rust-lang / rust-lang/rustfmt

Crash when formatting complex file

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C-bug
Dominant language
Rust
Stars
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Forks
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Avg merge
2d 13h
Merged PRs (30d)
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Description

cargo fmt and cargo rustfmt crash when processing https://github.com/mobiusklein/mzdata/blob/34b2d6feb3201140991fa66b53960ab8141c7ed7/src/io/infer_format.rs. See below for traceback.

Toolchain: stable-x86_64-pc-windows-msvc
Version: rustc 1.76.0 (07dca489a 2024-02-04)
Platform: Windows 10

Supposition

This file specifically started to crash the formatter when I added a few large, complex generic algebraic types, Source and Sink, and another generic-heavy trait to consume them, MassSpectrometryReadWriteProcess.

Traceback:

Details
hread 'main' panicked at src\tools\rustfmt\src\items.rs:547:10:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0:     0x7fffed4822c2 - ::fmt::h7851e041f2b8bcc2
   1:     0x7fffed4b4cdd - core::fmt::write::h1642dfca37b49735
   2:     0x7fffed478ca1 - ::fmt::h7801514a6fc13a4a
   3:     0x7fffed4820ea - std::sys_common::backtrace::lock::h8caaa69a6cc2258b
   4:     0x7fffed485529 - std::panicking::default_hook::h67f6260a0bf37eca
   5:     0x7fffed4851e5 - std::panicking::default_hook::h67f6260a0bf37eca
   6:     0x7ffff1d0fb03 - ::write_fmt
   7:     0x7fffed485b43 - std::panicking::rust_panic_with_hook::h870983d929e74e12
   8:     0x7fffed4859ab - ::take_box::h971268ed26284d4c
   9:     0x7fffed482bc9 - ::fmt::h7851e041f2b8bcc2
  10:     0x7fffed4856b2 - rust_begin_unwind
  11:     0x7fffed4da447 - core::panicking::panic_fmt::ha5dd7a91f3010b68
  12:     0x7fffed4da522 - core::panicking::panic::h61d0277f5e1a7407
  13:     0x7ff64a524bde - 
  14:     0x7ff64a51c2d6 - 
  15:     0x7ff64a52a2ea - 
  16:     0x7ff64a4992b8 - 
  17:     0x7ff64a49fa3b - 
  18:     0x7ff64a49cf53 - 
  19:     0x7ff64a497690 - 
  20:     0x7ff64a482682 - 
  21:     0x7ff64a4961af - 
  22:     0x7ff64a4806bf - 
  23:     0x7ff64a47e5c4 - 
  24:     0x7ff64a49bcb6 - 
  25:     0x7ff64a4974dc - 
  26:     0x7fffed46ae32 - std::rt::lang_start_internal::h68f55995b3e4e811
  27:     0x7ff64a4834fc - 
  28:     0x7ff64a83acbc - 
  29:     0x7ff8b1ea7344 - BaseThreadInitThunk
  30:     0x7ff8b35426b1 - RtlUserThreadStart

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the crash with cargo fmt or cargo rustfmt on src/io/infer_format.rs from the reported mzdata revision, then inspect src/tools/rustfmt/src/items.rs around line 547 and the supplied traceback. Done means the formatter processes this complex generic file without panicking on the reported Windows toolchain.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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