ICE during async closure experiments

[chadaustin]

rustc-ice-2024-07-04T18_10_25-10188.txt

Code

Minimizing the code is nontrivial. Let me know if it is required to make a branch that reproduces the issue.

Meta

nightly-x86_64-pc-windows-msvc unchanged - rustc 1.81.0-nightly (aa1d4f682 2024-07-03)

Error output

See attached rust-ice.

[chadaustin]

Oh, here's the error message:

error: internal compiler error: compiler\rustc_middle\src\ty\mod.rs:1588:13: item_name: no name for DefPath { data: [DisambiguatedDefPathData { data: TypeNs("ChannelSender"), disambiguator: 0 }, DisambiguatedDefPathData { data: TypeNs(""
), disambiguator: 0 }], krate: crate0 }

[compiler-errors]

Minimizing the code is nontrivial. Let me know if it is required to make a branch that reproduces the issue.

Yep, I can't fix this with no code. It's not clear what the issue is from the ICE backtrace alone.

[matthiaskrgr]

you could probably fix #125099 and it would fix this one as well?

[chadaustin]

Clone the batch-channel project and check out the async-closure-autobatch:

git clone https://github.com/chadaustin/batch-channel.git
cd batch-channel
git checkout async-closure-autobatch

Then cargo check the throughput benchmark:

cargo +nightly check --bench throughput

[theemathas]

Self-contained reproduction (probably can be minimized further):

use std::future::Future;

trait AsyncCallback<A>: FnOnce(A) -> Self::Fut {
    type Fut: Future<Output = ()>;
}

impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
    type Fut = Out;
}

struct BatchSender<T>(T);

trait ChannelSender<T>: Clone + Send {
    type BatchSender;

    fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
    where
        F: for<'a> AsyncCallback<&'a mut Self::BatchSender>;
}

struct Sender<T>(T);

impl<T: Send> ChannelSender<T> for Sender<T> {
    type BatchSender = BatchSender<T>;

    fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
    where
        F: for<'a> AsyncCallback<&'a mut Self::BatchSender>,
    {
        async {}
    }
}

Error output

    Checking batch-channel v0.0.0 (/Users/timch/Documents/batch-channel)
error[E0277]: expected a `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
  --> src/lib.rs:26:5
   |
26 | /     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
27 | |     where
28 | |         F: for<'a> AsyncCallback<&'a mut Self::BatchSender>,
   | |____________________________________________________________^ expected an `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here

error[E0277]: expected a `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
  --> src/lib.rs:26:36
   |
26 |     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here
note: required by a bound in `<Sender<T> as ChannelSender<T>>::autobatch`
  --> src/lib.rs:28:12
   |
26 |     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
   |        --------- required by a bound in this associated function
27 |     where
28 |         F: for<'a> AsyncCallback<&'a mut Self::BatchSender>,
   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `<Sender<T> as ChannelSender<T>>::autobatch`

error[E0277]: the trait bound `Sender<T>: Clone` is not satisfied
  --> src/lib.rs:23:36
   |
23 | impl<T: Send> ChannelSender<T> for Sender<T> {
   |                                    ^^^^^^^^^ the trait `Clone` is not implemented for `Sender<T>`
   |
note: required by a bound in `ChannelSender`
  --> src/lib.rs:13:25
   |
13 | trait ChannelSender<T>: Clone + Send {
   |                         ^^^^^ required by this bound in `ChannelSender`

error[E0277]: the trait bound `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>` is not satisfied
  --> src/lib.rs:28:12
   |
28 |         F: for<'a> AsyncCallback<&'a mut Self::BatchSender>,
   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> FnOnce(&'a mut BatchSender<T>)` is not implemented for `F`, which is required by `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here
note: the requirement `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>` appears on the `impl`'s method `autobatch` but not on the corresponding trait's method
  --> src/lib.rs:16:8
   |
13 | trait ChannelSender<T>: Clone + Send {
   |       ------------- in this trait
...
16 |     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
   |        ^^^^^^^^^ this trait's method doesn't have the requirement `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>`

