From f40877feeb17c538a73fe6294d48af123251a8c5 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 10:39:24 +0100
Subject: [PATCH 1/8] Add 12 num::NonZero* types for each primitive integer

RFC: https://github.com/rust-lang/rfcs/pull/2307
---
 src/libcore/nonzero.rs |  2 +-
 src/libcore/num/mod.rs | 87 ++++++++++++++++++++++++++++++++++++++++++
 src/libstd/lib.rs      |  1 +
 src/libstd/num.rs      | 11 ++++++
 4 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/src/libcore/nonzero.rs b/src/libcore/nonzero.rs
index 2c966eb3b5794..c6a1dab561757 100644
--- a/src/libcore/nonzero.rs
+++ b/src/libcore/nonzero.rs
@@ -62,7 +62,7 @@ impl_zeroable_for_integer_types! {
 /// NULL or 0 that might allow certain optimizations.
 #[lang = "non_zero"]
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Debug, Hash)]
-pub struct NonZero<T: Zeroable>(T);
+pub struct NonZero<T: Zeroable>(pub(crate) T);
 
 impl<T: Zeroable> NonZero<T> {
     /// Creates an instance of NonZero with the provided value.
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 09ab7060d37db..d3556ef742b53 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -15,9 +15,96 @@
 use convert::{Infallible, TryFrom};
 use fmt;
 use intrinsics;
+use nonzero::NonZero;
 use ops;
 use str::FromStr;
 
+macro_rules! impl_nonzero_fmt {
+    ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
+        $(
+            #[$stability]
+            impl fmt::$Trait for $Ty {
+                #[inline]
+                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    self.get().fmt(f)
+                }
+            }
+        )+
+    }
+}
+
+macro_rules! nonzero_integers {
+    ( #[$stability: meta] $( $Ty: ident($Int: ty); )+ ) => {
+        $(
+            /// An integer that is known not to equal zero.
+            ///
+            /// This may enable some memory layout optimization such as:
+            ///
+            /// ```rust
+            /// # #![feature(nonzero)]
+            /// use std::mem::size_of;
+            /// assert_eq!(size_of::<Option<std::num::NonZeroU32>>(), size_of::<u32>());
+            /// ```
+            #[$stability]
+            #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+            pub struct $Ty(NonZero<$Int>);
+
+            impl $Ty {
+                /// Create a non-zero without checking the value.
+                ///
+                /// # Safety
+                ///
+                /// The value must not be zero.
+                #[$stability]
+                #[inline]
+                pub const unsafe fn new_unchecked(n: $Int) -> Self {
+                    $Ty(NonZero(n))
+                }
+
+                /// Create a non-zero if the given value is not zero.
+                #[$stability]
+                #[inline]
+                pub fn new(n: $Int) -> Option<Self> {
+                    if n != 0 {
+                        Some($Ty(NonZero(n)))
+                    } else {
+                        None
+                    }
+                }
+
+                /// Returns the value as a primitive type.
+                #[$stability]
+                #[inline]
+                pub fn get(self) -> $Int {
+                    self.0 .0
+                }
+
+            }
+
+            impl_nonzero_fmt! {
+                #[$stability]
+                (Debug, Display, Binary, Octal, LowerHex, UpperHex) for $Ty
+            }
+        )+
+    }
+}
+
+nonzero_integers! {
+    #[unstable(feature = "nonzero", issue = "27730")]
+    NonZeroU8(u8); NonZeroI8(i8);
+    NonZeroU16(u16); NonZeroI16(i16);
+    NonZeroU32(u32); NonZeroI32(i32);
+    NonZeroU64(u64); NonZeroI64(i64);
+    NonZeroUsize(usize); NonZeroIsize(isize);
+}
+
+nonzero_integers! {
+    // Change this to `#[unstable(feature = "i128", issue = "35118")]`
+    // if other NonZero* integer types are stabilizied before 128-bit integers
+    #[unstable(feature = "nonzero", issue = "27730")]
+    NonZeroU128(u128); NonZeroI128(i128);
+}
+
 /// Provides intentionally-wrapped arithmetic on `T`.
 ///
 /// Operations like `+` on `u32` values is intended to never overflow,
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 70a1f82c9a159..5c0a83fde102f 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -282,6 +282,7 @@
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
 #![feature(exhaustive_patterns)]
+#![feature(nonzero)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]
 #![feature(on_unimplemented)]
diff --git a/src/libstd/num.rs b/src/libstd/num.rs
index a2c133954a327..5e0406ca2202c 100644
--- a/src/libstd/num.rs
+++ b/src/libstd/num.rs
@@ -21,6 +21,17 @@ pub use core::num::{FpCategory, ParseIntError, ParseFloatError, TryFromIntError}
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::Wrapping;
 
