cargo fmt crashes in Rust 1.81.0

[ajewellamz]

lib.rs.gz

Un-gzip the attached lib.rs
make it the only file in a crate
run cargo fmt
See

thread 'main' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order
stack backtrace:
   0:        0x103e69aa3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::haf41a54e7ed5fe07
   1:        0x103eb45cb - core::fmt::write::h526161fad96c5ad5
   2:        0x103e5f69e - std::io::Write::write_fmt::h4de0398536c8b0e4

As an aside - with previous versions of Rust, cargo fmt also failed on this file.
It didn't crash, but it left trailing spaces on some lines, and then reported failure.

[ytmimi]

Hey @ajewellamz what exact version of cargo fmt / rustfmt are you using. You can run cargo fmt --version to get that info.

Also, any chance you can get this down to a reproducible code snippet that you can add inline? That would be best. rustfmt can run just fine on code that doesn't compile (as long as it parses) so my suggestion would be to slowly remove function, struct, enum, macro, and trait definitions / impls from the file until you're able to narrow down what's causing the issue. It would be a great help 🙏🏼

[ajewellamz]

rustfmt 1.7.1-stable (eeb90cda 2024-09-04)

I won't be able to do any work on this until next week at the earliest.
I was assuming you could just run it in the debugger or something, if you had a fail case.

[ajewellamz]

Ok, here's a minimal fail case. I've tried deleting various parts, and it seems to always succeed.

pub use ::dafny_runtime::Sequence;
pub use ::std::rc::Rc;
pub use crate::r#_StructuredEncryptionUtil_Compile::CanonCryptoItem;
pub use ::dafny_runtime::itertools::Itertools;
pub use crate::software::amazon::cryptography::dbencryptionsdk::structuredencryption::internaldafny::types::CryptoAction;
pub use crate::software::amazon::cryptography::materialproviders::internaldafny::types::EncryptedDataKey;
pub use ::dafny_runtime::Object;
pub use crate::software::amazon::cryptography::primitives::internaldafny::types::IAwsCryptographicPrimitivesClient;
pub use crate::software::amazon::cryptography::materialproviders::internaldafny::types::AlgorithmSuiteInfo;
pub use ::dafny_runtime::DafnyCharUTF16;
pub use crate::r#_StructuredEncryptionUtil_Compile::MessageID;
pub use crate::software::amazon::cryptography::materialproviders::internaldafny::types::EncryptionMaterials;
pub use crate::r#_Wrappers_Compile::Outcome;
pub use ::dafny_runtime::string_utf16_of;
pub use ::dafny_runtime::int;
pub use ::dafny_runtime::MapBuilder;
pub use ::dafny_runtime::_System::nat;
pub use crate::software::amazon::cryptography::primitives::internaldafny::types::HMacInput;
pub use ::dafny_runtime::rd;
pub use ::dafny_runtime::truncate;
pub use ::dafny_runtime::DafnyTypeEq;
pub use ::dafny_runtime::DafnyType;

[ytmimi]

Thanks! confirming that with rustfmt +1.81 (rustfmt 1.7.1-stable (eeb90cda 2024-09-04)) I'm able to reproduce the panic with the above example:

