Auto merge of #84767 - scottmcm:try_trait_actual, r=lcnr

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

diff --git a/clippy_lints/src/eval_order_dependence.rs b/clippy_lints/src/eval_order_dependence.rs
index 83cee11c3a85921d8615326974d4254f2901dfd5..41acf55dd7d572ec8a75994ec4e924ad4e0c70be 100644 (file)
--- a/clippy_lints/src/eval_order_dependence.rs
+++ b/clippy_lints/src/eval_order_dependence.rs
@@ -1,4 +1,6 @@
-use crate::utils::{get_parent_expr, path_to_local, path_to_local_id, span_lint, span_lint_and_note};
+use clippy_utils::diagnostics::{span_lint, span_lint_and_note};
+use clippy_utils::{get_parent_expr, path_to_local, path_to_local_id};
+use if_chain::if_chain;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -69,29 +71,28 @@
 impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         // Find a write to a local variable.
-        match expr.kind {
-            ExprKind::Assign(ref lhs, ..) | ExprKind::AssignOp(_, ref lhs, _) => {
-                if let Some(var) = path_to_local(lhs) {
-                    let mut visitor = ReadVisitor {
-                        cx,
-                        var,
-                        write_expr: expr,
-                        last_expr: expr,
-                    };
-                    check_for_unsequenced_reads(&mut visitor);
-                }
-            },
-            _ => {},
-        }
+        let var = if_chain! {
+            if let ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) = expr.kind;
+            if let Some(var) = path_to_local(lhs);
+            if expr.span.desugaring_kind().is_none();
+            then { var } else { return; }
+        };
+        let mut visitor = ReadVisitor {
+            cx,
+            var,
+            write_expr: expr,
+            last_expr: expr,
+        };
+        check_for_unsequenced_reads(&mut visitor);
     }
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
         match stmt.kind {
-            StmtKind::Local(ref local) => {
-                if let Local { init: Some(ref e), .. } = **local {
+            StmtKind::Local(local) => {
+                if let Local { init: Some(e), .. } = local {
                     DivergenceVisitor { cx }.visit_expr(e);
                 }
             },
-            StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
+            StmtKind::Expr(e) | StmtKind::Semi(e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
             StmtKind::Item(..) => {},
         }
     }
@@ -105,7 +106,7 @@ impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
     fn maybe_walk_expr(&mut self, e: &'tcx Expr<'_>) {
         match e.kind {
             ExprKind::Closure(..) => {},
-            ExprKind::Match(ref e, arms, _) => {
+            ExprKind::Match(e, arms, _) => {
                 self.visit_expr(e);
                 for arm in arms {
                     if let Some(Guard::If(if_expr)) = arm.guard {
@@ -129,7 +130,7 @@ impl<'a, 'tcx> Visitor<'tcx> for DivergenceVisitor<'a, 'tcx> {
     fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
         match e.kind {
             ExprKind::Continue(_) | ExprKind::Break(_, _) | ExprKind::Ret(_) => self.report_diverging_sub_expr(e),
-            ExprKind::Call(ref func, _) => {
+            ExprKind::Call(func, _) => {
                 let typ = self.cx.typeck_results().expr_ty(func);
                 match typ.kind() {
                     ty::FnDef(..) | ty::FnPtr(_) => {
@@ -265,14 +266,14 @@ fn check_expr<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, expr: &'tcx Expr<'_>) -
 
 fn check_stmt<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, stmt: &'tcx Stmt<'_>) -> StopEarly {
     match stmt.kind {
-        StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => check_expr(vis, expr),
+        StmtKind::Expr(expr) | StmtKind::Semi(expr) => check_expr(vis, expr),
         // If the declaration is of a local variable, check its initializer
         // expression if it has one. Otherwise, keep going.
-        StmtKind::Local(ref local) => local
+        StmtKind::Local(local) => local
             .init
             .as_ref()
             .map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr)),
-        _ => StopEarly::KeepGoing,
+        StmtKind::Item(..) => StopEarly::KeepGoing,
     }
 }
 
@@ -304,7 +305,7 @@ fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
                     self.cx,
                     EVAL_ORDER_DEPENDENCE,
                     expr.span,
-                    "unsequenced read of a variable",
+                    &format!("unsequenced read of `{}`", self.cx.tcx.hir().name(self.var)),
                     Some(self.write_expr.span),
                     "whether read occurs before this write depends on evaluation order",
                 );
@@ -342,7 +343,7 @@ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 /// Returns `true` if `expr` is the LHS of an assignment, like `expr = ...`.
 fn is_in_assignment_position(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     if let Some(parent) = get_parent_expr(cx, expr) {
-        if let ExprKind::Assign(ref lhs, ..) = parent.kind {
+        if let ExprKind::Assign(lhs, ..) = parent.kind {
             return lhs.hir_id == expr.hir_id;
         }
     }