Rollup merge of #70201 - cuviper:clone_into, r=dtolnay

Small tweaks in ToOwned::clone_into

- `<[T]>::clone_into` is slightly more optimized.
- `CStr::clone_into` is new, letting it reuse its allocation.
- `OsStr::clone_into` now forwards to the underlying slice/`Vec`.

2 files changed, 8 insertions, 0 deletions

diff --git a/src/libstd/sys_common/os_str_bytes.rs b/src/libstd/sys_common/os_str_bytes.rs
index aa6cc33d831..984c032e2a3 100644
--- a/src/libstd/sys_common/os_str_bytes.rs
+++ b/src/libstd/sys_common/os_str_bytes.rs
@@ -173,6 +173,10 @@ impl Slice {
         Buf { inner: self.inner.to_vec() }
     }
 
+    pub fn clone_into(&self, buf: &mut Buf) {
+        self.inner.clone_into(&mut buf.inner)
+    }
+
     #[inline]
     pub fn into_box(&self) -> Box<Slice> {
         let boxed: Box<[u8]> = self.inner.into();
diff --git a/src/libstd/sys_common/wtf8.rs b/src/libstd/sys_common/wtf8.rs
index fc6614552a9..a98407da448 100644
--- a/src/libstd/sys_common/wtf8.rs
+++ b/src/libstd/sys_common/wtf8.rs
@@ -613,6 +613,10 @@ impl Wtf8 {
         }
     }
 
+    pub fn clone_into(&self, buf: &mut Wtf8Buf) {
+        self.bytes.clone_into(&mut buf.bytes)
+    }
+
     /// Boxes this `Wtf8`.
     #[inline]
     pub fn into_box(&self) -> Box<Wtf8> {