resolve the conflict in compiler/rustc_session/src/parse.rs

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

diff --git a/clippy_lints/src/identity_op.rs b/clippy_lints/src/identity_op.rs
index 1896751ff6ffaf65f948338016986ce6af5c68bc..f824f20ca40a017b28d725fcc452fc50f3209e55 100644 (file)
--- a/clippy_lints/src/identity_op.rs
+++ b/clippy_lints/src/identity_op.rs
@@ -1,25 +1,28 @@
-use rustc::ty;
-use rustc_hir::*;
+use clippy_utils::source::snippet;
+use rustc_hir::{BinOp, BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 
-use crate::consts::{constant_simple, Constant};
-use crate::utils::{clip, snippet, span_lint, unsext};
+use clippy_utils::consts::{constant_simple, Constant};
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::{clip, unsext};
 
 declare_clippy_lint! {
-    /// **What it does:** Checks for identity operations, e.g., `x + 0`.
+    /// ### What it does
+    /// Checks for identity operations, e.g., `x + 0`.
     ///
-    /// **Why is this bad?** This code can be removed without changing the
+    /// ### Why is this bad?
+    /// This code can be removed without changing the
     /// meaning. So it just obscures what's going on. Delete it mercilessly.
     ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
+    /// ### Example
     /// ```rust
     /// # let x = 1;
     /// x / 1 + 0 * 1 - 0 | 0;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub IDENTITY_OP,
     complexity,
     "using identity operations, e.g., `x + 0` or `y / 1`"
@@ -27,12 +30,15 @@
 
 declare_lint_pass!(IdentityOp => [IDENTITY_OP]);
 
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityOp {
-    fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
+impl<'tcx> LateLintPass<'tcx> for IdentityOp {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
         if e.span.from_expansion() {
             return;
         }
-        if let ExprKind::Binary(ref cmp, ref left, ref right) = e.kind {
+        if let ExprKind::Binary(cmp, left, right) = e.kind {
+            if is_allowed(cx, cmp, left, right) {
+                return;
+            }
             match cmp.node {
                 BinOpKind::Add | BinOpKind::BitOr | BinOpKind::BitXor => {
                     check(cx, left, 0, e.span, right.span);
@@ -54,10 +60,19 @@ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
     }
 }
 
-#[allow(clippy::cast_possible_wrap)]
-fn check(cx: &LateContext<'_, '_>, e: &Expr<'_>, m: i8, span: Span, arg: Span) {
-    if let Some(Constant::Int(v)) = constant_simple(cx, cx.tables, e) {
-        let check = match cx.tables.expr_ty(e).kind {
+fn is_allowed(cx: &LateContext<'_>, cmp: BinOp, left: &Expr<'_>, right: &Expr<'_>) -> bool {
+    // This lint applies to integers
+    !cx.typeck_results().expr_ty(left).peel_refs().is_integral()
+        || !cx.typeck_results().expr_ty(right).peel_refs().is_integral()
+        // `1 << 0` is a common pattern in bit manipulation code
+        || (cmp.node == BinOpKind::Shl
+            && constant_simple(cx, cx.typeck_results(), right) == Some(Constant::Int(0))
+            && constant_simple(cx, cx.typeck_results(), left) == Some(Constant::Int(1)))
+}
+
+fn check(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span) {
+    if let Some(Constant::Int(v)) = constant_simple(cx, cx.typeck_results(), e).map(Constant::peel_refs) {
+        let check = match *cx.typeck_results().expr_ty(e).peel_refs().kind() {
             ty::Int(ity) => unsext(cx.tcx, -1_i128, ity),
             ty::Uint(uty) => clip(cx.tcx, !0, uty),
             _ => return,