error[E0277]: the trait bound `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>` is not satisfied
  --> src/lib.rs:26:5
   |
26 | /     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
27 | |     where
28 | |         F: for<'a> AsyncCallback<&'a mut Self::BatchSender>,
   | |____________________________________________________________^ the trait `for<'a> FnOnce(&'a mut BatchSender<T>)` is not implemented for `F`, which is required by `for<'a> F: AsyncCallback<&'a mut BatchSender<T>>`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here
note: required by a bound in `ChannelSender::{synthetic#0}`
  --> src/lib.rs:18:12
   |
18 |         F: for<'a> AsyncCallback<&'a mut Self::BatchSender>;
   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ChannelSender::{synthetic#0}`

error[E0277]: expected a `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
  --> src/lib.rs:26:36
   |
26 |     fn autobatch<F>(self, f: F) -> impl Future<Output = ()> + Send
   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here

error: internal compiler error: compiler/rustc_middle/src/ty/mod.rs:1588:13: item_name: no name for DefPath { data: [DisambiguatedDefPathData { data: TypeNs("ChannelSender"), disambiguator: 0 }, DisambiguatedDefPathData { data: TypeNs(""), disambiguator: 0 }], krate: crate0 }

thread 'rustc' panicked at compiler/rustc_middle/src/ty/mod.rs:1588:13:
Box<dyn Any>
stack backtrace:
   0:        0x1052b6e30 - <std::sys::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::he7fc263c3ae60281
   1:        0x1052fa124 - core::fmt::write::he0bb149810b76b94
   2:        0x1052acf10 - std::io::Write::write_fmt::h961f49b732a1ce21
   3:        0x1052b6c88 - std::sys::backtrace::print::h805bc4620f3151a6
   4:        0x1052b9298 - std::panicking::default_hook::{{closure}}::h1847e4937d8814b8
   5:        0x1052b8f64 - std::panicking::default_hook::hd04f2dc85931a3af
   6:        0x10f15bb04 - <alloc[59dcbdbca7e8a995]::boxed::Box<rustc_driver_impl[c003af3b489365f2]::install_ice_hook::{closure#0}> as core[4a89e3a3d2972735]::ops::function::Fn<(&dyn for<'a, 'b> core[4a89e3a3d2972735]::ops::function::Fn<(&'a std[791662d3d9623b74]::panic::PanicHookInfo<'b>,), Output = ()> + core[4a89e3a3d2972735]::marker::Sync + core[4a89e3a3d2972735]::marker::Send, &std[791662d3d9623b74]::panic::PanicHookInfo)>>::call
   7:        0x1052b9e28 - std::panicking::rust_panic_with_hook::hfb7f8fd8d6ca280d
   8:        0x10f1e7dd0 - std[791662d3d9623b74]::panicking::begin_panic::<rustc_errors[924265ee8801bfcb]::ExplicitBug>::{closure#0}
   9:        0x10f1e46f0 - std[791662d3d9623b74]::sys::backtrace::__rust_end_short_backtrace::<std[791662d3d9623b74]::panicking::begin_panic<rustc_errors[924265ee8801bfcb]::ExplicitBug>::{closure#0}, !>
  10:        0x11355b278 - std[791662d3d9623b74]::panicking::begin_panic::<rustc_errors[924265ee8801bfcb]::ExplicitBug>
  11:        0x10f1c40cc - <rustc_errors[924265ee8801bfcb]::diagnostic::BugAbort as rustc_errors[924265ee8801bfcb]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:        0x10fe69648 - rustc_middle[8bc529f0e8dcc906]::util::bug::opt_span_bug_fmt::<rustc_span[68cecb55101cab86]::span_encoding::Span>::{closure#0}
  13:        0x10fe69588 - rustc_middle[8bc529f0e8dcc906]::ty::context::tls::with_opt::<rustc_middle[8bc529f0e8dcc906]::util::bug::opt_span_bug_fmt<rustc_span[68cecb55101cab86]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:        0x10fe69554 - rustc_middle[8bc529f0e8dcc906]::ty::context::tls::with_context_opt::<rustc_middle[8bc529f0e8dcc906]::ty::context::tls::with_opt<rustc_middle[8bc529f0e8dcc906]::util::bug::opt_span_bug_fmt<rustc_span[68cecb55101cab86]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:        0x1135f9e00 - rustc_middle[8bc529f0e8dcc906]::util::bug::bug_fmt
  16:        0x10fd0cfec - <rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt>::item_name
  17:        0x110bec424 - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::suggestions::TypeErrCtxtExt>::note_obligation_cause_code::<rustc_span[68cecb55101cab86]::ErrorGuaranteed, rustc_type_ir[a61c6928091218fd]::binder::Binder<rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt, rustc_type_ir[a61c6928091218fd]::predicate::TraitPredicate<rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt>>>
