assertion failed: trying to encode a dep node twice #150018
Description
As I've suspected #149916 revealed a bug in rustc's query system on multiple threads. I was trying to build rustc itself with the nightly toolchain as stage0 after doing git checkout build fails while trying to compile rustc_lint_defs.
Error
thread 'rustc' (199561) panicked at compiler/rustc_query_system/src/dep_graph/graph.rs:1392:9:
assertion `left == right` failed: trying to encode a dep node twice
left: 64535
right: 4294967295
backtrace
stack backtrace:
0: __rustc::rust_begin_unwind
1: core::panicking::panic_fmt
2: core::panicking::assert_failed_inner
3: core::panicking::assert_failed::<u32, u32>
4: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
5: rustc_query_impl::plumbing::force_from_dep_node::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>>
6: <rustc_query_impl::plumbing::query_callback<rustc_query_impl::query_impl::mir_drops_elaborated_and_const_checked::QueryType>::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_query_system::dep_graph::dep_node::DepNode, rustc_query_system::dep_graph::serialized::SerializedDepNodeIndex)>>::call_once
7: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
8: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
9: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
10: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
11: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::DepsType>>::try_mark_green::<rustc_query_impl::plumbing::QueryCtxt>
12: rustc_query_system::query::plumbing::ensure_must_run::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 32]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>
13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_hir_analysis::check_crate::{closure#2}>::{closure#0}
14: rustc_data_structures::sync::parallel::par_slice::par_rec::<&rustc_span::def_id::LocalDefId, rustc_data_structures::sync::parallel::par_for_each_in<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_hir_analysis::check_crate::{closure#2}>::{closure#0}>::{closure#0}::{closure#0}>
15: <rustc_thread_pool::job::StackJob<rustc_thread_pool::latch::SpinLatch, rustc_thread_pool::join::join_context<rustc_thread_pool::join::join::call<(), rustc_data_structures::sync::parallel::par_slice::par_rec<&rustc_span::def_id::LocalDefId, rustc_data_structures::sync::parallel::par_for_each_in<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_hir_analysis::check_crate::{closure#2}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#1}>::{closure#0}, rustc_thread_pool::join::join::call<(), rustc_data_structures::sync::parallel::par_slice::par_rec<&rustc_span::def_id::LocalDefId, rustc_data_structures::sync::parallel::par_for_each_in<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_hir_analysis::check_crate::{closure#2}>::{closure#0}>::{closure#0}::{closure#0}>::{closure#2}>::{closure#0}, (), ()>::{closure#0}::{closure#0}, ()> as rustc_thread_pool::job::Job>::execute
16: <rustc_thread_pool::registry::WorkerThread>::wait_or_steal_until_cold
17: <rustc_thread_pool::registry::ThreadBuilder>::run
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
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: please attach the file at `/home/huawei/dev/rust/rustc-ice-2025-12-15T10_49_29-199385.txt` to your bug report
note: compiler flags: --crate-type lib -C opt-level=3 -C embed-bitcode=no -C debuginfo=line-tables-only -C debug-assertions=on -C incremental=[REDACTED] -C symbol-mangling-version=v0 -Z annotate-moves -Z unstable-options -Z macro-backtrace -C split-debuginfo=off -C force-frame-pointers=true -C llvm-args=-import-instr-limit=10 -C link-args=-Wl,-z,origin -C link-args=-Wl,-rpath,$ORIGIN/../lib -Z on-broken-pipe=kill -C lto=off -Z threads=24 -Z binary-dep-depinfo -Z tls-model=initial-exec -Z force-unstable-if-unmarked
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `<impl at compiler/rustc_lint_defs/src/lib.rs:557:1: 557:10>::default_fields_for_macro`
#1 [analysis] running analysis passes on crate `rustc_lint_defs`
end of query stack
there was a panic while trying to force a dep node
try_mark_green dep node stack:
#0 mir_for_ctfe(rustc_lint_defs[912f]::{impl#9}::default_fields_for_macro)
#1 eval_to_allocation_raw(6a497d626948f9b4-2f772ebace64724b)
#2 eval_to_const_value_raw(6a497d626948f9b4-2f772ebace64724b)
#3 eval_static_initializer(rustc_lint_defs[912f]::builtin::UNCONDITIONAL_PANIC)
end of try_mark_green dep node stack
error: could not compile `rustc_lint_defs` (lib)
It is surprisingly persistent as and I was unable to get it go away just by retriggering the incremental compilation using after some rebuilds goes away. We can infer from the error that compiler finds itself in a situation where it tries to mark one dep node as both green and red.touch src/lib.rs but deleting incremental folder fixes this per usual
Rust version
Stage 0:
rustc 1.94.0-nightly (0208ee09b 2025-12-14)
binary: rustc
commit-hash: 0208ee09be465f69005a7a12c28d5eccac7d5f34
commit-date: 2025-12-14
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.5
Steps to reproduce
Do a clean build x build library --stage 1 at 52fda2e, then git checkout to ba45f0b and without cleaning try rebuilding it the same way again. And don't forget to set RUSTFLAGS_BOOTSTRAP to -Zthreads=n where n > 1.