src/tools/clippy/clippy_lints/src/casts/cast_abs_to_unsigned.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::msrvs::{self, Msrv};
   3 use clippy_utils::sugg::Sugg;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::{Expr, ExprKind};
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::{self, Ty};
   8
   9 use super::CAST_ABS_TO_UNSIGNED;
  10
  11 pub(super) fn check(
  12     cx: &LateContext<'_>,
  13     expr: &Expr<'_>,
  14     cast_expr: &Expr<'_>,
  15     cast_from: Ty<'_>,
  16     cast_to: Ty<'_>,
  17     msrv: &Msrv,
  18 ) {
  19     if msrv.meets(msrvs::UNSIGNED_ABS)
  20         && let ty::Int(from) = cast_from.kind()
  21         && let ty::Uint(to) = cast_to.kind()
  22         && let ExprKind::MethodCall(method_path, receiver, ..) = cast_expr.kind
  23         && method_path.ident.name.as_str() == "abs"
  24     {
  25         let span = if from.bit_width() == to.bit_width() {
  26             expr.span
  27         } else {
  28             // if the result of `.unsigned_abs` would be a different type, keep the cast
  29             // e.g. `i64 -> usize`, `i16 -> u8`
  30             cast_expr.span
  31         };
  32
  33         span_lint_and_sugg(
  34             cx,
  35             CAST_ABS_TO_UNSIGNED,
  36             span,
  37             &format!("casting the result of `{cast_from}::abs()` to {cast_to}"),
  38             "replace with",
  39             format!("{}.unsigned_abs()", Sugg::hir(cx, receiver, "..").maybe_par()),
  40             Applicability::MachineApplicable,
  41         );
  42     }
  43 }