compiler panic when moving struct definition

[zvkemp]

Code

Code is part of a private repo, so I can't share everything. The change involved moving a struct definition (the ApplicationSummaryKey in the below example) from one module to a new submodule of that module. It is triggered by cargo build or cargo test (possibly other commands). Was not triggered by nightly, but it's unclear if that's because there wasn't a stale nightly build already.

This is the function at the top of the query stack when the panic occurs:

    pub(crate) async fn commit_buffer_in_transaction(
        &mut self,
        db: &mut sqlx::Transaction<'_, Postgres>,
    ) -> Result<HashSet<ApplicationSummaryKey<T::Span>>, Error> {
        let mut keys = HashSet::new();

        for (key, summary) in self.data.drain() {
            summary.commit(&mut *db).await?;
            keys.insert(key);
        }

        Ok(keys)
    }

Also note this crate is part of a workspace, and the panic only happens when run from the workspace root; it does not happen if run in the crate's subdirectory. A cargo clean -p {crate} fixed the issue, and now I cannot reproduce it.

Meta

rustc --version --verbose:

rustc 1.58.0 (02072b482 2022-01-11)
binary: rustc
commit-hash: 02072b482a8b5357f7fb5e5637444ae30e423c40
commit-date: 2022-01-11
host: aarch64-apple-darwin
release: 1.58.0
LLVM version: 13.0.0

Error output

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/02072b482a8b5357f7fb5e5637444ae30e423c40/compiler/rustc_hir/src/definitions.rs:452:14

Backtrace

stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: <rustc_middle::ty::context::TyCtxt>::def_path_hash_to_def_id
   4: <rustc_query_system::dep_graph::dep_node::DepNode<rustc_middle::dep_graph::dep_node::DepKind> as rustc_middle::dep_graph::dep_node::DepNodeExt>::extract_def_id
   5: rustc_query_impl::query_callbacks::hir_owner::force_from_dep_node
   6: <rustc_middle::ty::context::TyCtxt as rustc_query_system::dep_graph::DepContext>::try_force_from_dep_node
   7: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
   8: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
   9: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
  10: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_green::<rustc_query_impl::plumbing::QueryCtxt>
  11: rustc_query_system::query::plumbing::try_load_from_disk_and_cache_in_memory::<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>
  12: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>>
  13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::unsafety_check_result, rustc_query_impl::plumbing::QueryCtxt>
  14: <rustc_mir_transform::check_unsafety::UnsafetyChecker as rustc_middle::mir::visit::Visitor>::visit_rvalue
  15: rustc_mir_transform::check_unsafety::unsafety_check_result
  16: <rustc_mir_transform::check_unsafety::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  17: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>
  18: rustc_data_structures::stack::ensure_sufficient_stack::<(&rustc_middle::mir::query::UnsafetyCheckResult, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtx
t, rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>::{closure#3}>
  19: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>>
  20: rustc_query_system::query::plumbing::force_query::<rustc_query_impl::queries::unsafety_check_result, rustc_query_impl::plumbing::QueryCtxt>
  21: rustc_query_impl::query_callbacks::unsafety_check_result::force_from_dep_node
  22: <rustc_middle::ty::context::TyCtxt as rustc_query_system::dep_graph::DepContext>::try_force_from_dep_node
  23: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
  24: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
  25: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
  26: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_green::<rustc_query_impl::plumbing::QueryCtxt>
  27: rustc_query_system::query::plumbing::try_load_from_disk_and_cache_in_memory::<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::BorrowCheckResult>
  28: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::BorrowCheckResult>>
  29: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
  30: rustc_typeck::collect::type_of::type_of
  31: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId, &rustc_middle::ty::TyS>
  32: rustc_data_structures::stack::ensure_sufficient_stack::<(&rustc_middle::ty::TyS, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::D
efId, &rustc_middle::ty::TyS>::{closure#3}>
  33: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, &rustc_middle::ty::TyS>>
  34: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt>
  35: <rustc_middle::ty::util::OpaqueTypeExpander>::expand_opaque_ty
  36: <smallvec::SmallVec<[&rustc_middle::ty::TyS; 8]> as core::iter::traits::collect::Extend<&rustc_middle::ty::TyS>>::extend::<core::iter::adapters::map::Map<core::iter::adapters::copied::Copied<core::slice::iter::Iter<&rustc_middle::ty::TyS>>, ru
stc_middle::ty::util::fold_list<rustc_middle::ty::util::OpaqueTypeExpander, &rustc_middle::ty::TyS, <&rustc_middle::ty::list::List<&rustc_middle::ty::TyS> as rustc_middle::ty::fold::TypeFoldable>::super_fold_with<rustc_middle::ty::util::OpaqueTypeEx
pander>::{closure#0}>::{closure#1}>>
  37: rustc_middle::ty::util::fold_list::<rustc_middle::ty::util::OpaqueTypeExpander, &rustc_middle::ty::TyS, <&rustc_middle::ty::list::List<&rustc_middle::ty::TyS> as rustc_middle::ty::fold::TypeFoldable>::super_fold_with<rustc_middle::ty::util::Op
aqueTypeExpander>::{closure#0}>
  38: <&rustc_middle::ty::TyS as rustc_middle::ty::fold::TypeFoldable>::super_fold_with::<rustc_middle::ty::util::OpaqueTypeExpander>
  39: <smallvec::SmallVec<[rustc_middle::ty::subst::GenericArg; 8]> as core::iter::traits::collect::Extend<rustc_middle::ty::subst::GenericArg>>::extend::<core::iter::adapters::map::Map<core::iter::adapters::copied::Copied<core::slice::iter::Iter<ru
stc_middle::ty::subst::GenericArg>>, <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::super_fold_with<rustc_middle::ty::util::OpaqueTypeExpander>::{closure#0}>>
  40: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::fold_with::<rustc_middle::ty::util::OpaqueTypeExpander>
  41: <&rustc_middle::ty::TyS as rustc_middle::ty::fold::TypeFoldable>::super_fold_with::<rustc_middle::ty::util::OpaqueTypeExpander>
  42: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::fold_with::<rustc_middle::ty::util::OpaqueTypeExpander>
  43: <rustc_middle::ty::util::OpaqueTypeExpander>::expand_opaque_ty
  44: <rustc_middle::ty::util::OpaqueTypeExpander>::expand_opaque_ty
  45: <rustc_middle::ty::context::TyCtxt>::try_expand_impl_trait_type
  46: rustc_typeck::check::check::check_item_type
  47: <rustc_middle::hir::map::Map>::visit_item_likes_in_module::<rustc_typeck::check::CheckItemTypesVisitor>
  48: rustc_typeck::check::check::check_mod_item_types
  49: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId, ()>
  50: rustc_data_structures::stack::ensure_sufficient_stack::<((), rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::LocalDefId, ()>::{clo
sure#3}>
  51: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, ()>>
  52: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
  53: <rustc_middle::hir::map::Map>::for_each_module::<rustc_typeck::check_crate::{closure#6}::{closure#0}>
  54: rustc_typeck::check_crate
  55: rustc_interface::passes::analysis
  56: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>
  57: rustc_data_structures::stack::ensure_sufficient_stack::<(core::result::Result<(), rustc_errors::ErrorReported>, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::Q
ueryCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>::{closure#3}>
  58: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorReported>>>
  59: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
  60: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorReported>>
  61: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorReported>>
  62: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#
1}>
  63: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver:
:run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.



