`doc_markdown` now fires on private items

[kpreid]

Summary

Previously, doc_markdown would only lint public documentation. Now it also lints documentation on private items (which Rustdoc does not document by default). This isn't necessarily wrong, but it is a new behavior in nightly Clippy (not 1.76.0 or 1.77.0-beta.7), and I don't see any issue or PR describing it as an intended change, so I suspect it is a bug.

Lint Name

doc_markdown

Reproducer

I tried this code:

#![warn(clippy::doc_markdown)]
#![allow(unused)]

pub struct Foo {
    /// some_identifier
    bar: u8,
}

I saw this happen:

warning: item in documentation is missing backticks
 --> src/lib.rs:5:9
  |
5 |     /// some_identifier
  |         ^^^^^^^^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown
note: the lint level is defined here
 --> src/lib.rs:1:9
  |
1 | #![warn(clippy::doc_markdown)]
  |         ^^^^^^^^^^^^^^^^^^^^
help: try
  |
5 |     /// `some_identifier`
  |         ~~~~~~~~~~~~~~~~~

I expected to see this happen: No warning

Version

rustc 1.78.0-nightly (9c3ad802d 2024-03-07)
binary: rustc
commit-hash: 9c3ad802d9b9633d60d3a74668eb1be819212d34
commit-date: 2024-03-07
host: x86_64-apple-darwin
release: 1.78.0-nightly
LLVM version: 18.1.0

Additional Labels

No response

[Alexendoo]

Private items do get linted by doc lints, the change you're seeing here is because docs on struct fields and enum variants were (unintentionally) not being checked. That got fixed by #12342