+#[unstable(feature = "nonzero", issue = "27730")]
+pub use core::num::{
+    NonZeroU8, NonZeroI8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32,
+    NonZeroU64, NonZeroI64, NonZeroUsize, NonZeroIsize,
+};
+
+// Change this to `#[unstable(feature = "i128", issue = "35118")]`
+// if other NonZero* integer types are stabilizied before 128-bit integers
+#[unstable(feature = "nonzero", issue = "27730")]
+pub use core::num::{NonZeroU128, NonZeroI128};
+
 #[cfg(test)] use fmt;
 #[cfg(test)] use ops::{Add, Sub, Mul, Div, Rem};
 

From 2d13ddb6e14322edcd07135a436d0d848d127fb2 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 10:58:48 +0100
Subject: [PATCH 2/8] Use NonNull<_> instead of NonZero<*const _> in btree
 internals

---
 src/liballoc/btree/node.rs | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/liballoc/btree/node.rs b/src/liballoc/btree/node.rs
index c1618043ce66f..464f8f2f4eced 100644
--- a/src/liballoc/btree/node.rs
+++ b/src/liballoc/btree/node.rs
@@ -43,8 +43,7 @@
 
 use core::marker::PhantomData;
 use core::mem;
-use core::nonzero::NonZero;
-use core::ptr::{self, Unique};
+use core::ptr::{self, Unique, NonNull};
 use core::slice;
 
 use boxed::Box;
@@ -149,14 +148,12 @@ impl<K, V> BoxedNode<K, V> {
         }
     }
 
-    unsafe fn from_ptr(ptr: NonZero<*const LeafNode<K, V>>) -> Self {
-        BoxedNode { ptr: Unique::new_unchecked(ptr.get() as *mut LeafNode<K, V>) }
+    unsafe fn from_ptr(ptr: NonNull<LeafNode<K, V>>) -> Self {
+        BoxedNode { ptr: Unique::from(ptr) }
     }
 
-    fn as_ptr(&self) -> NonZero<*const LeafNode<K, V>> {
-        unsafe {
-            NonZero::from(self.ptr.as_ref())
-        }
+    fn as_ptr(&self) -> NonNull<LeafNode<K, V>> {
+        NonNull::from(self.ptr)
     }
 }
 
@@ -276,7 +273,7 @@ impl<K, V> Root<K, V> {
 ///   `NodeRef` could be pointing to either type of node.
 pub struct NodeRef<BorrowType, K, V, Type> {
     height: usize,
-    node: NonZero<*const LeafNode<K, V>>,
+    node: NonNull<LeafNode<K, V>>,
     // This is null unless the borrow type is `Mut`
     root: *const Root<K, V>,
     _marker: PhantomData<(BorrowType, Type)>
@@ -302,7 +299,7 @@ unsafe impl<K: Send, V: Send, Type> Send
 impl<BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Internal> {
     fn as_internal(&self) -> &InternalNode<K, V> {
         unsafe {
-            &*(self.node.get() as *const InternalNode<K, V>)
+            &*(self.node.as_ptr() as *mut InternalNode<K, V>)
         }
     }
 }
@@ -310,7 +307,7 @@ impl<BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Internal> {
 impl<'a, K, V> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
     fn as_internal_mut(&mut self) -> &mut InternalNode<K, V> {
         unsafe {
-            &mut *(self.node.get() as *mut InternalNode<K, V>)
+            &mut *(self.node.as_ptr() as *mut InternalNode<K, V>)
         }
     }
 }
@@ -352,7 +349,7 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
 
     fn as_leaf(&self) -> &LeafNode<K, V> {
         unsafe {
-            &*self.node.get()
+            self.node.as_ref()
         }
     }
 
