make Box<str>::clone simpler & safer

matklad · matklad · commit 0653e78ae1b3 · 2019-05-27T21:17:12.000+03:00
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
@@ -395,11 +395,9 @@ impl<T: Clone> Clone for Box<T> {
 #[stable(feature = "box_slice_clone", since = "1.3.0")]
 impl Clone for Box<str> {
     fn clone(&self) -> Self {
-        let len = self.len();
-        let buf = RawVec::with_capacity(len);
+        let buf: Box<[u8]> = self.as_bytes().into();
         unsafe {
-            ptr::copy_nonoverlapping(self.as_ptr(), buf.ptr(), len);
-            from_boxed_utf8_unchecked(buf.into_box())
+            from_boxed_utf8_unchecked(buf)
         }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -395,11 +395,9 @@ impl<T: Clone> Clone for Box<T> {`
`395`	`395`	`#[stable(feature = "box_slice_clone", since = "1.3.0")]`
`396`	`396`	`impl Clone for Box<str> {`
`397`	`397`	`fn clone(&self) -> Self {`
`398`		`- let len = self.len();`
`399`		`- let buf = RawVec::with_capacity(len);`
	`398`	`+ let buf: Box<[u8]> = self.as_bytes().into();`
`400`	`399`	`unsafe {`
`401`		`- ptr::copy_nonoverlapping(self.as_ptr(), buf.ptr(), len);`
`402`		`- from_boxed_utf8_unchecked(buf.into_box())`
	`400`	`+ from_boxed_utf8_unchecked(buf)`
`403`	`401`	`}`
`404`	`402`	`}`
`405`	`403`	`}`