2 use rustc_hir::def::Res;
3 use rustc_hir::intravisit::{self, walk_expr, NestedVisitorMap, Visitor};
4 use rustc_hir::{Arm, Expr, ExprKind, HirId, QPath, Stmt};
5 use rustc_lint::LateContext;
6 use rustc_middle::hir::map::Map;
8 /// returns `true` if expr contains match expr desugared from try
9 fn contains_try(expr: &hir::Expr<'_>) -> bool {
14 impl<'hir> intravisit::Visitor<'hir> for TryFinder {
17 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
18 intravisit::NestedVisitorMap::None
21 fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) {
26 hir::ExprKind::Match(_, _, hir::MatchSource::TryDesugar) => self.found = true,
27 _ => intravisit::walk_expr(self, expr),
32 let mut visitor = TryFinder { found: false };
33 visitor.visit_expr(expr);
37 pub fn find_all_ret_expressions<'hir, F>(_cx: &LateContext<'_>, expr: &'hir hir::Expr<'hir>, callback: F) -> bool
39 F: FnMut(&'hir hir::Expr<'hir>) -> bool,
47 struct WithStmtGuarg<'a, F> {
48 val: &'a mut RetFinder<F>,
52 impl<F> RetFinder<F> {
53 fn inside_stmt(&mut self, in_stmt: bool) -> WithStmtGuarg<'_, F> {
54 let prev_in_stmt = std::mem::replace(&mut self.in_stmt, in_stmt);
62 impl<F> std::ops::Deref for WithStmtGuarg<'_, F> {
63 type Target = RetFinder<F>;
65 fn deref(&self) -> &Self::Target {
70 impl<F> std::ops::DerefMut for WithStmtGuarg<'_, F> {
71 fn deref_mut(&mut self) -> &mut Self::Target {
76 impl<F> Drop for WithStmtGuarg<'_, F> {
78 self.val.in_stmt = self.prev_in_stmt;
82 impl<'hir, F: FnMut(&'hir hir::Expr<'hir>) -> bool> intravisit::Visitor<'hir> for RetFinder<F> {
85 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
86 intravisit::NestedVisitorMap::None
89 fn visit_stmt(&mut self, stmt: &'hir hir::Stmt<'_>) {
90 intravisit::walk_stmt(&mut *self.inside_stmt(true), stmt)
93 fn visit_expr(&mut self, expr: &'hir hir::Expr<'_>) {
99 hir::ExprKind::Ret(Some(expr)) => self.inside_stmt(false).visit_expr(expr),
100 _ => intravisit::walk_expr(self, expr),
104 hir::ExprKind::If(cond, then, else_opt) => {
105 self.inside_stmt(true).visit_expr(cond);
106 self.visit_expr(then);
107 if let Some(el) = else_opt {
111 hir::ExprKind::Match(cond, arms, _) => {
112 self.inside_stmt(true).visit_expr(cond);
114 self.visit_expr(arm.body);
117 hir::ExprKind::Block(..) => intravisit::walk_expr(self, expr),
118 hir::ExprKind::Ret(Some(expr)) => self.visit_expr(expr),
119 _ => self.failed |= !(self.cb)(expr),
125 !contains_try(expr) && {
126 let mut ret_finder = RetFinder {
131 ret_finder.visit_expr(expr);
136 pub struct LocalUsedVisitor {
137 pub local_hir_id: HirId,
141 impl LocalUsedVisitor {
142 pub fn new(local_hir_id: HirId) -> Self {
149 fn check<T>(&mut self, t: T, visit: fn(&mut Self, T)) -> bool {
151 std::mem::replace(&mut self.used, false)
154 pub fn check_arm(&mut self, arm: &Arm<'_>) -> bool {
155 self.check(arm, Self::visit_arm)
158 pub fn check_expr(&mut self, expr: &Expr<'_>) -> bool {
159 self.check(expr, Self::visit_expr)
162 pub fn check_stmt(&mut self, stmt: &Stmt<'_>) -> bool {
163 self.check(stmt, Self::visit_stmt)
167 impl<'v> Visitor<'v> for LocalUsedVisitor {
170 fn visit_expr(&mut self, expr: &'v Expr<'v>) {
171 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
172 if let Res::Local(id) = path.res {
173 if id == self.local_hir_id {
179 walk_expr(self, expr);
182 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
183 NestedVisitorMap::None