ICE: `assertion failed: src.layout.ty.is_integral() || src.layout.ty.is_char() || src.layout.ty.is_bool()`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(generic_const_exprs)]
#![feature(min_generic_const_args)]
fn foo<const N: u32>(a: [(); N as usize]) {}

const C: f32 = 1.0;

fn main() {
    foo::<C>();
}

original:

//@ revisions: simple adt_const_params full
#![cfg_attr(full, feature(adt_const_params, ))]
#[cfg_attr(full, allow(incomplete_features))]
#![deny(const_evaluatable_unchecked)]
#![cfg_attr(adt_const_params, allow(incomplete_features))]

fn foo<const N: u32>(a: [(); N as usize]) {
    [(); braced_braced_expr!{}];
    //~^ error: unconstrained generic constant
}
//[adt_const_params]~^^ ERROR `&'static ()` can't be used as a const parameter type

const C: f32 = 1.0;

fn main() {
    foo::<C>();
}

Version information

rustc 1.90.0-nightly (fd9ca711a 2025-07-05)
binary: rustc
commit-hash: fd9ca711a3a0e2bd5bd33a345fa4439348111006
commit-date: 2025-07-05
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.7

Possibly related line of code:

rust/compiler/rustc_const_eval/src/interpret/cast.rs

Lines 149 to 161 in fd9ca71

	/// Handles 'IntToInt' and 'IntToFloat' casts.
	pub fn int_to_int_or_float(
	&self,
	src: &ImmTy<'tcx, M::Provenance>,
	cast_to: TyAndLayout<'tcx>,
	) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
	assert!(src.layout.ty.is_integral() || src.layout.ty.is_char() || src.layout.ty.is_bool());
	assert!(cast_to.ty.is_floating_point() || cast_to.ty.is_integral() || cast_to.ty.is_char());
	interp_ok(ImmTy::from_scalar(
	self.cast_from_int_like(src.to_scalar(), src.layout, cast_to.ty)?,
	cast_to,
	))

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zcrate-attr=feature(generic_const_exprs) -Zcrate-attr=feature(min_generic_const_args)

Program output

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>: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 `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:12
  |
1 | #![feature(min_generic_const_args)]
  |            ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information


thread 'rustc' panicked at compiler/rustc_const_eval/src/interpret/cast.rs:155:9:
assertion failed: src.layout.ty.is_integral() || src.layout.ty.is_char() ||
    src.layout.ty.is_bool()
stack backtrace:
   0:     0x769bcc329c03 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hdcaf038ccc22af60
   1:     0x769bcca02bbf - core::fmt::write::h6a2dc0c1e0319253
   2:     0x769bcc31f843 - std::io::Write::write_fmt::hf80ee03682e93b18
   3:     0x769bcc329a62 - std::sys::backtrace::BacktraceLock::print::hb64b84ed3955e559
   4:     0x769bcc32d4fa - std::panicking::default_hook::{{closure}}::h054930d99c890fe0
   5:     0x769bcc32d07f - std::panicking::default_hook::h45a7dd1d52c6f734
   6:     0x769bcb3fa983 - std[97ade9a0245a6b27]::panicking::update_hook::<alloc[b9dae7385774dacd]::boxed::Box<rustc_driver_impl[9e5e8cd112afe598]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x769bcc32dd4b - std::panicking::rust_panic_with_hook::h3b65872abefdcb8f
   8:     0x769bcc32da16 - std::panicking::begin_panic_handler::{{closure}}::hb1f6277d296c3bf1
   9:     0x769bcc32a0d9 - std::sys::backtrace::__rust_end_short_backtrace::haea44604407e5a79
  10:     0x769bcc32d72d - __rustc[40318619b3c9f340]::rust_begin_unwind
  11:     0x769bc8aa7ee0 - core::panicking::panic_fmt::h6566078d388a5fbd
  12:     0x769bc8dfe79c - core::panicking::panic::h4c68868fa581b4af
  13:     0x769bcd850117 - <rustc_const_eval[6dd836cff3abf228]::interpret::eval_context::InterpCx<rustc_const_eval[6dd836cff3abf228]::const_eval::machine::CompileTimeMachine>>::eval_rvalue_into_place
  14:     0x769bcd82e13c - rustc_const_eval[6dd836cff3abf228]::const_eval::eval_queries::eval_to_allocation_raw_provider
  15:     0x769bcd82d57e - rustc_query_impl[fb780613ca4d2a4e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb780613ca4d2a4e]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 24usize]>>
  16:     0x769bcd820627 - rustc_query_system[f1707db06e6fa3b0]::query::plumbing::try_execute_query::<rustc_query_impl[fb780613ca4d2a4e]::DynamicConfig<rustc_query_system[f1707db06e6fa3b0]::query::caches::DefaultCache<rustc_middle[ff99e1b4bd010738]::ty::PseudoCanonicalInput<rustc_middle[ff99e1b4bd010738]::mir::interpret::GlobalId>, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[fb780613ca4d2a4e]::plumbing::QueryCtxt, false>
  17:     0x769bcd8201dd - rustc_query_impl[fb780613ca4d2a4e]::query_impl::eval_to_allocation_raw::get_query_non_incr::__rust_end_short_backtrace
  18:     0x769bcd821e9e - rustc_const_eval[6dd836cff3abf228]::const_eval::valtrees::eval_to_valtree
  19:     0x769bcd821c4f - rustc_query_impl[fb780613ca4d2a4e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb780613ca4d2a4e]::query_impl::eval_to_valtree::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 16usize]>>
  20:     0x769bccdcb455 - rustc_query_system[f1707db06e6fa3b0]::query::plumbing::try_execute_query::<rustc_query_impl[fb780613ca4d2a4e]::DynamicConfig<rustc_query_system[f1707db06e6fa3b0]::query::caches::DefaultCache<rustc_middle[ff99e1b4bd010738]::ty::PseudoCanonicalInput<rustc_middle[ff99e1b4bd010738]::mir::interpret::GlobalId>, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[fb780613ca4d2a4e]::plumbing::QueryCtxt, false>
  21:     0x769bccdcb004 - rustc_query_impl[fb780613ca4d2a4e]::query_impl::eval_to_valtree::get_query_non_incr::__rust_end_short_backtrace
  22:     0x769bccdc9eaa - <rustc_middle[ff99e1b4bd010738]::ty::context::TyCtxt>::const_eval_resolve_for_typeck
  23:     0x769bccdc8a05 - rustc_trait_selection[4e9fe4a9859c8b31]::traits::try_evaluate_const
  24:     0x769bce4936c4 - rustc_trait_selection[4e9fe4a9859c8b31]::traits::const_evaluatable::is_const_evaluatable.cold
  25:     0x769bcd3b0208 - <rustc_trait_selection[4e9fe4a9859c8b31]::traits::fulfill::FulfillProcessor as rustc_data_structures[2cc1fac43b691bbd]::obligation_forest::ObligationProcessor>::process_obligation
  26:     0x769bcca05882 - <rustc_data_structures[2cc1fac43b691bbd]::obligation_forest::ObligationForest<rustc_trait_selection[4e9fe4a9859c8b31]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[4e9fe4a9859c8b31]::traits::fulfill::FulfillProcessor>
  27:     0x769bcccc0a8b - <rustc_hir_typeck[ce2a1fa2b9119d4e]::fn_ctxt::FnCtxt>::check_expr_call
  28:     0x769bcd757807 - <rustc_hir_typeck[ce2a1fa2b9119d4e]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  29:     0x769bcd73e3ad - <rustc_hir_typeck[ce2a1fa2b9119d4e]::fn_ctxt::FnCtxt>::check_expr_block
  30:     0x769bcd757d60 - <rustc_hir_typeck[ce2a1fa2b9119d4e]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  31:     0x769bcd7481ba - rustc_hir_typeck[ce2a1fa2b9119d4e]::check::check_fn
  32:     0x769bcdbddac9 - rustc_hir_typeck[ce2a1fa2b9119d4e]::typeck_with_inspect::{closure#0}
  33:     0x769bcdbca570 - rustc_query_impl[fb780613ca4d2a4e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb780613ca4d2a4e]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 8usize]>>
  34:     0x769bccbbdcee - rustc_query_system[f1707db06e6fa3b0]::query::plumbing::try_execute_query::<rustc_query_impl[fb780613ca4d2a4e]::DynamicConfig<rustc_data_structures[2cc1fac43b691bbd]::vec_cache::VecCache<rustc_span[352e7d0a703a4e7e]::def_id::LocalDefId, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[f1707db06e6fa3b0]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[fb780613ca4d2a4e]::plumbing::QueryCtxt, false>
  35:     0x769bccbbd689 - rustc_query_impl[fb780613ca4d2a4e]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  36:     0x769bcd19379c - rustc_hir_analysis[6759024d2effcf7c]::check_crate
  37:     0x769bcd3624e3 - rustc_interface[cb6a4d0f1d73c708]::passes::analysis
  38:     0x769bcd3620eb - rustc_query_impl[fb780613ca4d2a4e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb780613ca4d2a4e]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 0usize]>>
  39:     0x769bcdaadb7c - rustc_query_system[f1707db06e6fa3b0]::query::plumbing::try_execute_query::<rustc_query_impl[fb780613ca4d2a4e]::DynamicConfig<rustc_query_system[f1707db06e6fa3b0]::query::caches::SingleCache<rustc_middle[ff99e1b4bd010738]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[fb780613ca4d2a4e]::plumbing::QueryCtxt, false>
  40:     0x769bcdaad852 - rustc_query_impl[fb780613ca4d2a4e]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  41:     0x769bcdcf0796 - rustc_interface[cb6a4d0f1d73c708]::passes::create_and_enter_global_ctxt::<core[74ad8051f0bf9a77]::option::Option<rustc_interface[cb6a4d0f1d73c708]::queries::Linker>, rustc_driver_impl[9e5e8cd112afe598]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  42:     0x769bcdcca2c3 - rustc_interface[cb6a4d0f1d73c708]::interface::run_compiler::<(), rustc_driver_impl[9e5e8cd112afe598]::run_compiler::{closure#0}>::{closure#1}
  43:     0x769bcdc8fc38 - std[97ade9a0245a6b27]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[cb6a4d0f1d73c708]::util::run_in_thread_with_globals<rustc_interface[cb6a4d0f1d73c708]::util::run_in_thread_pool_with_globals<rustc_interface[cb6a4d0f1d73c708]::interface::run_compiler<(), rustc_driver_impl[9e5e8cd112afe598]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  44:     0x769bcdc8f916 - <<std[97ade9a0245a6b27]::thread::Builder>::spawn_unchecked_<rustc_interface[cb6a4d0f1d73c708]::util::run_in_thread_with_globals<rustc_interface[cb6a4d0f1d73c708]::util::run_in_thread_pool_with_globals<rustc_interface[cb6a4d0f1d73c708]::interface::run_compiler<(), rustc_driver_impl[9e5e8cd112afe598]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[74ad8051f0bf9a77]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  45:     0x769bcdc8df3d - std::sys::pal::unix::thread::Thread::new::thread_start::h34e83f2a2995614d
  46:     0x769bc765f7eb - <unknown>
  47:     0x769bc76e318c - <unknown>
  48:                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 1.90.0-nightly (fd9ca711a 2025-07-05) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=feature(generic_const_exprs) -Z crate-attr=feature(min_generic_const_args) -Z dump-mir-dir=dir

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `foo::{constant#0}`
#1 [eval_to_valtree] evaluating type-level constant
#2 [typeck] type-checking `main`
#3 [analysis] running analysis passes on this crate
end of query stack
warning: 2 warnings emitted

@rustbot label +F-generic_const_exprs +F-min_generic_const_args