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future miscompiling to ud2 #60709

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ambr-e opened this issue May 10, 2019 · 7 comments
Closed

future miscompiling to ud2 #60709

ambr-e opened this issue May 10, 2019 · 7 comments
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A-async-await Area: Async & Await AsyncAwait-Triaged Async-await issues that have been triaged during a working group meeting. E-needs-test Call for participation: Writing correctness tests. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@ambr-e
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ambr-e commented May 10, 2019

Using rustc 1.36.0-nightly (3991285 2019-04-25), the following test compiles to ud2, when using the following command: rustc --edition=2018 -Copt-level=z -Cdebuginfo=2 --test test.rs -o test. Both the opt-level and debuginfo are necessary to get ud2.

#![feature(async_await, await_macro)]
#![allow(unused)]

#[cfg(test)]
mod tests {
    use std::future::Future;
    use std::task::Poll;
    use std::task::Context;
    use std::pin::Pin;
    use std::rc::Rc;
    
    struct Never();
    impl Future for Never {
        type Output = ();
        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
            Poll::Pending
        }
    }

    #[test]
    fn crashing_test() {
        let fut = async {
            let _rc = Rc::new(()); // Also crashes with Arc
            await!(Never());
        };
        let _bla = fut; // Moving the future is required.
    }
}

@cramertj @tmandry

@cramertj
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This does not reproduce for me on current nightly (rustc 1.36.0-nightly (a784a8022 2019-05-09)). I wonder if some of @tmandry's generator representation work has affected this.

@Centril Centril added A-async-await Area: Async & Await E-needs-test Call for participation: Writing correctness tests. labels May 10, 2019
@Centril
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Centril commented May 10, 2019

@cramertj In that case, add it as a regression test?

@tmandry
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tmandry commented May 10, 2019

This was fixed by #59897, specifically 5a7af54. I'm not sure why, though.

@cramertj
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@tmandry possibly the inhabitedness fix?

@tmandry
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tmandry commented May 10, 2019

@cramertj I was thinking that, but Never in this example is very much inhabited.

@cramertj
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@tmandry yeah- the stack slot that it returns to is never going to be hit, though, since it's always pending. Not sure if that matters...

@nikomatsakis nikomatsakis added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. AsyncAwait-Triaged Async-await issues that have been triaged during a working group meeting. labels Jun 4, 2019
@nikomatsakis
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Marking as deferred, not blocking stabilization.

tmandry added a commit to tmandry/rust that referenced this issue Jun 14, 2019
Centril added a commit to Centril/rust that referenced this issue Jun 14, 2019
bors added a commit that referenced this issue Jun 14, 2019
Rollup of 5 pull requests

Successful merges:

 - #61704 (Pass LLVM linker flags to librustc_llvm build)
 - #61792 (Add ui test for issue 51301)
 - #61803 (typeck: small refactoring, add 'fn write_resolution')
 - #61805 (typeck: Fix ICE for blocks in repeat expr count.)
 - #61818 (Issue #60709 test)

Failed merges:

r? @ghost
Centril added a commit to Centril/rust that referenced this issue Jun 29, 2019
bors added a commit that referenced this issue Jun 29, 2019
Rollup of 7 pull requests

Successful merges:

 - #61199 (Revert "Set test flag when rustdoc is running with --test option" )
 - #61755 (Add `--pass $mode` to compiletest through `./x.py`)
 - #61818 (Issue #60709 test)
 - #62023 (publish_toolstate: don't use 'new' from inside the loop)
 - #62104 (Inform the query system about properties of queries at compile time)
 - #62163 (Avoid mem::uninitialized() in std::sys::unix)
 - #62204 (doc(libcore) Fix CS)

Failed merges:

r? @ghost
@bors bors closed this as completed in 65021ec Jun 29, 2019
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Labels
A-async-await Area: Async & Await AsyncAwait-Triaged Async-await issues that have been triaged during a working group meeting. E-needs-test Call for participation: Writing correctness tests. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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