ICE: unexpected const placeholder

[matthiaskrgr]

Code

#![feature(return_type_notation)]
#![feature(generic_associated_types_extended)]
#![feature(trivial_bounds)]

trait HealthCheck {
    async fn check<const N: usize>() -> bool;
}

async fn do_health_check_par<HC>()
where
    HealthCheck: HealthCheck<Send(): Send> + Send + 'static,
{
}

Meta

rustc --version --verbose:

binary: rustc
commit-hash: 52fd9983996d9fcfb719749838336be66dee68f9
commit-date: 2024-10-10
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.1

Error output

warning: the feature `generic_associated_types_extended` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/crash.rs:2:12
  |
2 | #![feature(generic_associated_types_extended)]
  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #95451 <https://github.com/rust-lang/rust/issues/95451> for more information
  = note: `#[warn(incomplete_features)]` on by default

error: parenthesized generic arguments cannot be used in associated type constraints
  --> /tmp/crash.rs:11:30
   |
11 |     HealthCheck: HealthCheck<Send(): Send> + Send + 'static,
   |                              ^^^^--
   |                                  |
   |                                  help: remove these parentheses

error[E0220]: associated type `Send` not found for `HealthCheck`
  --> /tmp/crash.rs:11:30
   |
11 |     HealthCheck: HealthCheck<Send(): Send> + Send + 'static,
   |                              ^^^^ associated type `Send` not found

Backtrace

error: internal compiler error: compiler/rustc_infer/src/infer/freshen.rs:178:17: unexpected const !130_0

thread 'rustc' panicked at compiler/rustc_infer/src/infer/freshen.rs:178:17:
Box<dyn Any>
stack backtrace:
   0:     0x7714989dd24a - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h87acf85b5211808c
   1:     0x7714992034a6 - core::fmt::write::h1830300cff8013e6
   2:     0x77149a40bb91 - std::io::Write::write_fmt::hff4c51c59db7db45
   3:     0x7714989dd0a2 - std::sys::backtrace::BacktraceLock::print::h5e8429acc66fa0b4
   4:     0x7714989df576 - std::panicking::default_hook::{{closure}}::h47c5621b8a2933e4
   5:     0x7714989df3c0 - std::panicking::default_hook::h4c51255dc678cdff
   6:     0x771497a315df - std[39bba8b06d71f7a0]::panicking::update_hook::<alloc[c38a7ac3bd25a6f5]::boxed::Box<rustc_driver_impl[2b16dbb9274b0adb]::install_ice_hook::{closure#0}>>::{closure#0}
   7:     0x7714989dfc88 - std::panicking::rust_panic_with_hook::hfa48cfa9339c55df
   8:     0x771497a6b7c1 - std[39bba8b06d71f7a0]::panicking::begin_panic::<rustc_errors[f6e17c2fb5aa1767]::ExplicitBug>::{closure#0}
   9:     0x771497a5e866 - std[39bba8b06d71f7a0]::sys::backtrace::__rust_end_short_backtrace::<std[39bba8b06d71f7a0]::panicking::begin_panic<rustc_errors[f6e17c2fb5aa1767]::ExplicitBug>::{closure#0}, !>
  10:     0x771497a59d99 - std[39bba8b06d71f7a0]::panicking::begin_panic::<rustc_errors[f6e17c2fb5aa1767]::ExplicitBug>
  11:     0x771497a75051 - <rustc_errors[f6e17c2fb5aa1767]::diagnostic::BugAbort as rustc_errors[f6e17c2fb5aa1767]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x7714980d1124 - rustc_middle[29f16e95e513605a]::util::bug::opt_span_bug_fmt::<rustc_span[6ca13cbf14de63a0]::span_encoding::Span>::{closure#0}
  13:     0x7714980b6f9a - rustc_middle[29f16e95e513605a]::ty::context::tls::with_opt::<rustc_middle[29f16e95e513605a]::util::bug::opt_span_bug_fmt<rustc_span[6ca13cbf14de63a0]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7714980b6e2b - rustc_middle[29f16e95e513605a]::ty::context::tls::with_context_opt::<rustc_middle[29f16e95e513605a]::ty::context::tls::with_opt<rustc_middle[29f16e95e513605a]::util::bug::opt_span_bug_fmt<rustc_span[6ca13cbf14de63a0]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7714955faad0 - rustc_middle[29f16e95e513605a]::util::bug::bug_fmt
  16:     0x771499f446fb - <rustc_infer[175fb04e3dbeac18]::infer::freshen::TypeFreshener as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_const
  17:     0x771499337449 - <rustc_middle[29f16e95e513605a]::ty::Ty as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeSuperFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_super_fold_with::<rustc_infer[175fb04e3dbeac18]::infer::freshen::TypeFreshener>
  18:     0x771499e990c5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  19:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  20:     0x771499a89bea - rustc_trait_selection[51e218581841b494]::traits::project::poly_project_and_unify_term
  21:     0x771495defc36 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  22:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  23:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  24:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  25:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
  26:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
  27:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
  28:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
  29:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  30:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  31:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  32:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  33:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
  34:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
  35:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
  36:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
  37:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  38:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  39:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  40:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  41:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
  42:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
  43:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
  44:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
  45:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  46:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  47:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  48:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  49:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
  50:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
  51:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
  52:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
  53:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  54:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  55:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  56:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  57:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
  58:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
  59:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
  60:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
  61:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
  62:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
  63:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
  64:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
  65:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>

