src/tools/clippy/clippy_lints/src/methods/bytes_nth.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::source::snippet_with_applicability;
   3 use clippy_utils::ty::is_type_lang_item;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::{Expr, LangItem};
   6 use rustc_lint::LateContext;
   7
   8 use super::BYTES_NTH;
   9
  10 pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, recv: &'tcx Expr<'tcx>, n_arg: &'tcx Expr<'tcx>) {
  11     let ty = cx.typeck_results().expr_ty(recv).peel_refs();
  12     let caller_type = if ty.is_str() {
  13         "str"
  14     } else if is_type_lang_item(cx, ty, LangItem::String) {
  15         "String"
  16     } else {
  17         return;
  18     };
  19     let mut applicability = Applicability::MachineApplicable;
  20     span_lint_and_sugg(
  21         cx,
  22         BYTES_NTH,
  23         expr.span,
  24         &format!("called `.bytes().nth()` on a `{caller_type}`"),
  25         "try",
  26         format!(
  27             "{}.as_bytes().get({})",
  28             snippet_with_applicability(cx, recv.span, "..", &mut applicability),
  29             snippet_with_applicability(cx, n_arg.span, "..", &mut applicability)
  30         ),
  31         applicability,
  32     );
  33 }