aarch64/usr/lib/rustlib/src/rust/library/backtrace/crates/dylib-dep/src/lib.rs

#![allow(improper_ctypes_definitions)]

type Pos = (&'static str, u32);

macro_rules! pos {
    () => {
        (file!(), line!())
    };
}

#[no_mangle]
pub extern "C" fn foo(outer: Pos, inner: fn(Pos, Pos)) {
    inner(outer, pos!());
}