internal compiler error when copying borrow of leaked Box into async move closure for FutureExt::then

[Pr0methean]

Summary

Reproducer

I tried to run cd main && cargo clippy against Pr0methean/OcHd-RustBuild@5a9dee8. The code near where the error arose is:

        let max_colors = Box::leak(Box::new(pixels + 1));
        let image_task = self.add_to(ctx, side_length);
        let wrapped_task = task.then(async move |mut uncapped: SimpleArcow<ColorDescription>| {
            uncapped.cap_indexed(*max_colors, image_task).await;
            uncapped
        })
        .boxed()
        .shared();

The error I get is

error: internal compiler error: broken MIR in DefId(0:642 ~ ochd[a7c9]::image_tasks::task_spec::{impl#15}::get_color_description_task::{closure#6}) (bb0[0]): equate_normalized_input_or_output: `Coroutine(DefId(0:643 ~ ochd[a7c9]::image_tasks::task_spec::{impl#15}::get_color_description_task::{closure#6}::{closure#0}), [i32, std::future::ResumeTy, (), image_tasks::cloneable::Arcow<'?2, image_tasks::task_spec::ColorDescription, image_tasks::task_spec::ColorDescription>, CoroutineWitness(DefId(0:643 ~ ochd[a7c9]::image_tasks::task_spec::{impl#15}::get_color_description_task::{closure#6}::{closure#0}), []), (image_tasks::cloneable::Arcow<'?1, image_tasks::task_spec::ColorDescription, image_tasks::task_spec::ColorDescription>, &'?3 mut usize, futures_util::future::Shared<std::pin::Pin<std::boxed::Box<dyn [Binder(Trait(futures_util::Future), []), Binder(Projection(ExistentialProjection { def_id: DefId(2:44307 ~ core[3b7f]::future::future::Future::Output), args: [], term: Term::Ty(image_tasks::cloneable::Arcow<'?4, image_tasks::MaybeFromPool<resvg::tiny_skia::Pixmap>, image_tasks::MaybeFromPool<resvg::tiny_skia::Pixmap>>) }), []), Binder(AutoTrait(DefId(2:31925 ~ core[3b7f]::marker::Send)), [])] + '?5, std::alloc::Global>>>)])==Coroutine(DefId(0:643 ~ ochd[a7c9]::image_tasks::task_spec::{impl#15}::get_color_description_task::{closure#6}::{closure#0}), [i32, std::future::ResumeTy, (), image_tasks::cloneable::Arcow<'?20, image_tasks::task_spec::ColorDescription, image_tasks::task_spec::ColorDescription>, CoroutineWitness(DefId(0:643 ~ ochd[a7c9]::image_tasks::task_spec::{impl#15}::get_color_description_task::{closure#6}::{closure#0}), []), (image_tasks::cloneable::Arcow<'?21, image_tasks::task_spec::ColorDescription, image_tasks::task_spec::ColorDescription>, &'?22 usize, futures_util::future::Shared<std::pin::Pin<std::boxed::Box<dyn [Binder(Trait(futures_util::Future), []), Binder(Projection(ExistentialProjection { def_id: DefId(2:44307 ~ core[3b7f]::future::future::Future::Output), args: [], term: Term::Ty(image_tasks::cloneable::Arcow<'?23, image_tasks::MaybeFromPool<resvg::tiny_skia::Pixmap>, image_tasks::MaybeFromPool<resvg::tiny_skia::Pixmap>>) }), []), Binder(AutoTrait(DefId(2:31925 ~ core[3b7f]::marker::Send)), [])] + '?24, std::alloc::Global>>>)])` failed with `NoSolution`
    --> src/image_tasks/task_spec.rs:1159:38
     |
1159 |           let wrapped_task = task.then(async move |mut uncapped: SimpleArcow<ColorDescription>| {
     |  ______________________________________^
1160 | |             uncapped.cap_indexed(*max_colors, image_task).await;
1161 | |             uncapped
1162 | |         })
     | |_________^
     |
note: delayed at compiler/rustc_borrowck/src/type_check/input_output.rs:213:17
         0: std::backtrace::Backtrace::create
         1: std::backtrace::Backtrace::capture
         2: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         3: <rustc_errors::DiagCtxt>::emit_diagnostic
         4: <rustc_errors::diagnostic::DiagnosticBuilder>::emit_producing_error_guaranteed
         5: <rustc_borrowck::type_check::TypeChecker>::equate_normalized_input_or_output
         6: rustc_borrowck::type_check::type_check
         7: rustc_borrowck::nll::compute_regions
         8: rustc_borrowck::do_mir_borrowck
         9: rustc_borrowck::mir_borrowck
        10: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        11: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        12: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        13: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        14: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
        15: <rustc_borrowck::type_check::TypeChecker>::prove_closure_bounds
        16: <rustc_borrowck::type_check::TypeChecker>::check_rvalue
        17: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
        18: rustc_borrowck::type_check::type_check
        19: rustc_borrowck::nll::compute_regions
        20: rustc_borrowck::do_mir_borrowck
        21: rustc_borrowck::mir_borrowck
        22: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        23: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        24: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        25: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        26: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}
        27: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
        28: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#1}>
        29: rustc_interface::passes::analysis
        30: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        31: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
        32: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        33: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        34: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        35: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
        36: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}::{closure#0}>
        37: rustc_span::create_session_globals_then::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}>
        38: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        39: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        40: std::sys::pal::unix::thread::Thread::new::thread_start
        41: __pthread_start
    --> src/image_tasks/task_spec.rs:1159:38
     |
1159 |           let wrapped_task = task.then(async move |mut uncapped: SimpleArcow<ColorDescription>| {
     |  ______________________________________^
1160 | |             uncapped.cap_indexed(*max_colors, image_task).await;
1161 | |             uncapped
1162 | |         })
     | |_________^

