a_Cargo.toml

[package]
name = "a"
version = "0.1.0"
authors = ["Alex Burka <[email protected]>"]

[dependencies]
static-cond = "*"

a_src_lib.rs

#![feature(use_extern_macros)]

extern crate static_cond;

pub use static_cond::static_cond;

#[macro_export]
macro_rules! a {
    ($x:tt, $y:tt, $z:tt) => {
        static_cond! { if $x == $y { $z } }
    }
}

b_Cargo.toml

[package]
name = "b"
version = "0.1.0"
authors = ["Alex Burka <[email protected]>"]

[dependencies]
a = { path = "../a" }

b_src_main.rs

#![feature(use_extern_macros)]

extern crate a;
use a::{static_cond, a};

fn main() {
    a!(true, true, { println!("Hello, world!"); });
}