Function pio_dist_warnings 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pio_dist_warnings(
    net: *const PioDistNetwork,
    warnbuf: *mut c_char,
    warnlen: usize,
) -> usize

Parse warnings retained on the handle (everything the reader could not represent or had to assume), \n-joined and written into the caller warnbuf (truncated to fit, always NUL-terminated). Returns the total byte length of the joined message; call with NULL/0 to size first, then fill — the same idiom as pio_warnings. Returns 0 for a NULL handle.