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

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