<snip>

1010:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
1011:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
1012:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
1013:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
1014:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
1015:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
1016:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
1017:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
1018:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
1019:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
1020:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
1021:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
1022:     0x771499e9d1f5 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::poly_select::{closure#0}
1023:     0x771499a94890 - rustc_trait_selection[51e218581841b494]::traits::project::opt_normalize_projection_term
1024:     0x771499a915b3 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_ty
1025:     0x771499a909c1 - <&rustc_middle[29f16e95e513605a]::ty::list::RawList<(), rustc_middle[29f16e95e513605a]::ty::generic_args::GenericArg> as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFoldable<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer>
1026:     0x771499a901e0 - <rustc_trait_selection[51e218581841b494]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[aeae2260a8e42b9a]::fold::TypeFolder<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt>>::fold_predicate
1027:     0x77149999fd89 - rustc_trait_selection[51e218581841b494]::traits::normalize::normalize_with_depth_to::<rustc_middle[29f16e95e513605a]::ty::predicate::Clause>
1028:     0x771499aef3ae - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::confirm_candidate
1029:     0x771495decd8d - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
1030:     0x771495e1a435 - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::candidate_from_obligation
1031:     0x771499ab03bc - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::evaluate_trait_predicate_recursively
1032:     0x7714992e9c5e - <rustc_trait_selection[51e218581841b494]::traits::select::SelectionContext>::evaluate_root_obligation
1033:     0x7714992e8212 - rustc_traits[f9de722fbc0fac2a]::evaluate_obligation::evaluate_obligation
1034:     0x7714992e7ca9 - rustc_query_impl[577202e9d6ff7d36]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[577202e9d6ff7d36]::query_impl::evaluate_obligation::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 2usize]>>
1035:     0x7714992e722b - rustc_query_system[e421b998c28443f5]::query::plumbing::try_execute_query::<rustc_query_impl[577202e9d6ff7d36]::DynamicConfig<rustc_query_system[e421b998c28443f5]::query::caches::DefaultCache<rustc_type_ir[aeae2260a8e42b9a]::canonical::Canonical<rustc_middle[29f16e95e513605a]::ty::context::TyCtxt, rustc_middle[29f16e95e513605a]::ty::ParamEnvAnd<rustc_middle[29f16e95e513605a]::ty::predicate::Predicate>>, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[577202e9d6ff7d36]::plumbing::QueryCtxt, false>
1036:     0x7714992e6e7a - rustc_query_impl[577202e9d6ff7d36]::query_impl::evaluate_obligation::get_query_non_incr::__rust_end_short_backtrace
1037:     0x77149569bcc7 - <rustc_trait_selection[51e218581841b494]::traits::fulfill::FulfillProcessor as rustc_data_structures[c6998ca21e3f6fd0]::obligation_forest::ObligationProcessor>::process_obligation
1038:     0x7714993f32c1 - <rustc_data_structures[c6998ca21e3f6fd0]::obligation_forest::ObligationForest<rustc_trait_selection[51e218581841b494]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[51e218581841b494]::traits::fulfill::FulfillProcessor>
1039:     0x7714993efcc1 - <rustc_trait_selection[51e218581841b494]::traits::engine::ObligationCtxt<rustc_trait_selection[51e218581841b494]::traits::FulfillmentError>>::assumed_wf_types_and_report_errors
1040:     0x7714999836f5 - rustc_hir_analysis[7d1658e465b44263]::check::wfcheck::check_item_fn
1041:     0x771496b5386f - rustc_hir_analysis[7d1658e465b44263]::check::wfcheck::check_well_formed
