ICE: layout_of: unexpected const: {const error}

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(min_generic_const_args)]
#[repr(simd)]
struct T([isize; N]);

static X: T = T();

original:

//@ run-pass
#![target_feature(enable = "avx")]

#[repr(simd)]
struct T([isize; N]);

static X: T = T([0.0, 1.5, 0.0]);

fn main() {
    let _ = X;
}

Version information

rustc 1.87.0-nightly (fd17deacc 2025-03-04)
binary: rustc
commit-hash: fd17deacce374a4185c882795be162e17b557050
commit-date: 2025-03-04
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

Possibly related line of code:

rust/compiler/rustc_ty_utils/src/layout.rs

Lines 167 to 179 in fd17dea

	ty::ConstKind::Infer(_)
	| ty::ConstKind::Bound(..)
	| ty::ConstKind::Placeholder(_)
	| ty::ConstKind::Error(_) => {
	// `ty::ConstKind::Error` is handled at the top of `layout_of_uncached`
	// (via `ty.error_reported()`).
	bug!("layout_of: unexpected const: {ct:?}");
	}
	}
	}
	fn layout_of_uncached<'tcx>(
	cx: &LayoutCx<'tcx>,

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

Program output

error[E0425]: cannot find value `N` in this scope
 --> /tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs:2:18
  |
2 | struct T([isize; N]);
  |                  ^ not found in this scope
  |
help: you might be missing a const parameter
  |
2 | struct T<const N: /* Type */>([isize; N]);
  |         +++++++++++++++++++++

error[E0658]: SIMD types are experimental and possibly buggy
 --> /tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs:1:1
  |
1 | #[repr(simd)]
  | ^^^^^^^^^^^^^
  |
  = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
  = help: add `#![feature(repr_simd)]` to the crate attributes to enable
  = note: this compiler was built on 2025-03-04; consider upgrading it if it is out of date

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:9
  |
1 | 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[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs:4:19
  |
4 | static X: T = T();
  |                   ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs`

error[E0061]: this struct takes 1 argument but 0 arguments were supplied
 --> /tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs:4:15
  |
4 | static X: T = T();
  |               ^-- argument #1 is missing
  |
note: tuple struct defined here
 --> /tmp/icemaker_global_tempdir.ROUzTbiGr8Hi/rustc_testrunner_tmpdir_reporting.GaMdaKkEqCKw/mvce.rs:2:8
  |
2 | struct T([isize; N]);
  |        ^
help: provide the argument
  |
4 | static X: T = T(/* value */);
  |                 +++++++++++

error: internal compiler error: compiler/rustc_ty_utils/src/layout.rs:173:13: layout_of: unexpected const: {const error}


