ICE: $ident: found TraitItem(TraitItem

[matthiaskrgr]

auto-reduced (treereduce-rust):

//@compile-flags: --edition=2024
pub trait TraitWAssocConst {
    const A: TraitWAssocConst<A = 0>;
}

original:

#![feature(generic_const_exprs)]
pub trait TraitWAssocConst {
  const A: TraitWAssocConst<A=0>;
}

fn main<A: TraitWAssocConst<A=32>>() {
  TraitWAssocConst<A=0>:: TraitWAssocConst<A=32> ();
}

Version information

rustc 1.87.0-nightly (20f0108ad 2025-03-08)
binary: rustc
commit-hash: 20f0108ada90e37c2350ad68fdc6afe56f51539d
commit-date: 2025-03-08
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

Possibly related line of code:

rust/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

Lines 204 to 216 in 20f0108

	label: &str,
	sugg: Vec<(Span, String)>,
	diag: &mut Diag<'_>,
	) -> bool {
	let tcx = self.tcx();
	let parent_id = tcx.hir_get_parent_item(self_ty.hir_id).def_id;
	let parent_item = tcx.hir_node_by_def_id(parent_id).expect_item();
	// If the parent item is an enum, don't suggest the dyn trait.
	if let hir::ItemKind::Enum(..) = parent_item.kind {
	return false;
	}

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2024

Program output

error[E0658]: associated const equality is incomplete
 --> /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:31
  |
2 |     const A: TraitWAssocConst<A = 0>;
  |                               ^^^^^
  |
  = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
  = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
  = note: this compiler was built on 2025-03-08; consider upgrading it if it is out of date

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:3:2
  |
3 | }
  |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs`


