gistfile1.txt

warning: `extern` block uses type `fn(*mut u8, *mut u8, usize, *mut u8, *mut usize) -> zz::io::Result`, which is not FFI-safe
  --> src/../target/release/rs/io_unix.rs:21:48
   |
21 |     pub fn unix( Zfd: std::os::raw::c_int)  -> super::io::Io;
   |                                                ^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using an `extern fn(...) -> ...` function pointer instead
   = note: this function pointer has Rust-specific calling convention