ICE: `cannot call const_of_item on a non-type_const BodyId`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(min_generic_const_args)]
const EXAMPLE: &[u8] = include_bytes!();

static BUF: [u8; EXAMPLE] = { arr };

original:

//@compile-flags: -Zmir-opt-level=5 -Zvalidate-mir
#![feature(min_generic_const_args)]
const EXAMPLE: &[u8] = include_bytes!("/proc/cpuinfo");

static BUF: [u8; EXAMPLE] = { arr };

fn main() {
    println!("/proc/cpuinfo", BUF.len());
}

Version information

rustc 1.93.0-nightly (72b21e1a6 2025-11-08)
binary: rustc
commit-hash: 72b21e1a64dbbbb3b59ac7ce21363c366a894b79
commit-date: 2025-11-08
host: x86_64-unknown-linux-gnu
release: 1.93.0-nightly
LLVM version: 21.1.3

Possibly related line of code:

rust/compiler/rustc_hir_analysis/src/collect.rs

Lines 1598 to 1610 in 72b21e1

	span_bug!(tcx.def_span(def_id), "`const_of_item` expected a const or assoc const item")
	}
	};
	let ct_arg = match ct_rhs {
	hir::ConstItemRhs::TypeConst(ct_arg) => ct_arg,
	hir::ConstItemRhs::Body(body_id) => {
	bug!("cannot call const_of_item on a non-type_const {body_id:?}")
	}
	};
	let icx = ItemCtxt::new(tcx, def_id);
	let identity_args = ty::GenericArgs::identity_for_item(tcx, def_id);
	let ct = icx
	.lowerer()

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zincremental-verify-ich=yes -Cincremental=<dir> -Cdebuginfo=2 -Clink-dead-code=true -Zvalidate-mir -Zquery-dep-graph -Zthreads=4 --edition=2024

Program output

error: include_bytes! takes 1 argument
 --> /tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs:2:24
  |
2 | const EXAMPLE: &[u8] = include_bytes!();
  |                        ^^^^^^^^^^^^^^^^

error[E0425]: cannot find value `arr` in this scope
   --> /tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs:4:31
    |
  4 | static BUF: [u8; EXAMPLE] = { arr };
    |                               ^^^ help: a tuple variant with a similar name exists: `Err`
    |
   ::: /home/matthias/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/result.rs:566:5
    |
566 |     Err(#[stable(feature = "rust1", since = "1.0.0")] E),
    |     --- similarly named tuple variant `Err` defined here

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs:1:12
  |
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

warning: unnecessary braces around assigned value
 --> /tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs:4:29
  |
4 | static BUF: [u8; EXAMPLE] = { arr };
  |                             ^^   ^^
  |
  = note: `#[warn(unused_braces)]` (part of `#[warn(unused)]`) on by default
help: remove these braces
  |
4 - static BUF: [u8; EXAMPLE] = { arr };
4 + static BUF: [u8; EXAMPLE] = arr;
  |

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs:4:37
  |
4 | static BUF: [u8; EXAMPLE] = { arr };
  |                                     ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.yBgXHzx7A8aP/rustc_testrunner_tmpdir_reporting.26gI3I7I9Tsb/mvce.rs`

error: internal compiler error: compiler/rustc_hir_analysis/src/collect.rs:1604:13: cannot call const_of_item on a non-type_const BodyId { hir_id: HirId(DefId(0:3 ~ mvce[4e7e]::EXAMPLE).6) }


