2 use crate::visitors::{for_each_expr, for_each_expr_with_closures, Descend};
3 use core::ops::ControlFlow;
5 use rustc_hir::intravisit::{self, Visitor};
6 use rustc_hir::HirIdSet;
7 use rustc_hir::{Expr, ExprKind, HirId, Node};
8 use rustc_hir_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
9 use rustc_infer::infer::TyCtxtInferExt;
10 use rustc_lint::LateContext;
11 use rustc_middle::hir::nested_filter;
12 use rustc_middle::mir::FakeReadCause;
15 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
16 pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> Option<HirIdSet> {
17 let mut delegate = MutVarsDelegate {
18 used_mutably: HirIdSet::default(),
21 let infcx = cx.tcx.infer_ctxt().build();
25 expr.hir_id.owner.def_id,
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 fn update(&mut self, cat: &PlaceWithHirId<'tcx>) {
48 match cat.place.base {
49 PlaceBase::Local(id) => {
50 self.used_mutably.insert(id);
52 PlaceBase::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.
63 impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
64 fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {}
66 fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, bk: ty::BorrowKind) {
67 if bk == ty::BorrowKind::MutBorrow {
72 fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
76 fn fake_read(&mut self, _: &rustc_hir_typeck::expr_use_visitor::PlaceWithHirId<'tcx>, _: FakeReadCause, _: HirId) {}
79 pub struct ParamBindingIdCollector {
80 pub binding_hir_ids: Vec<hir::HirId>,
82 impl<'tcx> ParamBindingIdCollector {
83 fn collect_binding_hir_ids(body: &'tcx hir::Body<'tcx>) -> Vec<hir::HirId> {
84 let mut hir_ids: Vec<hir::HirId> = Vec::new();
85 for param in body.params.iter() {
86 let mut finder = ParamBindingIdCollector {
87 binding_hir_ids: Vec::new(),
89 finder.visit_param(param);
90 for hir_id in &finder.binding_hir_ids {
91 hir_ids.push(*hir_id);
97 impl<'tcx> intravisit::Visitor<'tcx> for ParamBindingIdCollector {
98 fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
99 if let hir::PatKind::Binding(_, hir_id, ..) = pat.kind {
100 self.binding_hir_ids.push(hir_id);
102 intravisit::walk_pat(self, pat);
106 pub struct BindingUsageFinder<'a, 'tcx> {
107 cx: &'a LateContext<'tcx>,
108 binding_ids: Vec<hir::HirId>,
111 impl<'a, 'tcx> BindingUsageFinder<'a, 'tcx> {
112 pub fn are_params_used(cx: &'a LateContext<'tcx>, body: &'tcx hir::Body<'tcx>) -> bool {
113 let mut finder = BindingUsageFinder {
115 binding_ids: ParamBindingIdCollector::collect_binding_hir_ids(body),
118 finder.visit_body(body);
122 impl<'a, 'tcx> intravisit::Visitor<'tcx> for BindingUsageFinder<'a, 'tcx> {
123 type NestedFilter = nested_filter::OnlyBodies;
125 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
126 if !self.usage_found {
127 intravisit::walk_expr(self, expr);
131 fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, _: hir::HirId) {
132 if let hir::def::Res::Local(id) = path.res {
133 if self.binding_ids.contains(&id) {
134 self.usage_found = true;
139 fn nested_visit_map(&mut self) -> Self::Map {
144 pub fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
145 for_each_expr(expression, |e| {
147 ExprKind::Ret(..) | ExprKind::Break(..) | ExprKind::Continue(..) => ControlFlow::Break(()),
148 // Something special could be done here to handle while or for loop
149 // desugaring, as this will detect a break if there's a while loop
150 // or a for loop inside the expression.
151 _ if e.span.from_expansion() => ControlFlow::Break(()),
152 _ => ControlFlow::Continue(()),
158 pub fn local_used_after_expr(cx: &LateContext<'_>, local_id: HirId, after: &Expr<'_>) -> bool {
159 let Some(block) = utils::get_enclosing_block(cx, local_id) else { return false };
165 // let closure = || local;
168 let in_loop_or_closure = cx
171 .parent_iter(after.hir_id)
172 .take_while(|&(id, _)| id != block.hir_id)
177 kind: ExprKind::Loop(..) | ExprKind::Closure { .. },
182 if in_loop_or_closure {
186 let mut past_expr = false;
187 for_each_expr_with_closures(cx, block, |e| {
188 if e.hir_id == after.hir_id {
190 ControlFlow::Continue(Descend::No)
191 } else if past_expr && utils::path_to_local_id(e, local_id) {
192 ControlFlow::Break(())
194 ControlFlow::Continue(Descend::Yes)