ICE: xx has parameters, but no args were provided in instantiate

[rucsesec]

Code

#![feature(generic_const_exprs)]

trait TypeTrait {
    type Assoc;
}

struct A<const B: <dyn TypeTrait<Assoc = i32> as TypeTrait>::Assoc = 1, C>(C);

fn main() {}

Rust Version

rustc 1.92.0-nightly (a9d0a6f15 2025-09-16)
binary: rustc
commit-hash: a9d0a6f15533a364816c4d81e2192009ef601d33
commit-date: 2025-09-16
host: x86_64-unknown-linux-gnu
release: 1.92.0-nightly
LLVM version: 21.1.1

Current error output

error: generic parameters with a default must be trailing
 --> <source>:7:16
  |
7 | struct A<const B: <dyn TypeTrait<Assoc = i32> as TypeTrait>::Assoc = 1, C>(C);
  |                ^

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <source>:1:12
  |
1 | #![feature(generic_const_exprs)]
  |            ^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
  = note: `#[warn(incomplete_features)]` on by default


thread 'rustc' (3) panicked at /rustc-dev/a454fccb02df9d361f1201b747c01257f58a8b37/compiler/rustc_type_ir/src/binder.rs:641:13:
Binder { value: TraitPredicate(<C as std::marker::Sized>, polarity:Positive), bound_vars: [] } has parameters, but no args were provided in instantiate

