Macros in Rust tend to have a reputation for being complex and magical, the likes which only seasoned wizards like @dtolnay can hope to understand, let alone master.
Rust’s declarative macros provide a mechanism for pattern matching on arbitrary syntax to generate valid Rust code at compile time. I use them all the time for simple search/replace style operations like generating tests that have a lot of boilerplate, or straightforward trait implementations for a large number of types….