[ICE]: term_kind: index out of bounds

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(generic_const_exprs)]
fn new<const N: usize>()
where
    [(); N * 1]:,
{
}

fn test<const N: usize>()
where
    [(); N - usize::MAX * 1]:,
{
    new
}

original:

#![feature(generic_const_exprs)]
fn new<const N: usize>()
where
    [(); N * 1]: {}
    
    
fn test<const N: usize>()
where
    [(); N - usize::MAX * 1]:,
{
    new
}

fn main() {}

Version information

rustc 1.99.0-nightly (c7d7da342 2026-07-19)
binary: rustc
commit-hash: c7d7da3428c0e8b261e1ce1687e7228cf053cc62
commit-date: 2026-07-19
host: x86_64-unknown-linux-gnu
release: 1.99.0-nightly
LLVM version: 22.1.8

Possibly related line of code:

rust/compiler/rustc_type_ir/src/term_kind.rs

Lines 246 to 258 in c7d7da3

	}
	/// The following methods work only with (trait) associated term projections.
	// FIXME: Replace by an impl on Alias<ProjectionAliasTermKind>
	impl<I: Interner> AliasTerm<I> {
	pub fn self_ty(self) -> I::Ty {
	self.args.type_at(0)
	}
	pub fn with_replaced_self_ty(self, interner: I, self_ty: I::Ty) -> Self {
	AliasTerm::new(
	interner,
	self.kind,

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

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.V9VWQjeM5YHh/rustc_testrunner_tmpdir_reporting.f8g9LrITVseG/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

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.V9VWQjeM5YHh/rustc_testrunner_tmpdir_reporting.f8g9LrITVseG/mvce.rs:13:2
   |
13 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.V9VWQjeM5YHh/rustc_testrunner_tmpdir_reporting.f8g9LrITVseG/mvce.rs`


