ICE: `leftover child captures?`

[matthiaskrgr]

auto-reduced (treereduce-rust):

pub fn test(test: &u64, temp: &u64) {
    async |check, a, b| {
        temp.abs_diff(12);
    };
}

original:

#![feature(async_closure, async_fn_traits)]

fn main() {}

pub fn test(test: &u64, temp: &u64) {
    let test = test.clone();
    async |check, a, b| {
        temp.abs_diff(12);
        test.clone();
    };
}

Version information

rustc 1.79.0-nightly (3a0db6c15 2024-04-13)
binary: rustc
commit-hash: 3a0db6c15251a56a02f4d0171d3e9586f86abd44
commit-date: 2024-04-13
host: x86_64-unknown-linux-gnu
release: 1.79.0-nightly
LLVM version: 18.1.3

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2021

Program output

error[E0658]: async closures are unstable
 --> /tmp/icemaker_global_tempdir.NfjNL9cyB5N3/rustc_testrunner_tmpdir_reporting.W54CO64GoeWB/mvce.rs:2:5
  |
2 |     async |check, a, b| {
  |     ^^^^^
  |
  = note: see issue #62290 <https://github.com/rust-lang/rust/issues/62290> for more information
  = help: add `#![feature(async_closure)]` to the crate attributes to enable
  = note: this compiler was built on 2024-04-13; consider upgrading it if it is out of date
  = help: to use an async block, remove the `||`: `async {`

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.NfjNL9cyB5N3/rustc_testrunner_tmpdir_reporting.W54CO64GoeWB/mvce.rs:5:2
  |
5 | }
  |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.NfjNL9cyB5N3/rustc_testrunner_tmpdir_reporting.W54CO64GoeWB/mvce.rs`

