rust-lang / rust-lang/rust

ICE: `layout_of: unexpected const: {const error}`

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C-bug F-min_generic_const_args I-ICE S-bug-has-test T-compiler
Dominant language
Rust
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Description

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:
https://github.com/rust-lang/rust/blob/fd17deacce374a4185c882795be162e17b557050/compiler/rustc_ty_utils/src/layout.rs#L167-L179

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  = note: this compiler was built on 2025-03-04; consider upgrading it if it is out of date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

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Run the reduced reproducer with the rustc command shown, then inspect compiler/rustc_ty_utils/src/layout.rs around lines 167-179 and the extract_const_value/layout_of_uncached frames in the backtrace. The result should report diagnostics without triggering the internal compiler error for this input.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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