+use if_chain::if_chain;
+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 rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_tool_lint, lint_array};
-use syntax::source_map::Span;
-use crate::utils::{in_macro, snippet, span_lint, unsext, clip};
-use rustc::ty;
+use crate::utils::{clip, snippet, span_lint, unsext};
-/// **What it does:** Checks for identity operations, e.g. `x + 0`.
-///
-/// **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:**
-/// ```rust
-/// x / 1 + 0 * 1 - 0 | 0
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for identity operations, e.g., `x + 0`.
+ ///
+ /// **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:**
+ /// ```rust
+ /// # let x = 1;
+ /// x / 1 + 0 * 1 - 0 | 0;
+ /// ```
pub IDENTITY_OP,
complexity,
- "using identity operations, e.g. `x + 0` or `y / 1`"
+ "using identity operations, e.g., `x + 0` or `y / 1`"
}
-#[derive(Copy, Clone)]
-pub struct IdentityOp;
+declare_lint_pass!(IdentityOp => [IDENTITY_OP]);
-impl LintPass for IdentityOp {
- fn get_lints(&self) -> LintArray {
- lint_array!(IDENTITY_OP)
- }
-}
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityOp {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
- if in_macro(e.span) {
+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.node {
+ if let ExprKind::Binary(cmp, ref left, ref 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);
}
}
+fn is_allowed(cx: &LateContext<'_>, cmp: BinOp, left: &Expr<'_>, right: &Expr<'_>) -> bool {
+ // `1 << 0` is a common pattern in bit manipulation code
+ if_chain! {
+ if let BinOpKind::Shl = cmp.node;
+ if let Some(Constant::Int(0)) = constant_simple(cx, cx.typeck_results(), right);
+ if let Some(Constant::Int(1)) = constant_simple(cx, cx.typeck_results(), left);
+ then {
+ return true;
+ }
+ }
+
+ false
+}
+
#[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).sty {
+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) {
+ let check = match *cx.typeck_results().expr_ty(e).kind() {
ty::Int(ity) => unsext(cx.tcx, -1_i128, ity),
ty::Uint(uty) => clip(cx.tcx, !0, uty),
_ => return,