Closed
Description
I tried this code:
use std::{future::Future, pin::Pin};
trait Handler<R> {
type Resp;
type Future: Future<Output = Self::Resp> + Send + 'static;
fn call(self) -> Self::Future;
}
impl<R, F, Res, Fut> Handler<R> for F
where
Res: 'static,
Fut: Future<Output = Res> + Send,
F: FnOnce() -> Fut + Send + Clone + 'static,
{
type Resp = Res;
type Future = Pin<Box<dyn Future<Output = Self::Resp> + Send>>;
fn call(self) -> Self::Future {
Box::pin(async move {
let res = self().await;
res
})
}
}
fn require_handler<H: Handler<()>>(h: H) {}
async fn handler() -> () {
let a = &1 as *const i32;
async {}.await;
}
fn main() {
require_handler(handler)
}I expected to see this happen:
build failed, because this future doesn't implement Send, so this function shouldn't implement Handler
error: future cannot be sent between threads safely
--> src/main.rs:35:21
|
35 | require_handler(handler)
| ^^^^^^^ future returned by `handler` is not `Send`
|
= help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*const i32`
note: future is not `Send` as this value is used across an await
--> src/main.rs:31:13
|
30 | let a = &1 as *const i32;
| - has type `*const i32` which is not `Send`
31 | async {}.await;
| ^^^^^^ await occurs here, with `a` maybe used later
32 | }
| - `a` is later dropped here
note: required by a bound in `require_handler`
--> src/main.rs:27:23
|
27 | fn require_handler<H: Handler<()>>(h: H) {}
| ^^^^^^^^^^^ required by this bound in `require_handler`
Instead, this happened:
build pass
Meta
rustc --version --verbose:
rustc 1.70.0-nightly (e3dfeeaa4 2023-03-07)
binary: rustc
commit-hash: e3dfeeaa45f117281b19773d67f3f253de65cee1
commit-date: 2023-03-07
host: aarch64-apple-darwin
release: 1.70.0-nightly
LLVM version: 15.0.7
Backtrace
<backtrace>
this bug is introduced by this PR #103695.