thread 'rustc' panicked at compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs:210:61:
$ident: found TraitItem(TraitItem { ident: A#0, owner_id: DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A), generics: Generics { params: [], predicates: [], has_where_clause_predicates: false, where_clause_span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:37: 2:37 (#0), span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:12: 2:12 (#0) }, kind: Const(Ty { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).8), span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:14: 2:37 (#0), kind: TraitObject([PolyTraitRef { bound_generic_params: [], modifiers: TraitBoundModifiers { constness: Never, polarity: Positive }, trait_ref: TraitRef { path: Path { span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:14: 2:37 (#0), res: Def(Trait, DefId(0:3 ~ mvce[a2ab]::TraitWAssocConst)), segments: [PathSegment { ident: TraitWAssocConst#0, hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).5), res: Def(Trait, DefId(0:3 ~ mvce[a2ab]::TraitWAssocConst)), args: Some(GenericArgs { args: [], constraints: [AssocItemConstraint { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).4), ident: A#0, gen_args: GenericArgs { args: [], constraints: [], parenthesized: No, span_ext: no-location (#0) }, kind: Equality { term: Const(ConstArg { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).3), kind: Anon(AnonConst { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).1), def_id: DefId(0:5 ~ mvce[a2ab]::TraitWAssocConst::A::{constant#0}), body: BodyId { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).2) }, span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:35: 2:36 (#0) }) }) }, span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:31: 2:36 (#0) }], parenthesized: No, span_ext: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:30: 2:37 (#0) }), infer_args: false }] }, hir_ref_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).6) }, span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:14: 2:37 (#0) }], TaggedRef { pointer: Lifetime { hir_id: HirId(DefId(0:4 ~ mvce[a2ab]::TraitWAssocConst::A).7), ident: #0, res: ImplicitObjectLifetimeDefault }, tag: None }) }, None), span: /tmp/icemaker_global_tempdir.xCmlSFx4hmpo/rustc_testrunner_tmpdir_reporting.tPdpsshuU7cG/mvce.rs:2:5: 2:38 (#0), defaultness: Default { has_value: false } })
stack backtrace:
   0:     0x735d0f5c6f34 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h07b2089c80742ed5
   1:     0x735d0fe05aa2 - core::fmt::write::h332ae571ae4a9cc4
   2:     0x735d111e3a11 - std::io::Write::write_fmt::h0c761025205b813c
   3:     0x735d0f5c6d92 - std::sys::backtrace::BacktraceLock::print::hbba93a9383b9fa8a
   4:     0x735d0f5c9672 - std::panicking::default_hook::{{closure}}::h00e63950a63732af
   5:     0x735d0f5c9264 - std::panicking::default_hook::h400dc9bc1b724c37
   6:     0x735d0e7204e7 - std[c20316ad899fcaf5]::panicking::update_hook::<alloc[2db8fd01bd7ea837]::boxed::Box<rustc_driver_impl[153d3eccf0c7c750]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x735d0f5c9ee3 - std::panicking::rust_panic_with_hook::he428532615a29ae4
   8:     0x735d0f5c9bda - std::panicking::begin_panic_handler::{{closure}}::h498acb37174be106
   9:     0x735d0f5c73f9 - std::sys::backtrace::__rust_end_short_backtrace::h2c0df5d26e60f09c
  10:     0x735d0f5c989d - rust_begin_unwind
  11:     0x735d0c25df10 - core::panicking::panic_fmt::h35b514d9ffb031f4
  12:     0x735d0e7ecf81 - rustc_hir[229de859651313c0]::hir::expect_failed::<&rustc_hir[229de859651313c0]::hir::Node>
  13:     0x735d1105f858 - <dyn rustc_hir_analysis[2ac45909935d36a1]::hir_ty_lowering::HirTyLowerer>::prohibit_or_lint_bare_trait_object_ty
  14:     0x735d10566736 - <dyn rustc_hir_analysis[2ac45909935d36a1]::hir_ty_lowering::HirTyLowerer>::lower_ty
  15:     0x735d103618cd - rustc_hir_analysis[2ac45909935d36a1]::collect::type_of::type_of
  16:     0x735d10359d2a - rustc_query_impl[824584145395502d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[824584145395502d]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 8usize]>>
  17:     0x735d10161332 - rustc_query_system[75007086aa92bf3]::query::plumbing::try_execute_query::<rustc_query_impl[824584145395502d]::DynamicConfig<rustc_query_system[75007086aa92bf3]::query::caches::DefIdCache<rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[824584145395502d]::plumbing::QueryCtxt, false>
  18:     0x735d10160edf - rustc_query_impl[824584145395502d]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  19:     0x735d10597699 - <rustc_hir_analysis[2ac45909935d36a1]::collect::CollectItemTypesVisitor as rustc_hir[229de859651313c0]::intravisit::Visitor>::visit_trait_item
  20:     0x735d105899ef - rustc_hir_analysis[2ac45909935d36a1]::check::wfcheck::check_well_formed
  21:     0x735d1058754d - rustc_query_impl[824584145395502d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[824584145395502d]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 1usize]>>
  22:     0x735d10587004 - rustc_query_system[75007086aa92bf3]::query::plumbing::try_execute_query::<rustc_query_impl[824584145395502d]::DynamicConfig<rustc_data_structures[59c1b7daa758d1f8]::vec_cache::VecCache<rustc_span[268b27c29cacb432]::def_id::LocalDefId, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[75007086aa92bf3]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[824584145395502d]::plumbing::QueryCtxt, false>
  23:     0x735d10586abf - rustc_query_impl[824584145395502d]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  24:     0x735d105845f0 - rustc_hir_analysis[2ac45909935d36a1]::check::wfcheck::check_mod_type_wf
  25:     0x735d105840df - rustc_query_impl[824584145395502d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[824584145395502d]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 1usize]>>
  26:     0x735d10e96d56 - rustc_query_system[75007086aa92bf3]::query::plumbing::try_execute_query::<rustc_query_impl[824584145395502d]::DynamicConfig<rustc_query_system[75007086aa92bf3]::query::caches::DefaultCache<rustc_span[268b27c29cacb432]::def_id::LocalModDefId, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[824584145395502d]::plumbing::QueryCtxt, false>
  27:     0x735d10e96aff - rustc_query_impl[824584145395502d]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  28:     0x735d1017f9cf - rustc_hir_analysis[2ac45909935d36a1]::check_crate
  29:     0x735d1032807a - rustc_interface[7e29b5e2b62c504d]::passes::run_required_analyses
  30:     0x735d10dc1b7a - rustc_interface[7e29b5e2b62c504d]::passes::analysis
  31:     0x735d10dc1b59 - rustc_query_impl[824584145395502d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[824584145395502d]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 0usize]>>
  32:     0x735d10eda3cb - rustc_query_system[75007086aa92bf3]::query::plumbing::try_execute_query::<rustc_query_impl[824584145395502d]::DynamicConfig<rustc_query_system[75007086aa92bf3]::query::caches::SingleCache<rustc_middle[b1dca1d1b343b3c]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[824584145395502d]::plumbing::QueryCtxt, false>
  33:     0x735d10eda0b9 - rustc_query_impl[824584145395502d]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  34:     0x735d10f1577d - rustc_interface[7e29b5e2b62c504d]::passes::create_and_enter_global_ctxt::<core[8e02e1de5014891c]::option::Option<rustc_interface[7e29b5e2b62c504d]::queries::Linker>, rustc_driver_impl[153d3eccf0c7c750]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  35:     0x735d10f056a0 - rustc_interface[7e29b5e2b62c504d]::interface::run_compiler::<(), rustc_driver_impl[153d3eccf0c7c750]::run_compiler::{closure#0}>::{closure#1}
  36:     0x735d10dabe48 - std[c20316ad899fcaf5]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[7e29b5e2b62c504d]::util::run_in_thread_with_globals<rustc_interface[7e29b5e2b62c504d]::util::run_in_thread_pool_with_globals<rustc_interface[7e29b5e2b62c504d]::interface::run_compiler<(), rustc_driver_impl[153d3eccf0c7c750]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  37:     0x735d10dac734 - <<std[c20316ad899fcaf5]::thread::Builder>::spawn_unchecked_<rustc_interface[7e29b5e2b62c504d]::util::run_in_thread_with_globals<rustc_interface[7e29b5e2b62c504d]::util::run_in_thread_pool_with_globals<rustc_interface[7e29b5e2b62c504d]::interface::run_compiler<(), rustc_driver_impl[153d3eccf0c7c750]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[8e02e1de5014891c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  38:     0x735d10dadb2b - std::sys::pal::unix::thread::Thread::new::thread_start::h63137a35d539f669
  39:     0x735d0aea370a - <unknown>
  40:     0x735d0af27aac - <unknown>
  41:                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 1.87.0-nightly (20f0108ad 2025-03-08) running on x86_64-unknown-linux-gnu

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

query stack during panic:
#0 [type_of] computing type of `TraitWAssocConst::A`
#1 [check_well_formed] checking that `TraitWAssocConst::A` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [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]

This is regressed around 14 crash files that we had fixed in the past (which is quite a lot)

bisects to #138042

[matthiaskrgr]

I guess this was not found in CI because it requires edition >=2021 and we run with 2015 by default

[matthiaskrgr]

seems this is problematic for
ForeignItem(ForeignItem, ImplItem(ImplItem and TraitItem(TraitItem