thread 'rustc' panicked at compiler/rustc_ty_utils/src/layout.rs:173:13:
Box<dyn Any>
stack backtrace:
   0:     0x77fdd11dad94 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h38d103f25b5fc9da
   1:     0x77fdd1a057e2 - core::fmt::write::h51e5c982d87d838d
   2:     0x77fdd2cd4511 - std::io::Write::write_fmt::h24e7c9ef42bcecab
   3:     0x77fdd11dabf2 - std::sys::backtrace::BacktraceLock::print::h2f36236a0c89f5ad
   4:     0x77fdd11dd4d2 - std::panicking::default_hook::{{closure}}::hfa3a01d30bf38a16
   5:     0x77fdd11dd0c4 - std::panicking::default_hook::h73a43ec84dfb2d2e
   6:     0x77fdd032bdd7 - std[5b59e6f68f39e4a3]::panicking::update_hook::<alloc[a5cfa563521ef073]::boxed::Box<rustc_driver_impl[3a7877a37badcc56]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x77fdd11ddd43 - std::panicking::rust_panic_with_hook::h7086c047409dd55a
   8:     0x77fdd03683b1 - std[5b59e6f68f39e4a3]::panicking::begin_panic::<rustc_errors[e91cd7d082a11be2]::ExplicitBug>::{closure#0}
   9:     0x77fdd035c7c6 - std[5b59e6f68f39e4a3]::sys::backtrace::__rust_end_short_backtrace::<std[5b59e6f68f39e4a3]::panicking::begin_panic<rustc_errors[e91cd7d082a11be2]::ExplicitBug>::{closure#0}, !>
  10:     0x77fdd035c5a7 - std[5b59e6f68f39e4a3]::panicking::begin_panic::<rustc_errors[e91cd7d082a11be2]::ExplicitBug>
  11:     0x77fdd0371ec1 - <rustc_errors[e91cd7d082a11be2]::diagnostic::BugAbort as rustc_errors[e91cd7d082a11be2]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x77fdd094d656 - rustc_middle[20fb34f80dd5af75]::util::bug::opt_span_bug_fmt::<rustc_span[c14b644df6d3ab3c]::span_encoding::Span>::{closure#0}
  13:     0x77fdd0934f7a - rustc_middle[20fb34f80dd5af75]::ty::context::tls::with_opt::<rustc_middle[20fb34f80dd5af75]::util::bug::opt_span_bug_fmt<rustc_span[c14b644df6d3ab3c]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x77fdd0934deb - rustc_middle[20fb34f80dd5af75]::ty::context::tls::with_context_opt::<rustc_middle[20fb34f80dd5af75]::ty::context::tls::with_opt<rustc_middle[20fb34f80dd5af75]::util::bug::opt_span_bug_fmt<rustc_span[c14b644df6d3ab3c]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x77fdced45b50 - rustc_middle[20fb34f80dd5af75]::util::bug::bug_fmt
  16:     0x77fdd326f432 - rustc_ty_utils[3cda2ba246e4c872]::layout::extract_const_value.cold
  17:     0x77fdd2087928 - rustc_ty_utils[3cda2ba246e4c872]::layout::layout_of_uncached
  18:     0x77fdd207b74e - rustc_ty_utils[3cda2ba246e4c872]::layout::layout_of
  19:     0x77fdd207b6aa - rustc_query_impl[d10ddfe12c3a8e74]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d10ddfe12c3a8e74]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 16usize]>>
  20:     0x77fdd207a64d - rustc_query_system[3033f91d22641c6f]::query::plumbing::try_execute_query::<rustc_query_impl[d10ddfe12c3a8e74]::DynamicConfig<rustc_query_system[3033f91d22641c6f]::query::caches::DefaultCache<rustc_middle[20fb34f80dd5af75]::ty::PseudoCanonicalInput<rustc_middle[20fb34f80dd5af75]::ty::Ty>, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[d10ddfe12c3a8e74]::plumbing::QueryCtxt, false>
  21:     0x77fdd207a264 - rustc_query_impl[d10ddfe12c3a8e74]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  22:     0x77fdd2c16a6f - rustc_middle[20fb34f80dd5af75]::query::plumbing::query_get_at::<rustc_query_system[3033f91d22641c6f]::query::caches::DefaultCache<rustc_middle[20fb34f80dd5af75]::ty::PseudoCanonicalInput<rustc_middle[20fb34f80dd5af75]::ty::Ty>, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 16usize]>>>
  23:     0x77fdd2c1668c - rustc_hir_analysis[dfda97e7ebe3f086]::check::check::check_static_inhabited
  24:     0x77fdd22216a0 - rustc_hir_analysis[dfda97e7ebe3f086]::check::check::check_item_type
  25:     0x77fdd2217f55 - rustc_hir_analysis[dfda97e7ebe3f086]::check::wfcheck::check_well_formed
  26:     0x77fdd221690d - rustc_query_impl[d10ddfe12c3a8e74]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d10ddfe12c3a8e74]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 1usize]>>
