Incremental compilation doesn't work in dropbox

I'm sorry, I don't have time to create a minimal example for this, but I will keep the following commit unsquashed for a little while anyway:
https://github.com/aetilley/cool_rust/commit/29e7613178bd1d94495c12b517e4782a080cbbdb

Meta

rustc --version --verbose:

rustc 1.83.0 (90b35a623 2024-11-26)
binary: rustc
commit-hash: 90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf
commit-date: 2024-11-26
host: aarch64-apple-darwin
release: 1.83.0
LLVM version: 19.1.1

Error output

arthurtilley@Arthurs-MacBook-Pro-5 cool_rust % cargo check
    Checking cool_rust v0.1.0 (/Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust)
thread 'rustc' panicked at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/compiler/rustc_middle/src/query/on_disk_cache.rs:520:5:
assertion `left == right` failed
  left: 4
 right: 0
stack backtrace:
   0:        0x11060b0ac - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h7adefaad4a31afc0
   1:        0x10da6ebf4 - core::fmt::write::h381c0b0ce6ab972a
   2:        0x1105ff040 - std::io::Write::write_fmt::h75af97148630d8d3
   3:        0x11060af6c - std::sys::backtrace::BacktraceLock::print::h8baf33e22611de71
   4:        0x11060d440 - std::panicking::default_hook::{{closure}}::h369c7295ef58c5b1
   5:        0x11060d28c - std::panicking::default_hook::h50746358288a9d6a
   6:        0x10e5fb6f8 - <alloc[9e098254554c5838]::boxed::Box<rustc_driver_impl[2ba876bd46efdf49]::install_ice_hook::{closure#0}> as core[6ba870000645607f]::ops::function::Fn<(&dyn for<'a, 'b> core[6ba870000645607f]::ops::function::Fn<(&'a std[18ac8b95e3b389da]::panic::PanicHookInfo<'b>,), Output = ()> + core[6ba870000645607f]::marker::Send + core[6ba870000645607f]::marker::Sync, &std[18ac8b95e3b389da]::panic::PanicHookInfo)>>::call
   7:        0x11060dccc - std::panicking::rust_panic_with_hook::h7d795911432661cb
   8:        0x11060d948 - std::panicking::begin_panic_handler::{{closure}}::h36f15310ecbde379
   9:        0x11060b554 - std::sys::backtrace::__rust_end_short_backtrace::heed121414170e0c7
  10:        0x11060d60c - _rust_begin_unwind
  11:        0x112cf8b54 - core::panicking::panic_fmt::h17b1b80ec02ffd19
  12:        0x112cf8ee8 - core::panicking::assert_failed_inner::h13f6fb8338d443dd
  13:        0x112ea2588 - core[6ba870000645607f]::panicking::assert_failed::<u64, u64>
  14:        0x10fd45fd4 - <rustc_middle[5138617138d99ce9]::query::on_disk_cache::OnDiskCache>::load_indexed::<core[6ba870000645607f]::option::Option<rustc_span[1fbc2a1e28a50ad9]::def_id::DefId>>
  15:        0x10fbb5bac - rustc_query_impl[54d0809e421041ba]::plumbing::try_load_from_disk::<core[6ba870000645607f]::option::Option<rustc_span[1fbc2a1e28a50ad9]::def_id::DefId>>
  16:        0x10fc0a7b8 - <rustc_query_impl[54d0809e421041ba]::query_impl::associated_type_for_effects::dynamic_query::{closure#6} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, &rustc_span[1fbc2a1e28a50ad9]::def_id::DefId, rustc_query_system[f55e8beb91aab0dd]::dep_graph::serialized::SerializedDepNodeIndex, rustc_query_system[f55e8beb91aab0dd]::dep_graph::graph::DepNodeIndex)>>::call_once
  17:        0x10fb222cc - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::try_execute_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::DefIdCache<rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt, true>
  18:        0x10fd18f80 - rustc_query_impl[54d0809e421041ba]::query_impl::associated_type_for_effects::get_query_incr::__rust_end_short_backtrace
  19:        0x110528400 - rustc_ty_utils[cb1fa69e8b366b18]::assoc::associated_item_def_ids
  20:        0x10fbbd8c4 - rustc_query_impl[54d0809e421041ba]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[54d0809e421041ba]::query_impl::associated_item_def_ids::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 16usize]>>
  21:        0x10fc05788 - <rustc_query_impl[54d0809e421041ba]::query_impl::associated_item_def_ids::dynamic_query::{closure#2} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, rustc_span[1fbc2a1e28a50ad9]::def_id::DefId)>>::call_once
  22:        0x10fb18600 - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::try_execute_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::DefIdCache<rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt, true>
  23:        0x10fb0e09c - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::force_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::DefIdCache<rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt>
  24:        0x10fb88c34 - <rustc_query_impl[54d0809e421041ba]::plumbing::query_callback<rustc_query_impl[54d0809e421041ba]::query_impl::associated_item_def_ids::QueryType>::{closure#0} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, rustc_query_system[f55e8beb91aab0dd]::dep_graph::dep_node::DepNode)>>::call_once
  25:        0x10fc76168 - <rustc_query_system[f55e8beb91aab0dd]::dep_graph::graph::DepGraphData<rustc_middle[5138617138d99ce9]::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt>
  26:        0x10fc75ef8 - <rustc_query_system[f55e8beb91aab0dd]::dep_graph::graph::DepGraphData<rustc_middle[5138617138d99ce9]::dep_graph::DepsType>>::try_mark_green::<rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt>
  27:        0x10fb12ff0 - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::ensure_must_run::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::DefIdCache<rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt>
  28:        0x10fd18490 - rustc_query_impl[54d0809e421041ba]::query_impl::associated_items::get_query_incr::__rust_end_short_backtrace
  29:        0x10e870108 - rustc_hir_analysis[5678387cd3e92ec4]::collect::lower_item
  30:        0x10e860d60 - <rustc_hir_analysis[5678387cd3e92ec4]::collect::CollectItemTypesVisitor as rustc_hir[627793020afa6ea6]::intravisit::Visitor>::visit_item
  31:        0x10e94eac0 - rustc_hir_analysis[5678387cd3e92ec4]::check::wfcheck::check_well_formed
