Auto merge of #8901 - Jarcho:sharing_code, r=dswij

[rust.git] / clippy_lints / src / shadow.rs

diff --git a/clippy_lints/src/shadow.rs b/clippy_lints/src/shadow.rs
index db32b8d740b3ed26573392add794115279f1d862..bf318c055dad1d48ae38e37b2ceb70fad1a75b74 100644 (file)
--- a/clippy_lints/src/shadow.rs
+++ b/clippy_lints/src/shadow.rs
@@ -5,9 +5,7 @@
 use rustc_hir::def::Res;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::hir_id::ItemLocalId;
-use rustc_hir::{
-    Block, Body, BodyOwnerKind, Expr, ExprKind, HirId, Let, Node, Pat, PatKind, QPath, UnOp,
-};
+use rustc_hir::{Block, Body, BodyOwnerKind, Expr, ExprKind, HirId, Let, Node, Pat, PatKind, QPath, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::{Span, Symbol};
@@ -25,10 +23,12 @@
     /// ### Example
     /// ```rust
     /// # let x = 1;
-    /// // Bad
     /// let x = &x;
+    /// ```
     ///
-    /// // Good
+    /// Use instead:
+    /// ```rust
+    /// # let x = 1;
     /// let y = &x; // use different variable name
     /// ```
     #[clippy::version = "pre 1.29.0"]
@@ -81,11 +81,14 @@
     /// # let y = 1;
     /// # let z = 2;
     /// let x = y;
-    ///
-    /// // Bad
     /// let x = z; // shadows the earlier binding
+    /// ```
     ///
-    /// // Good
+    /// Use instead:
+    /// ```rust
+    /// # let y = 1;
+    /// # let z = 2;
+    /// let x = y;
     /// let w = z; // use different variable name
     /// ```
     #[clippy::version = "pre 1.29.0"]
@@ -141,34 +144,34 @@ fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
 
     fn check_body(&mut self, cx: &LateContext<'_>, body: &Body<'_>) {
         let hir = cx.tcx.hir();
-        if !matches!(hir.body_owner_kind(hir.body_owner_def_id(body.id())), BodyOwnerKind::Closure)
-        {
+        if !matches!(
+            hir.body_owner_kind(hir.body_owner_def_id(body.id())),
+            BodyOwnerKind::Closure
+        ) {
             self.bindings.push(FxHashMap::default());
         }
     }
 
     fn check_body_post(&mut self, cx: &LateContext<'_>, body: &Body<'_>) {
         let hir = cx.tcx.hir();
-        if !matches!(hir.body_owner_kind(hir.body_owner_def_id(body.id())), BodyOwnerKind::Closure)
-        {
+        if !matches!(
+            hir.body_owner_kind(hir.body_owner_def_id(body.id())),
+            BodyOwnerKind::Closure
+        ) {
             self.bindings.pop();
         }
     }
 }
 
-fn is_shadow(
-    cx: &LateContext<'_>,
-    owner: LocalDefId,
-    first: ItemLocalId,
-    second: ItemLocalId,
-) -> bool {
-    let scope_tree = &cx
-        .tcx
-        .typeck_body(cx.tcx.hir().body_owned_by(cx.tcx.hir().local_def_id_to_hir_id(owner)))
-        .region_scope_tree;
-    let first_scope = scope_tree.var_scope(first).unwrap();
-    let second_scope = scope_tree.var_scope(second).unwrap();
-    scope_tree.is_subscope_of(second_scope, first_scope)
+fn is_shadow(cx: &LateContext<'_>, owner: LocalDefId, first: ItemLocalId, second: ItemLocalId) -> bool {
+    let scope_tree = cx.tcx.region_scope_tree(owner.to_def_id());
+    if let Some(first_scope) = scope_tree.var_scope(first) {
+        if let Some(second_scope) = scope_tree.var_scope(second) {
+            return scope_tree.is_subscope_of(second_scope, first_scope);
+        }
+    }
+
+    false
 }
 
 fn lint_shadow(cx: &LateContext<'_>, pat: &Pat<'_>, shadowed: HirId, span: Span) {
@@ -180,16 +183,15 @@ fn lint_shadow(cx: &LateContext<'_>, pat: &Pat<'_>, shadowed: HirId, span: Span)
                 snippet(cx, expr.span, "..")
             );
             (SHADOW_SAME, msg)
-        }
+        },
         Some(expr) if is_local_used(cx, expr, shadowed) => {
             let msg = format!("`{}` is shadowed", snippet(cx, pat.span, "_"));
             (SHADOW_REUSE, msg)
-        }
+        },
         _ => {
-            let msg =
-                format!("`{}` shadows a previous, unrelated binding", snippet(cx, pat.span, "_"));
+            let msg = format!("`{}` shadows a previous, unrelated binding", snippet(cx, pat.span, "_"));
             (SHADOW_UNRELATED, msg)
-        }
+        },
     };
     span_lint_and_note(
         cx,
@@ -218,7 +220,14 @@ fn is_self_shadow(cx: &LateContext<'_>, pat: &Pat<'_>, mut expr: &Expr<'_>, hir_
         expr = match expr.kind {
             ExprKind::Box(e)
             | ExprKind::AddrOf(_, _, e)
-            | ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _)
+            | ExprKind::Block(
+                &Block {
+                    stmts: [],
+                    expr: Some(e),
+                    ..
+                },
+                _,
+            )
             | ExprKind::Unary(UnOp::Deref, e) => e,
             ExprKind::Path(QPath::Resolved(None, path)) => break path.res == Res::Local(hir_id),
             _ => break false,