don't suggest to use cloned for Cow in unnecessary_to_owned

Author: lapla-cogito

clippy_lints/src/methods/unnecessary_to_owned.rs

@@ -221,6 +221,19 @@ fn check_into_iter_call_arg(
         if unnecessary_iter_cloned::check_for_loop_iter(cx, parent, method_name, receiver, true) {
             return true;
         }
+        if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(receiver), sym::Cow) {
+            span_lint_and_sugg(
+                cx,
+                UNNECESSARY_TO_OWNED,
+                parent.span,
+                format!("unnecessary use of `{method_name}`"),
+                "use",
+                format!("{receiver_snippet}.into_owned()"),
+                Applicability::MaybeIncorrect,
+            );
+            return true;
+        }
+
         let cloned_or_copied = if is_copy(cx, item_ty) && msrv.meets(msrvs::ITERATOR_COPIED) {
             "copied"
         } else {

tests/ui/unnecessary_to_owned.rs

@@ -587,3 +587,9 @@ fn borrow_checks() {
     HashSet::<i32>::new().foo::<&str>(&"".to_owned());
     HashSet::<String>::new().get(&1.to_string());
 }
+
+fn issue13624() -> impl IntoIterator {
+    let cow: Cow<'_, Vec<String>> = Cow::Owned(vec![String::from("foo")]);
+
+    cow.into_owned().into_iter()
+}

tests/ui/unnecessary_to_owned.stderr

@@ -589,5 +589,11 @@ error: unnecessary use of `to_vec`
 LL |     s.remove(&(&["b"]).to_vec());
    |              ^^^^^^^^^^^^^^^^^^ help: replace it with: `(&["b"]).as_slice()`
 
-error: aborting due to 88 previous errors
+error: unnecessary use of `into_owned`
+  --> tests/ui/unnecessary_to_owned.rs:594:5
+   |
+LL |     cow.into_owned().into_iter()
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `cow.into_owned()`
+
+error: aborting due to 89 previous errors