thread 'rustc' (3116536) panicked at compiler/rustc_hir_analysis/src/collect.rs:1604:13:
Box<dyn Any>
stack backtrace:
   0:     0x7fb5c1e71253 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hcca3c0a1d1647c59
   1:     0x7fb5c2601afc - core::fmt::write::h4102dd63eb97ae71
   2:     0x7fb5c1e25cd3 - std::io::Write::write_fmt::hb7012c2a8b8fd004
   3:     0x7fb5c1e373d2 - std::sys::backtrace::BacktraceLock::print::he1cfc27585b288a1
   4:     0x7fb5c1e3d429 - std::panicking::default_hook::{{closure}}::h56f78913e42eddcc
   5:     0x7fb5c1e3cf53 - std::panicking::default_hook::hd9ae249ab356fc25
   6:     0x7fb5c0e2f3d1 - std[155e3b79a2821849]::panicking::update_hook::<alloc[c4b61704c478c018]::boxed::Box<rustc_driver_impl[c3522bc1b3059489]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7fb5c1e3d84f - std::panicking::panic_with_hook::ha085a42b834d510b
   8:     0x7fb5c0e6b951 - std[155e3b79a2821849]::panicking::begin_panic::<rustc_errors[cff983c337c2971c]::ExplicitBug>::{closure#0}
   9:     0x7fb5c0e5ddf6 - std[155e3b79a2821849]::sys::backtrace::__rust_end_short_backtrace::<std[155e3b79a2821849]::panicking::begin_panic<rustc_errors[cff983c337c2971c]::ExplicitBug>::{closure#0}, !>
  10:     0x7fb5c0e5b549 - std[155e3b79a2821849]::panicking::begin_panic::<rustc_errors[cff983c337c2971c]::ExplicitBug>
  11:     0x7fb5c0e89fc1 - <rustc_errors[cff983c337c2971c]::diagnostic::BugAbort as rustc_errors[cff983c337c2971c]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x7fb5c141272a - rustc_middle[3cd47588377ceff1]::util::bug::opt_span_bug_fmt::<rustc_span[7edc6483ad12113b]::span_encoding::Span>::{closure#0}
  13:     0x7fb5c14128aa - rustc_middle[3cd47588377ceff1]::ty::context::tls::with_opt::<rustc_middle[3cd47588377ceff1]::util::bug::opt_span_bug_fmt<rustc_span[7edc6483ad12113b]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7fb5c14032bb - rustc_middle[3cd47588377ceff1]::ty::context::tls::with_context_opt::<rustc_middle[3cd47588377ceff1]::ty::context::tls::with_opt<rustc_middle[3cd47588377ceff1]::util::bug::opt_span_bug_fmt<rustc_span[7edc6483ad12113b]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7fb5bf1a4880 - rustc_middle[3cd47588377ceff1]::util::bug::bug_fmt
  16:     0x7fb5c0fddd0f - rustc_hir_analysis[8bda365d173e2f68]::collect::const_of_item
  17:     0x7fb5c18104f3 - rustc_query_impl[79ff6c9466bd5884]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[79ff6c9466bd5884]::query_impl::const_of_item::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 8usize]>>
  18:     0x7fb5c2959a01 - rustc_query_system[aa5312ee5c7c29d1]::query::plumbing::try_execute_query::<rustc_query_impl[79ff6c9466bd5884]::DynamicConfig<rustc_query_system[aa5312ee5c7c29d1]::query::caches::DefIdCache<rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[79ff6c9466bd5884]::plumbing::QueryCtxt, true>
  19:     0x7fb5c18aa037 - rustc_query_impl[79ff6c9466bd5884]::query_impl::const_of_item::get_query_incr::__rust_end_short_backtrace
  20:     0x7fb5c3a631dd - <rustc_trait_selection[bfcb0e0196f4a7bc]::traits::normalize::AssocTypeNormalizer>::normalize_free_alias::{closure#0}
  21:     0x7fb5c281d1aa - <rustc_trait_selection[bfcb0e0196f4a7bc]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[f7821b71b42b6d71]::fold::TypeFolder<rustc_middle[3cd47588377ceff1]::ty::context::TyCtxt>>::fold_const
  22:     0x7fb5c281f7d7 - <rustc_middle[3cd47588377ceff1]::ty::Ty as rustc_type_ir[f7821b71b42b6d71]::fold::TypeSuperFoldable<rustc_middle[3cd47588377ceff1]::ty::context::TyCtxt>>::super_fold_with::<rustc_trait_selection[bfcb0e0196f4a7bc]::traits::normalize::AssocTypeNormalizer>
  23:     0x7fb5c2eec2bd - <rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::WfCheckingCtxt>::deeply_normalize::<rustc_middle[3cd47588377ceff1]::ty::Ty>
  24:     0x7fb5c2f0a0ee - rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::check_static_item
  25:     0x7fb5c3020237 - rustc_hir_analysis[8bda365d173e2f68]::collect::type_of::type_of
  26:     0x7fb5c261d926 - rustc_query_impl[79ff6c9466bd5884]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[79ff6c9466bd5884]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 8usize]>>
  27:     0x7fb5c2959a01 - rustc_query_system[aa5312ee5c7c29d1]::query::plumbing::try_execute_query::<rustc_query_impl[79ff6c9466bd5884]::DynamicConfig<rustc_query_system[aa5312ee5c7c29d1]::query::caches::DefIdCache<rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[79ff6c9466bd5884]::plumbing::QueryCtxt, true>
  28:     0x7fb5c2959146 - rustc_query_impl[79ff6c9466bd5884]::query_impl::type_of::get_query_incr::__rust_end_short_backtrace
  29:     0x7fb5c2e193f6 - rustc_hir_analysis[8bda365d173e2f68]::check::check::check_item_type
  30:     0x7fb5c2e1385c - rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::check_well_formed
  31:     0x7fb5c2e13835 - rustc_query_impl[79ff6c9466bd5884]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[79ff6c9466bd5884]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 1usize]>>
