fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
if let Some(mutex) = is_mutex_lock_call(self.cx, expr) {
self.found_mutex = Some(mutex);
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
if let Some(mutex) = is_mutex_lock_call(self.cx, expr) {
self.found_mutex = Some(mutex);