Backtrace

thread 'main' panicked at library/core/src/slice/sort/shared/smallsort.rs:862:5:
user-provided comparison function does not correctly implement a total order
stack backtrace:
   0:        0x10316373c - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h243268f17d714c7f
   1:        0x1031a6688 - core::fmt::write::hb3cfb8a30e72d7ff
   2:        0x103159720 - std::io::Write::write_fmt::hfb2314975de9ecf1
   3:        0x103165c4c - std::panicking::default_hook::{{closure}}::h14c7718ccf39d316
   4:        0x103165870 - std::panicking::default_hook::hc62e60da3be2f352
   5:        0x10cd5c5b8 - <alloc[47bc6d386d7ae45f]::boxed::Box<rustc_driver_impl[54c40c94c6cfc0b2]::install_ice_hook::{closure#0}> as core[f827f14b5e761a5d]::ops::function::Fn<(&dyn for<'a, 'b> core[f827f14b5e761a5d]::ops::function::Fn<(&'a std[4f7d7c3ef984657a]::panic::PanicHookInfo<'b>,), Output = ()> + core[f827f14b5e761a5d]::marker::Sync + core[f827f14b5e761a5d]::marker::Send, &std[4f7d7c3ef984657a]::panic::PanicHookInfo)>>::call
   6:        0x103166868 - std::panicking::rust_panic_with_hook::h09e8a656f11e82b2
   7:        0x103166150 - std::panicking::begin_panic_handler::{{closure}}::h1230eb3cc91b241c
   8:        0x103163bc8 - std::sys::backtrace::__rust_end_short_backtrace::hc3491307aceda2c2
   9:        0x103165e40 - _rust_begin_unwind
  10:        0x1031c0ad8 - core::panicking::panic_fmt::ha4b80a05b9fff47a
  11:        0x1031a8c84 - core::slice::sort::shared::smallsort::panic_on_ord_violation::h9a9b9a4ea28b52bf
  12:        0x1020fed34 - core[f827f14b5e761a5d]::slice::sort::shared::smallsort::small_sort_general_with_scratch::<rustfmt_nightly[2afeb25615a25c73]::imports::UseTree, <rustfmt_nightly[2afeb25615a25c73]::imports::UseTree as core[f827f14b5e761a5d]::cmp::PartialOrd>::lt>
  13:        0x1021469a4 - core[f827f14b5e761a5d]::slice::sort::stable::quicksort::quicksort::<rustfmt_nightly[2afeb25615a25c73]::imports::UseTree, <rustfmt_nightly[2afeb25615a25c73]::imports::UseTree as core[f827f14b5e761a5d]::cmp::PartialOrd>::lt>
  14:        0x1021a1108 - core[f827f14b5e761a5d]::slice::sort::stable::drift::sort::<rustfmt_nightly[2afeb25615a25c73]::imports::UseTree, <rustfmt_nightly[2afeb25615a25c73]::imports::UseTree as core[f827f14b5e761a5d]::cmp::PartialOrd>::lt>
  15:        0x1020bdedc - core[f827f14b5e761a5d]::slice::sort::stable::driftsort_main::<rustfmt_nightly[2afeb25615a25c73]::imports::UseTree, <rustfmt_nightly[2afeb25615a25c73]::imports::UseTree as core[f827f14b5e761a5d]::cmp::PartialOrd>::lt, alloc[47bc6d386d7ae45f]::vec::Vec<rustfmt_nightly[2afeb25615a25c73]::imports::UseTree>>
  16:        0x102192af8 - rustfmt_nightly[2afeb25615a25c73]::reorder::rewrite_reorderable_or_regroupable_items
  17:        0x1021ae510 - <rustfmt_nightly[2afeb25615a25c73]::visitor::FmtVisitor>::visit_items_with_reordering
  18:        0x1021b9dd4 - <rustfmt_nightly[2afeb25615a25c73]::visitor::FmtVisitor>::format_separate_mod
  19:        0x102047714 - rustfmt_nightly[2afeb25615a25c73]::formatting::format_project::<rustfmt_nightly[2afeb25615a25c73]::Session<std[4f7d7c3ef984657a]::io::stdio::Stdout>>
  20:        0x102045adc - <scoped_tls[df49f867320abf2e]::ScopedKey<rustc_span[ab16d476329f5d04]::SessionGlobals>>::with::<<rustfmt_nightly[2afeb25615a25c73]::Session<std[4f7d7c3ef984657a]::io::stdio::Stdout>>::format_input_inner::{closure#0}, core[f827f14b5e761a5d]::result::Result<rustfmt_nightly[2afeb25615a25c73]::FormatReport, rustfmt_nightly[2afeb25615a25c73]::ErrorKind>>
  21:        0x102043bd4 - <scoped_tls[df49f867320abf2e]::ScopedKey<rustc_span[ab16d476329f5d04]::SessionGlobals>>::set::<rustc_span[ab16d476329f5d04]::create_session_if_not_set_then<core[f827f14b5e761a5d]::result::Result<rustfmt_nightly[2afeb25615a25c73]::FormatReport, rustfmt_nightly[2afeb25615a25c73]::ErrorKind>, <rustfmt_nightly[2afeb25615a25c73]::Session<std[4f7d7c3ef984657a]::io::stdio::Stdout>>::format_input_inner::{closure#0}>::{closure#0}, core[f827f14b5e761a5d]::result::Result<rustfmt_nightly[2afeb25615a25c73]::FormatReport, rustfmt_nightly[2afeb25615a25c73]::ErrorKind>>
  22:        0x102047060 - rustc_span[ab16d476329f5d04]::create_session_if_not_set_then::<core[f827f14b5e761a5d]::result::Result<rustfmt_nightly[2afeb25615a25c73]::FormatReport, rustfmt_nightly[2afeb25615a25c73]::ErrorKind>, <rustfmt_nightly[2afeb25615a25c73]::Session<std[4f7d7c3ef984657a]::io::stdio::Stdout>>::format_input_inner::{closure#0}>
  23:        0x1020325a8 - rustfmt[4ddeb7d779b6c40f]::format_and_emit_report::<std[4f7d7c3ef984657a]::io::stdio::Stdout>
  24:        0x102031c40 - rustfmt[4ddeb7d779b6c40f]::execute
  25:        0x10202ffac - rustfmt[4ddeb7d779b6c40f]::main
  26:        0x10204a668 - std[4f7d7c3ef984657a]::sys::backtrace::__rust_begin_short_backtrace::<fn(), ()>
  27:        0x102042734 - std[4f7d7c3ef984657a]::rt::lang_start::<()>::{closure#0}
  28:        0x10314c0b8 - std::rt::lang_start_internal::hdd117cb81a316264
  29:        0x102033080 - _main

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rustfmt/issues/new?labels=bug