  32:        0x10fbbbeec - rustc_query_impl[54d0809e421041ba]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[54d0809e421041ba]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>
  33:        0x10fbfbff8 - <rustc_query_impl[54d0809e421041ba]::query_impl::check_well_formed::dynamic_query::{closure#2} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, rustc_span[1fbc2a1e28a50ad9]::def_id::LocalDefId)>>::call_once
  34:        0x10fb67ad4 - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::try_execute_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::VecCache<rustc_span[1fbc2a1e28a50ad9]::def_id::LocalDefId, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt, true>
  35:        0x10fd2f8a0 - rustc_query_impl[54d0809e421041ba]::query_impl::check_well_formed::get_query_incr::__rust_end_short_backtrace
  36:        0x10e89820c - <rustc_data_structures[4ea10da2abf0fcab]::sync::parallel::ParallelGuard>::run::<core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>, rustc_data_structures[4ea10da2abf0fcab]::sync::parallel::disabled::try_par_for_each_in<&[rustc_hir[627793020afa6ea6]::hir::ItemId], rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed, <rustc_middle[5138617138d99ce9]::hir::ModuleItems>::par_items<rustc_hir_analysis[5678387cd3e92ec4]::check::wfcheck::check_mod_type_wf::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  37:        0x10e95774c - rustc_hir_analysis[5678387cd3e92ec4]::check::wfcheck::check_mod_type_wf
  38:        0x10fbbbec8 - rustc_query_impl[54d0809e421041ba]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[54d0809e421041ba]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>
  39:        0x10fbfbe30 - <rustc_query_impl[54d0809e421041ba]::query_impl::check_mod_type_wf::dynamic_query::{closure#2} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, rustc_span[1fbc2a1e28a50ad9]::def_id::LocalModDefId)>>::call_once
  40:        0x10fb452d0 - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::try_execute_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::DefaultCache<rustc_span[1fbc2a1e28a50ad9]::def_id::LocalModDefId, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt, true>
  41:        0x10fd1d13c - rustc_query_impl[54d0809e421041ba]::query_impl::check_mod_type_wf::get_query_incr::__rust_end_short_backtrace
  42:        0x10e899004 - <rustc_data_structures[4ea10da2abf0fcab]::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures[4ea10da2abf0fcab]::sync::parallel::disabled::par_for_each_in<&[rustc_hir[627793020afa6ea6]::hir_id::OwnerId], <rustc_middle[5138617138d99ce9]::hir::map::Map>::par_for_each_module<rustc_hir_analysis[5678387cd3e92ec4]::check_crate::{closure#0}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  43:        0x10e965e18 - <rustc_session[b1216d5a4a65f438]::session::Session>::time::<(), rustc_hir_analysis[5678387cd3e92ec4]::check_crate::{closure#0}>
  44:        0x10e8d6214 - rustc_hir_analysis[5678387cd3e92ec4]::check_crate
  45:        0x10ef434b0 - rustc_interface[b7ee42a0f694265f]::passes::analysis
  46:        0x10fbbf2fc - rustc_query_impl[54d0809e421041ba]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[54d0809e421041ba]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>
  47:        0x10fc0e5b4 - <rustc_query_impl[54d0809e421041ba]::query_impl::analysis::dynamic_query::{closure#2} as core[6ba870000645607f]::ops::function::FnOnce<(rustc_middle[5138617138d99ce9]::ty::context::TyCtxt, ())>>::call_once
  48:        0x10fb2805c - rustc_query_system[f55e8beb91aab0dd]::query::plumbing::try_execute_query::<rustc_query_impl[54d0809e421041ba]::DynamicConfig<rustc_query_system[f55e8beb91aab0dd]::query::caches::SingleCache<rustc_middle[5138617138d99ce9]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[54d0809e421041ba]::plumbing::QueryCtxt, true>
  49:        0x10fd0be80 - rustc_query_impl[54d0809e421041ba]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  50:        0x10e64aca0 - <rustc_middle[5138617138d99ce9]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[2ba876bd46efdf49]::run_compiler::{closure#0}::{closure#1}::{closure#5}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>
  51:        0x10e64a3c8 - <rustc_interface[b7ee42a0f694265f]::interface::Compiler>::enter::<rustc_driver_impl[2ba876bd46efdf49]::run_compiler::{closure#0}::{closure#1}, core[6ba870000645607f]::result::Result<core[6ba870000645607f]::option::Option<rustc_interface[b7ee42a0f694265f]::queries::Linker>, rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>
  52:        0x10e6408b4 - rustc_span[1fbc2a1e28a50ad9]::create_session_globals_then::<core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>, rustc_interface[b7ee42a0f694265f]::util::run_in_thread_with_globals<rustc_interface[b7ee42a0f694265f]::interface::run_compiler<core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>, rustc_driver_impl[2ba876bd46efdf49]::run_compiler::{closure#0}>::{closure#1}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}>
  53:        0x10e6300ac - std[18ac8b95e3b389da]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[b7ee42a0f694265f]::util::run_in_thread_with_globals<rustc_interface[b7ee42a0f694265f]::interface::run_compiler<core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>, rustc_driver_impl[2ba876bd46efdf49]::run_compiler::{closure#0}>::{closure#1}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>
  54:        0x10e647f48 - <<std[18ac8b95e3b389da]::thread::Builder>::spawn_unchecked_<rustc_interface[b7ee42a0f694265f]::util::run_in_thread_with_globals<rustc_interface[b7ee42a0f694265f]::interface::run_compiler<core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>, rustc_driver_impl[2ba876bd46efdf49]::run_compiler::{closure#0}>::{closure#1}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6ba870000645607f]::result::Result<(), rustc_span[1fbc2a1e28a50ad9]::ErrorGuaranteed>>::{closure#1} as core[6ba870000645607f]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  55:        0x110618050 - std::sys::pal::unix::thread::Thread::new::thread_start::h44ebc83f14222f58
  56:        0x1989d1f94 - __pthread_joiner_wake

