ICE: Unwrap none in `rustc_query_system/src/query/plumbing.rs`

[Darksonn]

This ICE occurred on commit 8986ab1 in a CI for a PR to Tokio, during cross-compilation to i686-unknown-linux-gnu. Rerunning the CI step made it complete successfully, so I am unable to reproduce the issue. The other CI steps for other targets also succeeded.

Meta

rustc --version --verbose:

rustc 1.68.2 (9eb3afe9e 2023-03-27)
binary: rustc
commit-hash: 9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0
commit-date: 2023-03-27
host: x86_64-unknown-linux-gnu
release: 1.68.2
LLVM version: 15.0.6

Error output

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/compiler/rustc_query_system/src/query/plumbing.rs:269:41
stack backtrace:
   0: rust_begin_unwind
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/panicking.rs:64:14
   2: core::panicking::panic
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/panicking.rs:114:5
   3: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::evaluate_obligation, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
   4: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::predicate_must_hold_modulo_regions
   5: rustc_ty_utils::common_traits::is_copy_raw
   6: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::is_copy_raw, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
   7: rustc_ty_utils::needs_drop::needs_drop_raw
   8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::needs_drop_raw, rustc_query_impl::plumbing::QueryCtxt>
   9: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::needs_drop_raw
  10: rustc_mir_dataflow::drop_flag_effects::on_all_children_bits::on_all_children_bits::<rustc_mir_dataflow::drop_flag_effects::on_all_drop_children_bits<rustc_mir_transform::elaborate_drops::find_dead_unwinds::{closure#0}>::{closure#0}>
  11: <rustc_mir_transform::elaborate_drops::ElaborateDrops as rustc_middle::mir::MirPass>::run_pass
  12: rustc_mir_transform::run_analysis_to_runtime_passes
  13: rustc_mir_transform::mir_drops_elaborated_and_const_checked
  14: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_drops_elaborated_and_const_checked, rustc_query_impl::plumbing::QueryCtxt>
  15: rustc_mir_transform::optimized_mir
  16: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::optimized_mir, rustc_query_impl::plumbing::QueryCtxt>
  17: rustc_monomorphize::collector::collect_neighbours
  18: rustc_monomorphize::collector::collect_items_rec
  19: rustc_monomorphize::collector::collect_items_rec
  20: rustc_monomorphize::collector::collect_items_rec
  21: <rustc_session::session::Session>::time::<(), rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}>
  22: rustc_monomorphize::collector::collect_crate_mono_items
  23: rustc_monomorphize::partitioning::collect_and_partition_mono_items
  24: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::collect_and_partition_mono_items, rustc_query_impl::plumbing::QueryCtxt>
  25: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::collect_and_partition_mono_items
  26: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend>
  27: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  28: <rustc_session::session::Session>::time::<alloc::boxed::Box<dyn core::any::Any>, rustc_interface::passes::start_codegen::{closure#0}>
  29: rustc_interface::passes::start_codegen
  30: <rustc_interface::queries::Queries>::ongoing_codegen
  31: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  32: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

note: 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: rustc 1.68.2 (9eb3afe9e 2023-03-27) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2

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

query stack during panic:
#0 [is_copy_raw] computing whether `tokio::io::seek::Seek<'_, tokio::io::util::buf_reader::BufReader<test_buffered_reader_seek_underflow::{closure#0}::PositionReader>>` is `Copy`
#1 [needs_drop_raw] computing whether `[async block@tokio/tests/io_buf_reader.rs:133:1: 133:15]` needs drop
#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `test_buffered_reader_seek_underflow`
#3 [optimized_mir] optimizing MIR for `test_buffered_reader_seek_underflow`
#4 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: could not compile `tokio`

[jyn514]

Relevant code:

rust/compiler/rustc_query_system/src/query/plumbing.rs

Lines 250 to 269 in 9eb3afe

	/// Completes the query by updating the query cache with the `result`,
	/// signals the waiter and forgets the JobOwner, so it won't poison the query
	fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
	where
	C: QueryCache<Key = K>,
	{
	// We can move out of `self` here because we `mem::forget` it below
	let key = unsafe { ptr::read(&self.key) };
	let state = self.state;
	// Forget ourself so our destructor won't poison the query
	mem::forget(self);
	let (job, result) = {
	let job = {
	#[cfg(parallel_compiler)]
	let mut lock = state.active.get_shard_by_value(&key).lock();
	#[cfg(not(parallel_compiler))]
	let mut lock = state.active.lock();
	match lock.remove(&key).unwrap() {

[philpax]

I just encountered this (I believe - not sure if the trace is exactly the same) also during a CI build of a PR to Ambient.

Details:

• stable-x86_64-unknown-linux-gnu unchanged - rustc 1.68.2 (9eb3afe9e 2023-03-27)
• Ubuntu 20.04, x86-64 native build, no cross-compilation

I've attached the raw CI log, which contains the full stack trace. All other builds succeeded, and this build succeeded upon retrying.

Worth noting that we cache our Rust target directory with https://github.com/Leafwing-Studios/cargo-cache, if that's at all relevant.

Relevant section of the log:
https://gist.github.com/philpax/f51385483e366df051252a91ab38b1b6

ambient-ci-rustc-panic.txt