if let Some(mut snippet) = snippet_opt(cx, callee.span) {
if_chain! {
if let ty::Closure(_, substs) = callee_ty.peel_refs().kind();
- if let ClosureKind::FnMut = substs.as_closure().kind();
+ if substs.as_closure().kind() == ClosureKind::FnMut;
if get_enclosing_loop_or_closure(cx.tcx, expr).is_some()
|| UsedAfterExprVisitor::is_found(cx, callee);