Comments - The Rust Reference

# Comments

Comments in Rust code follow the general C++ style of line (`//`) and block (`/* ... */`) comment forms. Nested block comments are supported.

Line comments beginning with exactly three slashes (`///`), and block comments (`/** ... */`), are interpreted as a special syntax for `doc` attributes. That is, they are equivalent to writing `#[doc="..."]` around the body of the comment, i.e., `/// Foo` turns into `#[doc="Foo"]`.

Line comments beginning with `//!` and block comments `/*! ... */` are doc comments that apply to the parent of the comment, rather than the item that follows. That is, they are equivalent to writing `#![doc="..."]` around the body of the comment. `//!` comments are usually used to document modules that occupy a source file.

Non-doc comments are interpreted as a form of whitespace.