async lambda with capture ICE #127012
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C-bug
Category: This is a bug.
F-async_closure
`#![feature(async_closure)]`
I-ICE
Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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facundo-villa
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C-bug
rustbot
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It can also be triggered like this. #![feature(async_closure)]
use futures::future::join_all;
async fn fun<'a>(param: &'a u32) {
let _ = join_all((0..3).map(async |_| {
format!("{}", param)
})).await;
}
fn main() {
futures::executor::block_on(fun(&1));
} |
|
Minimized: #![feature(async_closure)]
// Only Fn and FnMut cause an ICE. FnOnce doesn't.
fn call<T>(mut f: impl FnMut() -> T) {
f(); // Discard the returned future. No await needed for ICE.
}
fn main() {
let x = 1_i32;
call(async || x);
}Error output |
|
Note: In the original code, changing |
Regression in #125259 |
bors
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Jul 2, 2024
…v-shim, r=oli-obk Fix `FnMut::call_mut`/`Fn::call` shim for async closures that capture references I adjusted async closures to be able to implement `Fn` and `FnMut` *even if* they capture references, as long as those references did not need to borrow data from the closure captures themselves. See rust-lang#125259. However, when I did this, I didn't actually relax an assertion in the `build_construct_coroutine_by_move_shim` shim code, which builds the `Fn`/`FnMut`/`FnOnce` implementations for async closures. Therefore, if we actually tried to *call* `FnMut`/`Fn` on async closures, it would ICE. This PR adjusts this assertion to ensure that we only capture immutable references in closures if they implement `Fn`/`FnMut`. It also adds a bunch of tests and makes more of the async-closure tests into `build-pass` since we often care about these tests actually generating the right closure shims and stuff. I think it might be excessive to *always* use build-pass here, but 🤷 it's not that big of a deal. Fixes rust-lang#127019 Fixes rust-lang#127012 r? oli-obk
bors
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to rust-lang-ci/rust
that referenced
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Jul 2, 2024
…v-shim, r=oli-obk Fix `FnMut::call_mut`/`Fn::call` shim for async closures that capture references I adjusted async closures to be able to implement `Fn` and `FnMut` *even if* they capture references, as long as those references did not need to borrow data from the closure captures themselves. See rust-lang#125259. However, when I did this, I didn't actually relax an assertion in the `build_construct_coroutine_by_move_shim` shim code, which builds the `Fn`/`FnMut`/`FnOnce` implementations for async closures. Therefore, if we actually tried to *call* `FnMut`/`Fn` on async closures, it would ICE. This PR adjusts this assertion to ensure that we only capture immutable references in closures if they implement `Fn`/`FnMut`. It also adds a bunch of tests and makes more of the async-closure tests into `build-pass` since we often care about these tests actually generating the right closure shims and stuff. I think it might be excessive to *always* use build-pass here, but 🤷 it's not that big of a deal. Fixes rust-lang#127019 Fixes rust-lang#127012 r? oli-obk
saethlin
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rustc --version --verbose:Error output
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