fn is_mutex_lock_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
if_chain! {
- if let ExprKind::MethodCall(path, [self_arg, ..], _) = &expr.kind;
+ if let ExprKind::MethodCall(path, self_arg, ..) = &expr.kind;
if path.ident.as_str() == "lock";
let ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
if is_type_diagnostic_item(cx, ty, sym::Mutex);