src/tools/clippy/clippy_lints/src/methods/bytes_count_to_len.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 if_chain::if_chain;
   5 use rustc_errors::Applicability;
   6 use rustc_hir as hir;
   7 use rustc_lint::LateContext;
   8
   9 use super::BYTES_COUNT_TO_LEN;
  10
  11 pub(super) fn check<'tcx>(
  12     cx: &LateContext<'tcx>,
  13     expr: &'tcx hir::Expr<'_>,
  14     count_recv: &'tcx hir::Expr<'_>,
  15     bytes_recv: &'tcx hir::Expr<'_>,
  16 ) {
  17     if_chain! {
  18         if let Some(bytes_id) = cx.typeck_results().type_dependent_def_id(count_recv.hir_id);
  19         if let Some(impl_id) = cx.tcx.impl_of_method(bytes_id);
  20         if cx.tcx.type_of(impl_id).is_str();
  21         let ty = cx.typeck_results().expr_ty(bytes_recv).peel_refs();
  22         if ty.is_str() || is_type_lang_item(cx, ty, hir::LangItem::String);
  23         then {
  24             let mut applicability = Applicability::MachineApplicable;
  25             span_lint_and_sugg(
  26                 cx,
  27                 BYTES_COUNT_TO_LEN,
  28                 expr.span,
  29                 "using long and hard to read `.bytes().count()`",
  30                 "consider calling `.len()` instead",
  31                 format!("{}.len()", snippet_with_applicability(cx, bytes_recv.span, "..", &mut applicability)),
  32                 applicability
  33             );
  34         }
  35     };
  36 }