ICE: thread 'rustc' panicked at 'index out of bounds: the len is 52 but the index is 58', compiler/rustc_query_impl/src/on_disk_cache.rs:726:18

[edmorley]

Code

I have saved a copy of the repo state + target directory that triggers this ICE, that I can provide on request :-)
The repo is: https://github.com/Malax/libcnb.rs

Meta

rustc --version --verbose:

rustc 1.59.0-beta.3 (92c92fb3c 2022-01-20)
binary: rustc
commit-hash: 92c92fb3c14a19a565aab416c4d357e0872a4408
commit-date: 2022-01-20
host: x86_64-apple-darwin
release: 1.59.0-beta.3
LLVM version: 13.0.0

Error output

thread 'rustc' panicked at 'index out of bounds: the len is 52 but the index is 58', compiler/rustc_query_impl/src/on_disk_cache.rs:726:18

Backtrace

$ RUST_BACKTRACE=1 cargo test basic
   Compiling libcnb-test v0.1.0 (/Users/emorley/src/libcnb.rs/libcnb-test)
warning: unused import: `fs_extra::dir::CopyOptions`
 --> libcnb-test/src/build.rs:1:5
  |
1 | use fs_extra::dir::CopyOptions;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused variable: `app_dir`
  --> libcnb-test/src/build.rs:12:5
   |
12 |     app_dir: impl AsRef<Path>,
   |     ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_app_dir`
   |
   = note: `#[warn(unused_variables)]` on by default

warning: variant is never constructed: `CannotCreateAppTempDirectory`
  --> libcnb-test/src/build.rs:46:5
   |
46 |     CannotCreateAppTempDirectory(std::io::Error),
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: variant is never constructed: `CannotCopyAppToTempDirectory`
  --> libcnb-test/src/build.rs:49:5
   |
49 |     CannotCopyAppToTempDirectory(fs_extra::error::Error),
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at 'index out of bounds: the len is 52 but the index is 58', compiler/rustc_query_impl/src/on_disk_cache.rs:726:18
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic_bounds_check
   3: <rustc_span::span_encoding::Span as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
   4: <rustc_middle::ty::VariantDef as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
   5: <rustc_query_impl::on_disk_cache::CacheDecoder as rustc_serialize::serialize::Decoder>::read_seq::<alloc::vec::Vec<rustc_middle::ty::VariantDef>, <alloc::vec::Vec<rustc_middle::ty::VariantDef> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>
   6: <rustc_middle::ty::adt::AdtDef as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
   7: <rustc_middle::ty::sty::TyKind as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
   8: <&rustc_middle::ty::TyS as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
   9: <rustc_query_impl::on_disk_cache::CacheDecoder as rustc_middle::ty::codec::TyDecoder>::cached_ty_for_shorthand::<<&rustc_middle::ty::TyS as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>
  10: <&rustc_middle::ty::TyS as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  11: <rustc_middle::ty::subst::GenericArg as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  12: <core::result::Result<rustc_middle::ty::subst::GenericArg, alloc::string::String> as rustc_middle::ty::context::InternIteratorElement<rustc_middle::ty::subst::GenericArg, &rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg>>>::intern_with::<core::iter::adapters::map::Map<core::ops::range::Range<usize>, <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>, <rustc_middle::ty::context::TyCtxt>::mk_substs<core::iter::adapters::map::Map<core::ops::range::Range<usize>, <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>>::{closure#0}>
  13: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  14: <rustc_middle::ty::sty::TyKind as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  15: <&rustc_middle::ty::TyS as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  16: <rustc_middle::mir::Constant as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  17: <rustc_middle::mir::Operand as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  18: <rustc_middle::mir::terminator::Terminator as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  19: <rustc_query_impl::on_disk_cache::CacheDecoder as rustc_serialize::serialize::Decoder>::read_option::<core::option::Option<rustc_middle::mir::terminator::Terminator>, <core::option::Option<rustc_middle::mir::terminator::Terminator> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>
  20: <rustc_middle::mir::BasicBlockData as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode
  21: <rustc_query_impl::on_disk_cache::CacheDecoder as rustc_serialize::serialize::Decoder>::read_seq::<alloc::vec::Vec<rustc_middle::mir::BasicBlockData>, <alloc::vec::Vec<rustc_middle::mir::BasicBlockData> as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>
  22: <rustc_query_impl::on_disk_cache::CacheDecoder as rustc_serialize::serialize::Decoder>::read_struct::<rustc_middle::mir::Body, <rustc_middle::mir::Body as rustc_serialize::serialize::Decodable<rustc_query_impl::on_disk_cache::CacheDecoder>>::decode::{closure#0}>
  23: <rustc_query_impl::on_disk_cache::OnDiskCache>::try_load_query_result::<&rustc_middle::mir::Body>
  24: rustc_query_system::query::plumbing::try_load_from_disk_and_cache_in_memory::<rustc_query_impl::plumbing::QueryCtxt, rustc_span::def_id::DefId, &rustc_middle::mir::Body>
  25: 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::mir::Body>>
  26: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::optimized_mir, rustc_query_impl::plumbing::QueryCtxt>
  27: <rustc_metadata::rmeta::encoder::EncodeContext>::encode_crate_root
  28: rustc_metadata::rmeta::encoder::encode_metadata_impl
  29: rustc_data_structures::sync::join::<rustc_metadata::rmeta::encoder::encode_metadata::{closure#0}, rustc_metadata::rmeta::encoder::encode_metadata::{closure#1}, rustc_metadata::rmeta::encoder::EncodedMetadata, ()>
  30: rustc_metadata::rmeta::encoder::encode_metadata
  31: <rustc_interface::queries::Queries>::ongoing_codegen
  32: <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>>
  33: 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}>
  34: rustc_interface::interface::create_compiler_and_run::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>
  35: <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 1.59.0-beta.3 (92c92fb3c 2022-01-20) 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 [optimized_mir] optimizing MIR for `<impl at libcnb-test/src/lib.rs:84:1: 181:2>::run`
end of query stack
warning: `libcnb-test` (lib) generated 4 warnings
error: could not compile `libcnb-test`; 4 warnings emitted

[hkratz]

Should be gone after a cargo clean.

@rustbot label +A-incr-comp

[Aaron1011]

This should be fixed in the latest nightly by #92533