1 use rustc::lint::LateContext;
3 use rustc::hir::def::Def;
5 use rustc::middle::expr_use_visitor::*;
6 use rustc::middle::mem_categorization::cmt_;
7 use rustc::middle::mem_categorization::Categorization;
9 use rustc_data_structures::fx::FxHashSet;
10 use syntax::source_map::Span;
12 /// Returns a set of mutated local variable ids or None if mutations could not be determined.
13 pub fn mutated_variables<'a, 'tcx: 'a>(expr: &'tcx Expr, cx: &'a LateContext<'a, 'tcx>) -> Option<FxHashSet<HirId>> {
14 let mut delegate = MutVarsDelegate {
15 used_mutably: FxHashSet::default(),
18 let def_id = def_id::DefId::local(expr.hir_id.owner);
19 let region_scope_tree = &cx.tcx.region_scope_tree(def_id);
20 ExprUseVisitor::new(&mut delegate, cx.tcx, cx.param_env, region_scope_tree, cx.tables, None).walk_expr(expr);
25 Some(delegate.used_mutably)
28 pub fn is_potentially_mutated<'a, 'tcx: 'a>(
31 cx: &'a LateContext<'a, 'tcx>,
33 let id = match variable.def {
34 Def::Local(id) | Def::Upvar(id, ..) => id,
37 mutated_variables(expr, cx).map_or(true, |mutated| mutated.contains(&cx.tcx.hir().node_to_hir_id(id)))
40 struct MutVarsDelegate {
41 used_mutably: FxHashSet<HirId>,
45 impl<'tcx> MutVarsDelegate {
46 #[allow(clippy::similar_names)]
47 fn update(&mut self, cat: &'tcx Categorization<'_>) {
49 Categorization::Local(id) => {
50 self.used_mutably.insert(id);
52 Categorization::Upvar(_) => {
53 //FIXME: This causes false negatives. We can't get the `NodeId` from
54 //`Categorization::Upvar(_)`. So we search for any `Upvar`s in the
55 //`while`-body, not just the ones in the condition.
58 Categorization::Deref(ref cmt, _) | Categorization::Interior(ref cmt, _) => self.update(&cmt.cat),
64 impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
65 fn consume(&mut self, _: HirId, _: Span, _: &cmt_<'tcx>, _: ConsumeMode) {}
67 fn matched_pat(&mut self, _: &Pat, _: &cmt_<'tcx>, _: MatchMode) {}
69 fn consume_pat(&mut self, _: &Pat, _: &cmt_<'tcx>, _: ConsumeMode) {}
71 fn borrow(&mut self, _: HirId, _: Span, cmt: &cmt_<'tcx>, _: ty::Region<'_>, bk: ty::BorrowKind, _: LoanCause) {
72 if let ty::BorrowKind::MutBorrow = bk {
77 fn mutate(&mut self, _: HirId, _: Span, cmt: &cmt_<'tcx>, _: MutateMode) {
81 fn decl_without_init(&mut self, _: HirId, _: Span) {}