3 use rustc_hir::intravisit;
4 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
5 use rustc_hir::HirIdSet;
6 use rustc_hir::{Expr, ExprKind, HirId};
7 use rustc_infer::infer::TyCtxtInferExt;
8 use rustc_lint::LateContext;
9 use rustc_middle::hir::map::Map;
10 use rustc_middle::mir::FakeReadCause;
12 use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
14 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
15 pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> Option<HirIdSet> {
16 let mut delegate = MutVarsDelegate {
17 used_mutably: HirIdSet::default(),
20 cx.tcx.infer_ctxt().enter(|infcx| {
34 Some(delegate.used_mutably)
37 pub fn is_potentially_mutated<'tcx>(variable: HirId, expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> bool {
38 mutated_variables(expr, cx).map_or(true, |mutated| mutated.contains(&variable))
41 struct MutVarsDelegate {
42 used_mutably: HirIdSet,
46 impl<'tcx> MutVarsDelegate {
47 #[allow(clippy::similar_names)]
48 fn update(&mut self, cat: &PlaceWithHirId<'tcx>) {
49 match cat.place.base {
50 PlaceBase::Local(id) => {
51 self.used_mutably.insert(id);
53 PlaceBase::Upvar(_) => {
54 //FIXME: This causes false negatives. We can't get the `NodeId` from
55 //`Categorization::Upvar(_)`. So we search for any `Upvar`s in the
56 //`while`-body, not just the ones in the condition.
64 impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
65 fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {}
67 fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, bk: ty::BorrowKind) {
68 if let ty::BorrowKind::MutBorrow = bk {
73 fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
77 fn fake_read(&mut self, _: rustc_typeck::expr_use_visitor::Place<'tcx>, _: FakeReadCause, _: HirId) {}
80 pub struct ParamBindingIdCollector {
81 binding_hir_ids: Vec<hir::HirId>,
83 impl<'tcx> ParamBindingIdCollector {
84 fn collect_binding_hir_ids(body: &'tcx hir::Body<'tcx>) -> Vec<hir::HirId> {
85 let mut hir_ids: Vec<hir::HirId> = Vec::new();
86 for param in body.params.iter() {
87 let mut finder = ParamBindingIdCollector {
88 binding_hir_ids: Vec::new(),
90 finder.visit_param(param);
91 for hir_id in &finder.binding_hir_ids {
92 hir_ids.push(*hir_id);
98 impl<'tcx> intravisit::Visitor<'tcx> for ParamBindingIdCollector {
101 fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
102 if let hir::PatKind::Binding(_, hir_id, ..) = pat.kind {
103 self.binding_hir_ids.push(hir_id);
105 intravisit::walk_pat(self, pat);
108 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
109 intravisit::NestedVisitorMap::None
113 pub struct BindingUsageFinder<'a, 'tcx> {
114 cx: &'a LateContext<'tcx>,
115 binding_ids: Vec<hir::HirId>,
118 impl<'a, 'tcx> BindingUsageFinder<'a, 'tcx> {
119 pub fn are_params_used(cx: &'a LateContext<'tcx>, body: &'tcx hir::Body<'tcx>) -> bool {
120 let mut finder = BindingUsageFinder {
122 binding_ids: ParamBindingIdCollector::collect_binding_hir_ids(body),
125 finder.visit_body(body);
129 impl<'a, 'tcx> intravisit::Visitor<'tcx> for BindingUsageFinder<'a, 'tcx> {
130 type Map = Map<'tcx>;
132 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
133 if !self.usage_found {
134 intravisit::walk_expr(self, expr);
138 fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, _: hir::HirId) {
139 if let hir::def::Res::Local(id) = path.res {
140 if self.binding_ids.contains(&id) {
141 self.usage_found = true;
146 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
147 intravisit::NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
151 struct ReturnBreakContinueMacroVisitor {
152 seen_return_break_continue: bool,
155 impl ReturnBreakContinueMacroVisitor {
156 fn new() -> ReturnBreakContinueMacroVisitor {
157 ReturnBreakContinueMacroVisitor {
158 seen_return_break_continue: false,
163 impl<'tcx> Visitor<'tcx> for ReturnBreakContinueMacroVisitor {
164 type Map = Map<'tcx>;
165 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
166 NestedVisitorMap::None
169 fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
170 if self.seen_return_break_continue {
171 // No need to look farther if we've already seen one of them
175 ExprKind::Ret(..) | ExprKind::Break(..) | ExprKind::Continue(..) => {
176 self.seen_return_break_continue = true;
178 // Something special could be done here to handle while or for loop
179 // desugaring, as this will detect a break if there's a while loop
180 // or a for loop inside the expression.
182 if utils::in_macro(ex.span) {
183 self.seen_return_break_continue = true;
185 rustc_hir::intravisit::walk_expr(self, ex);
192 pub fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
193 let mut recursive_visitor = ReturnBreakContinueMacroVisitor::new();
194 recursive_visitor.visit_expr(expression);
195 recursive_visitor.seen_return_break_continue
198 pub struct UsedAfterExprVisitor<'a, 'tcx> {
199 cx: &'a LateContext<'tcx>,
200 expr: &'tcx Expr<'tcx>,
203 used_after_expr: bool,
205 impl<'a, 'tcx> UsedAfterExprVisitor<'a, 'tcx> {
206 pub fn is_found(cx: &'a LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
207 utils::path_to_local(expr).map_or(false, |definition| {
208 let mut visitor = UsedAfterExprVisitor {
213 used_after_expr: false,
215 utils::get_enclosing_block(cx, definition).map_or(false, |block| {
216 visitor.visit_block(block);
217 visitor.used_after_expr
223 impl<'a, 'tcx> intravisit::Visitor<'tcx> for UsedAfterExprVisitor<'a, 'tcx> {
224 type Map = Map<'tcx>;
226 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
227 NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
230 fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
231 if self.used_after_expr {
235 if expr.hir_id == self.expr.hir_id {
236 self.past_expr = true;
237 } else if self.past_expr && utils::path_to_local_id(expr, self.definition) {
238 self.used_after_expr = true;
240 intravisit::walk_expr(self, expr);