From 843181172892af2fdb7755e77c39227aba252c83 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Sun, 15 Oct 2017 13:15:41 +0000
Subject: [PATCH 1/2] Bring back slice::ref_slice as slice::from_ref.

These functions were deprecated and removed in 1.5, but such simple
functionality shouldn't require using unsafe code, and it isn't
cluttering libstd too much.
---
 src/liballoc/slice.rs    |  2 ++
 src/libcore/slice/mod.rs | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs
index 2045d5ddd972d..56450d4e08c99 100644
--- a/src/liballoc/slice.rs
+++ b/src/liballoc/slice.rs
@@ -119,6 +119,8 @@ pub use core::slice::{SplitN, RSplitN, SplitNMut, RSplitNMut};
 pub use core::slice::{RSplit, RSplitMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{from_raw_parts, from_raw_parts_mut};
+#[stable(feature = "from_ref", since = "1.22.0")]
+pub use core::slice::{from_ref, from_ref_mut};
 #[unstable(feature = "slice_get_slice", issue = "35729")]
 pub use core::slice::SliceIndex;
 
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index 5039bef631e51..ff9c00cf73d19 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -2450,6 +2450,22 @@ pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
     mem::transmute(Repr { data: p, len: len })
 }
 
+/// Converts a reference to T into a slice of length 1 (without copying).
+#[stable(feature = "from_ref", since = "1.22.0")]
+pub fn from_ref<T>(s: &T) -> &[T] {
+    unsafe {
+        from_raw_parts(s, 1)
+    }
+}
+
+/// Converts a reference to T into a slice of length 1 (without copying).
+#[stable(feature = "from_ref", since = "1.22.0")]
+pub fn from_ref_mut<T>(s: &mut T) -> &mut [T] {
+    unsafe {
+        from_raw_parts_mut(s, 1)
+    }
+}
+
 // This function is public only because there is no other way to unit test heapsort.
 #[unstable(feature = "sort_internals", reason = "internal to sort module", issue = "0")]
 #[doc(hidden)]

From 1cc88be2ebc67e1f0e7ff57c12dec45ef9abc2ae Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Wed, 1 Nov 2017 21:56:17 +0000
Subject: [PATCH 2/2] De-stabilize core::slice::{from_ref, from_ref_mut}.

---
 src/liballoc/lib.rs      | 1 +
 src/liballoc/slice.rs    | 2 +-
 src/libcore/slice/mod.rs | 4 ++--
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 0cbfc9e9dacbb..f654a6b5ba471 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -93,6 +93,7 @@
 #![feature(dropck_eyepatch)]
 #![feature(exact_size_is_empty)]
 #![feature(fmt_internals)]
+#![feature(from_ref)]
 #![feature(fundamental)]
 #![feature(fused)]
 #![feature(generic_param_attrs)]
diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs
index 56450d4e08c99..0c5fec2cf7499 100644
--- a/src/liballoc/slice.rs
+++ b/src/liballoc/slice.rs
@@ -119,7 +119,7 @@ pub use core::slice::{SplitN, RSplitN, SplitNMut, RSplitNMut};
 pub use core::slice::{RSplit, RSplitMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{from_raw_parts, from_raw_parts_mut};
-#[stable(feature = "from_ref", since = "1.22.0")]
+#[unstable(feature = "from_ref", issue = "45703")]
 pub use core::slice::{from_ref, from_ref_mut};
 #[unstable(feature = "slice_get_slice", issue = "35729")]
 pub use core::slice::SliceIndex;
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index ff9c00cf73d19..57e5ae28664e0 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -2451,7 +2451,7 @@ pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
 }
 
 /// Converts a reference to T into a slice of length 1 (without copying).
-#[stable(feature = "from_ref", since = "1.22.0")]
+#[unstable(feature = "from_ref", issue = "45703")]
 pub fn from_ref<T>(s: &T) -> &[T] {
     unsafe {
         from_raw_parts(s, 1)
@@ -2459,7 +2459,7 @@ pub fn from_ref<T>(s: &T) -> &[T] {
 }
 
 /// Converts a reference to T into a slice of length 1 (without copying).
-#[stable(feature = "from_ref", since = "1.22.0")]
+#[unstable(feature = "from_ref", issue = "45703")]
 pub fn from_ref_mut<T>(s: &mut T) -> &mut [T] {
     unsafe {
         from_raw_parts_mut(s, 1)