[ICE]: mgca: `No HirId for DefId`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(min_generic_const_args)]
trait Iter<
    const FN: fn() = {
        || {
            use std::io::*;
            write!(_, "")
        }
    },
>
{
}

original:

#![feature(min_generic_const_args)]
trait Iter<
    const FN: fn() = {
        || {
            use std::io::*;
            write!(_, "")
        }
    },
>
{
}
fn main() {}

Version information

rustc 1.96.0-nightly (148adf223 2026-03-29)
binary: rustc
commit-hash: 148adf223edb0444eb1f99753919dd2080c2a534
commit-date: 2026-03-29
host: x86_64-unknown-linux-gnu
release: 1.96.0-nightly
LLVM version: 22.1.2

Possibly related line of code:

rust/compiler/rustc_middle/src/hir/mod.rs

Lines 472 to 484 in 148adf2

	providers.hir_crate_items = map::hir_crate_items;
	providers.crate_hash = map::crate_hash;
	providers.hir_module_items = map::hir_module_items;
	providers.local_def_id_to_hir_id = |tcx, def_id| match tcx.hir_crate(()).owner(tcx, def_id) {
	MaybeOwner::Owner(_) => HirId::make_owner(def_id),
	MaybeOwner::NonOwner(hir_id) => hir_id,
	MaybeOwner::Phantom => bug!("No HirId for {:?}", def_id),
	};
	providers.opt_hir_owner_nodes =
	|tcx, id| tcx.hir_crate(()).owner(tcx, id).as_owner().map(|i| &i.nodes);
	providers.hir_owner_parent_q = |tcx, owner_id| tcx.hir_owner_parent_impl(owner_id);
	providers.hir_attr_map = |tcx, id| {
	tcx.hir_crate(()).owner(tcx, id.def_id).as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs)

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

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.gtjR7mSpPDPS/rustc_testrunner_tmpdir_reporting.jUQXCaNRBYM2/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

error: complex const arguments must be placed inside of a `const` block
 --> /tmp/icemaker_global_tempdir.gtjR7mSpPDPS/rustc_testrunner_tmpdir_reporting.jUQXCaNRBYM2/mvce.rs:4:9
  |
4 | /         || {
5 | |             use std::io::*;
6 | |             write!(_, "")
7 | |         }
  | |_________^

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.gtjR7mSpPDPS/rustc_testrunner_tmpdir_reporting.jUQXCaNRBYM2/mvce.rs:11:2
   |
11 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.gtjR7mSpPDPS/rustc_testrunner_tmpdir_reporting.jUQXCaNRBYM2/mvce.rs`

error: using function pointers as const generic parameters is forbidden
 --> /tmp/icemaker_global_tempdir.gtjR7mSpPDPS/rustc_testrunner_tmpdir_reporting.jUQXCaNRBYM2/mvce.rs:3:15
  |
3 |     const FN: fn() = {
  |               ^^^^
  |
  = note: the only supported types are integers, `bool`, and `char`

error: internal compiler error: /rustc-dev/148adf223edb0444eb1f99753919dd2080c2a534/compiler/rustc_middle/src/hir/mod.rs:478:32: No HirId for DefId(0:5 ~ mvce[777f]::Iter::{closure#0})