@@ -382,7 +379,8 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
         >,
         Self
     > {
-        if let Some(non_zero) = NonZero::new(self.as_leaf().parent as *const LeafNode<K, V>) {
+        let parent_as_leaf = self.as_leaf().parent as *const LeafNode<K, V>;
+        if let Some(non_zero) = NonNull::new(parent_as_leaf as *mut _) {
             Ok(Handle {
                 node: NodeRef {
                     height: self.height + 1,
@@ -498,7 +496,7 @@ impl<'a, K, V, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
 
     fn as_leaf_mut(&mut self) -> &mut LeafNode<K, V> {
         unsafe {
-            &mut *(self.node.get() as *mut LeafNode<K, V>)
+            self.node.as_mut()
         }
     }
 
@@ -1241,12 +1239,12 @@ impl<'a, K, V> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>, marker::
                 }
 
                 Heap.dealloc(
-                    right_node.node.get() as *mut u8,
+                    right_node.node.as_ptr() as *mut u8,
                     Layout::new::<InternalNode<K, V>>(),
                 );
             } else {
                 Heap.dealloc(
-                    right_node.node.get() as *mut u8,
+                    right_node.node.as_ptr() as *mut u8,
                     Layout::new::<LeafNode<K, V>>(),
                 );
             }

From 67f46ce1122121849890ad51c35f0eb6ded14b6f Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 11:02:06 +0100
Subject: [PATCH 3/8] Use num::NonZero* instead of NonZero<_> in rustc and
 tests

---
 src/libcore/tests/nonzero.rs                  | 14 ++++-----
 src/librustc/ty/subst.rs                      |  6 ++--
 .../obligation_forest/node_index.rs           |  6 ++--
 src/librustc_mir/dataflow/move_paths/mod.rs   |  6 ++--
 src/test/run-pass/enum-null-pointer-opt.rs    |  9 +++---
 src/test/run-pass/issue-23433.rs              |  2 +-
 src/test/ui/print_type_sizes/niche-filling.rs | 31 +++++++------------
 .../ui/print_type_sizes/niche-filling.stdout  | 10 +++---
 8 files changed, 38 insertions(+), 46 deletions(-)

diff --git a/src/libcore/tests/nonzero.rs b/src/libcore/tests/nonzero.rs
index a795dd575043d..9eaf7529dd3cf 100644
--- a/src/libcore/tests/nonzero.rs
+++ b/src/libcore/tests/nonzero.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::nonzero::NonZero;
+use core::num::NonZeroU32;
 use core::option::Option;
 use core::option::Option::{Some, None};
 use std::mem::size_of;
@@ -16,28 +16,28 @@ use std::mem::size_of;
 #[test]
 fn test_create_nonzero_instance() {
     let _a = unsafe {
-        NonZero::new_unchecked(21)
+        NonZeroU32::new_unchecked(21)
     };
 }
 
 #[test]
 fn test_size_nonzero_in_option() {
-    assert_eq!(size_of::<NonZero<u32>>(), size_of::<Option<NonZero<u32>>>());
+    assert_eq!(size_of::<NonZeroU32>(), size_of::<Option<NonZeroU32>>());
 }
 
 #[test]
 fn test_match_on_nonzero_option() {
     let a = Some(unsafe {
-        NonZero::new_unchecked(42)
+        NonZeroU32::new_unchecked(42)
     });
     match a {
         Some(val) => assert_eq!(val.get(), 42),
-        None => panic!("unexpected None while matching on Some(NonZero(_))")
+        None => panic!("unexpected None while matching on Some(NonZeroU32(_))")
     }
 
-    match unsafe { Some(NonZero::new_unchecked(43)) } {
+    match unsafe { Some(NonZeroU32::new_unchecked(43)) } {
         Some(val) => assert_eq!(val.get(), 43),
-        None => panic!("unexpected None while matching on Some(NonZero(_))")
+        None => panic!("unexpected None while matching on Some(NonZeroU32(_))")
     }
 }
 
diff --git a/src/librustc/ty/subst.rs b/src/librustc/ty/subst.rs
index a301049fe1c40..e7b58ae1564aa 100644
--- a/src/librustc/ty/subst.rs
+++ b/src/librustc/ty/subst.rs
@@ -19,11 +19,11 @@ use syntax_pos::{Span, DUMMY_SP};
 use rustc_data_structures::accumulate_vec::AccumulateVec;
 
 use core::intrinsics;
-use core::nonzero::NonZero;
 use std::fmt;
 use std::iter;
 use std::marker::PhantomData;
 use std::mem;
+use std::num::NonZeroUsize;
 
