Rustdoc has a concept called "passes". These are transformations that rustdoc runs on your documentation before producing its final output.

In addition to the passes below, check out the docs for these flags:

• --passes
• --no-defaults

By default, rustdoc will run some passes, namely:

• strip-hidden
• strip-private
• collapse-docs
• unindent-comments

However, strip-private implies strip-private-imports, and so effectively, all passes are run by default.

This pass implements the #[doc(hidden)] attribute. When this pass runs, it checks each item, and if it is annotated with this attribute, it removes it from rustdoc's output.

Without this pass, these items will remain in the output.

When you write a doc comment like this:

/// This is a documentation comment.

There's a space between the /// and that T. That spacing isn't intended to be a part of the output; it's there for humans, to help separate the doc comment syntax from the text of the comment. This pass is what removes that space.

The exact rules are left under-specified so that we can fix issues that we find.

Without this pass, the exact number of spaces is preserved.

With this pass, multiple #[doc] attributes are converted into one single documentation string.

For example:

#[doc = "This is the first line."]
#[doc = "This is the second line."]

Gets collapsed into a single doc string of

This is the first line.
This is the second line.

This removes documentation for any non-public items, so for example:

/// These are private docs.
struct Private;

/// These are public docs.
pub struct Public;

This pass removes the docs for Private, since they're not public.

This pass implies strip-priv-imports.

This is the same as strip-private, but for extern crate and use statements instead of items.