clippy_lints/src/casts/cast_abs_to_unsigned.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::sugg::Sugg;
   3 use clippy_utils::{meets_msrv, msrvs};
   4 use rustc_errors::Applicability;
   5 use rustc_hir::{Expr, ExprKind};
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::{self, Ty};
   8 use rustc_semver::RustcVersion;
   9
  10 use super::CAST_ABS_TO_UNSIGNED;
  11
  12 pub(super) fn check(
  13     cx: &LateContext<'_>,
  14     expr: &Expr<'_>,
  15     cast_expr: &Expr<'_>,
  16     cast_from: Ty<'_>,
  17     cast_to: Ty<'_>,
  18     msrv: Option<RustcVersion>,
  19 ) {
  20     if meets_msrv(msrv, msrvs::UNSIGNED_ABS)
  21         && let ty::Int(from) = cast_from.kind()
  22         && let ty::Uint(to) = cast_to.kind()
  23         && let ExprKind::MethodCall(method_path, receiver, ..) = cast_expr.kind
  24         && method_path.ident.name.as_str() == "abs"
  25     {
  26         let span = if from.bit_width() == to.bit_width() {
  27             expr.span
  28         } else {
  29             // if the result of `.unsigned_abs` would be a different type, keep the cast
  30             // e.g. `i64 -> usize`, `i16 -> u8`
  31             cast_expr.span
  32         };
  33
  34         span_lint_and_sugg(
  35             cx,
  36             CAST_ABS_TO_UNSIGNED,
  37             span,
  38             &format!("casting the result of `{cast_from}::abs()` to {cast_to}"),
  39             "replace with",
  40             format!("{}.unsigned_abs()", Sugg::hir(cx, receiver, "..").maybe_par()),
  41             Applicability::MachineApplicable,
  42         );
  43     }
  44 }