thread 'rustc' (1387308) panicked at /rustc-dev/c7d7da3428c0e8b261e1ce1687e7228cf053cc62/compiler/rustc_type_ir/src/term_kind.rs:252:19:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0:     0x7fc2fdae2346 - <<std[bb656dee0c1a7164]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[cf8fb3d9e41ef217]::fmt::Display>::fmt
   1:     0x7fc2fe20a310 - core[cf8fb3d9e41ef217]::fmt::write
   2:     0x7fc2fdaf75ac - <std[bb656dee0c1a7164]::sys::stdio::unix::Stderr as core[cf8fb3d9e41ef217]::io::write::Write>::write_fmt
   3:     0x7fc2fdab3fda - std[bb656dee0c1a7164]::panicking::default_hook::{closure#0}
   4:     0x7fc2fdad4a73 - std[bb656dee0c1a7164]::panicking::default_hook
   5:     0x7fc2fca8947b - std[bb656dee0c1a7164]::panicking::update_hook::<alloc[3446759d461fd26]::boxed::Box<rustc_driver_impl[a9408d480ad75656]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7fc2fdad4f12 - std[bb656dee0c1a7164]::panicking::panic_with_hook
   7:     0x7fc2fdab4092 - std[bb656dee0c1a7164]::panicking::panic_handler::{closure#0}
   8:     0x7fc2fdaac099 - std[bb656dee0c1a7164]::sys::backtrace::__rust_end_short_backtrace::<std[bb656dee0c1a7164]::panicking::panic_handler::{closure#0}, !>
   9:     0x7fc2fdab59ed - __rustc[2cdb6cc0f92420]::rust_begin_unwind
  10:     0x7fc2faa391dc - core[cf8fb3d9e41ef217]::panicking::panic_fmt
  11:     0x7fc2fa77b6d9 - core[cf8fb3d9e41ef217]::panicking::panic_bounds_check
  12:     0x7fc30034b220 - <&rustc_middle[1b51c4dae9648f9a]::ty::list::RawList<(), rustc_middle[1b51c4dae9648f9a]::ty::generic_args::GenericArg> as rustc_type_ir[265bd1e63db516e4]::inherent::GenericArgs<rustc_middle[1b51c4dae9648f9a]::ty::context::TyCtxt>>::type_at.cold
  13:     0x7fc2fd8db59a - <rustc_trait_selection[1d6ffb784f11fbdc]::traits::wf::WfPredicates>::add_wf_preds_for_inherent_projection
  14:     0x7fc2feb2a386 - <rustc_trait_selection[1d6ffb784f11fbdc]::traits::wf::WfPredicates as rustc_type_ir[265bd1e63db516e4]::visit::TypeVisitor<rustc_middle[1b51c4dae9648f9a]::ty::context::TyCtxt>>::visit_const
  15:     0x7fc2fe8bee7c - <rustc_trait_selection[1d6ffb784f11fbdc]::traits::fulfill::FulfillProcessor as rustc_data_structures[cc1c0a08c9af2296]::obligation_forest::ObligationProcessor>::process_obligation
  16:     0x7fc2fe205c91 - <rustc_data_structures[cc1c0a08c9af2296]::obligation_forest::ObligationForest<rustc_trait_selection[1d6ffb784f11fbdc]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[1d6ffb784f11fbdc]::traits::fulfill::FulfillProcessor>
  17:     0x7fc2fe58cb99 - <rustc_hir_typeck[d340f8d6c940519f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  18:     0x7fc2fe596bec - <rustc_hir_typeck[d340f8d6c940519f]::fn_ctxt::FnCtxt>::check_expr_block
  19:     0x7fc2fe58c5ce - <rustc_hir_typeck[d340f8d6c940519f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  20:     0x7fc2fe5b61c6 - rustc_hir_typeck[d340f8d6c940519f]::check::check_fn
  21:     0x7fc2ff425ee7 - rustc_hir_typeck[d340f8d6c940519f]::typeck_with_inspect::{closure#0}
  22:     0x7fc2ff424670 - rustc_query_impl[91105c57d45a8e7d]::query_impl::typeck_root::invoke_provider_fn::__rust_begin_short_backtrace
  23:     0x7fc2fe651869 - rustc_query_impl[91105c57d45a8e7d]::execution::try_execute_query::<rustc_data_structures[cc1c0a08c9af2296]::vec_cache::VecCache<rustc_span[3e8afa6d2baecbb6]::def_id::LocalDefId, rustc_middle[1b51c4dae9648f9a]::query::erase::ErasedData<[u8; 8usize]>, rustc_middle[1b51c4dae9648f9a]::dep_graph::graph::DepNodeIndex>, false>
  24:     0x7fc2fe6512c3 - rustc_query_impl[91105c57d45a8e7d]::query_impl::typeck_root::execute_query_non_incr::__rust_end_short_backtrace
  25:     0x7fc2fe65465e - <rustc_middle[1b51c4dae9648f9a]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_hir_analysis[da5de8c042b7d03e]::check_crate::{closure#1}>::{closure#0}
  26:     0x7fc2fe653f5e - rustc_hir_analysis[da5de8c042b7d03e]::check_crate
  27:     0x7fc2fe64df75 - rustc_interface[bd87170b5770ef6e]::passes::analysis
  28:     0x7fc2ff3ad3c7 - rustc_query_impl[91105c57d45a8e7d]::execution::try_execute_query::<rustc_middle[1b51c4dae9648f9a]::query::caches::SingleCache<rustc_middle[1b51c4dae9648f9a]::query::erase::ErasedData<[u8; 0usize]>>, false>
  29:     0x7fc2ff3ad0a9 - rustc_query_impl[91105c57d45a8e7d]::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
  30:     0x7fc2ff3d0b8d - rustc_interface[bd87170b5770ef6e]::interface::run_compiler::<(), rustc_driver_impl[a9408d480ad75656]::run_compiler::{closure#0}>::{closure#2}
  31:     0x7fc2ff3764a4 - std[bb656dee0c1a7164]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[bd87170b5770ef6e]::util::run_in_thread_with_globals<rustc_interface[bd87170b5770ef6e]::util::run_in_thread_pool_with_globals<rustc_interface[bd87170b5770ef6e]::interface::run_compiler<(), rustc_driver_impl[a9408d480ad75656]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  32:     0x7fc2ff376273 - <std[bb656dee0c1a7164]::thread::lifecycle::spawn_unchecked<rustc_interface[bd87170b5770ef6e]::util::run_in_thread_with_globals<rustc_interface[bd87170b5770ef6e]::util::run_in_thread_pool_with_globals<rustc_interface[bd87170b5770ef6e]::interface::run_compiler<(), rustc_driver_impl[a9408d480ad75656]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[cf8fb3d9e41ef217]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  33:     0x7fc2ff381048 - <std[bb656dee0c1a7164]::sys::thread::unix::Thread>::new::thread_start
  34:     0x7fc2f8a97739 - <unknown>
  35:     0x7fc2f8b1bedc - <unknown>
  36:                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 1.99.0-nightly (c7d7da342 2026-07-19) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck_root] type-checking `test`
#1 [analysis] running analysis passes on crate `mvce`
end of query stack
error: aborting due to 1 previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0601`.

@rustbot label +F-generic_const_exprs