thread 'rustc' panicked at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/compiler/rustc_middle/src/ty/closure.rs:465:9:
assertion `left == right` failed: leftover child captures?
  left: Some((0, CapturedPlace { var_ident: temp#0, place: Place { base_ty: &ReLateParam(DefId(0:3 ~ mvce[c50b]::test), BrNamed(DefId(0:7 ~ mvce[c50b]::test::'_#1), '_)) u64, base: Upvar(UpvarId(HirId(DefId(0:3 ~ mvce[c50b]::test).4);`temp`;DefId(0:5 ~ mvce[c50b]::test::{closure#0}::{closure#0}))), projections: [Projection { ty: u64, kind: Deref }] }, info: CaptureInfo { capture_kind_expr_id: Some(HirId(DefId(0:3 ~ mvce[c50b]::test).34)), path_expr_id: Some(HirId(DefId(0:3 ~ mvce[c50b]::test).34)), capture_kind: ByRef(ImmBorrow) }, mutability: Not, region: Some('?0) }))
 right: None
stack backtrace:
   0:     0x723435201c05 - std::backtrace_rs::backtrace::libunwind::trace::he67d23302a415162
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x723435201c05 - std::backtrace_rs::backtrace::trace_unsynchronized::h39e708adc62db50c
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x723435201c05 - std::sys_common::backtrace::_print_fmt::h2cd8591d0bde0854
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x723435201c05 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hefdd442146db74bf
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x723435250f3b - core::fmt::rt::Argument::fmt::h7a4c8d2d1224ab4a
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/core/src/fmt/rt.rs:142:9
   5:     0x723435250f3b - core::fmt::write::hf0b695e14076a26d
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/core/src/fmt/mod.rs:1153:17
   6:     0x7234351f680f - std::io::Write::write_fmt::h71fcd2625aa9c332
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/io/mod.rs:1832:15
   7:     0x7234352019de - std::sys_common::backtrace::_print::hdeb11c462cc75e10
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7234352019de - std::sys_common::backtrace::print::h191e80b695c7e36e
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x723435204359 - std::panicking::default_hook::{{closure}}::h8d77c83f4f715071
  10:     0x72343520409d - std::panicking::default_hook::h5f0148e464f5b814
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/panicking.rs:291:9
  11:     0x723431a7664c - std[885a30522c002bbc]::panicking::update_hook::<alloc[e68b43253f4aa917]::boxed::Box<rustc_driver_impl[90e9a40ab560bf54]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x723435204a5c - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h67d1278a639bc027
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/alloc/src/boxed.rs:2032:9
  13:     0x723435204a5c - std::panicking::rust_panic_with_hook::h7b2f32c16086f787
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/panicking.rs:792:13
  14:     0x723435204806 - std::panicking::begin_panic_handler::{{closure}}::hc9d8693313be9056
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/panicking.rs:657:13
  15:     0x7234352020c9 - std::sys_common::backtrace::__rust_end_short_backtrace::h6aae8c655dbc3423
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x723435204537 - rust_begin_unwind
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/panicking.rs:645:5
  17:     0x72343524d3d6 - core::panicking::panic_fmt::hf0b729b119d27b91
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/core/src/panicking.rs:72:14
  18:     0x72343524d99f - core::panicking::assert_failed_inner::h260765b39fc64692
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/core/src/panicking.rs:397:23
  19:     0x723431bf60db - core[75462145d81de164]::panicking::assert_failed::<core[75462145d81de164]::option::Option<(usize, &rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace)>, core[75462145d81de164]::option::Option<(usize, &rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace)>>
  20:     0x723431c240d1 - <core[75462145d81de164]::iter::sources::from_coroutine::FromCoroutine<rustc_middle[634cd321d1104505]::ty::closure::analyze_coroutine_closure_captures<rustc_middle[634cd321d1104505]::ty::Ty, core[75462145d81de164]::iter::adapters::flatten::Flatten<core[75462145d81de164]::option::IntoIter<core[75462145d81de164]::iter::adapters::flatten::FlatMap<indexmap[9236e8704059c4ca]::map::iter::Values<rustc_hir[b517bd588d68daf0]::hir_id::HirId, alloc[e68b43253f4aa917]::vec::Vec<rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace>>, core[75462145d81de164]::slice::iter::Iter<rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace>, <rustc_middle[634cd321d1104505]::ty::typeck_results::TypeckResults>::closure_min_captures_flattened::{closure#0}::{closure#0}>>>, core[75462145d81de164]::iter::adapters::skip::Skip<core[75462145d81de164]::iter::adapters::flatten::Flatten<core[75462145d81de164]::option::IntoIter<core[75462145d81de164]::iter::adapters::flatten::FlatMap<indexmap[9236e8704059c4ca]::map::iter::Values<rustc_hir[b517bd588d68daf0]::hir_id::HirId, alloc[e68b43253f4aa917]::vec::Vec<rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace>>, core[75462145d81de164]::slice::iter::Iter<rustc_middle[634cd321d1104505]::ty::closure::CapturedPlace>, <rustc_middle[634cd321d1104505]::ty::typeck_results::TypeckResults>::closure_min_captures_flattened::{closure#0}::{closure#0}>>>>, <rustc_hir_typeck[6df0519c0ec70ff8]::fn_ctxt::FnCtxt>::analyze_closure::{closure#0}>::{closure#0}> as core[75462145d81de164]::iter::traits::iterator::Iterator>::next
