clippy_lints/src/methods/cloned_instead_of_copied.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::ty::{get_iterator_item_ty, is_copy};
   3 use clippy_utils::{is_trait_method, meets_msrv};
   4 use rustc_errors::Applicability;
   5 use rustc_hir::Expr;
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty;
   8 use rustc_semver::RustcVersion;
   9 use rustc_span::{sym, Span};
  10
  11 use super::CLONED_INSTEAD_OF_COPIED;
  12
  13 const ITERATOR_COPIED_MSRV: RustcVersion = RustcVersion::new(1, 36, 0);
  14 const OPTION_COPIED_MSRV: RustcVersion = RustcVersion::new(1, 35, 0);
  15
  16 pub fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, span: Span, msrv: Option<&RustcVersion>) {
  17     let recv_ty = cx.typeck_results().expr_ty_adjusted(recv);
  18     let inner_ty = match recv_ty.kind() {
  19         // `Option<T>` -> `T`
  20         ty::Adt(adt, subst)
  21             if cx.tcx.is_diagnostic_item(sym::option_type, adt.did) && meets_msrv(msrv, &OPTION_COPIED_MSRV) =>
  22         {
  23             subst.type_at(0)
  24         },
  25         _ if is_trait_method(cx, expr, sym::Iterator) && meets_msrv(msrv, &ITERATOR_COPIED_MSRV) => {
  26             match get_iterator_item_ty(cx, recv_ty) {
  27                 // <T as Iterator>::Item
  28                 Some(ty) => ty,
  29                 _ => return,
  30             }
  31         },
  32         _ => return,
  33     };
  34     match inner_ty.kind() {
  35         // &T where T: Copy
  36         ty::Ref(_, ty, _) if is_copy(cx, ty) => {},
  37         _ => return,
  38     };
  39     span_lint_and_sugg(
  40         cx,
  41         CLONED_INSTEAD_OF_COPIED,
  42         span,
  43         "used `cloned` where `copied` could be used instead",
  44         "try",
  45         "copied".into(),
  46         Applicability::MachineApplicable,
  47     )
  48 }