3 files changed, 103 insertions, 1 deletions
diff --git a/tests/ui/unnecessary_to_owned.fixed b/tests/ui/unnecessary_to_owned.fixed
index 7f01c981a93..1afa5ab54c4 100644
--- a/tests/ui/unnecessary_to_owned.fixed
+++ b/tests/ui/unnecessary_to_owned.fixed
@@ -530,3 +530,39 @@ mod issue_11952 {
         IntoFuture::into_future(foo([], &0));
     }
 }
+
+fn borrow_checks() {
+    use std::borrow::Borrow;
+    use std::collections::HashSet;
+
+    fn inner(a: &[&str]) {
+        let mut s = HashSet::from([vec!["a"]]);
+        s.remove(a); //~ ERROR: unnecessary use of `to_vec`
+    }
+
+    let mut s = HashSet::from(["a".to_string()]);
+    s.remove("b"); //~ ERROR: unnecessary use of `to_owned`
+    s.remove("b"); //~ ERROR: unnecessary use of `to_string`
+    // Should not warn.
+    s.remove("b");
+
+    let mut s = HashSet::from([vec!["a"]]);
+    s.remove(["b"].as_slice()); //~ ERROR: unnecessary use of `to_vec`
+    s.remove((&["b"]).as_slice()); //~ ERROR: unnecessary use of `to_vec`
+
+    // Should not warn.
+    s.remove(&["b"].to_vec().clone());
+    s.remove(["a"].as_slice());
+
+    trait SetExt {
+        fn foo<Q: Borrow<str>>(&self, _: &String);
+    }
+
+    impl<K> SetExt for HashSet<K> {
+        fn foo<Q: Borrow<str>>(&self, _: &String) {}
+    }
+
+    // Should not lint!
+    HashSet::<i32>::new().foo::<&str>(&"".to_owned());
+    HashSet::<String>::new().get(&1.to_string());
+}
diff --git a/tests/ui/unnecessary_to_owned.rs b/tests/ui/unnecessary_to_owned.rs
index a270ed1e1c2..aa88dde43bf 100644
--- a/tests/ui/unnecessary_to_owned.rs
+++ b/tests/ui/unnecessary_to_owned.rs
@@ -530,3 +530,39 @@ mod issue_11952 {
         IntoFuture::into_future(foo([].to_vec(), &0));
     }
 }
+
+fn borrow_checks() {
+    use std::borrow::Borrow;
+    use std::collections::HashSet;
+
+    fn inner(a: &[&str]) {
+        let mut s = HashSet::from([vec!["a"]]);
+        s.remove(&a.to_vec()); //~ ERROR: unnecessary use of `to_vec`
+    }
+
+    let mut s = HashSet::from(["a".to_string()]);
+    s.remove(&"b".to_owned()); //~ ERROR: unnecessary use of `to_owned`
+    s.remove(&"b".to_string()); //~ ERROR: unnecessary use of `to_string`
+    // Should not warn.
+    s.remove("b");
+
+    let mut s = HashSet::from([vec!["a"]]);
+    s.remove(&["b"].to_vec()); //~ ERROR: unnecessary use of `to_vec`
+    s.remove(&(&["b"]).to_vec()); //~ ERROR: unnecessary use of `to_vec`
+
+    // Should not warn.
+    s.remove(&["b"].to_vec().clone());
+    s.remove(["a"].as_slice());
+
+    trait SetExt {
+        fn foo<Q: Borrow<str>>(&self, _: &String);
+    }
+
+    impl<K> SetExt for HashSet<K> {
+        fn foo<Q: Borrow<str>>(&self, _: &String) {}
+    }
+
+    // Should not lint!
+    HashSet::<i32>::new().foo::<&str>(&"".to_owned());
+    HashSet::<String>::new().get(&1.to_string());
+}
diff --git a/tests/ui/unnecessary_to_owned.stderr b/tests/ui/unnecessary_to_owned.stderr
index d4199f8a30a..5475df9c7b9 100644
--- a/tests/ui/unnecessary_to_owned.stderr
+++ b/tests/ui/unnecessary_to_owned.stderr
@@ -523,5 +523,35 @@ error: unnecessary use of `to_vec`
 LL |         IntoFuture::into_future(foo([].to_vec(), &0));
    |                                     ^^^^^^^^^^^ help: use: `[]`
 
-error: aborting due to 80 previous errors
+error: unnecessary use of `to_vec`
+  --> tests/ui/unnecessary_to_owned.rs:540:18
+   |
+LL |         s.remove(&a.to_vec());
+   |                  ^^^^^^^^^^^ help: replace it with: `a`
+
+error: unnecessary use of `to_owned`
+  --> tests/ui/unnecessary_to_owned.rs:544:14
+   |
+LL |     s.remove(&"b".to_owned());
+   |              ^^^^^^^^^^^^^^^ help: replace it with: `"b"`
+
+error: unnecessary use of `to_string`
+  --> tests/ui/unnecessary_to_owned.rs:545:14
+   |
+LL |     s.remove(&"b".to_string());
+   |              ^^^^^^^^^^^^^^^^ help: replace it with: `"b"`
+
+error: unnecessary use of `to_vec`
+  --> tests/ui/unnecessary_to_owned.rs:550:14
+   |
+LL |     s.remove(&["b"].to_vec());
+   |              ^^^^^^^^^^^^^^^ help: replace it with: `["b"].as_slice()`
+
+error: unnecessary use of `to_vec`
+  --> tests/ui/unnecessary_to_owned.rs:551:14
+   |
+LL |     s.remove(&(&["b"]).to_vec());
+   |              ^^^^^^^^^^^^^^^^^^ help: replace it with: `(&["b"]).as_slice()`
+
+error: aborting due to 85 previous errors