src/tools/clippy/clippy_lints/src/suspicious_xor_used_as_pow.rs

   1 use clippy_utils::{numeric_literal::NumericLiteral, source::snippet_with_context};
   2 use rustc_errors::Applicability;
   3 use rustc_hir::{BinOpKind, Expr, ExprKind};
   4 use rustc_lint::{LateContext, LateLintPass, LintContext};
   5 use rustc_middle::lint::in_external_macro;
   6 use rustc_session::{declare_lint_pass, declare_tool_lint};
   7
   8 declare_clippy_lint! {
   9     /// ### What it does
  10     /// Warns for a Bitwise XOR (`^`) operator being probably confused as a powering. It will not trigger if any of the numbers are not in decimal.
  11     /// ### Why is this bad?
  12     /// It's most probably a typo and may lead to unexpected behaviours.
  13     /// ### Example
  14     /// ```rust
  15     /// let x = 3_i32 ^ 4_i32;
  16     /// ```
  17     /// Use instead:
  18     /// ```rust
  19     /// let x = 3_i32.pow(4);
  20     /// ```
  21     #[clippy::version = "1.66.0"]
  22     pub SUSPICIOUS_XOR_USED_AS_POW,
  23     restriction,
  24     "XOR (`^`) operator possibly used as exponentiation operator"
  25 }
  26 declare_lint_pass!(ConfusingXorAndPow => [SUSPICIOUS_XOR_USED_AS_POW]);
  27
  28 impl LateLintPass<'_> for ConfusingXorAndPow {
  29     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
  30         if !in_external_macro(cx.sess(), expr.span) &&
  31                 let ExprKind::Binary(op, left, right) = &expr.kind &&
  32             op.node == BinOpKind::BitXor &&
  33             left.span.ctxt() == right.span.ctxt() &&
  34             let ExprKind::Lit(lit_left) = &left.kind &&
  35             let ExprKind::Lit(lit_right) = &right.kind &&
  36             let snip_left = snippet_with_context(cx, lit_left.span, lit_left.span.ctxt(), "..", &mut Applicability::MaybeIncorrect) &&
  37             let snip_right = snippet_with_context(cx, lit_right.span, lit_right.span.ctxt(), "..", &mut Applicability::MaybeIncorrect) &&
  38             let Some(left_val) = NumericLiteral::from_lit_kind(&snip_left.0, &lit_left.node) &&
  39             let Some(right_val) = NumericLiteral::from_lit_kind(&snip_right.0, &lit_right.node) &&
  40                         left_val.is_decimal() &&
  41                         right_val.is_decimal() {
  42                                         clippy_utils::diagnostics::span_lint_and_sugg(
  43                                                 cx,
  44                                                 SUSPICIOUS_XOR_USED_AS_POW,
  45                                                 expr.span,
  46                                                 "`^` is not the exponentiation operator",
  47                                                 "did you mean to write",
  48                                                 format!("{}.pow({})", left_val.format(), right_val.format()),
  49                                                 Applicability::MaybeIncorrect,
  50                                             );
  51                 }
  52     }
  53 }