  18:        0x110bf3a9c - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::suggestions::TypeErrCtxtExt>::note_obligation_cause_code::<rustc_span[68cecb55101cab86]::ErrorGuaranteed, rustc_type_ir[a61c6928091218fd]::binder::Binder<rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt, rustc_type_ir[a61c6928091218fd]::predicate::TraitPredicate<rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt>>>::{closure#6}
  19:        0x110bf1b38 - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::suggestions::TypeErrCtxtExt>::note_obligation_cause_code::<rustc_span[68cecb55101cab86]::ErrorGuaranteed, rustc_middle[8bc529f0e8dcc906]::ty::predicate::Predicate>
  20:        0x110c04f60 - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt>::note_obligation_cause
  21:        0x110bfce1c - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::type_err_ctxt_ext::TypeErrCtxtExt>::report_selection_error
  22:        0x110c0abfc - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt>::report_fulfillment_error
  23:        0x110bfb85c - <rustc_infer[170c1ed4a1849e00]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[33aed0349f5813fa]::traits::error_reporting::type_err_ctxt_ext::TypeErrCtxtExt>::report_fulfillment_errors
  24:        0x10f54ae9c - rustc_hir_analysis[dbec75d63dfe474d]::check::check::check_impl_items_against_trait
  25:        0x10f54339c - rustc_hir_analysis[dbec75d63dfe474d]::check::check::check_item_type
  26:        0x10f521c64 - rustc_hir_analysis[dbec75d63dfe474d]::check::wfcheck::check_well_formed
  27:        0x1106225cc - rustc_query_impl[f1d8f2bcea61389e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>
  28:        0x1107016ac - <rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_well_formed::dynamic_query::{closure#2} as core[4a89e3a3d2972735]::ops::function::FnOnce<(rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt, rustc_hir[7a2e70a68ac31600]::hir_id::OwnerId)>>::call_once
  29:        0x1105d8268 - rustc_query_system[8ffd5b92dfc530c8]::query::plumbing::try_execute_query::<rustc_query_impl[f1d8f2bcea61389e]::DynamicConfig<rustc_query_system[8ffd5b92dfc530c8]::query::caches::VecCache<rustc_hir[7a2e70a68ac31600]::hir_id::OwnerId, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[f1d8f2bcea61389e]::plumbing::QueryCtxt, true>
  30:        0x1107c0f34 - rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_well_formed::get_query_incr::__rust_end_short_backtrace
  31:        0x10f50ba4c - rustc_middle[8bc529f0e8dcc906]::query::plumbing::query_ensure_error_guaranteed::<rustc_query_system[8ffd5b92dfc530c8]::query::caches::VecCache<rustc_hir[7a2e70a68ac31600]::hir_id::OwnerId, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>, ()>
  32:        0x10f4ff304 - <rustc_data_structures[288cf1eb93b81d30]::sync::parallel::ParallelGuard>::run::<core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>, rustc_data_structures[288cf1eb93b81d30]::sync::parallel::enabled::try_par_for_each_in<&[rustc_hir[7a2e70a68ac31600]::hir::ImplItemId], rustc_span[68cecb55101cab86]::ErrorGuaranteed, <rustc_middle[8bc529f0e8dcc906]::hir::ModuleItems>::par_impl_items<rustc_hir_analysis[dbec75d63dfe474d]::check::wfcheck::check_mod_type_wf::{closure#1}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  33:        0x10f3b6fa0 - <rustc_middle[8bc529f0e8dcc906]::hir::ModuleItems>::par_items::<rustc_hir_analysis[dbec75d63dfe474d]::check::wfcheck::check_mod_type_wf::{closure#0}>
  34:        0x10f527b5c - rustc_hir_analysis[dbec75d63dfe474d]::check::wfcheck::check_mod_type_wf
  35:        0x110622580 - rustc_query_impl[f1d8f2bcea61389e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>
  36:        0x110701430 - <rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_mod_type_wf::dynamic_query::{closure#2} as core[4a89e3a3d2972735]::ops::function::FnOnce<(rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt, rustc_span[68cecb55101cab86]::def_id::LocalModDefId)>>::call_once
  37:        0x11057e474 - rustc_query_system[8ffd5b92dfc530c8]::query::plumbing::try_execute_query::<rustc_query_impl[f1d8f2bcea61389e]::DynamicConfig<rustc_query_system[8ffd5b92dfc530c8]::query::caches::DefaultCache<rustc_span[68cecb55101cab86]::def_id::LocalModDefId, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[f1d8f2bcea61389e]::plumbing::QueryCtxt, true>
