }
}

async fn eval_with_imported() -> anyhow::Result<String> {

    let mut config = Config::new();
    config.async_support(true);
    config.wasm_component_model(true);
    let engine = Engine::new(&config)?;
    let component =
        wasmtime::component::Component::from_file(&engine, "../pasm-wit/pasm-wit-component.wasm")?;

    let mut linker = wasmtime::component::Linker::new(&engine);
    Http::add_to_linker(&mut linker, |state: &mut HttpState| state)?;

    let mut store = Store::new(&engine, HttpState {});
    let (bindings, _) = Http::instantiate_async(&mut store, &component, &linker).await?;

    let res = bindings.call_mainfn(&mut store).await?;

    Ok(res)
}

fails with error:

error[E0706]: functions in traits cannot be declared `async`
  --> src/main.rs:9:1
   |
9  | / wasmtime::component::bindgen!({
10 | |     world: "http",
11 | |     async: true,
12 | | });
   | |__^ `async` because of this
   |
   = note: `async` trait functions are not currently supported
   = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

according to doc, HttpImports is supposed to have async_trait but I don't see it in cargo expand:

use wasmtime::*;
pub struct Http {
    mainfn: wasmtime::component::Func,
}
pub trait HttpImports {
    async fn request(&mut self, url: String) -> anyhow::Result<String>;
}

also posted on zulip

Wasmtime GitHub notifications bot (Feb 23 2023 at 23:47):

Giom-fm commented on issue #5743:

Unfortunately, I have the same error. i am using
wasmtime = { git = "https://github.com/bytecodealliance/wasmtime", features = ["component-model"], branch = 'release-6.0.0' } in my cargo.toml.

When I run cargo expand I don't see anything that looks like the async_trait annotation is set correctly.

pub struct HelloWorld {
    greet: wasmtime::component::Func,
}
pub trait HelloWorldImports {
    async fn name(&mut self) -> anyhow::Result<String>;
}

My code looks like that:

wasmtime::component::bindgen!({
    path: "guest/wit",
    world: "host",
    async: true
});

struct HelloWorldState {
    name: String,
}

#[async_trait]
impl HelloWorldImports for HelloWorldState {
    async fn name(&mut self) -> Result<String> {
        Ok(self.name.clone())
    }
}

Error is:

error[E0706]: functions in traits cannot be declared `async`
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ `async` because of this
   |
   = note: `async` trait functions are not currently supported
   = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

error: method `name` should be async because the method from the trait is async
  --> src/main.rs:28:5
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__- required because the trait method is async
...
28 |       async fn name(&mut self) -> Result<String> {
   |       ^^^^^

error: future cannot be sent between threads safely
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ future created by async block is not `Send`
   |
   = help: within `[async block@src/main.rs:11:1: 15:3]`, the trait `Send` is not implemented for `impl Future<Output = std::result::Result<std::string::String, anyhow::Error>>`
note: future is not `Send` as it awaits another future which is not `Send`
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ await occurs here on type `impl Future<Output = std::result::Result<std::string::String, anyhow::Error>>`, which is not `Send`
   = note: required for the cast from `[async block@src/main.rs:11:1: 15:3]` to the object type `dyn Future<Output = std::result::Result<(std::string::String,), anyhow::Error>> + Send`
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0706`.

Wasmtime GitHub notifications bot (Feb 23 2023 at 23:52):

Giom-fm edited a comment on issue #5743:

Unfortunately, I have the same error. i am using
wasmtime = { git = "https://github.com/bytecodealliance/wasmtime", features = ["component-model"], branch = 'release-6.0.0' } in my cargo.toml.

When I run cargo expand I don't see anything that looks like the async_trait annotation is set correctly.

pub struct HelloWorld {
    greet: wasmtime::component::Func,
}
pub trait HelloWorldImports {
    async fn name(&mut self) -> anyhow::Result<String>;
}

My code looks like that:

wasmtime::component::bindgen!({
    path: "guest/wit",
    world: "host",
    async: true
});

struct HelloWorldState {
    name: String,
}

#[async_trait]
impl HelloWorldImports for HelloWorldState {
    async fn name(&mut self) -> Result<String> {
        Ok(self.name.clone())
    }
}

Error is:

error[E0706]: functions in traits cannot be declared `async`
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ `async` because of this
   |
   = note: `async` trait functions are not currently supported
   = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

error: method `name` should be async because the method from the trait is async
  --> src/main.rs:28:5
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__- required because the trait method is async
...
28 |       async fn name(&mut self) -> Result<String> {
   |       ^^^^^

error: future cannot be sent between threads safely
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ future created by async block is not `Send`
   |
   = help: within `[async block@src/main.rs:11:1: 15:3]`, the trait `Send` is not implemented for `impl Future<Output = std::result::Result<std::string::String, anyhow::Error>>`
note: future is not `Send` as it awaits another future which is not `Send`
  --> src/main.rs:11:1
   |
11 | / wasmtime::component::bindgen!({
12 | |     path: "guest/wit",
13 | |     world: "host",
14 | |     async: true
15 | | });
   | |__^ await occurs here on type `impl Future<Output = std::result::Result<std::string::String, anyhow::Error>>`, which is not `Send`
   = note: required for the cast from `[async block@src/main.rs:11:1: 15:3]` to the object type `dyn Future<Output = std::result::Result<(std::string::String,), anyhow::Error>> + Send`
   = note: this error originates in the macro `wasmtime::component::bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0706`.

Wasmtime GitHub notifications bot (Feb 23 2023 at 23:56):

bjorn3 commented on issue #5743:

The fix will be part of wasmtime 7.0.0 I think.

Wasmtime GitHub notifications bot (Feb 24 2023 at 10:02):

Giom-fm commented on issue #5743:

Ah yes you are right. A quick lookup shows that the fix is currently only on the main branch.
Thanks!

Last updated: Oct 23 2024 at 20:03 UTC