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

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::paths;
   3 use clippy_utils::source::snippet_with_macro_callsite;
   4 use clippy_utils::ty::{is_type_diagnostic_item, match_type};
   5 use rustc_errors::Applicability;
   6 use rustc_hir as hir;
   7 use rustc_lint::LateContext;
   8 use rustc_middle::ty;
   9 use rustc_span::symbol::{sym, Symbol};
  10
  11 use super::CLONE_ON_REF_PTR;
  12
  13 pub(super) fn check(
  14     cx: &LateContext<'_>,
  15     expr: &hir::Expr<'_>,
  16     method_name: Symbol,
  17     receiver: &hir::Expr<'_>,
  18     args: &[hir::Expr<'_>],
  19 ) {
  20     if !(args.is_empty() && method_name == sym::clone) {
  21         return;
  22     }
  23     let obj_ty = cx.typeck_results().expr_ty(receiver).peel_refs();
  24
  25     if let ty::Adt(_, subst) = obj_ty.kind() {
  26         let caller_type = if is_type_diagnostic_item(cx, obj_ty, sym::Rc) {
  27             "Rc"
  28         } else if is_type_diagnostic_item(cx, obj_ty, sym::Arc) {
  29             "Arc"
  30         } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) {
  31             "Weak"
  32         } else {
  33             return;
  34         };
  35
  36         let snippet = snippet_with_macro_callsite(cx, receiver.span, "..");
  37
  38         span_lint_and_sugg(
  39             cx,
  40             CLONE_ON_REF_PTR,
  41             expr.span,
  42             "using `.clone()` on a ref-counted pointer",
  43             "try this",
  44             format!("{caller_type}::<{}>::clone(&{snippet})", subst.type_at(0)),
  45             Applicability::Unspecified, // Sometimes unnecessary ::<_> after Rc/Arc/Weak
  46         );
  47     }
  48 }