  38:        0x1107b1f30 - rustc_query_impl[f1d8f2bcea61389e]::query_impl::check_mod_type_wf::get_query_incr::__rust_end_short_backtrace
  39:        0x10f4ff8a8 - <rustc_data_structures[288cf1eb93b81d30]::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures[288cf1eb93b81d30]::sync::parallel::enabled::par_for_each_in<&rustc_hir[7a2e70a68ac31600]::hir_id::OwnerId, &[rustc_hir[7a2e70a68ac31600]::hir_id::OwnerId], <rustc_middle[8bc529f0e8dcc906]::hir::map::Map>::par_for_each_module<rustc_hir_analysis[dbec75d63dfe474d]::check_crate::{closure#0}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  40:        0x10f4e2b68 - <rustc_session[eb968a6fff6375c9]::session::Session>::time::<(), rustc_hir_analysis[dbec75d63dfe474d]::check_crate::{closure#0}>
  41:        0x10f4e0e8c - rustc_hir_analysis[dbec75d63dfe474d]::check_crate
  42:        0x10fa6b85c - rustc_interface[ff3e7bd95de52456]::passes::analysis
  43:        0x1106277d4 - rustc_query_impl[f1d8f2bcea61389e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1d8f2bcea61389e]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>
  44:        0x1106c91d0 - <rustc_query_impl[f1d8f2bcea61389e]::query_impl::analysis::dynamic_query::{closure#2} as core[4a89e3a3d2972735]::ops::function::FnOnce<(rustc_middle[8bc529f0e8dcc906]::ty::context::TyCtxt, ())>>::call_once
  45:        0x110542040 - rustc_query_system[8ffd5b92dfc530c8]::query::plumbing::try_execute_query::<rustc_query_impl[f1d8f2bcea61389e]::DynamicConfig<rustc_query_system[8ffd5b92dfc530c8]::query::caches::SingleCache<rustc_middle[8bc529f0e8dcc906]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[f1d8f2bcea61389e]::plumbing::QueryCtxt, true>
  46:        0x1107a3778 - rustc_query_impl[f1d8f2bcea61389e]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  47:        0x10f0f1e80 - <rustc_middle[8bc529f0e8dcc906]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[c003af3b489365f2]::run_compiler::{closure#0}::{closure#1}::{closure#5}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>
  48:        0x10f123578 - <rustc_interface[ff3e7bd95de52456]::interface::Compiler>::enter::<rustc_driver_impl[c003af3b489365f2]::run_compiler::{closure#0}::{closure#1}, core[4a89e3a3d2972735]::result::Result<core[4a89e3a3d2972735]::option::Option<rustc_interface[ff3e7bd95de52456]::queries::Linker>, rustc_span[68cecb55101cab86]::ErrorGuaranteed>>
  49:        0x10f10f684 - rustc_span[68cecb55101cab86]::create_session_globals_then::<core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>, rustc_interface[ff3e7bd95de52456]::util::run_in_thread_with_globals<rustc_interface[ff3e7bd95de52456]::util::run_in_thread_pool_with_globals<rustc_interface[ff3e7bd95de52456]::interface::run_compiler<core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>, rustc_driver_impl[c003af3b489365f2]::run_compiler::{closure#0}>::{closure#1}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}>
  50:        0x10f0f37f8 - std[791662d3d9623b74]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[ff3e7bd95de52456]::util::run_in_thread_with_globals<rustc_interface[ff3e7bd95de52456]::util::run_in_thread_pool_with_globals<rustc_interface[ff3e7bd95de52456]::interface::run_compiler<core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>, rustc_driver_impl[c003af3b489365f2]::run_compiler::{closure#0}>::{closure#1}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>
  51:        0x10f0f0c6c - <<std[791662d3d9623b74]::thread::Builder>::spawn_unchecked_<rustc_interface[ff3e7bd95de52456]::util::run_in_thread_with_globals<rustc_interface[ff3e7bd95de52456]::util::run_in_thread_pool_with_globals<rustc_interface[ff3e7bd95de52456]::interface::run_compiler<core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>, rustc_driver_impl[c003af3b489365f2]::run_compiler::{closure#0}>::{closure#1}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[4a89e3a3d2972735]::result::Result<(), rustc_span[68cecb55101cab86]::ErrorGuaranteed>>::{closure#2} as core[4a89e3a3d2972735]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  52:        0x1052c2374 - std::sys::pal::unix::thread::Thread::new::thread_start::h3cbd0bca5805ff8b
  53:        0x19a536f94 - __pthread_joiner_wake

