clippy_lints/src/methods/implicit_clone.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use if_chain::if_chain;
   3 use rustc_errors::Applicability;
   4 use rustc_hir as hir;
   5 use rustc_hir::ExprKind;
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty::TyS;
   8 use rustc_span::symbol::Symbol;
   9
  10 use super::IMPLICIT_CLONE;
  11 use clippy_utils::is_diagnostic_assoc_item;
  12
  13 pub fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, trait_diagnostic: Symbol) {
  14     if_chain! {
  15         if let ExprKind::MethodCall(method_path, _, [arg], _) = &expr.kind;
  16         let return_type = cx.typeck_results().expr_ty(&expr);
  17         let input_type = cx.typeck_results().expr_ty(arg).peel_refs();
  18         if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
  19         if let Some(ty_name) = input_type.ty_adt_def().map(|adt_def| cx.tcx.item_name(adt_def.did));
  20         if TyS::same_type(return_type, input_type);
  21         if is_diagnostic_assoc_item(cx, expr_def_id, trait_diagnostic);
  22         then {
  23             span_lint_and_sugg(
  24                 cx,IMPLICIT_CLONE,method_path.ident.span,
  25                 &format!("implicitly cloning a `{}` by calling `{}` on its dereferenced type", ty_name, method_path.ident.name),
  26                 "consider using",
  27                 "clone".to_string(),
  28                 Applicability::MachineApplicable
  29             );
  30         }
  31     }
  32 }