error: calling `Mutex::lock` inside the scope of another `Mutex::lock` causes a deadlock
  --> $DIR/if_let_mutex.rs:9:5
   |
LL | /     if let Err(locked) = m.lock() {
LL | |         do_stuff(locked);
LL | |     } else {
LL | |         let lock = m.lock().unwrap();
LL | |         do_stuff(lock);
LL | |     };
   | |_____^
   |
   = note: `-D clippy::if-let-mutex` implied by `-D warnings`
   = help: move the lock call outside of the `if let ...` expression

error: aborting due to previous error