1042:     0x771499bd53eb - rustc_query_impl[577202e9d6ff7d36]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[577202e9d6ff7d36]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>
1043:     0x771499bd4b51 - rustc_query_system[e421b998c28443f5]::query::plumbing::try_execute_query::<rustc_query_impl[577202e9d6ff7d36]::DynamicConfig<rustc_query_system[e421b998c28443f5]::query::caches::VecCache<rustc_span[6ca13cbf14de63a0]::def_id::LocalDefId, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[577202e9d6ff7d36]::plumbing::QueryCtxt, false>
1044:     0x771499bd47d0 - rustc_query_impl[577202e9d6ff7d36]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
1045:     0x771499bd567f - rustc_hir_analysis[7d1658e465b44263]::check::wfcheck::check_mod_type_wf
1046:     0x771499bd54a5 - rustc_query_impl[577202e9d6ff7d36]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[577202e9d6ff7d36]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>
1047:     0x77149a101d3b - rustc_query_system[e421b998c28443f5]::query::plumbing::try_execute_query::<rustc_query_impl[577202e9d6ff7d36]::DynamicConfig<rustc_query_system[e421b998c28443f5]::query::caches::DefaultCache<rustc_span[6ca13cbf14de63a0]::def_id::LocalModDefId, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[577202e9d6ff7d36]::plumbing::QueryCtxt, false>
1048:     0x77149a101aed - rustc_query_impl[577202e9d6ff7d36]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
1049:     0x77149963387b - rustc_hir_analysis[7d1658e465b44263]::check_crate
1050:     0x7714996305d7 - rustc_interface[3d22ab4a16c914f1]::passes::run_required_analyses
1051:     0x771499f29a5e - rustc_interface[3d22ab4a16c914f1]::passes::analysis
1052:     0x771499f29a31 - rustc_query_impl[577202e9d6ff7d36]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[577202e9d6ff7d36]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>
1053:     0x77149a1138ae - rustc_query_system[e421b998c28443f5]::query::plumbing::try_execute_query::<rustc_query_impl[577202e9d6ff7d36]::DynamicConfig<rustc_query_system[e421b998c28443f5]::query::caches::SingleCache<rustc_middle[29f16e95e513605a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[577202e9d6ff7d36]::plumbing::QueryCtxt, false>
1054:     0x77149a11358f - rustc_query_impl[577202e9d6ff7d36]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
1055:     0x771499f39a5e - rustc_interface[3d22ab4a16c914f1]::interface::run_compiler::<core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>, rustc_driver_impl[2b16dbb9274b0adb]::run_compiler::{closure#0}>::{closure#1}
1056:     0x771499fc1d50 - std[39bba8b06d71f7a0]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3d22ab4a16c914f1]::util::run_in_thread_with_globals<rustc_interface[3d22ab4a16c914f1]::util::run_in_thread_pool_with_globals<rustc_interface[3d22ab4a16c914f1]::interface::run_compiler<core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>, rustc_driver_impl[2b16dbb9274b0adb]::run_compiler::{closure#0}>::{closure#1}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>::{closure#0}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>
1057:     0x771499fc2417 - <<std[39bba8b06d71f7a0]::thread::Builder>::spawn_unchecked_<rustc_interface[3d22ab4a16c914f1]::util::run_in_thread_with_globals<rustc_interface[3d22ab4a16c914f1]::util::run_in_thread_pool_with_globals<rustc_interface[3d22ab4a16c914f1]::interface::run_compiler<core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>, rustc_driver_impl[2b16dbb9274b0adb]::run_compiler::{closure#0}>::{closure#1}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>::{closure#0}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5ae4016a0c652b3c]::result::Result<(), rustc_span[6ca13cbf14de63a0]::ErrorGuaranteed>>::{closure#1} as core[5ae4016a0c652b3c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
1058:     0x771499fc3301 - std::sys::pal::unix::thread::Thread::new::thread_start::hc0595517bea46b79
1059:     0x77149b80139d - <unknown>
1060:     0x77149b88649c - <unknown>
1061:                0x0 - <unknown>