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: rustc 1.83.0 (90b35a623 2024-11-26) running on aarch64-apple-darwin

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

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

query stack during panic:

thread 'rustc' has overflowed its stack
fatal runtime error: stack overflow
error: could not compile `cool_rust` (lib)

Caused by:
  process didn't exit successfully: `/Users/arthurtilley/.rustup/toolchains/stable-aarch64-apple-darwin/bin/rustc --crate-name cool_rust --edition=2021 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=173 --crate-type lib --emit=dep-info,metadata -C embed-bitcode=no -C debuginfo=2 -C split-debuginfo=unpacked --check-cfg 'cfg(docsrs)' --check-cfg 'cfg(feature, values())' -C metadata=a633a5e12806e4c7 -C extra-filename=-a633a5e12806e4c7 --out-dir /Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust/target/debug/deps -C incremental=/Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust/target/debug/incremental -L dependency=/Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust/target/debug/deps --extern lalrpop_util=/Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust/target/debug/deps/liblalrpop_util-17b04e3143ce965c.rmeta --extern logos=/Users/arthurtilley/Library/CloudStorage/Dropbox/PersonalDrop/DropDev/cool_rust/target/debug/deps/liblogos-d4e436ddf730bfdc.rmeta` (signal: 6, SIGABRT: process abort signal)
arthurtilley@Arthurs-MacBook-Pro-5 cool_rust % 

<backtrace>

Start by reproducing the failure with cargo check in the linked cool_rust commit, focusing on incremental compilation in Dropbox. Read compiler/rustc_middle/src/query/on_disk_cache.rs around line 520 and compare the reported load_indexed stack frames. Done means the project no longer panics during this workflow, with a regression test or other verification for the reproduced case.