1 files changed, 29 insertions, 0 deletions
diff --git a/src/tools/clippy/src/docs/mut_mutex_lock.txt b/src/tools/clippy/src/docs/mut_mutex_lock.txt
new file mode 100644
index 000000000..5e9ad8a3f
--- /dev/null
+++ b/src/tools/clippy/src/docs/mut_mutex_lock.txt
@@ -0,0 +1,29 @@
+### What it does
+Checks for `&mut Mutex::lock` calls
+
+### Why is this bad?
+`Mutex::lock` is less efficient than
+calling `Mutex::get_mut`. In addition you also have a statically
+guarantee that the mutex isn't locked, instead of just a runtime
+guarantee.
+
+### Example
+```
+use std::sync::{Arc, Mutex};
+
+let mut value_rc = Arc::new(Mutex::new(42_u8));
+let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
+
+let mut value = value_mutex.lock().unwrap();
+*value += 1;
+```
+Use instead:
+```
+use std::sync::{Arc, Mutex};
+
+let mut value_rc = Arc::new(Mutex::new(42_u8));
+let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
+
+let value = value_mutex.get_mut().unwrap();
+*value += 1;
+```
+\ No newline at end of file