query stack during panic:
#0 [unsafety_check_result] unsafety-checking `rollups::rollup_buffer::<impl at application-summarizer/src/rollups/rollup_buffer.rs:19:1: 109:2>::commit_buffer_in_transaction::{closure#0}`
#1 [unsafety_check_result] unsafety-checking `rollups::rollup_buffer::<impl at application-summarizer/src/rollups/rollup_buffer.rs:19:1: 109:2>::commit_buffer_in_transaction`
#2 [mir_borrowck] borrow-checking `rollups::rollup_buffer::<impl at application-summarizer/src/rollups/rollup_buffer.rs:19:1: 109:2>::commit_buffer_in_transaction`
#3 [type_of] computing type of `rollups::rollup_buffer::<impl at application-summarizer/src/rollups/rollup_buffer.rs:19:1: 109:2>::commit_buffer_in_transaction::{opaque#0}`
#4 [check_mod_item_types] checking item types in top-level module
#5 [analysis] running analysis passes on this crate

[Aaron1011]

@zvkemp Can you try the following to see if you can reproduce this again:

1. Run cargo clean
2. Undo the change you made (e.g. move ApplicationSummaryKey back to its original location, and undo any other changes you made)
3. Run cargo build from the workspace root
4. Re-apply the change (move ApplicationSummaryKey to the new location)
5. Run cargo build again

[zvkemp]

@aaron1101 Unfortunately I can't reproduce the issue again using that procedure; in hindsight I should have copied the target directory state before running cargo clean. I'll reply to this issue again if I end up getting it working (or rather not working).

