Rust's God Mode

A practical introduction to Rust procedural macros covering all three macro types (derive, function-like, attribute) and both implementation approaches (declarative vs procedural). Walks through building function-like procedural macros step by step: starting with a passthrough 'nothing' macro, then a 'time_this' macro that measures block execution time, and finally a 'hash_set!' macro. Covers key ecosystem crates including proc-macro2, quote, and syn, explains token stream internals (Ident, Punct, Literal, Group token tree variants), and discusses macro hygiene best practices like using scoped blocks and fully qualified paths.