Add new lint `if_then_panic`

[rust.git] / clippy_utils / src / usage.rs

diff --git a/clippy_utils/src/usage.rs b/clippy_utils/src/usage.rs
index 54f110988d7352f63e5b75ea32f776d5e58ab2c0..098ec175fe2d91fcf530df7b6885c81d64e42fa1 100644 (file)
--- a/clippy_utils/src/usage.rs
+++ b/clippy_utils/src/usage.rs
@@ -1,21 +1,20 @@
 use crate as utils;
-use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
-use rustc_hir::def::Res;
 use rustc_hir::intravisit;
 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
-use rustc_hir::{Expr, ExprKind, HirId, Path};
+use rustc_hir::HirIdSet;
+use rustc_hir::{Expr, ExprKind, HirId};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
 use rustc_middle::mir::FakeReadCause;
 use rustc_middle::ty;
-use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
+use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
 
 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
-pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> Option<FxHashSet<HirId>> {
+pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> Option<HirIdSet> {
     let mut delegate = MutVarsDelegate {
-        used_mutably: FxHashSet::default(),
+        used_mutably: HirIdSet::default(),
         skip: false,
     };
     cx.tcx.infer_ctxt().enter(|infcx| {
@@ -35,16 +34,12 @@ pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) ->
     Some(delegate.used_mutably)
 }
 
-pub fn is_potentially_mutated<'tcx>(variable: &'tcx Path<'_>, expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> bool {
-    if let Res::Local(id) = variable.res {
-        mutated_variables(expr, cx).map_or(true, |mutated| mutated.contains(&id))
-    } else {
-        true
-    }
+pub fn is_potentially_mutated<'tcx>(variable: HirId, expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> bool {
+    mutated_variables(expr, cx).map_or(true, |mutated| mutated.contains(&variable))
 }
 
 struct MutVarsDelegate {
-    used_mutably: FxHashSet<HirId>,
+    used_mutably: HirIdSet,
     skip: bool,
 }
 
@@ -59,7 +54,7 @@ fn update(&mut self, cat: &PlaceWithHirId<'tcx>) {
                 //FIXME: This causes false negatives. We can't get the `NodeId` from
                 //`Categorization::Upvar(_)`. So we search for any `Upvar`s in the
                 //`while`-body, not just the ones in the condition.
-                self.skip = true
+                self.skip = true;
             },
             _ => {},
         }
@@ -67,16 +62,16 @@ fn update(&mut self, cat: &PlaceWithHirId<'tcx>) {
 }
 
 impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
-    fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId, _: ConsumeMode) {}
+    fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {}
 
     fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, bk: ty::BorrowKind) {
         if let ty::BorrowKind::MutBorrow = bk {
-            self.update(&cmt)
+            self.update(cmt);
         }
     }
 
     fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
-        self.update(&cmt)
+        self.update(cmt);
     }
 
     fn fake_read(&mut self, _: rustc_typeck::expr_use_visitor::Place<'tcx>, _: FakeReadCause, _: HirId) {}
@@ -199,3 +194,50 @@ pub fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
     recursive_visitor.visit_expr(expression);
     recursive_visitor.seen_return_break_continue
 }
+
+pub struct UsedAfterExprVisitor<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    expr: &'tcx Expr<'tcx>,
+    definition: HirId,
+    past_expr: bool,
+    used_after_expr: bool,
+}
+impl<'a, 'tcx> UsedAfterExprVisitor<'a, 'tcx> {
+    pub fn is_found(cx: &'a LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
+        utils::path_to_local(expr).map_or(false, |definition| {
+            let mut visitor = UsedAfterExprVisitor {
+                cx,
+                expr,
+                definition,
+                past_expr: false,
+                used_after_expr: false,
+            };
+            utils::get_enclosing_block(cx, definition).map_or(false, |block| {
+                visitor.visit_block(block);
+                visitor.used_after_expr
+            })
+        })
+    }
+}
+
+impl<'a, 'tcx> intravisit::Visitor<'tcx> for UsedAfterExprVisitor<'a, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
+    }
+
+    fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
+        if self.used_after_expr {
+            return;
+        }
+
+        if expr.hir_id == self.expr.hir_id {
+            self.past_expr = true;
+        } else if self.past_expr && utils::path_to_local_id(expr, self.definition) {
+            self.used_after_expr = true;
+        } else {
+            intravisit::walk_expr(self, expr);
+        }
+    }
+}