From f30f569f3ba0667414074dd8d95685ea5348c77a Mon Sep 17 00:00:00 2001
From: Tobias Bucher <tobiasbucher5991@gmail.com>
Date: Wed, 3 Feb 2016 13:57:02 +0100
Subject: [PATCH] Add `Cow::from` for `Vec` and slices

Fixes #31354.
---
 src/libcollections/vec.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index a49b7304643cc..805d9a9807a33 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1505,6 +1505,20 @@ impl<'a> From<&'a str> for Vec<u8> {
 // Clone-on-write
 ////////////////////////////////////////////////////////////////////////////////
 
+#[stable(feature = "cow_from_vec", since = "1.7.0")]
+impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> {
+    fn from(s: &'a [T]) -> Cow<'a, [T]> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_vec", since = "1.7.0")]
+impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> {
+    fn from(v: Vec<T>) -> Cow<'a, [T]> {
+        Cow::Owned(v)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
     fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {