ICE `expected ConstKind::Value, got {const error}`

[matthiaskrgr]

Code

#![feature(transmutability)]
#![feature(min_generic_const_args)]

use std::mem::{Assume, TransmuteFrom};

struct W<'a>(&'a ());

fn test<'a>()
where
    W<'a>: TransmuteFrom<
        (),
        {
            Assume {
                alignment: const { true },
                lifetimes: const { true },
                safety: const { true },
                validity: true, // boom
            }
        },
    >,
{
}

fn main() {
    test()
}

Meta

rustc --version --verbose:

rustc 1.94.0-nightly (7b5cde737 2025-12-27)
binary: rustc
commit-hash: 7b5cde7370b82fecf700071dda98c3fbc7d41fae
commit-date: 2025-12-27
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.8

Error output

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> a.rs:2:12
  |
2 | #![feature(min_generic_const_args)]
  |            ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information
  = note: `#[warn(incomplete_features)]` on by default

error: complex const arguments must be placed inside of a `const` block
  --> a.rs:17:27
   |
17 |                 validity: true, // boom
   |                           ^^^^

Backtrace

error: internal compiler error: /rustc-dev/7b5cde7370b82fecf700071dda98c3fbc7d41fae/compiler/rustc_middle/src/ty/consts.rs:258:18: expected ConstKind::Value, got {const error}


thread 'rustc' (3293447) panicked at /rustc-dev/7b5cde7370b82fecf700071dda98c3fbc7d41fae/compiler/rustc_middle/src/ty/consts.rs:258:18:
Box<dyn Any>
stack backtrace:
   0:     0x7fe9bba53393 - <<std[d04b43a2428f6e7c]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[5301abcae13ad7a]::fmt::Display>::fmt
   1:     0x7fe9bc010b88 - core[5301abcae13ad7a]::fmt::write
   2:     0x7fe9bba69aa6 - <std[d04b43a2428f6e7c]::sys::stdio::unix::Stderr as std[d04b43a2428f6e7c]::io::Write>::write_fmt
   3:     0x7fe9bba29c48 - std[d04b43a2428f6e7c]::panicking::default_hook::{closure#0}
   4:     0x7fe9bba472d3 - std[d04b43a2428f6e7c]::panicking::default_hook
   5:     0x7fe9baa21aca - std[d04b43a2428f6e7c]::panicking::update_hook::<alloc[966711e2d4248474]::boxed::Box<rustc_driver_impl[d4ed2211832a1e45]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7fe9bba475b2 - std[d04b43a2428f6e7c]::panicking::panic_with_hook
   7:     0x7fe9baa5e371 - std[d04b43a2428f6e7c]::panicking::begin_panic::<rustc_errors[cb139601f36bb398]::ExplicitBug>::{closure#0}
   8:     0x7fe9baa4e866 - std[d04b43a2428f6e7c]::sys::backtrace::__rust_end_short_backtrace::<std[d04b43a2428f6e7c]::panicking::begin_panic<rustc_errors[cb139601f36bb398]::ExplicitBug>::{closure#0}, !>
   9:     0x7fe9baa4be3c - std[d04b43a2428f6e7c]::panicking::begin_panic::<rustc_errors[cb139601f36bb398]::ExplicitBug>
  10:     0x7fe9baa7c2b1 - <rustc_errors[cb139601f36bb398]::diagnostic::BugAbort as rustc_errors[cb139601f36bb398]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7fe9bb02b659 - rustc_middle[b12d616c0d1b1d17]::util::bug::opt_span_bug_fmt::<rustc_span[41c12b187d0c00e0]::span_encoding::Span>::{closure#0}
  12:     0x7fe9bb02b7e2 - rustc_middle[b12d616c0d1b1d17]::ty::context::tls::with_opt::<rustc_middle[b12d616c0d1b1d17]::util::bug::opt_span_bug_fmt<rustc_span[41c12b187d0c00e0]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  13:     0x7fe9bb01c6db - rustc_middle[b12d616c0d1b1d17]::ty::context::tls::with_context_opt::<rustc_middle[b12d616c0d1b1d17]::ty::context::tls::with_opt<rustc_middle[b12d616c0d1b1d17]::util::bug::opt_span_bug_fmt<rustc_span[41c12b187d0c00e0]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  14:     0x7fe9b8afb2b4 - rustc_middle[b12d616c0d1b1d17]::util::bug::bug_fmt
  15:     0x7fe9bb03ae5d - <rustc_middle[b12d616c0d1b1d17]::ty::consts::Const>::to_value
  16:     0x7fe9bb96bae0 - <rustc_transmute[a12e57d9e66745af]::Assume>::from_const
  17:     0x7fe9bd04651a - <rustc_trait_selection[7ed3222c48c013c]::traits::select::SelectionContext>::confirm_candidate
  18:     0x7fe9bc0a4f28 - <rustc_trait_selection[7ed3222c48c013c]::traits::select::SelectionContext>::evaluate_candidate::{closure#0}
  19:     0x7fe9bc0c5e76 - <rustc_trait_selection[7ed3222c48c013c]::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}::{closure#0}
  20:     0x7fe9bd2cfadc - <rustc_trait_selection[7ed3222c48c013c]::traits::select::SelectionContext>::poly_select::{closure#0}
  21:     0x7fe9bc7adc86 - <rustc_trait_selection[7ed3222c48c013c]::traits::fulfill::FulfillProcessor as rustc_data_structures[6f877b1072984333]::obligation_forest::ObligationProcessor>::process_obligation
  22:     0x7fe9bc0045a4 - <rustc_data_structures[6f877b1072984333]::obligation_forest::ObligationForest<rustc_trait_selection[7ed3222c48c013c]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[7ed3222c48c013c]::traits::fulfill::FulfillProcessor>
  23:     0x7fe9bc974632 - <rustc_trait_selection[7ed3222c48c013c]::traits::fulfill::FulfillmentContext<rustc_trait_selection[7ed3222c48c013c]::traits::FulfillmentError> as rustc_infer[f63cdcb0b0c4914b]::traits::engine::TraitEngine<rustc_trait_selection[7ed3222c48c013c]::traits::FulfillmentError>>::evaluate_obligations_error_on_ambiguity
  24:     0x7fe9bc96c96f - rustc_hir_analysis[f780883f01c706ba]::check::wfcheck::check_item_fn
  25:     0x7fe9bc9d3786 - rustc_hir_analysis[f780883f01c706ba]::check::check::check_item_type
  26:     0x7fe9bc9cf776 - rustc_hir_analysis[f780883f01c706ba]::check::wfcheck::check_well_formed
  27:     0x7fe9bc9cf757 - rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 1usize]>>
  28:     0x7fe9bc9cefcd - rustc_query_system[ff548912004eb624]::query::plumbing::try_execute_query::<rustc_query_impl[7dbdc15bcc8f2d5]::DynamicConfig<rustc_data_structures[6f877b1072984333]::vec_cache::VecCache<rustc_span[41c12b187d0c00e0]::def_id::LocalDefId, rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[ff548912004eb624]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::QueryCtxt, false>
  29:     0x7fe9bc9cead6 - rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7fe9bc9cc270 - rustc_hir_analysis[f780883f01c706ba]::check::wfcheck::check_type_wf
  31:     0x7fe9bc9cc15d - rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 1usize]>>
  32:     0x7fe9bd1cdf88 - rustc_query_system[ff548912004eb624]::query::plumbing::try_execute_query::<rustc_query_impl[7dbdc15bcc8f2d5]::DynamicConfig<rustc_query_system[ff548912004eb624]::query::caches::SingleCache<rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::QueryCtxt, false>
  33:     0x7fe9bd1cdd4e - rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
  34:     0x7fe9bc7f8174 - rustc_hir_analysis[f780883f01c706ba]::check_crate
  35:     0x7fe9bcee059b - rustc_interface[84bae928b5c4a14c]::passes::analysis
  36:     0x7fe9bcee01f5 - rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 0usize]>>
  37:     0x7fe9bd1cf766 - rustc_query_system[ff548912004eb624]::query::plumbing::try_execute_query::<rustc_query_impl[7dbdc15bcc8f2d5]::DynamicConfig<rustc_query_system[ff548912004eb624]::query::caches::SingleCache<rustc_middle[b12d616c0d1b1d17]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[7dbdc15bcc8f2d5]::plumbing::QueryCtxt, false>
  38:     0x7fe9bd1cf336 - rustc_query_impl[7dbdc15bcc8f2d5]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  39:     0x7fe9bd3cf614 - <rustc_interface[84bae928b5c4a14c]::passes::create_and_enter_global_ctxt<core[5301abcae13ad7a]::option::Option<rustc_interface[84bae928b5c4a14c]::queries::Linker>, rustc_driver_impl[d4ed2211832a1e45]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[5301abcae13ad7a]::ops::function::FnOnce<(&rustc_session[34b11767d146bd]::session::Session, rustc_middle[b12d616c0d1b1d17]::ty::context::CurrentGcx, alloc[966711e2d4248474]::sync::Arc<rustc_data_structures[6f877b1072984333]::jobserver::Proxy>, &std[d04b43a2428f6e7c]::sync::once_lock::OnceLock<rustc_middle[b12d616c0d1b1d17]::ty::context::GlobalCtxt>, &rustc_data_structures[6f877b1072984333]::sync::worker_local::WorkerLocal<rustc_middle[b12d616c0d1b1d17]::arena::Arena>, &rustc_data_structures[6f877b1072984333]::sync::worker_local::WorkerLocal<rustc_hir[bd2e92b33866e02d]::Arena>, rustc_driver_impl[d4ed2211832a1e45]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  40:     0x7fe9bd1f2358 - rustc_interface[84bae928b5c4a14c]::interface::run_compiler::<(), rustc_driver_impl[d4ed2211832a1e45]::run_compiler::{closure#0}>::{closure#1}
  41:     0x7fe9bd1926ce - std[d04b43a2428f6e7c]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[84bae928b5c4a14c]::util::run_in_thread_with_globals<rustc_interface[84bae928b5c4a14c]::util::run_in_thread_pool_with_globals<rustc_interface[84bae928b5c4a14c]::interface::run_compiler<(), rustc_driver_impl[d4ed2211832a1e45]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  42:     0x7fe9bd1924a0 - <std[d04b43a2428f6e7c]::thread::lifecycle::spawn_unchecked<rustc_interface[84bae928b5c4a14c]::util::run_in_thread_with_globals<rustc_interface[84bae928b5c4a14c]::util::run_in_thread_pool_with_globals<rustc_interface[84bae928b5c4a14c]::interface::run_compiler<(), rustc_driver_impl[d4ed2211832a1e45]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[5301abcae13ad7a]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7fe9bd197df8 - <std[d04b43a2428f6e7c]::sys::thread::unix::Thread>::new::thread_start
  44:     0x7fe9b6a9698b - <unknown>
  45:     0x7fe9b6b1a9cc - <unknown>
  46:                0x0 - <unknown>

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 `/tmp/im2/rustc-ice-2025-12-28T10_41_12-3293429.txt` to your bug report

note: rustc 1.94.0-nightly (7b5cde737 2025-12-27) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [check_well_formed] checking that `test` is well-formed
#1 [check_type_wf] checking that types are well-formed
#2 [analysis] running analysis passes on crate `a`
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

since #149114