ICE: `layout_of: unexpected type`

[cushionbadak]

Code

#![feature(unsafe_binders)]
#![feature(transmutability)]
#![feature(type_alias_impl_trait)]
#![allow(incomplete_features)]

trait OpaqueTrait {}
type OpaqueType = unsafe<> impl OpaqueTrait;
trait AnotherTrait {}
impl<T: std::mem::TransmuteFrom<()>> AnotherTrait for T {}
impl AnotherTrait for OpaqueType {}

pub fn main() {}

mutant from tests/ui/transmutability/malformed-program-gracefulness/coherence-bikeshed-intrinsic-from.rs

Meta

rustc --version --verbose:

rustc 1.89.0-nightly (bf64d66bd 2025-05-21)
binary: rustc
commit-hash: bf64d66bd58719fac2585eae5e546e5e1d9947f5
commit-date: 2025-05-21
host: aarch64-apple-darwin
release: 1.89.0-nightly
LLVM version: 20.1.5

Error output

command: rustc

error[E0277]: the trait bound `OpaqueType::{opaque#0}: Copy` is not satisfied
 --> abcd.rs:7:19
  |
7 | type OpaqueType = unsafe<> impl OpaqueTrait;
  |                   ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `OpaqueType::{opaque#0}`

error: internal compiler error: compiler/rustc_ty_utils/src/layout.rs:720:13: layout_of: unexpected type `_`


thread 'rustc' panicked at compiler/rustc_ty_utils/src/layout.rs:720:13:
Box<dyn Any>

Backtrace

thread 'rustc' panicked at compiler/rustc_ty_utils/src/layout.rs:720:13:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   2: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   6: rustc_ty_utils::layout::layout_of
      [... omitted 2 frames ...]
   7: <rustc_middle::ty::layout::LayoutCx as rustc_middle::ty::layout::LayoutOf>::spanned_layout_of
   8: rustc_ty_utils::layout::layout_of
      [... omitted 2 frames ...]
   9: rustc_transmute::layout::rustc::layout_of
  10: <rustc_transmute::layout::tree::Tree<rustc_transmute::layout::rustc::Def, rustc_transmute::layout::rustc::Ref>>::from_ty
  11: <rustc_transmute::rustc::TransmuteTypeEnv>::is_transmutable
  12: <rustc_trait_selection::solve::delegate::SolverDelegate as rustc_next_trait_solver::delegate::SolverDelegate>::is_transmutable
  13: <rustc_type_ir::predicate::TraitPredicate<rustc_middle::ty::context::TyCtxt> as rustc_next_trait_solver::solve::assembly::GoalKind<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::consider_builtin_transmute_candidate
  14: <rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::assemble_and_evaluate_candidates::<rustc_type_ir::predicate::TraitPredicate<rustc_middle::ty::context::TyCtxt>>
  15: <rustc_type_ir::search_graph::SearchGraph<rustc_next_trait_solver::solve::search_graph::SearchGraphDelegate<rustc_trait_selection::solve::delegate::SolverDelegate>, rustc_middle::ty::context::TyCtxt>>::with_new_goal::<<rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::evaluate_canonical_goal::{closure#0}::{closure#0}::{closure#0}>::{closure#2}
  16: <rustc_type_ir::search_graph::SearchGraph<rustc_next_trait_solver::solve::search_graph::SearchGraphDelegate<rustc_trait_selection::solve::delegate::SolverDelegate>, rustc_middle::ty::context::TyCtxt>>::with_new_goal::<<rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::evaluate_canonical_goal::{closure#0}::{closure#0}::{closure#0}>
  17: <rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::evaluate_goal_raw
  18: <rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::evaluate_goal
  19: <rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<rustc_trait_selection::solve::delegate::SolverDelegate, rustc_middle::ty::context::TyCtxt>>::enter_root::<core::result::Result<(rustc_next_trait_solver::solve::HasChanged, rustc_type_ir::solve::Certainty), rustc_type_ir::solve::NoSolution>, <rustc_trait_selection::solve::delegate::SolverDelegate as rustc_next_trait_solver::solve::eval_ctxt::SolverDelegateEvalExt>::evaluate_root_goal::{closure#0}>
  20: <rustc_trait_selection::solve::fulfill::FulfillmentCtxt<rustc_infer::traits::engine::ScrubbedTraitError> as rustc_infer::traits::engine::TraitEngine<rustc_infer::traits::engine::ScrubbedTraitError>>::select_where_possible
  21: <rustc_trait_selection::solve::fulfill::FulfillmentCtxt<rustc_infer::traits::engine::ScrubbedTraitError> as rustc_infer::traits::engine::TraitEngine<rustc_infer::traits::engine::ScrubbedTraitError>>::select_all_or_error
  22: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
  23: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation_no_overflow
  24: <rustc_infer::infer::InferCtxt>::probe::<(), <rustc_trait_selection::traits::coherence::AmbiguityCausesVisitor as rustc_trait_selection::solve::inspect::analyse::ProofTreeVisitor>::visit_goal::{closure#2}>
  25: <rustc_trait_selection::traits::coherence::AmbiguityCausesVisitor as rustc_trait_selection::solve::inspect::analyse::ProofTreeVisitor>::visit_goal
  26: rustc_trait_selection::traits::coherence::overlap
  27: rustc_trait_selection::traits::coherence::overlapping_impls
  28: <rustc_middle::traits::specialization_graph::Children as rustc_trait_selection::traits::specialize::specialization_graph::ChildrenExt>::insert
  29: <rustc_middle::traits::specialization_graph::Graph as rustc_trait_selection::traits::specialize::specialization_graph::GraphExt>::insert
  30: rustc_trait_selection::traits::specialize::specialization_graph_provider
      [... omitted 1 frame ...]
  31: rustc_hir_analysis::coherence::coherent_trait
      [... omitted 1 frame ...]
  32: rustc_middle::query::plumbing::query_ensure_error_guaranteed::<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 1]>>, ()>
  33: rustc_hir_analysis::check::wfcheck::check_item
  34: rustc_hir_analysis::check::wfcheck::check_well_formed
      [... omitted 1 frame ...]
  35: <rustc_middle::hir::ModuleItems>::par_opaques::<rustc_hir_analysis::check::wfcheck::check_mod_type_wf::{closure#4}>::{closure#0}
  36: rustc_hir_analysis::check::wfcheck::check_mod_type_wf
      [... omitted 1 frame ...]
  37: rustc_hir_analysis::check_crate
  38: rustc_interface::passes::run_required_analyses
  39: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  40: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>
  41: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/jisukbyun/workspace/250203 scratch/rustc-ice-2025-05-22T15_39_19-77784.txt` to your bug report