Backtrace

stack backtrace:
   0:     0x747bfca4bdf3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h830fbe15fbab381b
   1:     0x747bfd201b58 - core::fmt::write::hf661a9e75db120a3
   2:     0x747bfca00d71 - std::io::Write::write_fmt::he76c5adbbdfd1600
   3:     0x747bfca11d22 - std::sys::backtrace::BacktraceLock::print::hb87325f2dc6d4dfe
   4:     0x747bfca17c69 - std::panicking::default_hook::{{closure}}::h5e01ba9de3335cc4
   5:     0x747bfca17793 - std::panicking::default_hook::h47934e1f610fefc5
   6:     0x747bfba08797 - std[c207121dba9f4102]::panicking::update_hook::<alloc[fbc11b1b12ed36cd]::boxed::Box<rustc_driver_impl[d9438a736c8997f5]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x747bfca1808f - std::panicking::panic_with_hook::hfee0edaf348ac547
   8:     0x747bfca17e4a - std::panicking::panic_handler::{{closure}}::h6c6964ed9ca982a7
   9:     0x747bfca11e69 - std::sys::backtrace::__rust_end_short_backtrace::h232e83a0d4d66618
  10:     0x747bfc9f27ad - __rustc[b07eb43dc0c79c3a]::rust_begin_unwind
  11:     0x747bf90e71f0 - core::panicking::panic_fmt::he0731d8485d264bd
  12:     0x747bfd237f94 - <rustc_middle[ca952e998b261ea0]::ty::generics::GenericPredicates>::instantiate_into
  13:     0x747bfdaa9540 - <rustc_trait_selection[3e366344a3e1b36c]::traits::wf::WfPredicates>::nominal_obligations
  14:     0x747bfdab47da - <rustc_trait_selection[3e366344a3e1b36c]::traits::wf::WfPredicates as rustc_type_ir[a8998a4f8592c43f]::visit::TypeVisitor<rustc_middle[ca952e998b261ea0]::ty::context::TyCtxt>>::visit_const
  15:     0x747bfd980a0c - <rustc_trait_selection[3e366344a3e1b36c]::traits::fulfill::FulfillProcessor as rustc_data_structures[9517fc3c6a0ce3dd]::obligation_forest::ObligationProcessor>::process_obligation
  16:     0x747bfd204dc9 - <rustc_data_structures[9517fc3c6a0ce3dd]::obligation_forest::ObligationForest<rustc_trait_selection[3e366344a3e1b36c]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[3e366344a3e1b36c]::traits::fulfill::FulfillProcessor>
  17:     0x747bfda593aa - <rustc_trait_selection[3e366344a3e1b36c]::traits::fulfill::FulfillmentContext<rustc_trait_selection[3e366344a3e1b36c]::traits::FulfillmentError> as rustc_infer[892ccfba2d54b3f4]::traits::engine::TraitEngine<rustc_trait_selection[3e366344a3e1b36c]::traits::FulfillmentError>>::select_all_or_error
  18:     0x747bfda65b17 - rustc_hir_analysis[25a5ef209d74c11d]::check::wfcheck::check_type_defn
  19:     0x747bfdd957d7 - rustc_hir_analysis[25a5ef209d74c11d]::check::check::check_item_type
  20:     0x747bfdd901db - rustc_hir_analysis[25a5ef209d74c11d]::check::wfcheck::check_well_formed
  21:     0x747bfdd901a3 - rustc_query_impl[d2194a968fe82a14]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d2194a968fe82a14]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 1usize]>>
  22:     0x747bfdd8f9e3 - rustc_query_system[8aa47809e78cb5f0]::query::plumbing::try_execute_query::<rustc_query_impl[d2194a968fe82a14]::DynamicConfig<rustc_data_structures[9517fc3c6a0ce3dd]::vec_cache::VecCache<rustc_span[acd9e562735339de]::def_id::LocalDefId, rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[8aa47809e78cb5f0]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[d2194a968fe82a14]::plumbing::QueryCtxt, false>
  23:     0x747bfdd8f502 - rustc_query_impl[d2194a968fe82a14]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  24:     0x747bfdd8cab5 - rustc_hir_analysis[25a5ef209d74c11d]::check::wfcheck::check_type_wf
  25:     0x747bfdd8c9a7 - rustc_query_impl[d2194a968fe82a14]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d2194a968fe82a14]::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 1usize]>>
  26:     0x747bfe337794 - rustc_query_system[8aa47809e78cb5f0]::query::plumbing::try_execute_query::<rustc_query_impl[d2194a968fe82a14]::DynamicConfig<rustc_query_system[8aa47809e78cb5f0]::query::caches::SingleCache<rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[d2194a968fe82a14]::plumbing::QueryCtxt, false>
  27:     0x747bfe337576 - rustc_query_impl[d2194a968fe82a14]::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
  28:     0x747bfd48b5fa - rustc_hir_analysis[25a5ef209d74c11d]::check_crate
  29:     0x747bfd49c87e - rustc_interface[3a2987949cdbb48a]::passes::analysis
  30:     0x747bfd49c54b - rustc_query_impl[d2194a968fe82a14]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d2194a968fe82a14]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 0usize]>>
  31:     0x747bfe33e208 - rustc_query_system[8aa47809e78cb5f0]::query::plumbing::try_execute_query::<rustc_query_impl[d2194a968fe82a14]::DynamicConfig<rustc_query_system[8aa47809e78cb5f0]::query::caches::SingleCache<rustc_middle[ca952e998b261ea0]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[d2194a968fe82a14]::plumbing::QueryCtxt, false>
  32:     0x747bfe33de3e - rustc_query_impl[d2194a968fe82a14]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  33:     0x747bfe57d063 - rustc_interface[3a2987949cdbb48a]::passes::create_and_enter_global_ctxt::<core[c97f7de45acf1cc9]::option::Option<rustc_interface[3a2987949cdbb48a]::queries::Linker>, rustc_driver_impl[d9438a736c8997f5]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  34:     0x747bfe4c10fe - rustc_interface[3a2987949cdbb48a]::interface::run_compiler::<(), rustc_driver_impl[d9438a736c8997f5]::run_compiler::{closure#0}>::{closure#1}
  35:     0x747bfe3f5b38 - std[c207121dba9f4102]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3a2987949cdbb48a]::util::run_in_thread_with_globals<rustc_interface[3a2987949cdbb48a]::util::run_in_thread_pool_with_globals<rustc_interface[3a2987949cdbb48a]::interface::run_compiler<(), rustc_driver_impl[d9438a736c8997f5]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  36:     0x747bfe3f581c - <<std[c207121dba9f4102]::thread::Builder>::spawn_unchecked_<rustc_interface[3a2987949cdbb48a]::util::run_in_thread_with_globals<rustc_interface[3a2987949cdbb48a]::util::run_in_thread_pool_with_globals<rustc_interface[3a2987949cdbb48a]::interface::run_compiler<(), rustc_driver_impl[d9438a736c8997f5]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[c97f7de45acf1cc9]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  37:     0x747bfe3fbecd - std::sys::thread::unix::Thread::new::thread_start::h44739fe3c92fa2b0
  38:     0x747bf7a94ac3 - <unknown>
  39:     0x747bf7b26850 - <unknown>
  40:                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: please attach the file at `/app/rustc-ice-2025-09-19T06_35_16-1.txt` to your bug report

note: compiler flags: -C debuginfo=2 --crate-type bin -C linker=/opt/compiler-explorer/gcc-15.2.0/bin/gcc

query stack during panic:
#0 [check_well_formed] checking that `A` is well-formed
#1 [check_type_wf] checking that types are well-formed
... and 1 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
error: aborting due to 1 previous error; 1 warning emitted

Anything else?

The only open issue I found that is similar to this ICE error message is #143205, but there are some differences between them. I'm not sure if it's a duplicate issue.

It is more similar to #114317, but that one has already been closed.

[rucsesec]

It seems that using an alias can also trigger it.

#![feature(generic_const_exprs)]

type DefaultA<const B: ()> = A<B, i32>;

struct A<const B: () = DefaultA::<B>, C>(C);

fn main() {}

[GrigorenkoPV]

Regression in nightly-2021-09-01 (5d68044...29ef6cf)