error: macros cannot expand to foreign items

[jbclements]

I'm assuming this is supposed to be in the language, but not yet supported. I'm hoping to support it. Placeholder bug.

[jbclements]

I should at least include some code. Here's some code:

macro_rules! f_decl {
    () => (fn f ();)
}

extern {
    f_decl!();

}

[catamorphism]

Nominating for milestone 5, production-ready

[graydon]

Visiting for triage. My nomination vote goes with "feature complete"; this is a proper (if minor) feature. Unless it's implemented-and-buggy currently?

[graydon]

accepted for feature-complete milestone

[pnkfelix]

This need not block 1.0. Assigning P-low.

[huonw]

Triage bump (still an issue).

[julienw]

still an issue.

[julienw]

My own use case is I have a bunch of external functions like:

extern {
    pub fn manager_node_is_listening_device(manager: *mut Manager, home_id: u32, node_id: u8) -> bool;
    pub fn manager_node_is_frequent_listening_device(manager: *mut Manager, home_id: u32, node_id: u8) -> bool;
    pub fn manager_node_is_beaming_device(manager: *mut Manager, home_id: u32, node_id: u8) -> bool;
}

and I wanted to be more DRY:

macro_rules! node_getters {
    ( $($name: ident -> $t: ty),+ ) => {
        $(pub fn $name(manager: *mut Manager, home_id: u32, node_id: u8) -> $t;)*
    }
}

extern {
  node_getters! {
    manager_node_is_listening_device -> bool,
    manager_node_is_frequent_listening_device -> bool,
    manager_node_is_beaming_device -> bool
  }
}

(Note I have a bunch of more functions too)

[steveklabnik]

Triage: no comments in two years, and macro_rules is not being improved anymore. I'm going to close this.

[petrochenkov]

Macros work in foreign blocks now, but they are not yet stable and gated by feature(macros_in_extern).