Understanding Rust Error E0585

Rust Error E0585: Undocumented Comments

Rust Error E0585 occurs when a documentation comment is found but doesn't document any items in your code. Documentation comments should be followed by functions, types, modules, or other items to provide meaningful documentation.

Examples of Erroneous Code

Let's look at a code example that triggers Rust Error E0585:

fn main() {
    // The following doc comment will fail:
    /// This is a useless doc comment!

Here, the documentation comment (///) is not followed by any item that it documents, resulting in Rust Error E0585.

Correct Usage of Documentation Comments

To properly use documentation comments, they should be followed by items they describe, like structs, functions, types, or modules. Here are correct examples:

/// I'm documenting the following struct:
struct Foo;

/// I'm documenting the following function:
fn foo() {}

In the code above, the documentation comments are used correctly as they provide descriptions for the struct Foo and the function foo().

How to Fix Rust Error E0585

To resolve Rust Error E0585, you should either remove the unnecessary documentation comment or follow it with the item you intend to document. Here's a fixed version of the erroneous example:

fn main() {
    // The following doc comment is now followed by a function:
    /// This is a useful doc comment!
    fn useful_function() {}

In this example, Rust Error E0585 is resolved by following the documentation comment with the useful_function(), which it describes.