The proc-macro toolkit

It’s time to get your hands dirty. In this chapter, you’ll build your first procedural macros from scratch — starting with the bare minimum and gradually introducing the tools that make macro development practical.

You’ll learn:

• How proc-macro crates are structured and wired up
• What a derive macro actually returns
• How tokens and token streams work under the hood
• How proc-macro2 makes your macro code testable
• How syn parses Rust code into a structured representation
• How quote lets you generate code that looks like regular Rust
• The re-export pattern used by serde, thiserror, and most real-world macro crates

By the end of this chapter, you’ll be comfortable with the full derive-macro workflow: parse the input with syn, generate code with quote, and return it as a token stream.

Exercise

The exercise for this section is located in 03_basics/00_overview

A quick warm-up before diving in: use derive_more’s Display derive to implement Display for an enum. derive_more brings derive macros to many standard library traits — Display, From, Add, Deref, and more — saving you the hand-written boilerplate. It’s a good reminder of what derive macros look like from the user’s perspective — you’ll be building your own from the next section onwards.