index out of bounds: the len is 4 but the index is 140353459346585

[Lslightly]

Env:

$ cargo version --verbose
cargo 1.87.0-nightly (6cf826701 2025-03-14)
release: 1.87.0-nightly
commit-hash: 6cf8267012570f63d6b86e85a2ae5627de52df9e
commit-date: 2025-03-14
host: x86_64-unknown-linux-gnu
libgit2: 1.9.0 (sys:0.20.0 vendored)
libcurl: 8.12.1-DEV (sys:0.4.80+curl-8.12.1 vendored ssl:OpenSSL/3.4.1)
ssl: OpenSSL 3.4.1 11 Feb 2025
os: Ubuntu 24.4.0 (noble) [64-bit]

Demo repo: https://github.com/Lslightly-courses/cs431/tree/loom-index-out-of-bounds

# loom-index-out-of-bounds branch
git clone -b loom-index-out-of-bounds https://github.com/Lslightly-courses/cs431.git

Run source loom.sh in homework directory.

cd homework
LOOM_CHECKPOINT_INTERVAL=1 LOOM_CHECKPOINT_FILE=my_test.json cargo test --features check-loom,loom/checkpoint --test arc --release -- correctness::count_sync --nocapture --test-threads 1

Error:

thread 'correctness::count_sync' panicked at /home/lqw/.cargo/registry/src/rsproxy.cn-e3de039b2554c837/loom-0.7.2/src/rt/object.rs:286:38:
index out of bounds: the len is 4 but the index is 140476439911577
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
FAILED

I don't know whether loom can handle all cases. More user-friendly feedback might help.

[vincent-thomas]

I'm getting something similar:

thread 'test_send_empty' panicked at /Users/vt/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/loom-0.7.2/src/rt/object.rs:382:50:
index out of bounds: the len is 1 but the index is 5
stack backtrace:
   0:        0x100daec50 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hf35f9734f9a29483
   1:        0x100dcb3fc - core::fmt::write::h60ec6633daab7b35
   2:        0x100dac71c - std::io::Write::write_fmt::hc29709fdab2e34e2
   3:        0x100daeb04 - std::sys::backtrace::BacktraceLock::print::hca95bffd78053951
   4:        0x100db00a8 - std::panicking::default_hook::{{closure}}::h357ed4fbef22679d
   5:        0x100daff00 - std::panicking::default_hook::h0a4e133b151d5758
   6:        0x100db0b84 - std::panicking::rust_panic_with_hook::h557a23724a5de839
   7:        0x100db0764 - std::panicking::begin_panic_handler::{{closure}}::h269cace6208fef05
   8:        0x100daf100 - std::sys::backtrace::__rust_end_short_backtrace::h5be0da278f3aaec7
   9:        0x100db0440 - __rustc[de2ca18b4c54d5b8]::rust_begin_unwind
  10:        0x100de0944 - core::panicking::panic_fmt::h477ff48eff31ffa4
  11:        0x100de0ac4 - core::panicking::panic_bounds_check::h0b28316d3be9e695
  12:        0x100d00f38 - loom::rt::object::Ref<T>::set_action::h568b47bef07bf7e2
  13:        0x100cf2338 - scoped_tls::ScopedKey<T>::with::h9ffeebba560e1e71
  14:        0x100cf3fac - loom::rt::atomic::Atomic<T>::rmw::h85536a0a86d5d1d6
  15:        0x100d02b78 - loom::sync::atomic::int::AtomicU64::fetch_add::hcc71e658b6ce1b9