ICE: eii on impl: `expected statement`

[matthiaskrgr]

auto-reduced (treereduce-rust):

fn main() {
    #[eii]
    impl Bar {}
}

original:

#![feature(extern_item_impls)]
fn main() {
    #[eii]
    impl Bar {}
}

Version information

rustc 1.94.0-nightly (3f4dc1e02 2025-12-14)
binary: rustc
commit-hash: 3f4dc1e02d759aa3c3807d4efc1f7f6e293536a5
commit-date: 2025-12-14
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.5

Possibly related line of code:

rust/compiler/rustc_expand/src/base.rs

Lines 170 to 182 in 3f4dc1e

	}
	}
	pub fn expect_stmt(self) -> ast::Stmt {
	match self {
	Annotatable::Stmt(stmt) => *stmt,
	_ => panic!("expected statement"),
	}
	}
	pub fn expect_expr(self) -> Box<ast::Expr> {
	match self {
	Annotatable::Expr(expr) => expr,

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

Program output

error[E0658]: use of unstable library feature `extern_item_impls`
 --> /tmp/icemaker_global_tempdir.H7kAaxdihhDG/rustc_testrunner_tmpdir_reporting.UmhLa2FjaPWt/mvce.rs:2:7
  |
2 |     #[eii]
  |       ^^^
  |
  = note: see issue #125418 <https://github.com/rust-lang/rust/issues/125418> for more information
  = help: add `#![feature(extern_item_impls)]` to the crate attributes to enable
  = note: this compiler was built on 2025-12-14; consider upgrading it if it is out of date

error: `#[eii]` is only valid on functions
 --> /tmp/icemaker_global_tempdir.H7kAaxdihhDG/rustc_testrunner_tmpdir_reporting.UmhLa2FjaPWt/mvce.rs:2:5
  |
2 |     #[eii]
  |     ^^^^^^


thread 'rustc' (3711055) panicked at compiler/rustc_expand/src/base.rs:176:18:
expected statement
stack backtrace:
   0:     0x7f6b52190173 - <<std[e49fa185a119b89b]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[17865207963548b5]::fmt::Display>::fmt
   1:     0x7f6b52810648 - core[17865207963548b5]::fmt::write
   2:     0x7f6b521a67c6 - <std[e49fa185a119b89b]::sys::stdio::unix::Stderr as std[e49fa185a119b89b]::io::Write>::write_fmt
   3:     0x7f6b52166938 - std[e49fa185a119b89b]::panicking::default_hook::{closure#0}
   4:     0x7f6b52184043 - std[e49fa185a119b89b]::panicking::default_hook
   5:     0x7f6b511741d7 - std[e49fa185a119b89b]::panicking::update_hook::<alloc[756b9f94e2773738]::boxed::Box<rustc_driver_impl[e1c4671be5271ce8]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7f6b52184322 - std[e49fa185a119b89b]::panicking::panic_with_hook
   7:     0x7f6b52166a2a - std[e49fa185a119b89b]::panicking::panic_handler::{closure#0}
   8:     0x7f6b5215dab9 - std[e49fa185a119b89b]::sys::backtrace::__rust_end_short_backtrace::<std[e49fa185a119b89b]::panicking::panic_handler::{closure#0}, !>
   9:     0x7f6b521685ad - __rustc[df3bb69314ad135f]::rust_begin_unwind
  10:     0x7f6b4f46df0c - core[17865207963548b5]::panicking::panic_fmt
  11:     0x7f6b53db47a5 - <rustc_expand[ad9a400ec1ef25e2]::expand::MacroExpander>::fully_expand_fragment
  12:     0x7f6b53d5f998 - <rustc_expand[ad9a400ec1ef25e2]::expand::MacroExpander>::expand_crate
  13:     0x7f6b52ff45b2 - rustc_interface[50af632e35c6bce3]::passes::configure_and_expand
  14:     0x7f6b53965e98 - rustc_interface[50af632e35c6bce3]::passes::resolver_for_lowering_raw
  15:     0x7f6b53965c0d - rustc_query_impl[462c6a5584cea8d4]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[462c6a5584cea8d4]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7055997c00c0bb98]::query::erase::Erased<[u8; 16usize]>>
  16:     0x7f6b53965be7 - <rustc_query_impl[462c6a5584cea8d4]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2} as core[17865207963548b5]::ops::function::FnOnce<(rustc_middle[7055997c00c0bb98]::ty::context::TyCtxt, ())>>::call_once
  17:     0x7f6b53971b1f - rustc_query_system[5be0c069f6d5c539]::query::plumbing::try_execute_query::<rustc_query_impl[462c6a5584cea8d4]::DynamicConfig<rustc_query_system[5be0c069f6d5c539]::query::caches::SingleCache<rustc_middle[7055997c00c0bb98]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[462c6a5584cea8d4]::plumbing::QueryCtxt, false>
  18:     0x7f6b5397167c - rustc_query_impl[462c6a5584cea8d4]::query_impl::resolver_for_lowering_raw::get_query_non_incr::__rust_end_short_backtrace
  19:     0x7f6b53b2ccfb - <rustc_interface[50af632e35c6bce3]::passes::create_and_enter_global_ctxt<core[17865207963548b5]::option::Option<rustc_interface[50af632e35c6bce3]::queries::Linker>, rustc_driver_impl[e1c4671be5271ce8]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[17865207963548b5]::ops::function::FnOnce<(&rustc_session[307f8e7a4263bd4]::session::Session, rustc_middle[7055997c00c0bb98]::ty::context::CurrentGcx, alloc[756b9f94e2773738]::sync::Arc<rustc_data_structures[30161969bbcb553f]::jobserver::Proxy>, &std[e49fa185a119b89b]::sync::once_lock::OnceLock<rustc_middle[7055997c00c0bb98]::ty::context::GlobalCtxt>, &rustc_data_structures[30161969bbcb553f]::sync::worker_local::WorkerLocal<rustc_middle[7055997c00c0bb98]::arena::Arena>, &rustc_data_structures[30161969bbcb553f]::sync::worker_local::WorkerLocal<rustc_hir[5d00f225b65c0257]::Arena>, rustc_driver_impl[e1c4671be5271ce8]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  20:     0x7f6b539c19da - rustc_interface[50af632e35c6bce3]::interface::run_compiler::<(), rustc_driver_impl[e1c4671be5271ce8]::run_compiler::{closure#0}>::{closure#1}
  21:     0x7f6b53931d8e - std[e49fa185a119b89b]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[50af632e35c6bce3]::util::run_in_thread_with_globals<rustc_interface[50af632e35c6bce3]::util::run_in_thread_pool_with_globals<rustc_interface[50af632e35c6bce3]::interface::run_compiler<(), rustc_driver_impl[e1c4671be5271ce8]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  22:     0x7f6b53931b60 - <std[e49fa185a119b89b]::thread::lifecycle::spawn_unchecked<rustc_interface[50af632e35c6bce3]::util::run_in_thread_with_globals<rustc_interface[50af632e35c6bce3]::util::run_in_thread_pool_with_globals<rustc_interface[50af632e35c6bce3]::interface::run_compiler<(), rustc_driver_impl[e1c4671be5271ce8]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[17865207963548b5]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  23:     0x7f6b539374f8 - <std[e49fa185a119b89b]::sys::thread::unix::Thread>::new::thread_start
  24:     0x7f6b4d2969cb - <unknown>
  25:     0x7f6b4d31aa0c - <unknown>
  26:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

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 1.94.0-nightly (3f4dc1e02 2025-12-14) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.

@rustbot label +F-extern_item_impls