Clippy lint · Suspicious · checked with Clippy 0.1.99

clippy::empty_line_after_doc_comments: empty line after doc comment

What it meansChecks for empty lines after doc comments. It is in the suspicious group and warns by default.

What you see

warning: empty line after doc comment
 --> main.rs:3:1
  |
3 | / /// Some doc comment with a blank line after it.
4 | |
  | |_^
5 |   fn f() {}
  |   ---- the comment documents this function
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#empty_line_after_doc_comments
  = note: `#[warn(clippy::empty_line_after_doc_comments)]` on by default
  = help: if the empty line is unintentional, remove it

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

The doc comment may have meant to be an inner doc comment, regular comment or applied to some old code that is now commented out. If it was intended to be a doc comment, then the empty line should be removed.

Code that is most likely wrong or useless. Warns by default.

How to fix it

Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:

Flagged

/// Some doc comment with a blank line after it.

fn f() {}

/// Docs for `old_code`
// fn old_code() {}

fn new_code() {}

Write this instead

//! Convert it to an inner doc comment

// Or a regular comment

/// Or remove the empty line
fn f() {}

// /// Docs for `old_code`
// fn old_code() {}

fn new_code() {}

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::empty_line_after_doc_comments)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
empty_line_after_doc_comments = "allow"

One run

cargo clippy -- -A clippy::empty-line-after-doc-comments

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.

Suspiciousgroup

warndefault level

nofixed by cargo clippy --fix

1.70.0added in Rust

Clippy's own documentation

What it does

Checks for empty lines after doc comments.

Why is this bad?

Example

/// Some doc comment with a blank line after it.

fn f() {}

/// Docs for `old_code`
// fn old_code() {}

fn new_code() {}

Use instead:

//! Convert it to an inner doc comment

// Or a regular comment

/// Or remove the empty line
fn f() {}

// /// Docs for `old_code`
// fn old_code() {}

fn new_code() {}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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