clippy_lints/src/methods/implicit_clone.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::{is_diag_item_method, is_diag_trait_item};
   3 use if_chain::if_chain;
   4 use rustc_errors::Applicability;
   5 use rustc_hir as hir;
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::TyS;
   8 use rustc_span::{sym, Span};
   9
  10 use super::IMPLICIT_CLONE;
  11
  12 pub fn check(cx: &LateContext<'_>, method_name: &str, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, span: Span) {
  13     if_chain! {
  14         if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
  15         if match method_name {
  16             "to_os_string" => is_diag_item_method(cx, method_def_id, sym::OsStr),
  17             "to_owned" => is_diag_trait_item(cx, method_def_id, sym::ToOwned),
  18             "to_path_buf" => is_diag_item_method(cx, method_def_id, sym::Path),
  19             "to_vec" => cx.tcx.impl_of_method(method_def_id)
  20                 .map(|impl_did| Some(impl_did) == cx.tcx.lang_items().slice_alloc_impl())
  21                 == Some(true),
  22             _ => false,
  23         };
  24         let return_type = cx.typeck_results().expr_ty(expr);
  25         let input_type = cx.typeck_results().expr_ty(recv).peel_refs();
  26         if let Some(ty_name) = input_type.ty_adt_def().map(|adt_def| cx.tcx.item_name(adt_def.did));
  27         if TyS::same_type(return_type, input_type);
  28         then {
  29             span_lint_and_sugg(
  30                 cx,
  31                 IMPLICIT_CLONE,
  32                 span,
  33                 &format!("implicitly cloning a `{}` by calling `{}` on its dereferenced type", ty_name, method_name),
  34                 "consider using",
  35                 "clone".to_string(),
  36                 Applicability::MachineApplicable
  37             );
  38         }
  39     }
  40 }