Version

hennickc@f8ffc25e7f6e main % rustc -Vv
rustc 1.78.0-nightly (ef324565d 2024-02-27)
binary: rustc
commit-hash: ef324565d071c6d7e2477a195648549e33d6a465
commit-date: 2024-02-27
host: x86_64-apple-darwin
release: 1.78.0-nightly
LLVM version: 18.1.0

Reproducer

I tried this code:

<code>

I expected to see this happen:

Instead, this happened:

Version

No response

Additional Labels

No response

[Pr0methean]

BTW: I also consider it a bug that I couldn't simply move pixels into the closure without Box::new or Box::leak, since it's of type usize and therefore Copy. Another similar bug seems to be happening a short distance above, which I worked around using Arc::new:

                let bg_task = background.get_color_description_task(ctx);
                let fg_task = foreground.get_color_description_task(ctx);
                let bg_and_fg = join_all([bg_task, fg_task]);
                bg_and_fg.then(async move |mut bg_and_fg: Vec<SimpleArcow<ColorDescription>>| {
                    let fg = bg_and_fg.pop().unwrap();
                    let bg = bg_and_fg.pop().unwrap();
                    let max_colors = Arc::new(pixels + 1);
                    Arcow::from_owned(fg
                        .stack_on(&bg, *max_colors))
                }).boxed()

[Pr0methean]

Confirmed that this also happens on the latest nightly version:

rustc 1.79.0-nightly (c9f8f3438 2024-03-27)
binary: rustc
commit-hash: c9f8f3438a8134a413aa5d4903e0196e44e37bbc
commit-date: 2024-03-27
host: x86_64-apple-darwin
release: 1.79.0-nightly
LLVM version: 18.1.2

[y21]

@Pr0methean this looks more like a bug in the compiler rather than clippy, does this happen with cargo check too? Would like confirmation before moving it it over.

[Pr0methean]

Yes, it does happen with cargo check; output is attached.
cargo check errors.txt