[ICE]: stealing value which is locked

[zetanumbers]

Initially reported in #151509 (review)

This is A-parallel-compiler issue as it occurs only with -Zthreads=8

Code

Source code of rustc, commit 75b9d89.

Meta

rustc --version --verbose:

rustc 1.95.0-nightly (a33907a7a 2026-02-14)
binary: rustc
commit-hash: a33907a7a5381473eec8bcfa0c56e05a856a911c
commit-date: 2026-02-14
host: aarch64-apple-darwin
release: 1.95.0-nightly
LLVM version: 22.1.0

Error output

thread 'rustc' panicked at /rustc-dev/a33907a7a5381473eec8bcfa0c56e05a856a911c/compiler/rustc_mir_transform/src/lib.rs:549:25:
stealing value which is locked: ()

Backtrace

stack backtrace:
   0:        0x1139b8224 - <std[fb7650b96fc3e2b2]::backtrace::Backtrace>::create
   1:        0x1118a4b90 - std[fb7650b96fc3e2b2]::panicking::update_hook::<alloc[2c7721ec027e506c]::boxed::Box<rustc_driver_impl[fcca23ff68962ade]::install_ice_hook::{closure#1}>>::{closure#0}
   2:        0x1139c9788 - std[fb7650b96fc3e2b2]::panicking::panic_with_hook
   3:        0x1139ad720 - std[fb7650b96fc3e2b2]::panicking::panic_handler::{closure#0}
   4:        0x1139a40e8 - std[fb7650b96fc3e2b2]::sys::backtrace::__rust_end_short_backtrace::<std[fb7650b96fc3e2b2]::panicking::panic_handler::{closure#0}, !>
   5:        0x1139aecf0 - __rustc[b0419f81c5efee33]::rust_begin_unwind
   6:        0x1169e462c - core[5b2322a8d5f57ee]::panicking::panic_fmt
   7:        0x1169e4394 - core[5b2322a8d5f57ee]::result::unwrap_failed
   8:        0x1128e6e38 - rustc_mir_transform[93ce7f6be37bbafc]::mir_drops_elaborated_and_const_checked
   9:        0x112e1a58c - rustc_query_impl[abe004534d1d69cf]::execution::try_execute_query::<rustc_data_structures[2654685372cda76c]::vec_cache::VecCache<rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_middle[5ae9d75c2f1bdf17]::query::erase::ErasedData<[u8; 8usize]>, rustc_middle[5ae9d75c2f1bdf17]::dep_graph::graph::DepNodeIndex>, {rustc_query_impl[abe004534d1d69cf]::QueryFlags { is_anon: false, is_depth_limit: false, is_feedable: false }}, true>
  10:        0x112fe07ac - rustc_query_impl[abe004534d1d69cf]::query_impl::mir_drops_elaborated_and_const_checked::get_query_incr::__rust_end_short_backtrace
  11:        0x1121975ac - <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
  12:        0x11212ee10 - <rustc_data_structures[2654685372cda76c]::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#0}>
  13:        0x11219d990 - rustc_thread_pool[e1f27a471ba69f13]::join::join_context::<rustc_thread_pool[e1f27a471ba69f13]::join::join::call<(), rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#1}>::{closure#0}, rustc_thread_pool[e1f27a471ba69f13]::join::join::call<(), rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#2}>::{closure#0}, (), ()>::{closure#0}
  14:        0x11216cb30 - rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec::<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>
  15:        0x11222b49c - <rustc_thread_pool[e1f27a471ba69f13]::job::StackJob<rustc_thread_pool[e1f27a471ba69f13]::latch::SpinLatch, rustc_thread_pool[e1f27a471ba69f13]::join::join_context<rustc_thread_pool[e1f27a471ba69f13]::join::join::call<(), rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#1}>::{closure#0}, rustc_thread_pool[e1f27a471ba69f13]::join::join::call<(), rustc_data_structures[2654685372cda76c]::sync::parallel::par_slice::par_rec<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, rustc_data_structures[2654685372cda76c]::sync::parallel::par_for_each_in<&rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId, &[rustc_span[f00e5f7574cd0ad2]::def_id::LocalDefId], <rustc_middle[5ae9d75c2f1bdf17]::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface[4e0e0615d47554a1]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#2}>::{closure#0}, (), ()>::{closure#0}::{closure#0}, ()> as rustc_thread_pool[e1f27a471ba69f13]::job::Job>::execute
  16:        0x116b615f0 - <rustc_thread_pool[e1f27a471ba69f13]::registry::WorkerThread>::wait_or_steal_until_cold
  17:        0x1134d943c - <rustc_thread_pool[e1f27a471ba69f13]::registry::ThreadBuilder>::run
  18:        0x11189c1cc - std[fb7650b96fc3e2b2]::sys::backtrace::__rust_begin_short_backtrace::<<rustc_thread_pool[e1f27a471ba69f13]::ThreadPoolBuilder>::build_scoped<rustc_interface[4e0e0615d47554a1]::util::run_in_thread_pool_with_globals<rustc_interface[4e0e0615d47554a1]::interface::run_compiler<(), rustc_driver_impl[fcca23ff68962ade]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#0}, rustc_interface[4e0e0615d47554a1]::util::run_in_thread_pool_with_globals<rustc_interface[4e0e0615d47554a1]::interface::run_compiler<(), rustc_driver_impl[fcca23ff68962ade]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#1}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  19:        0x1118ac434 - <std[fb7650b96fc3e2b2]::thread::lifecycle::spawn_unchecked<<rustc_thread_pool[e1f27a471ba69f13]::ThreadPoolBuilder>::build_scoped<rustc_interface[4e0e0615d47554a1]::util::run_in_thread_pool_with_globals<rustc_interface[4e0e0615d47554a1]::interface::run_compiler<(), rustc_driver_impl[fcca23ff68962ade]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#0}, rustc_interface[4e0e0615d47554a1]::util::run_in_thread_pool_with_globals<rustc_interface[4e0e0615d47554a1]::interface::run_compiler<(), rustc_driver_impl[fcca23ff68962ade]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#5}::{closure#0}::{closure#1}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>::{closure#1} as core[5b2322a8d5f57ee]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  20:        0x1139d44b8 - <std[fb7650b96fc3e2b2]::sys::thread::unix::Thread>::new::thread_start
  21:        0x198f69c08 - __pthread_cond_wait


