rust-lang / rust-lang/rust-clippy

indexing does not trigger missing_panics_doc

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C-bug I-false-negative
Dominant language
Rust
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Description

Summary

missing_panics_doc does not trigger on indexing, which could panic. .get(...).unwrap() is equivalent and does get caught.

Lint Name

missing_panics_doc

Reproducer

I tried this code:

#![warn(clippy::missing_panics_doc)]

pub fn a(sl: &[u8]) {
    let _ = sl[2];
}

pub fn b(sl: &[u8]) {
    let _ = sl.get(2).unwrap();
}

I expected to see this happen:
warnings on both a and b

Instead, this happened:
warning only on b

Version
rustc 1.80.0 (051478957 2024-07-21)
binary: rustc
commit-hash: 051478957371ee0084a7c0913941d2a8c4757bb9
commit-date: 2024-07-21
host: x86_64-unknown-linux-gnu
release: 1.80.0
LLVM version: 18.1.7

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the missing_panics_doc lint and its handling of indexing expressions. Run the reproducer from the issue and compare diagnostics for sl[2] and sl.get(2).unwrap(). Done means the lint warns on both potentially panicking forms.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
devtools
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
50/100

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