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

   1 use super::utils::derefs_to_slice;
   2 use clippy_utils::diagnostics::span_lint_and_sugg;
   3 use clippy_utils::source::snippet_with_applicability;
   4 use clippy_utils::ty::is_type_diagnostic_item;
   5 use rustc_errors::Applicability;
   6 use rustc_hir::Expr;
   7 use rustc_lint::LateContext;
   8 use rustc_span::sym;
   9
  10 use super::ITER_COUNT;
  11
  12 pub(crate) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, recv: &'tcx Expr<'tcx>, iter_method: &str) {
  13     let ty = cx.typeck_results().expr_ty(recv);
  14     let caller_type = if derefs_to_slice(cx, recv, ty).is_some() {
  15         "slice"
  16     } else if is_type_diagnostic_item(cx, ty, sym::Vec) {
  17         "Vec"
  18     } else if is_type_diagnostic_item(cx, ty, sym::VecDeque) {
  19         "VecDeque"
  20     } else if is_type_diagnostic_item(cx, ty, sym::HashSet) {
  21         "HashSet"
  22     } else if is_type_diagnostic_item(cx, ty, sym::HashMap) {
  23         "HashMap"
  24     } else if is_type_diagnostic_item(cx, ty, sym::BTreeMap) {
  25         "BTreeMap"
  26     } else if is_type_diagnostic_item(cx, ty, sym::BTreeSet) {
  27         "BTreeSet"
  28     } else if is_type_diagnostic_item(cx, ty, sym::LinkedList) {
  29         "LinkedList"
  30     } else if is_type_diagnostic_item(cx, ty, sym::BinaryHeap) {
  31         "BinaryHeap"
  32     } else {
  33         return;
  34     };
  35     let mut applicability = Applicability::MachineApplicable;
  36     span_lint_and_sugg(
  37         cx,
  38         ITER_COUNT,
  39         expr.span,
  40         &format!("called `.{iter_method}().count()` on a `{caller_type}`"),
  41         "try",
  42         format!(
  43             "{}.len()",
  44             snippet_with_applicability(cx, recv.span, "..", &mut applicability),
  45         ),
  46         applicability,
  47     );
  48 }