clippy --fix "failed to automatically apply fixes suggested by rustc"

[tommythorn]

Summary

Thanks for the wonderful Clippy. I hope this bug report is helpful.

I have a C library that was translated by C2Rust and heavily cleaned up by hand. Alas, the terrible code that you (understandably) get from C2Rust seems to break Clippy's --fix option.

Reproducer

To reproduce: git clone https://github.com/tommythorn/repro-clippy-bug;cd repro-clippy-bug;cargo clippy --fix

With Rust 1.81.0 (eeb90cda1 2024-09-04) on macOS (but I think this happens on Linux also) I get

warning: failed to automatically apply fixes suggested by rustc to crate `repro_clippy_bug`

after fixes were automatically applied the compiler reported errors within these files:

  * src/softfloat/f128_to_f16.rs
  * src/softfloat/f16_div.rs
  * src/softfloat/f16_mul.rs
  * src/softfloat/f16_roundToInt.rs
  * src/softfloat/f32_to_f16.rs
  * src/softfloat/f64_to_f16.rs
  * src/softfloat/s_addMagsF16.rs
  * src/softfloat/s_mulAddF16.rs
  * src/softfloat/s_subMagsF16.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
warning: operator precedence can trip the unwary
  --> src/softfloat/f16_roundToInt.rs:22:15
   |
22 |           uiZ = uiA
   |  _______________^
23 | |             & ((1_i32 as u16 as i32) << 15_i32) + ((0_i32 as u16 as i32) << 10_i32)
24 | |                 as u64;
   | |______________________^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#precedence
   = note: `#[warn(clippy::precedence)]` on by default
help: consider parenthesizing your expression
   |
22 ~         uiZ = uiA & (((1_i32 as u16 as i32) << 15_i32) + ((0_i32 as u16 as i32) << 10_i32)
23 ~                 as u64);
   |
.... and a *LOT* more of this

Version

rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: x86_64-apple-darwin
release: 1.81.0
LLVM version: 18.1.7

Additional Labels

No response

[tommythorn]

I recognize the irony of quoting a truncated message that asks for the full output, so I attached it here.
clippy.out.txt