Type mismatch with async block to `dyn Future` coercion

[Veykril]

use core::future::Future;
use core::pin::Pin;

// expected Pin<Box<dyn Future<Output = ()> + Send, Global>>, found Pin<Box<impl Future<Output = ()>, Global>>
fn send() -> Pin<Box<dyn Future<Output = ()> + Send + 'static>> {
    Box::pin(async move {})
}

// expected Pin<Box<dyn Future<Output = ()>, Global>>, found Pin<Box<impl Future<Output = ()>, Global>>
fn not_send() -> Pin<Box<dyn Future<Output = ()> + 'static>> {
    Box::pin(async move {})
}

high priority as this affects all uses of async_trait

[kpreid]

Possibly-the-same-bug appears without async and Future: this code

fn foo() {
    let a = noise::Value::new();
    let b: noise::ScaleBias<'_, [f64; 2]> = noise::ScaleBias::new(&a).set_bias(1.0);
}

(with noise = "0.7.0") produces the false error expected &dyn NoiseFn<[f64; 2]>, found &Value. I haven't found a way to reproduce it with a simple locally-defined trait, though.

[Emilgardis]

is there a way to locally disable the check for cases where this hits?

[lnicola]

@Emilgardis not right now. Only per-project.

[BlackDex]

Isn't this fixed already?
The current latest nightly version works for me without any issues.

[flodiebold]

The error mentioned in the issue is still showing up, and so is the noise error.

[arilotter]

Any pointers on getting started on this bug? It's a major blocker for my Rust development use case - I can't use RA at all for work until this is fixed, and have to rely on cargo watch. Would love to help fix it.

[lnicola]

@arilotter this diagnostic is opt-in in newer RA versions.

[kpreid]

@lnicola Where is that controlled? I'm still getting the false error and I've checked my user and workspace VSCode settings.json for rust-analyzer settings that sound related to this, and I don't see any.

[flodiebold]

It's rust-analyzer.diagnostics.enableExperimental.

[kpreid]

I don't have that setting enabled. I'm on r-a extension v0.2.1040 server 5dce1ff02 2022-05-02 stable, and my settings files contain only the following r-a settings:

{
    "rust-analyzer.inlayHints.parameterHints": false,
    "rust-analyzer.inlayHints.maxLength": 5,
    "rust-analyzer.inlayHints.typeHints": false,
    "rust-analyzer.diagnostics.disabled": [
        "missing-unsafe"
    ],
    "rust-analyzer.inlayHints.enable": false
}

{
    "rust-analyzer.cargo.allFeatures": true,
    "rust-analyzer.assist.importPrefix": "crate",
    "rust-analyzer.checkOnSave.command": "clippy",
    "rust-analyzer.checkOnSave.allTargets": true,
    "rust-analyzer.assist.importGranularity": "module"
}