-use rustc::hir::*;
-use rustc::lint::*;
-use syntax::codemap::{Span, Spanned};
+use clippy_utils::diagnostics::span_lint;
+use if_chain::if_chain;
+use rustc_hir::{BinOpKind, Expr, ExprKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
-use consts::{self, Constant};
-use utils::span_lint;
+use crate::consts::{self, Constant};
-/// **What it does:** Checks for multiplication by -1 as a form of negation.
-///
-/// **Why is this bad?** It's more readable to just negate.
-///
-/// **Known problems:** This only catches integers (for now)
-///
-/// **Example:**
-/// ```rust
-/// x * -1
-/// ```
-declare_lint! {
+declare_clippy_lint! {
+ /// **What it does:** Checks for multiplication by -1 as a form of negation.
+ ///
+ /// **Why is this bad?** It's more readable to just negate.
+ ///
+ /// **Known problems:** This only catches integers (for now).
+ ///
+ /// **Example:**
+ /// ```ignore
+ /// x * -1
+ /// ```
pub NEG_MULTIPLY,
- Warn,
- "Warns on multiplying integers with -1"
+ style,
+ "multiplying integers with `-1`"
}
-#[derive(Copy, Clone)]
-pub struct NegMultiply;
+declare_lint_pass!(NegMultiply => [NEG_MULTIPLY]);
-impl LintPass for NegMultiply {
- fn get_lints(&self) -> LintArray {
- lint_array!(NEG_MULTIPLY)
- }
-}
-
-#[allow(match_same_arms)]
-impl LateLintPass for NegMultiply {
- fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
- if let ExprBinary(Spanned { node: BiMul, .. }, ref l, ref r) = e.node {
- match (&l.node, &r.node) {
- (&ExprUnary(..), &ExprUnary(..)) => (),
- (&ExprUnary(UnNeg, ref lit), _) => check_mul(cx, e.span, lit, r),
- (_, &ExprUnary(UnNeg, ref lit)) => check_mul(cx, e.span, lit, l),
- _ => (),
+#[allow(clippy::match_same_arms)]
+impl<'tcx> LateLintPass<'tcx> for NegMultiply {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+ if let ExprKind::Binary(ref op, ref left, ref right) = e.kind {
+ if BinOpKind::Mul == op.node {
+ match (&left.kind, &right.kind) {
+ (&ExprKind::Unary(..), &ExprKind::Unary(..)) => {},
+ (&ExprKind::Unary(UnOp::Neg, ref lit), _) => check_mul(cx, e.span, lit, right),
+ (_, &ExprKind::Unary(UnOp::Neg, ref lit)) => check_mul(cx, e.span, lit, left),
+ _ => {},
+ }
}
}
}
}
-fn check_mul(cx: &LateContext, span: Span, lit: &Expr, exp: &Expr) {
- if_let_chain!([
- let ExprLit(ref l) = lit.node,
- let Constant::Int(ref ci) = consts::lit_to_constant(&l.node),
- let Some(val) = ci.to_u64(),
- val == 1,
- cx.tcx.expr_ty(exp).is_integral()
- ], {
- span_lint(cx,
- NEG_MULTIPLY,
- span,
- "Negation by multiplying with -1");
- })
+fn check_mul(cx: &LateContext<'_>, span: Span, lit: &Expr<'_>, exp: &Expr<'_>) {
+ if_chain! {
+ if let ExprKind::Lit(ref l) = lit.kind;
+ if let Constant::Int(1) = consts::lit_to_constant(&l.node, cx.typeck_results().expr_ty_opt(lit));
+ if cx.typeck_results().expr_ty(exp).is_integral();
+ then {
+ span_lint(cx, NEG_MULTIPLY, span, "negation by multiplying with `-1`");
+ }
+ }
}