  21:     0x7234337cf624 - <rustc_hir_typeck[6df0519c0ec70ff8]::fn_ctxt::FnCtxt>::analyze_closure
  22:     0x72342ff0c0bb - <rustc_hir_typeck[6df0519c0ec70ff8]::upvar::InferBorrowKindVisitor as rustc_hir[b517bd588d68daf0]::intravisit::Visitor>::visit_expr
  23:     0x723432fe0ec4 - <rustc_hir_typeck[6df0519c0ec70ff8]::upvar::InferBorrowKindVisitor as rustc_hir[b517bd588d68daf0]::intravisit::Visitor>::visit_block
  24:     0x723432fe319c - rustc_hir_typeck[6df0519c0ec70ff8]::typeck
  25:     0x723432fe2889 - rustc_query_impl[20b47d821f71e0c0]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[20b47d821f71e0c0]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[634cd321d1104505]::query::erase::Erased<[u8; 8usize]>>
  26:     0x723432fceef1 - rustc_query_system[b7ba67b5501de1f1]::query::plumbing::try_execute_query::<rustc_query_impl[20b47d821f71e0c0]::DynamicConfig<rustc_query_system[b7ba67b5501de1f1]::query::caches::VecCache<rustc_span[1f0db57e54aaa535]::def_id::LocalDefId, rustc_middle[634cd321d1104505]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[20b47d821f71e0c0]::plumbing::QueryCtxt, false>
  27:     0x723432fcd80c - rustc_query_impl[20b47d821f71e0c0]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  28:     0x723432fcd3d4 - <rustc_middle[634cd321d1104505]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[813d3a9100b7eb57]::check_crate::{closure#4}>::{closure#0}
  29:     0x723432fcc0aa - rustc_hir_analysis[813d3a9100b7eb57]::check_crate
  30:     0x72343372b47a - rustc_interface[584c726233b098e3]::passes::analysis
  31:     0x72343372afd5 - rustc_query_impl[20b47d821f71e0c0]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[20b47d821f71e0c0]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[634cd321d1104505]::query::erase::Erased<[u8; 1usize]>>
  32:     0x723433c30f65 - rustc_query_system[b7ba67b5501de1f1]::query::plumbing::try_execute_query::<rustc_query_impl[20b47d821f71e0c0]::DynamicConfig<rustc_query_system[b7ba67b5501de1f1]::query::caches::SingleCache<rustc_middle[634cd321d1104505]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[20b47d821f71e0c0]::plumbing::QueryCtxt, false>
  33:     0x723433c30cc9 - rustc_query_impl[20b47d821f71e0c0]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  34:     0x723433ad5093 - rustc_interface[584c726233b098e3]::interface::run_compiler::<core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>, rustc_driver_impl[90e9a40ab560bf54]::run_compiler::{closure#0}>::{closure#0}
  35:     0x723433ba921d - std[885a30522c002bbc]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[584c726233b098e3]::util::run_in_thread_with_globals<rustc_interface[584c726233b098e3]::util::run_in_thread_pool_with_globals<rustc_interface[584c726233b098e3]::interface::run_compiler<core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>, rustc_driver_impl[90e9a40ab560bf54]::run_compiler::{closure#0}>::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>
  36:     0x723433ba902a - <<std[885a30522c002bbc]::thread::Builder>::spawn_unchecked_<rustc_interface[584c726233b098e3]::util::run_in_thread_with_globals<rustc_interface[584c726233b098e3]::util::run_in_thread_pool_with_globals<rustc_interface[584c726233b098e3]::interface::run_compiler<core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>, rustc_driver_impl[90e9a40ab560bf54]::run_compiler::{closure#0}>::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[75462145d81de164]::result::Result<(), rustc_span[1f0db57e54aaa535]::ErrorGuaranteed>>::{closure#2} as core[75462145d81de164]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  37:     0x72343520e95b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h7e43c058cec37c3f
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/alloc/src/boxed.rs:2018:9
  38:     0x72343520e95b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h318f41c47f558002
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/alloc/src/boxed.rs:2018:9
  39:     0x72343520e95b - std::sys::pal::unix::thread::Thread::new::thread_start::hb16ab7f697c5a952
                               at /rustc/3a0db6c15251a56a02f4d0171d3e9586f86abd44/library/std/src/sys/pal/unix/thread.rs:108:17
  40:     0x723434fac55a - <unknown>
  41:     0x723435029a3c - <unknown>
  42:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

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: rustc 1.79.0-nightly (3a0db6c15 2024-04-13) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z dump-mir-dir=dir

query stack during panic:
#0 [typeck] type-checking `test`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors

Some errors have detailed explanations: E0601, E0658.
For more information about an error, try `rustc --explain E0601`.

[matthiaskrgr]

pub fn test(temp: &u64) {
    async |_| {
        temp;
    };
}

pub fn main() {}

[compiler-errors]

Not fixed by #123834? Can't check -- not at my rust workstation.

[matthiaskrgr]

nope, still crashes with latest git master toolchain.

[compiler-errors]

kk

[matthiaskrgr]

BUT I only found 3 of those in one million files, instead of several thousands, so definitely an improvement 🙃