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(cx: &LateContext<'_>, expr: &hir::Expr<'_>, method_name: Symbol, args: &[hir::Expr<'_>]) {
  14     if !(args.len() == 1 && method_name == sym::clone) {
  15         return;
  16     }
  17     let arg = &args[0];
  18     let obj_ty = cx.typeck_results().expr_ty(arg).peel_refs();
  19
  20     if let ty::Adt(_, subst) = obj_ty.kind() {
  21         let caller_type = if is_type_diagnostic_item(cx, obj_ty, sym::Rc) {
  22             "Rc"
  23         } else if is_type_diagnostic_item(cx, obj_ty, sym::Arc) {
  24             "Arc"
  25         } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) {
  26             "Weak"
  27         } else {
  28             return;
  29         };
  30
  31         let snippet = snippet_with_macro_callsite(cx, arg.span, "..");
  32
  33         span_lint_and_sugg(
  34             cx,
  35             CLONE_ON_REF_PTR,
  36             expr.span,
  37             "using `.clone()` on a ref-counted pointer",
  38             "try this",
  39             format!("{}::<{}>::clone(&{})", caller_type, subst.type_at(0), snippet),
  40             Applicability::Unspecified, // Sometimes unnecessary ::<_> after Rc/Arc/Weak
  41         );
  42     }
  43 }