warning: this `match` can be collapsed into the outer `if let`
  --> crates/shadowsocks-service/src/local/redir/udprelay/sys/unix/macos.rs:58:21
   |
58 | /                     match errno {
59 | |                         libc::ENOPROTOOPT => {
60 | |                             trace!("failed to set SO_REUSEPORT, error: {}", err);
61 | |                         }
...  |
65 | |                         }
66 | |                     }
   | |_____________________^
   |
help: the outer pattern can be modified to include the inner pattern
  --> crates/shadowsocks-service/src/local/redir/udprelay/sys/unix/macos.rs:57:29
   |
57 |                 if let Some(errno) = err.raw_os_error() {
   |                             ^^^^^ replace this binding
58 |                     match errno {
59 |                         libc::ENOPROTOOPT => {
   |                         ^^^^^^^^^^^^^^^^^ with this pattern
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_match
   = note: `#[warn(clippy::collapsible_match)]` on by default