too_long_first_doc_comment adds outer-comment lines to inner-comments

[clarfonthey]

Summary

The auto-fix for this lint will add /// as the new line to //! comments, meaning it will break and cause a syntax error.

Reproducer

#![warn(clippy::too_long_first_doc_comment)]
//! This is a one-line summary.
//! This makes the one-line summary no longer one line.

autofixes to:

#![warn(clippy::too_long_first_doc_comment)]
//! This is a one-line summary.
///
//! This makes the one-line summary no longer one line.

Version

rustc 1.83.0-nightly (7042c269c 2024-09-23)
binary: rustc
commit-hash: 7042c269c166191cd5d8daf0409890903df7af57
commit-date: 2024-09-23
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

Additional Labels

@rustbot label +I-suggestion-causes-error

[y21]

This looks like a duplicate of #13309 and was already fixed in #13377. It should be fixed in nightly when the next sync happens