  27:     0x77fdd22163c4 - rustc_query_system[3033f91d22641c6f]::query::plumbing::try_execute_query::<rustc_query_impl[d10ddfe12c3a8e74]::DynamicConfig<rustc_data_structures[b42f330dfa9d8410]::vec_cache::VecCache<rustc_span[c14b644df6d3ab3c]::def_id::LocalDefId, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[3033f91d22641c6f]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[d10ddfe12c3a8e74]::plumbing::QueryCtxt, false>
  28:     0x77fdd2215e7f - rustc_query_impl[d10ddfe12c3a8e74]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  29:     0x77fdd221369d - rustc_hir_analysis[dfda97e7ebe3f086]::check::wfcheck::check_mod_type_wf
  30:     0x77fdd221349f - rustc_query_impl[d10ddfe12c3a8e74]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d10ddfe12c3a8e74]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 1usize]>>
  31:     0x77fdd2a34556 - rustc_query_system[3033f91d22641c6f]::query::plumbing::try_execute_query::<rustc_query_impl[d10ddfe12c3a8e74]::DynamicConfig<rustc_query_system[3033f91d22641c6f]::query::caches::DefaultCache<rustc_span[c14b644df6d3ab3c]::def_id::LocalModDefId, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[d10ddfe12c3a8e74]::plumbing::QueryCtxt, false>
  32:     0x77fdd2a342ff - rustc_query_impl[d10ddfe12c3a8e74]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  33:     0x77fdd20a608f - rustc_hir_analysis[dfda97e7ebe3f086]::check_crate
  34:     0x77fdd209fd9c - rustc_interface[2148282fb0834f58]::passes::run_required_analyses
  35:     0x77fdd28feefa - rustc_interface[2148282fb0834f58]::passes::analysis
  36:     0x77fdd28feed9 - rustc_query_impl[d10ddfe12c3a8e74]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d10ddfe12c3a8e74]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 0usize]>>
  37:     0x77fdd2a5290b - rustc_query_system[3033f91d22641c6f]::query::plumbing::try_execute_query::<rustc_query_impl[d10ddfe12c3a8e74]::DynamicConfig<rustc_query_system[3033f91d22641c6f]::query::caches::SingleCache<rustc_middle[20fb34f80dd5af75]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[d10ddfe12c3a8e74]::plumbing::QueryCtxt, false>
  38:     0x77fdd2a525f9 - rustc_query_impl[d10ddfe12c3a8e74]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  39:     0x77fdd2a79afd - rustc_interface[2148282fb0834f58]::passes::create_and_enter_global_ctxt::<core[436ac50667b45076]::option::Option<rustc_interface[2148282fb0834f58]::queries::Linker>, rustc_driver_impl[3a7877a37badcc56]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  40:     0x77fdd2af19e0 - rustc_interface[2148282fb0834f58]::interface::run_compiler::<(), rustc_driver_impl[3a7877a37badcc56]::run_compiler::{closure#0}>::{closure#1}
  41:     0x77fdd2920608 - std[5b59e6f68f39e4a3]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[2148282fb0834f58]::util::run_in_thread_with_globals<rustc_interface[2148282fb0834f58]::util::run_in_thread_pool_with_globals<rustc_interface[2148282fb0834f58]::interface::run_compiler<(), rustc_driver_impl[3a7877a37badcc56]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  42:     0x77fdd2920ef4 - <<std[5b59e6f68f39e4a3]::thread::Builder>::spawn_unchecked_<rustc_interface[2148282fb0834f58]::util::run_in_thread_with_globals<rustc_interface[2148282fb0834f58]::util::run_in_thread_pool_with_globals<rustc_interface[2148282fb0834f58]::interface::run_compiler<(), rustc_driver_impl[3a7877a37badcc56]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[436ac50667b45076]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x77fdd29222f7 - std::sys::pal::unix::thread::Thread::new::thread_start::hbb5e0f14d5ca8b98
  44:     0x77fdccaa370a - <unknown>
  45:     0x77fdccb27aac - <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: rustc 1.87.0-nightly (fd17deacc 2025-03-04) running on x86_64-unknown-linux-gnu

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

query stack during panic:
#0 [layout_of] computing layout of `T`
#1 [check_well_formed] checking that `X` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 5 previous errors; 1 warning emitted

Some errors have detailed explanations: E0061, E0425, E0601, E0658.
For more information about an error, try `rustc --explain E0061`.

@rustbot label +F-min_generic_const_args

[matthiaskrgr]

bisects to #137852

[matthiaskrgr]

without features:

#[repr(simd)]
struct a<const b : [c; 3]>([;; ""]);
#[derive(Copy, Clone)]
struct a<const b : [c; 3]>;