  32:     0x7fb5c2949e61 - rustc_query_system[aa5312ee5c7c29d1]::query::plumbing::try_execute_query::<rustc_query_impl[79ff6c9466bd5884]::DynamicConfig<rustc_data_structures[d0f0f5062ba2726]::vec_cache::VecCache<rustc_span[7edc6483ad12113b]::def_id::LocalDefId, rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[aa5312ee5c7c29d1]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[79ff6c9466bd5884]::plumbing::QueryCtxt, true>
  33:     0x7fb5c294c62d - rustc_query_impl[79ff6c9466bd5884]::query_impl::check_well_formed::get_query_incr::__rust_end_short_backtrace
  34:     0x7fb5c0f5b4eb - rustc_middle[3cd47588377ceff1]::query::inner::query_ensure_error_guaranteed::<rustc_data_structures[d0f0f5062ba2726]::vec_cache::VecCache<rustc_span[7edc6483ad12113b]::def_id::LocalDefId, rustc_middle[3cd47588377ceff1]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[aa5312ee5c7c29d1]::dep_graph::graph::DepNodeIndex>, ()>
  35:     0x7fb5c0f6c69e - rustc_data_structures[d0f0f5062ba2726]::sync::parallel::par_slice::par_rec::<&rustc_hir[b47be72a75dd08a9]::hir::ItemId, rustc_data_structures[d0f0f5062ba2726]::sync::parallel::try_par_for_each_in<&[rustc_hir[b47be72a75dd08a9]::hir::ItemId], rustc_span[7edc6483ad12113b]::ErrorGuaranteed, <rustc_middle[3cd47588377ceff1]::hir::ModuleItems>::par_items<rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::check_type_wf::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>
  36:     0x7fb5c102ea87 - <rustc_thread_pool[234d490567d5602b]::job::StackJob<rustc_thread_pool[234d490567d5602b]::latch::SpinLatch, rustc_thread_pool[234d490567d5602b]::join::join_context<rustc_thread_pool[234d490567d5602b]::join::join::call<(), rustc_data_structures[d0f0f5062ba2726]::sync::parallel::par_slice::par_rec<&rustc_hir[b47be72a75dd08a9]::hir::ItemId, rustc_data_structures[d0f0f5062ba2726]::sync::parallel::try_par_for_each_in<&[rustc_hir[b47be72a75dd08a9]::hir::ItemId], rustc_span[7edc6483ad12113b]::ErrorGuaranteed, <rustc_middle[3cd47588377ceff1]::hir::ModuleItems>::par_items<rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::check_type_wf::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#1}>::{closure#0}, rustc_thread_pool[234d490567d5602b]::join::join::call<(), rustc_data_structures[d0f0f5062ba2726]::sync::parallel::par_slice::par_rec<&rustc_hir[b47be72a75dd08a9]::hir::ItemId, rustc_data_structures[d0f0f5062ba2726]::sync::parallel::try_par_for_each_in<&[rustc_hir[b47be72a75dd08a9]::hir::ItemId], rustc_span[7edc6483ad12113b]::ErrorGuaranteed, <rustc_middle[3cd47588377ceff1]::hir::ModuleItems>::par_items<rustc_hir_analysis[8bda365d173e2f68]::check::wfcheck::check_type_wf::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#2}>::{closure#0}, (), ()>::{closure#0}::{closure#0}, ()> as rustc_thread_pool[234d490567d5602b]::job::Job>::execute
  37:     0x7fb5c1b47def - <rustc_thread_pool[234d490567d5602b]::registry::WorkerThread>::wait_or_steal_until_cold
  38:     0x7fb5c1b46891 - <rustc_thread_pool[234d490567d5602b]::registry::ThreadBuilder>::run
  39:     0x7fb5c0e2744d - std[155e3b79a2821849]::sys::backtrace::__rust_begin_short_backtrace::<<rustc_thread_pool[234d490567d5602b]::ThreadPoolBuilder>::build_scoped<rustc_interface[dd019e0167f5b788]::util::run_in_thread_pool_with_globals<rustc_interface[dd019e0167f5b788]::interface::run_compiler<(), rustc_driver_impl[c3522bc1b3059489]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#0}, rustc_interface[dd019e0167f5b788]::util::run_in_thread_pool_with_globals<rustc_interface[dd019e0167f5b788]::interface::run_compiler<(), rustc_driver_impl[c3522bc1b3059489]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#1}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  40:     0x7fb5c0e32a02 - <<std[155e3b79a2821849]::thread::Builder>::spawn_unchecked_<<rustc_thread_pool[234d490567d5602b]::ThreadPoolBuilder>::build_scoped<rustc_interface[dd019e0167f5b788]::util::run_in_thread_pool_with_globals<rustc_interface[dd019e0167f5b788]::interface::run_compiler<(), rustc_driver_impl[c3522bc1b3059489]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#0}, rustc_interface[dd019e0167f5b788]::util::run_in_thread_pool_with_globals<rustc_interface[dd019e0167f5b788]::interface::run_compiler<(), rustc_driver_impl[c3522bc1b3059489]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#1}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>::{closure#1} as core[e19504c39fe2c26b]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  41:     0x7fb5c344632f - std::sys::thread::unix::Thread::new::thread_start::h6124ec86ff25f360
  42:     0x7fb5bce969cb - <unknown>
  43:     0x7fb5bcf1aa0c - <unknown>
  44:                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 1.93.0-nightly (72b21e1a6 2025-11-08) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z incremental-verify-ich=yes -C incremental=[REDACTED] -C debuginfo=2 -C link-dead-code=true -Z validate-mir -Z query-dep-graph -Z threads=4

