rust/src/test/run-pass/extern-call-indirect.rs

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use std::libc;

mod rustrt {
    use std::libc;

    #[link(name = "rustrt")]
    extern {
        pub fn rust_dbg_call(cb: extern "C" fn(libc::uintptr_t) -> libc::uintptr_t,
                             data: libc::uintptr_t)
                             -> libc::uintptr_t;
    }
}

extern fn cb(data: libc::uintptr_t) -> libc::uintptr_t {
    if data == 1u {
        data
    } else {
        fact(data - 1u) * data
    }
}

fn fact(n: uint) -> uint {
    unsafe {
        info!("n = {}", n);
        rustrt::rust_dbg_call(cb, n)
    }
}

pub fn main() {
    let result = fact(10u);
    info!("result = {}", result);
    assert_eq!(result, 3628800u);
}