Rollup merge of #51912 - mbrubeck:more_box_slice_clone, r=alexcrichton

impl Clone for Box<CStr>, Box<OsStr>, Box<Path>

Implements #51908.

src/libstd/ffi/c_str.rs

@@ -706,6 +706,14 @@ impl From<Box<CStr>> for CString {
     }
 }
 
+#[stable(feature = "more_box_slice_clone", since = "1.29.0")]
+impl Clone for Box<CStr> {
+    #[inline]
+    fn clone(&self) -> Self {
+        (**self).into()
+    }
+}
+
 #[stable(feature = "box_from_c_string", since = "1.20.0")]
 impl From<CString> for Box<CStr> {
     #[inline]

src/libstd/ffi/os_str.rs

@@ -642,6 +642,14 @@ impl From<OsString> for Box<OsStr> {
     }
 }
 
+#[stable(feature = "more_box_slice_clone", since = "1.29.0")]
+impl Clone for Box<OsStr> {
+    #[inline]
+    fn clone(&self) -> Self {
+        self.to_os_string().into_boxed_os_str()
+    }
+}
+
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<OsString> for Arc<OsStr> {
     #[inline]

src/libstd/path.rs

@@ -1410,6 +1410,14 @@ impl From<PathBuf> for Box<Path> {
     }
 }
 
+#[stable(feature = "more_box_slice_clone", since = "1.29.0")]
+impl Clone for Box<Path> {
+    #[inline]
+    fn clone(&self) -> Self {
+        self.to_path_buf().into_boxed_path()
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T: ?Sized + AsRef<OsStr>> From<&'a T> for PathBuf {
     fn from(s: &'a T) -> PathBuf {