thread 'rustc' (3634809) panicked at /rustc-dev/148adf223edb0444eb1f99753919dd2080c2a534/compiler/rustc_middle/src/hir/mod.rs:478:32:
Box<dyn Any>
stack backtrace:
   0:     0x7f520ef8680b - <<std[321092190a068595]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[78175d3b44fe262f]::fmt::Display>::fmt
   1:     0x7f520f62f648 - core[78175d3b44fe262f]::fmt::write
   2:     0x7f520ef9d816 - <std[321092190a068595]::sys::stdio::unix::Stderr as std[321092190a068595]::io::Write>::write_fmt
   3:     0x7f520ef5c818 - std[321092190a068595]::panicking::default_hook::{closure#0}
   4:     0x7f520ef79c13 - std[321092190a068595]::panicking::default_hook
   5:     0x7f520df7e32c - std[321092190a068595]::panicking::update_hook::<alloc[aa3db4c38e3fedd6]::boxed::Box<rustc_driver_impl[60c97e9c0e13850d]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7f520ef79ef2 - std[321092190a068595]::panicking::panic_with_hook
   7:     0x7f520dfae1e1 - std[321092190a068595]::panicking::begin_panic::<rustc_errors[7e047add455c2402]::ExplicitBug>::{closure#0}
   8:     0x7f520dfa6c46 - std[321092190a068595]::sys::backtrace::__rust_end_short_backtrace::<std[321092190a068595]::panicking::begin_panic<rustc_errors[7e047add455c2402]::ExplicitBug>::{closure#0}, !>
   9:     0x7f520dfa4b48 - std[321092190a068595]::panicking::begin_panic::<rustc_errors[7e047add455c2402]::ExplicitBug>
  10:     0x7f520dfb9821 - <rustc_errors[7e047add455c2402]::diagnostic::BugAbort as rustc_errors[7e047add455c2402]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7f520e59acf9 - rustc_middle[30dff145c64b4f0a]::util::bug::opt_span_bug_fmt::<rustc_span[de740248dc9e234b]::span_encoding::Span>::{closure#0}
  12:     0x7f520e59ae82 - rustc_middle[30dff145c64b4f0a]::ty::context::tls::with_opt::<rustc_middle[30dff145c64b4f0a]::util::bug::opt_span_bug_fmt<rustc_span[de740248dc9e234b]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  13:     0x7f520e58b44b - rustc_middle[30dff145c64b4f0a]::ty::context::tls::with_context_opt::<rustc_middle[30dff145c64b4f0a]::ty::context::tls::with_opt<rustc_middle[30dff145c64b4f0a]::util::bug::opt_span_bug_fmt<rustc_span[de740248dc9e234b]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  14:     0x7f520bcfd9d4 - rustc_middle[30dff145c64b4f0a]::util::bug::bug_fmt
  15:     0x7f520f71c713 - rustc_query_impl[4af9f80b8fc12ef7]::query_impl::local_def_id_to_hir_id::invoke_provider_fn::__rust_begin_short_backtrace
  16:     0x7f520f71ba26 - rustc_query_impl[4af9f80b8fc12ef7]::execution::try_execute_query::<rustc_data_structures[ed5359664eeee2d9]::vec_cache::VecCache<rustc_span[de740248dc9e234b]::def_id::LocalDefId, rustc_middle[30dff145c64b4f0a]::query::erase::ErasedData<[u8; 8usize]>, rustc_middle[30dff145c64b4f0a]::dep_graph::graph::DepNodeIndex>, false>
  17:     0x7f520f71b785 - rustc_query_impl[4af9f80b8fc12ef7]::query_impl::local_def_id_to_hir_id::execute_query_non_incr::__rust_end_short_backtrace
  18:     0x7f520fd7da98 - <rustc_middle[30dff145c64b4f0a]::lint::ShallowLintLevelMap>::lint_level_id_at_node
  19:     0x7f520fd7ade0 - <rustc_middle[30dff145c64b4f0a]::ty::context::TyCtxt>::lint_level_at_node
  20:     0x7f520f71ad31 - rustc_hir_analysis[6338a0bcd6c3b359]::check_unused::check_unused_traits
  21:     0x7f521083ce89 - rustc_query_impl[4af9f80b8fc12ef7]::execution::try_execute_query::<rustc_middle[30dff145c64b4f0a]::query::caches::SingleCache<rustc_middle[30dff145c64b4f0a]::query::erase::ErasedData<[u8; 0usize]>>, false>
  22:     0x7f521083cb6d - rustc_query_impl[4af9f80b8fc12ef7]::query_impl::check_unused_traits::execute_query_non_incr::__rust_end_short_backtrace
  23:     0x7f520f777ddd - rustc_hir_analysis[6338a0bcd6c3b359]::check_crate
  24:     0x7f520f718127 - rustc_interface[bfde3c9897c6f3bb]::passes::analysis
  25:     0x7f521083ce89 - rustc_query_impl[4af9f80b8fc12ef7]::execution::try_execute_query::<rustc_middle[30dff145c64b4f0a]::query::caches::SingleCache<rustc_middle[30dff145c64b4f0a]::query::erase::ErasedData<[u8; 0usize]>>, false>
  26:     0x7f521083cc69 - rustc_query_impl[4af9f80b8fc12ef7]::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
  27:     0x7f521080c9e2 - rustc_interface[bfde3c9897c6f3bb]::interface::run_compiler::<(), rustc_driver_impl[60c97e9c0e13850d]::run_compiler::{closure#0}>::{closure#1}
  28:     0x7f52107f62fe - std[321092190a068595]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[bfde3c9897c6f3bb]::util::run_in_thread_with_globals<rustc_interface[bfde3c9897c6f3bb]::util::run_in_thread_pool_with_globals<rustc_interface[bfde3c9897c6f3bb]::interface::run_compiler<(), rustc_driver_impl[60c97e9c0e13850d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  29:     0x7f52107f6ba0 - <std[321092190a068595]::thread::lifecycle::spawn_unchecked<rustc_interface[bfde3c9897c6f3bb]::util::run_in_thread_with_globals<rustc_interface[bfde3c9897c6f3bb]::util::run_in_thread_pool_with_globals<rustc_interface[bfde3c9897c6f3bb]::interface::run_compiler<(), rustc_driver_impl[60c97e9c0e13850d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[78175d3b44fe262f]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  30:     0x7f52107f7a2c - <std[321092190a068595]::sys::thread::unix::Thread>::new::thread_start
  31:     0x7f520a2a597a - <unknown>
  32:     0x7f520a3292bc - <unknown>
  33:                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 1.96.0-nightly (148adf223 2026-03-29) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [local_def_id_to_hir_id] getting HIR ID of `Iter::{closure#0}`
#1 [check_unused_traits] checking unused trait imports in crate
#2 [analysis] running analysis passes on crate `mvce`
end of query stack
error: aborting due to 4 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0601`.

@rustbot label +F-min_generic_const_args

[matthiaskrgr]

since #149136

[mu001999]

@rustbot claim