Panic index out of bounds running `cargo test` (unreproducable)

[zhiburt]

Follow the compiler's note I decided to unveil this issue 😄

After first time I get the crash I ran cargo test 2 times and each time it was a crash but after that it went normally. I wasn't able to reproduce it.

I don't provide here the code since I consider it unreproducable.

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RUST_BACKTRACE=1 cargo test--verbose:

Backtrace:

thread 'rustc' panicked at 'index out of bounds: the len is 10 but the index is 10', src/librustc_middle/ty/query/on_disk_cache.rs:583:18
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/blob/master/CONTRIB..

note: rustc 1.44.0 (49cae5576 2020-06-01) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental

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

warning: 1 warning emitted

error: could not compile `rstext`.

To learn more, run the command again with —verbose.

rust-lang/rust
github.com
 
thread 'rustc' panicked at 'index out of bounds: the len is 10 but the index is 10', src/librustc_middle/ty/query/on_disk_cache.rs:583:18
stack backtrace:
0: backtrace::backtrace::libunwind::trace
at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
1: backtrace::backtrace::trace_unsynchronized
at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
2: std::sys_common::backtrace::_print_fmt
at src/libstd/sys_common/backtrace.rs:78
3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
at src/libstd/sys_common/backtrace.rs:59
4: core::fmt::write
at src/libcore/fmt/mod.rs:1069
5: std::io::Write::write_fmt
at src/libstd/io/mod.rs:1504
6: std::sys_common::backtrace::_print
at src/libstd/sys_common/backtrace.rs:62
7: std::sys_common::backtrace::print
at src/libstd/sys_common/backtrace.rs:49
8: std::panicking::default_hook::{{closure}}
at src/libstd/panicking.rs:198
9: std::panicking::default_hook
at src/libstd/panicking.rs:218
10: rustc_driver::report_ice
11: std::panicking::rust_panic_with_hook
at src/libstd/panicking.rs:515
12: rust_begin_unwind
at src/libstd/panicking.rs:419
13: core::panicking::panic_fmt
at src/libcore/panicking.rs:111
14: core::panicking::panic_bounds_check
at src/libcore/panicking.rs:69
15: <rustc_middle::ty::query::on_disk_cache::CacheDecoder as serialize::serialize::SpecializedDecoder<rustc_span::span_encoding::Span»::specialized_decode
16: <rustc_middle::mir::SourceInfo as serialize::serialize::Decodable>::decode
17: <rustc_middle::mir::Statement as serialize::serialize::Decodable>::decode
18: serialize::serialize::Decoder::read_seq
19: <rustc_middle::mir::BasicBlockData as serialize::serialize::Decodable>::decode
20: serialize::serialize::Decoder::read_seq
21: <rustc_middle::mir::Body as serialize::serialize::Decodable>::decode::{{closure}}
22: rustc_middle::ty::query::on_disk_cache::OnDiskCache::try_load_query_result
23: rustc_query_system::query::plumbing::get_query
24: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::instance_mir
25: rustc_mir::monomorphize::collector::collect_items_rec
26: rustc_mir::monomorphize::collector::collect_items_rec
27: rustc_mir::monomorphize::collector::collect_crate_mono_items
28: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
29: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::collect_and_partition_mono_items>::compute
30: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
32: rustc_query_system::query::plumbing::get_query
33: rustc_codegen_ssa::base::codegen_crate
34: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
35: rustc_session::utils::<impl rustc_session::session::Session>::time
36: rustc_interface::passes::start_codegen
37: rustc_middle::ty::context::tls::enter_global
38: rustc_interface::queries::Queries::ongoing_codegen
39: rustc_interface::interface::run_compiler_in_existing_thread_pool
40: scoped_tls::ScopedKey<T>::set
41: rustc_ast::attr::with_globals
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/blob/master/CONTRIB..

note: rustc 1.44.0 (49cae5576 2020-06-01) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [optimized_mir] processing `it_works::{{closure}}#0`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
warning: 1 warning
 
emitted

error: could not compile `rstext`.

Caused by:
process didn't exit successfully: `rustc —crate-name test —edition=2018 tests/test.rs —error-format=json —json=diagnostic-rendered-ansi —emit=dep-info,link -C debuginfo=2 —test -C metadata=d3af2c6bb91399d2 -C extra-filename=-d3af2c6bb91399d2 —out-dir /home/zhiburt/proj/po-rs/target/debug/deps -C incremental=/home/zhiburt/proj/po-rs/target/debug/incremental -L dependency=/home/zhiburt/proj/po-rs/target/debug/deps —extern rstext=/home/zhiburt/proj/po-rs/target/debug/deps/librstext-96bd2310391f3aca.rlib` (exit code: 101)