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An annotation in Rust isn't a macro. The Go equivalent would be a directive in a comment. For example: //go:repr c https://pkg.go.dev/cmd/compile#hdr-Compiler_

• xh-dude 5y ago
  Is the situation for Rust different than as described here: https://github.com/rust-lang/rfcs/pull/208 https://github.com/rust-lang/rfcs/pull/208 “Currently, attributes and macros/syntax extensions are both conceptually macros: they are user-definable syntactic extensions that transform token trees to token trees.” FWIW I definitely admit the point about Go compiler directives sort of cheating into this space a bit - I see them used responsibly for the most part but it’s a valid point. (Go’s struct tags OTOH, are an escape hatch I revile…).
  • adwn 5y ago
    > Is the situation for Rust different than as described here: https://github.com/rust-lang/rfcs/pull/208 https://github.com/rust-lang/rfcs/pull/208 In short: yes. The wording in that quote is imprecise: I suspect that by 'attributes', pcwalton was referring to user-definable attributes like #[serde(rename_all = "...")] and to custom derive macros like #[derive(Serializable)]. It is impossible to achieve the effects of the #[repr(C)] attribute using macros or token tree transformations.
  • previx 5y ago
    If you're asking if macros and attributes are interchangeable terms, no they're not.