query stack during panic:
panicked at /rustc/bf64d66bd58719fac2585eae5e546e5e1d9947f5/compiler/rustc_type_ir/src/ty_kind.rs:864:17:

thread panicked while processing panic. aborting.
[1]    77784 abort      rustc abcd.rs

Bisects to

searched nightlies: from nightly-2024-05-01 to nightly-2025-05-22
regressed nightly: nightly-2024-12-25
searched commit range: bdc6b3d...409998c
regressed commit: f334342

bisected with cargo-bisect-rustc v0.6.9

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --end=2025-05-22 --regress ice --preserve --script rustc -- abcd.rs

Notes

• ICE location: compiler/rustc_ty_utils/src/layout.rs Line-720
  

  rust/compiler/rustc_ty_utils/src/layout.rs

  Lines 713 to 722 in bf64d66

  	LayoutError::Unknown(ty)
  	};
  	return Err(error(cx, err));
  	}
  	ty::Bound(..) | ty::CoroutineWitness(..) | ty::Infer(_) | ty::Error(_) => {
  	// `ty::Error` is handled at the top of this function.
  	bug!("layout_of: unexpected type `{ty}`")
  	}
  	})

• Closed ICE Issue-139152 has identical ICE location.

• Second panic (while printing query stack I guess) occured at: compiler/rustc_type_ir/src/ty_kind.rs Line-864
  

  rust/compiler/rustc_type_ir/src/ty_kind.rs

  Lines 857 to 869 in bf64d66

  	#[cfg(feature = "nightly")]
  	impl<CTX> HashStable<CTX> for InferTy {
  	fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
  	use InferTy::*;
  	std::mem::discriminant(self).hash_stable(ctx, hasher);
  	match self {
  	TyVar(_) | IntVar(_) | FloatVar(_) => {
  	panic!("type variables should not be hashed: {self:?}")
  	}
  	FreshTy(v) | FreshIntTy(v) | FreshFloatTy(v) => v.hash_stable(ctx, hasher),
  	}
  	}
  	}

• I'm not sure whether all three features are needed to trigger the ICE.

@rustbot label +F-unsafe_binders +F-transmutability +F-type_alias_impl_trait

[compiler-errors]

This has nothing to do with unsafe binders:

#![feature(transmutability)]
#![feature(type_alias_impl_trait)]
#![allow(incomplete_features)]

trait OpaqueTrait {}

struct W<T>(T);

type OpaqueType = W<impl OpaqueTrait>;

trait AnotherTrait {}

impl<T: std::mem::TransmuteFrom<()>> AnotherTrait for T {}

impl AnotherTrait for OpaqueType {}

pub fn main() {}

[cushionbadak]

That code regression in nightly-2024-08-29

searched toolchains nightly-2024-05-01 through nightly-2025-05-22


********************************************************************************
Regression in nightly-2024-08-29
********************************************************************************

fetching https://static.rust-lang.org/dist/2024-08-28/channel-rust-nightly-git-commit-hash.txt
nightly manifest 2024-08-28: 40 B / 40 B [=======================================================] 100.00 % 774.01 KB/s converted 2024-08-28 to 1f12b9b0fdbe735968ac002792a720f0ba4faca6
fetching https://static.rust-lang.org/dist/2024-08-29/channel-rust-nightly-git-commit-hash.txt
nightly manifest 2024-08-29: 40 B / 40 B [=======================================================] 100.00 % 656.09 KB/s converted 2024-08-29 to 100fde5246bf56f22fb5cc85374dd841296fce0e
looking for regression commit between 2024-08-28 and 2024-08-29
fetching (via remote github) commits from max(1f12b9b0fdbe735968ac002792a720f0ba4faca6, 2024-08-26) to 100fde5246bf56f22fb5cc85374dd841296fce0e
ending github query because we found starting sha: 1f12b9b0fdbe735968ac002792a720f0ba4faca6
get_commits_between returning commits, len: 5
  commit[0] 2024-08-27: Auto merge of #129665 - matthiaskrgr:rollup-hy23k7d, r=matthiaskrgr
  commit[1] 2024-08-27: Auto merge of #128506 - compiler-errors:by-move-body, r=cjgillot
  commit[2] 2024-08-28: Auto merge of #129546 - compiler-errors:no-pred-on, r=fee1-dead
  commit[3] 2024-08-28: Auto merge of #129589 - saethlin:improve-panic-immediate-abort, r=tgross35
  commit[4] 2024-08-28: Auto merge of #129691 - matthiaskrgr:rollup-owlcr3m, r=matthiaskrgr
ERROR: no CI builds available between 1f12b9b0fdbe735968ac002792a720f0ba4faca6 and 100fde5246bf56f22fb5cc85374dd841296fce0e within last 167 days