[bergmark]

I think I ran across the same issue, but it was after switching git branches multiple times so finding a reproduction seems hard :( I ran cargo test in crate-a and while cargo was compiling crate-b i got:

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/02072b482a8b5357f7fb5e5637444ae30e423c40/compiler/rustc_hir/src/definitions.rs:452:14
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.58.0 (02072b482 2022-01-11) running on x86_64-apple-darwin

note: compiler flags: -C embed-bitcode=no -C split-debuginfo=unpacked -C debuginfo=2 -C incremental --crate-type lib

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

query stack during panic:
#0 [unsafety_check_result] unsafety-checking `handler::account::account_get::{closure#0}`
#1 [unsafety_check_result] unsafety-checking `handler::account::account_get`
end of query stack
error: could not compile `crate-b`

a clean build resolved it.

[zvkemp]

I've had another panic with a similar stacktrace, again after globally renaming a struct. This one is only triggered by cargo test.

@aaron1101 I've backed up the target directory this time, so please let me know if there's anything you'd like me to look at in more detail.

Backtrace

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/02072b482a8b5357f7fb5e5637444ae30e423c40/compiler/rustc_hir/src/definitions.rs:452:14
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: <rustc_middle::ty::context::TyCtxt>::def_path_hash_to_def_id
   4: <rustc_query_system::dep_graph::dep_node::DepNode<rustc_middle::dep_graph::dep_node::DepKind> as rustc_middle::dep_graph::dep_node::DepNodeExt>::extract_def_id
   5: rustc_query_impl::query_callbacks::hir_owner::force_from_dep_node
   6: <rustc_middle::ty::context::TyCtxt as rustc_query_system::dep_graph::DepContext>::try_force_from_dep_node
   7: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
   8: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
   9: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_green::<rustc_query_impl::plumbing::QueryCtxt>
  10: rustc_query_system::query::plumbing::ensure_must_run::<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::LocalDefId, rustc_span::def_id::LocalDefId>
  11: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::check_impl_item_well_formed, rustc_query_impl::plumbing::QueryCtxt>
  12: <core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::par_for_each_in<&alloc::vec::Vec<core::option::Option<rustc_hir::hir::OwnerInfo>>, <rustc_middle::hir::map::Map>::par_visit_all_item_likes<rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor>::{closure#0}>::{closure#0}::{closure#0}> as core::ops::function::FnOnce<()>>::call_once
  13: rustc_data_structures::sync::par_for_each_in::<&alloc::vec::Vec<core::option::Option<rustc_hir::hir::OwnerInfo>>, <rustc_middle::hir::map::Map>::par_visit_all_item_likes<rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor>::{closure#0}>
  14: <rustc_session::session::Session>::track_errors::<rustc_typeck::check_crate::{closure#5}, ()>
  15: rustc_typeck::check_crate
  16: rustc_interface::passes::analysis
  17: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>
  18: rustc_data_structures::stack::ensure_sufficient_stack::<(core::result::Result<(), rustc_errors::ErrorReported>, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>::{closure#3}>
  19: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorReported>>>
  20: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
  21: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorReported>>
  22: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorReported>>
  23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  24: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>
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 1.58.0 (02072b482 2022-01-11) running on aarch64-apple-darwin

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

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

query stack during panic:
#0 [analysis] running analysis passes on this crate

[Aaron1011]

@zvkemp Are you able to consistently reproduce the crash after running cargo clean by re-applying the sequence of building and editing that you performed?

[rsalmei]

I've just had it too, going to try cargo clean afterwards:

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/02072b482a8b5357f7fb5e5637444ae30e423c40/compiler/rustc_hir/src/definitions.rs:452:14
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.58.0 (02072b482 2022-01-11) running on x86_64-apple-darwin

note: compiler flags: -C embed-bitcode=no -C split-debuginfo=unpacked -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `impl core::future::future::Future<Output = core::result::Result<alloc::boxed::Box<(dyn warp::reply::Reply + 'static)>, core::convert::Infallible>>: core::marker::Send`  |  = note: this failure-note originates in the macro `mk_route` (in Nightly builds, run with -Z macro-backtrace for more info)

#1 [typeck] type-checking `api::run`
end of query stack

EDIT:
cargo clean did fix it.
I was refactoring some things and moved a module inside another directory. I think that was the trigger.

[ineiti]

Same thing here, but cargo clean fixed it. I had a not-too-old git-commit, so I tried to do:

git stash
cargo clean
cargo build
git stash pop
cargo build

But it didn't trigger the error...