rustc version: 1.95.0-nightly (a33907a7a 2026-02-14)
platform: aarch64-apple-darwin

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `<impl at compiler/rustc_errors/src/lib.rs:1170:1: 1170:19>::emit_diagnostic::{closure#3}::{closure#0}`
#1 [analysis] running analysis passes on crate `rustc_errors`
end of query stack

Reproduction steps

This method took me 10 minutes of incrementally rebuilding the rustc to reproduce on apple M1 pro. Run ./x b rustc in a clean git worktree of rust-lang/rust with build.rustc = "/path/to/nightly/rustc-2026-02-15, rust.incremental = true, rust.deny-warnings = false and rust.rustflags = "-Zthreads=8" set in bootstrap.toml. Then do a change from below diff to rustc source code:

diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 4467a281118..e79312458b3 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -162,3 +162,8 @@ fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
         }
     };
 }
+
+#[derive(Clone, Copy)]
+pub struct BadStruct {
+    int: u64,
+}

Finally run ./x b rustc again. It may sometimes not reproduce, in such case restore changes and ./x b rustc, then apply change and ./x b rustc until ICE is reproduced.

[Zoxc]

I haven't able to reproduce it (just running into other errors). You could try to change fn ensure_must_run to return (true, Some(dep_node)) instead of (!loadable, Some(dep_node)). That looks quite suspect.

[petrochenkov]

Triage: no minimized reproduction that we can add to the parallel test suite, and this will likely be fixed by #153472.
Update: #153472 was merged, now need to check whether this still reproduces.

[LorrensP-2158466]

I want to help with this but i am a bit confused.

@petrochenkov said this in the project goal:

Check whether #152662 still reproduces (make sure it reproduces on a33907a in your setup).

So to see if I understand this correctly:

1. build compiler on commit a33907a (stage 2 i presume)
2. checkout latest compiler on a clean tree
3. build latest compiler with that stage 2 compiler
4. apply change and compile again, see if ICE

Is this correct?

After which I can try and find a minimized repro.

[zetanumbers]

This issue no longer reproduces on current nightly.