src/tools/clippy/clippy_lints/src/operators/verbose_bit_mask.rs

   1 use clippy_utils::diagnostics::span_lint_and_then;
   2 use clippy_utils::sugg::Sugg;
   3 use rustc_ast::ast::LitKind;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::{BinOpKind, Expr, ExprKind};
   6 use rustc_lint::LateContext;
   7
   8 use super::VERBOSE_BIT_MASK;
   9
  10 pub(super) fn check<'tcx>(
  11     cx: &LateContext<'tcx>,
  12     e: &'tcx Expr<'_>,
  13     op: BinOpKind,
  14     left: &'tcx Expr<'_>,
  15     right: &'tcx Expr<'_>,
  16     threshold: u64,
  17 ) {
  18     if BinOpKind::Eq == op
  19         && let ExprKind::Binary(op1, left1, right1) = &left.kind
  20         && BinOpKind::BitAnd == op1.node
  21         && let ExprKind::Lit(lit) = &right1.kind
  22         && let LitKind::Int(n, _) = lit.node
  23         && let ExprKind::Lit(lit1) = &right.kind
  24         && let LitKind::Int(0, _) = lit1.node
  25         && n.leading_zeros() == n.count_zeros()
  26         && n > u128::from(threshold)
  27     {
  28         span_lint_and_then(
  29             cx,
  30             VERBOSE_BIT_MASK,
  31             e.span,
  32             "bit mask could be simplified with a call to `trailing_zeros`",
  33             |diag| {
  34                 let sugg = Sugg::hir(cx, left1, "...").maybe_par();
  35                 diag.span_suggestion(
  36                     e.span,
  37                     "try",
  38                     format!("{sugg}.trailing_zeros() >= {}", n.count_ones()),
  39                     Applicability::MaybeIncorrect,
  40                 );
  41             },
  42         );
  43     }
  44 }