No, indeed, the opposite. In Rust, these will surely be procedural macros, which comprise functions written in Rust which operate on Rust code, represented as token streams. The compiler compiles the macro, lexes your code, feeds it to the macro, gets a token stream back, parses that, and that's what it compiles.

Understanding a magic handler function involves understanding a particular subset of features of the Rust type system, and operating that mechanism in your head to see what happens.

Understanding a proc macro involves understanding arbitrary Rust.