ICE `try_lower_anon_const_lit: received const param which shouldn't be possible`

[matthiaskrgr]

snippet:

//@compile-flags: --crate-type=lib
#![feature(generic_const_exprs)]
#![feature(generic_const_items, min_generic_const_args)]
#[type_const]
const ITEM3<const N : usize> : usize = const {N};

Version information

rustc 1.94.0-nightly (c4aa646f1 2025-12-24)
binary: rustc
commit-hash: c4aa646f15e40bd3e64ddb5017b7b89b3646ac99
commit-date: 2025-12-24
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.8

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --crate-type=lib

Program output

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs: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

warning: the feature `generic_const_items` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:2:12
  |
2 | #![feature(generic_const_items, min_generic_const_args)]
  |            ^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #113521 <https://github.com/rust-lang/rust/issues/113521> for more information

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:2:33
  |
2 | #![feature(generic_const_items, min_generic_const_args)]
  |                                 ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information

warning: unnecessary braces around assigned value
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:4:46
  |
4 | const ITEM3<const N : usize> : usize = const {N};
  |                                              ^ ^
  |
  = note: `#[warn(unused_braces)]` (part of `#[warn(unused)]`) on by default
help: remove these braces
  |
4 - const ITEM3<const N : usize> : usize = const {N};
4 + const ITEM3<const N : usize> : usize = const N;
  |

warning: constant `ITEM3` is never used
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:4:7
  |
4 | const ITEM3<const N : usize> : usize = const {N};
  |       ^^^^^
  |
  = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default

warning: 5 warnings emitted

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: try_lower_anon_const_lit: received const param which shouldn't be possible
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:4:47
  |
4 | const ITEM3<const N : usize> : usize = const {N};
  |                                               ^
  |
note: delayed at /rustc-dev/c4aa646f15e40bd3e64ddb5017b7b89b3646ac99/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs:2530:31
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, &str>
         4: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_const_arg
         5: rustc_hir_analysis::collect::const_of_item
         6: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::const_of_item::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
         7: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
         8: rustc_query_impl::query_impl::const_of_item::get_query_non_incr::__rust_end_short_backtrace
         9: rustc_hir_analysis::check::wfcheck::check_type_const
        10: rustc_hir_analysis::check::check::check_item_type
        11: rustc_hir_analysis::check::wfcheck::check_well_formed
        12: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        13: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 1]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        14: rustc_query_impl::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
        15: rustc_hir_analysis::check::wfcheck::check_type_wf
        16: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        17: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        18: rustc_query_impl::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
        19: rustc_hir_analysis::check_crate
        20: rustc_interface::passes::analysis
        21: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        22: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        23: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        24: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
        25: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        26: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        27: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        28: <std::sys::thread::unix::Thread>::new::thread_start
        29: <unknown>
        30: <unknown>
      
 --> /tmp/icemaker_global_tempdir.EHoRCZVflgNi/rustc_testrunner_tmpdir_reporting.gu4uFe3r95BJ/mvce.rs:4:47
  |
4 | const ITEM3<const N : usize> : usize = const {N};
  |                                               ^

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 1.94.0-nightly (c4aa646f1 2025-12-24) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -Z dump-mir-dir=dir

query stack during panic:
end of query stack

@rustbot label +F-generic_const_exprs +F-generic_const_items +F-min_generic_const_args