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 `/tmp/rustc-ice-2024-10-11T09_35_41-93078.txt` to your bug report

note: compiler flags: --crate-type lib

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `(dyn HealthCheck + 'a): HealthCheck`
#1 [check_well_formed] checking that `do_health_check_par` is well-formed
end of query stack
error[E0782]: trait objects must include the `dyn` keyword
  --> /tmp/crash.rs:11:5
   |
11 |     HealthCheck: HealthCheck<Send(): Send> + Send + 'static,
   |     ^^^^^^^^^^^
   |
help: add `dyn` keyword before this trait
   |
11 |     dyn HealthCheck: HealthCheck<Send(): Send> + Send + 'static,
   |     +++

error: aborting due to 4 previous errors; 1 warning emitted

Some errors have detailed explanations: E0220, E0782.
For more information about an error, try `rustc --explain E0220`.

[cyrgani]

Reduced:

#![feature(generic_associated_types_extended)]
#![feature(trivial_bounds)]

trait HealthCheck {
    async fn check<const N: usize>();
}

fn do_health_check_par()
where
    HealthCheck: HealthCheck,
{
}

Removing #![feature(trivial_bounds)] causes the compiler to hang, instead of ICEing.

[szbergeron]

Hi All! Do we know what the expected behavior for this case should be?

As is, it runs into recursion limits and then bugs when TypeFreshener tries to fold a ConstKind::Placeholder left over afterwards.

My intuition is that it should behave exactly as it does when check is fn check<const N: usize>(); or fn check<const N: usize>(&self);: complain that HealthCheck is not object safe due to missing self or generic parameters and then exit gracefully.

Is this a reasonable/accurate assumption? (I'm new to reading rustc so my understanding may very well be off base!)

[szbergeron]

663da00 does change the behavior here for the current minified example, though I think there should still be a way of triggering the ICE now. I'll try to produce a new test that still exhibits the behavior after that.

EDIT: new repro that accommodates the changes:

#![feature(generic_associated_types_extended)]
#![feature(trivial_bounds)]

trait HealthCheck {
    async fn check<const N: usize>();
}

fn do_health_check_par()
where
    dyn HealthCheck: HealthCheck,
{
}

[szbergeron]

Additional experimentation to take out some red herrings, this also hangs rustc as when removing the trivial_bounds feature on the original issue:

#![feature(generic_associated_types_extended)]

trait U {
}

trait HealthCheck {
    fn check(&self) -> impl U;
}

fn do_health_check_par()
where
    dyn HealthCheck: HealthCheck,
{
}

The const param on check does force the ICE, but it continues to chase its own tail in binder for the trivial HealthCheck bound.

[fmease]

Similar reproducers:

cc #132672 (comment)
cc #132672 (comment)

[fmease]

The feature has been removed (#133768). Not reproducible without it.
The crash test has intentionally been removed.