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/Users/timch/Documents/batch-channel/rustc-ice-2024-07-05T17_15_43-26060.txt` to your bug report

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C split-debuginfo=unpacked -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [check_well_formed] checking that `<impl at src/lib.rs:23:1: 23:45>` is well-formed
#1 [check_mod_type_wf] checking that types are well-formed in top-level module
end of query stack
error[E0277]: expected a `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
  --> src/lib.rs:30:9
   |
30 |         async {}
   |         ^^^^^ expected an `FnOnce(&'a mut BatchSender<T>)` closure, found `F`
   |
   = note: expected a closure with arguments `(&mut <Sender<T> as ChannelSender<T>>::BatchSender,)`
              found a closure with arguments `(&'a mut BatchSender<T>,)`
note: required for `F` to implement `for<'a> AsyncCallback<&'a mut BatchSender<T>>`
  --> src/lib.rs:7:56
   |
7  | impl<A, Out: Future<Output = ()>, F: FnOnce(A) -> Out> AsyncCallback<A> for F {
   |                                      ----------------  ^^^^^^^^^^^^^^^^     ^
   |                                      |
   |                                      unsatisfied trait bound introduced here

For more information about this error, try `rustc --explain E0277`.
error: could not compile `batch-channel` (lib) due to 8 previous errors

Notably doesn't require the async_closure feature.

@rustbot label -F-async_closure

[compiler-errors]

Thanks!!

[theemathas]

Minimized (I can't get it smaller than this) and got rid of dependence on std:

trait MyFn<T> {
    type Output;
}

trait MyFnAlias<A>: MyFn<A, Output = Self::OutputAlias> {
    type OutputAlias;
}

impl<A, F: MyFn<A>> MyFnAlias<A> for F {
    type OutputAlias = F::Output;
}

struct Thing;
trait Trait {}
impl Trait for Thing {}

trait ChannelSender {
    type Arg;

    fn autobatch<F>(self) -> impl Trait
    where
        F: MyFnAlias<Self::Arg>;
}

struct Sender;

impl ChannelSender for Sender {
    type Arg = i32;

    fn autobatch<F>(self) -> impl Trait
    where
        F: MyFnAlias<Self::Arg>,
    {
        Thing
    }
}

I believe this code should compile.