query stack during panic:
#0 [const_of_item] computing the type-level value for `EXAMPLE`
#1 [type_of] computing type of `BUF`
#2 [check_well_formed] checking that `BUF` is well-formed
#3 [check_type_wf] checking that types are well-formed
#4 [analysis] running analysis passes on crate `mvce`
end of query stack
error: aborting due to 4 previous errors; 2 warnings emitted

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

@rustbot label +F-min_generic_const_args +-Zvalidate-mir

[matthiaskrgr]

#![feature(min_generic_const_args)]
const EXAMPLE : [u8; EXAMPLE];

[kpreid]

None of the code samples posted so far ICE for me on 1.93.0-nightly (2025-11-12 01867557cd7dbe256a03) — they all produce other errors. However, completing the syntax of the last one makes it ICE again:

#![feature(min_generic_const_args)]
const EXAMPLE : [u8; EXAMPLE] = [];

error: internal compiler error: cannot call const_of_item on a non-type_const
 --> src/lib.rs:2:1
  |
2 | const EXAMPLE : [u8; EXAMPLE] = [];
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
note: delayed at compiler/rustc_hir_analysis/src/collect.rs:1615:31 - disabled backtrace
...
query stack during panic:
end of query stack

[Keith-Cancel]

I just encountered this error with some code like below. It was a little more complicated in my actually source since it was generated by a macro. However, enabling min_generic_const_args for some experiments I want to try caused the ICE.

https://godbolt.org/z/6vM5jesM9

#![feature(min_generic_const_args)]

pub trait IntType: 'static + Sized {
    const SLC: &'static [Self];
}

impl IntType for u16 {
    const SLC: &'static [Self] = &{
        const LEN: usize = 17;
        let mut arr: [Self; LEN] = [0; LEN];
        let mut i = 0;
        while i < LEN {
            // .. do stuff
            i += 1;
        }
        arr
    };
}

error: internal compiler error: cannot call const_of_item on a non-type_const
 --> finder/src/main.rs:9:9
  |
9 |         const LEN: usize = 17;
  |         ^^^^^^^^^^^^^^^^
  |
note: delayed at /rustc-dev/e29fcf45e4ae686d77b490bf07320f0d3a2cf35f/compiler/rustc_hir_analysis/src/collect.rs:1545:31

.... I Omitted backtrace it's in attached txt
      
 --> finder/src/main.rs:9:9
  |
9 |         const LEN: usize = 17;
  |         ^^^^^^^^^^^^^^^^

note: rustc 1.94.0-nightly (e29fcf45e 2026-01-04) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

rustc-ice-2026-01-05T21_03_41-27135.txt

[reddevilmidzy]

fixed #152324

Since the syntax has been changed 152324, I don't think adding a test is necessary.