ICE: `type parameter `T/#1` (T/#1/1) out of range when instantiating, args=[?2t]`

[cushionbadak]

Code

Hand-reduced

#![feature(associated_const_equality)]

trait Trait {
    type TT;
}

pub struct NoPin;

pub trait PinA<PER> {
    const A: u8;
}

impl<PER> PinA<PER> for NoPin {
    const A: u8 = 0;
}

pub trait Pins<USART> {}

impl<USART, T> Pins<USART> for T where T: PinA<USART, A = 42> {}

struct S<T> {
    x: T,
}

impl<T> S<&dyn Trait> where NoPin: Pins<T> {}

fn main() {}

A mutant of tests/ui/generic-const-items/assoc-const-AnonConst-ice-108220.rs

Meta

rustc --version --verbose:

rustc 1.89.0-nightly (99e7c15e8 2025-06-01)
binary: rustc
commit-hash: 99e7c15e81385b38a8186b51edc4577d5d7b5bdd
commit-date: 2025-06-01
host: aarch64-apple-darwin
release: 1.89.0-nightly
LLVM version: 20.1.5

Error output

command: rustc

error[E0191]: the value of the associated type `TT` in `Trait` must be specified
  --> afidt_1_c2.rs:25:16
   |
4  |     type TT;
   |     ------- `TT` defined here
...
25 | impl<T> S<&dyn Trait> where NoPin: Pins<T> {}
   |                ^^^^^ help: specify the associated type: `Trait<TT = Type>`


thread 'rustc' panicked at /rustc/99e7c15e81385b38a8186b51edc4577d5d7b5bdd/compiler/rustc_type_ir/src/binder.rs:753:9:
type parameter `T/#1` (T/#1/1) out of range when instantiating, args=[?2t]

Backtrace

thread 'rustc' panicked at /rustc/99e7c15e81385b38a8186b51edc4577d5d7b5bdd/compiler/rustc_type_ir/src/binder.rs:753:9:
type parameter `T/#1` (T/#1/1) out of range when instantiating, args=[?2t]
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: <rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt>>::type_param_out_of_range
   3: <rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt> as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty
   4: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::generic_args::GenericArg> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt>>
   5: <rustc_middle::ty::consts::Const as rustc_type_ir::fold::TypeSuperFoldable<rustc_middle::ty::context::TyCtxt>>::super_fold_with::<rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt>>
   6: rustc_trait_selection::traits::project::opt_normalize_projection_term
   7: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_term::{closure#0}>
   8: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_predicate_recursively::{closure#0}::{closure#0}
   9: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_predicate_recursively
  10: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_candidate::{closure#0}::{closure#0}
  11: <rustc_infer::infer::InferCtxt>::probe::<core::result::Result<rustc_middle::traits::select::EvaluationResult, rustc_middle::traits::select::OverflowError>, <rustc_trait_selection::traits::select::SelectionContext>::evaluation_probe<<rustc_trait_selection::traits::select::SelectionContext>::evaluate_candidate::{closure#0}::{closure#0}>::{closure#0}>
  12: <rustc_trait_selection::traits::select::SelectionContext>::in_task::<<rustc_trait_selection::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}::{closure#0}, core::result::Result<core::option::Option<rustc_middle::traits::select::SelectionCandidate>, rustc_middle::traits::SelectionError>>::{closure#0}
  13: <rustc_trait_selection::traits::select::SelectionContext>::candidate_from_obligation
  14: <rustc_trait_selection::traits::select::SelectionContext>::poly_select::{closure#0}
  15: <rustc_trait_selection::traits::fulfill::FulfillProcessor>::process_trait_obligation
  16: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
  17: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
  18: <rustc_trait_selection::traits::fulfill::FulfillmentContext<rustc_trait_selection::traits::FulfillmentError> as rustc_infer::traits::engine::TraitEngine<rustc_trait_selection::traits::FulfillmentError>>::select_where_possible
  19: <rustc_trait_selection::traits::fulfill::FulfillmentContext<rustc_trait_selection::traits::FulfillmentError> as rustc_infer::traits::engine::TraitEngine<rustc_trait_selection::traits::FulfillmentError>>::select_all_or_error
  20: rustc_hir_analysis::check::wfcheck::check_item
  21: rustc_hir_analysis::check::wfcheck::check_well_formed
      [... omitted 1 frame ...]
  22: <rustc_middle::hir::ModuleItems>::par_opaques::<rustc_hir_analysis::check::wfcheck::check_mod_type_wf::{closure#4}>::{closure#0}
  23: rustc_hir_analysis::check::wfcheck::check_mod_type_wf
      [... omitted 1 frame ...]
  24: rustc_hir_analysis::check_crate
  25: rustc_interface::passes::run_required_analyses
  26: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  27: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>
  28: 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.

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: please attach the file at `/Users/jisukbyun/workspace/250203 scratch/rustc-ice-2025-06-02T15_09_43-2051.txt` to your bug report

query stack during panic:
#0 [check_well_formed] checking that `<impl at afidt_1_c2.rs:25:1: 25:43>` is well-formed
#1 [check_mod_type_wf] checking that types are well-formed in top-level module
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0191`.

Bisects to

searched nightlies: from nightly-2025-01-01 to nightly-2025-06-01
regressed nightly: nightly-2025-05-24
searched commit range: 2eef478...3e674b0
regressed commit: 52bf0cf

bisected with cargo-bisect-rustc v0.6.9

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

cargo bisect-rustc --end=2025-06-01 --regress ice --preserve --script rustc -- afidt_1_c2.rs

Notes

• ICE location: compiler/rustc_type_ir/src/binder.rs Line-753
  

  rust/compiler/rustc_type_ir/src/binder.rs

  Lines 752 to 760 in 99e7c15

  	fn type_param_out_of_range(&self, p: I::ParamTy, ty: I::Ty) -> ! {
  	panic!(
  	"type parameter `{:?}` ({:?}/{}) out of range when instantiating, args={:?}",
  	p,
  	ty,
  	p.index(),
  	self.args,
  	)
  	}

• Other open ICE issues of "type parameter ... out of range when instantiating" requires different features

@rustbot label +F-associated_const_equality

[cyrgani]

a bit shorter:

trait Trait {
    type TT;
}

trait PinA<T> {
    const A: u8;
}

impl<T> PinA<T> for () {
    const A: u8 = 0;
}

trait Pins<T> {}

impl<T> Pins<T> for () where (): PinA<T, A = 0> {}

struct S<T>(T);

impl<'a, T> S<&'a dyn Trait> where (): Pins<T> {}

fn main() {}