 /// An entity in the Rust typesystem, which can be one of
 /// several kinds (only types and lifetimes for now).
@@ -32,7 +32,7 @@ use std::mem;
 /// indicate the type (`Ty` or `Region`) it points to.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Kind<'tcx> {
-    ptr: NonZero<usize>,
+    ptr: NonZeroUsize,
     marker: PhantomData<(Ty<'tcx>, ty::Region<'tcx>)>
 }
 
@@ -63,7 +63,7 @@ impl<'tcx> UnpackedKind<'tcx> {
 
         Kind {
             ptr: unsafe {
-                NonZero::new_unchecked(ptr | tag)
+                NonZeroUsize::new_unchecked(ptr | tag)
             },
             marker: PhantomData
         }
diff --git a/src/librustc_data_structures/obligation_forest/node_index.rs b/src/librustc_data_structures/obligation_forest/node_index.rs
index a72cc6b57eade..37512e4bcd57f 100644
--- a/src/librustc_data_structures/obligation_forest/node_index.rs
+++ b/src/librustc_data_structures/obligation_forest/node_index.rs
@@ -8,18 +8,18 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::nonzero::NonZero;
+use std::num::NonZeroU32;
 use std::u32;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct NodeIndex {
-    index: NonZero<u32>,
+    index: NonZeroU32,
 }
 
 impl NodeIndex {
     pub fn new(value: usize) -> NodeIndex {
         assert!(value < (u32::MAX as usize));
-        NodeIndex { index: NonZero::new((value as u32) + 1).unwrap() }
+        NodeIndex { index: NonZeroU32::new((value as u32) + 1).unwrap() }
     }
 
     pub fn get(self) -> usize {
diff --git a/src/librustc_mir/dataflow/move_paths/mod.rs b/src/librustc_mir/dataflow/move_paths/mod.rs
index 7b6ebc6fba872..9f6cf8c036e19 100644
--- a/src/librustc_mir/dataflow/move_paths/mod.rs
+++ b/src/librustc_mir/dataflow/move_paths/mod.rs
@@ -29,17 +29,17 @@ mod abs_domain;
 // (which is likely to yield a subtle off-by-one error).
 pub(crate) mod indexes {
     use std::fmt;
-    use core::nonzero::NonZero;
+    use std::num::NonZeroUsize;
     use rustc_data_structures::indexed_vec::Idx;
 
     macro_rules! new_index {
         ($Index:ident, $debug_name:expr) => {
             #[derive(Copy, Clone, PartialEq, Eq, Hash)]
-            pub struct $Index(NonZero<usize>);
+            pub struct $Index(NonZeroUsize);
 
             impl Idx for $Index {
                 fn new(idx: usize) -> Self {
-                    $Index(NonZero::new(idx + 1).unwrap())
+                    $Index(NonZeroUsize::new(idx + 1).unwrap())
                 }
                 fn index(self) -> usize {
                     self.0.get() - 1
diff --git a/src/test/run-pass/enum-null-pointer-opt.rs b/src/test/run-pass/enum-null-pointer-opt.rs
index e296aff2782c5..12f17a1575e82 100644
--- a/src/test/run-pass/enum-null-pointer-opt.rs
+++ b/src/test/run-pass/enum-null-pointer-opt.rs
@@ -10,10 +10,9 @@
 
 #![feature(nonzero, core)]
 
-extern crate core;
-
-use core::nonzero::NonZero;
 use std::mem::size_of;
+use std::num::NonZeroUsize;
+use std::ptr::NonNull;
 use std::rc::Rc;
 use std::sync::Arc;
 
@@ -59,8 +58,8 @@ fn main() {
     assert_eq!(size_of::<[Box<isize>; 1]>(), size_of::<Option<[Box<isize>; 1]>>());
 
     // Should apply to NonZero
-    assert_eq!(size_of::<NonZero<usize>>(), size_of::<Option<NonZero<usize>>>());
-    assert_eq!(size_of::<NonZero<*mut i8>>(), size_of::<Option<NonZero<*mut i8>>>());
+    assert_eq!(size_of::<NonZeroUsize>(), size_of::<Option<NonZeroUsize>>());
+    assert_eq!(size_of::<NonNull<i8>>(), size_of::<Option<NonNull<i8>>>());
 
     // Should apply to types that use NonZero internally
     assert_eq!(size_of::<Vec<isize>>(), size_of::<Option<Vec<isize>>>());
diff --git a/src/test/run-pass/issue-23433.rs b/src/test/run-pass/issue-23433.rs
index 7af732f561deb..9547b2f08a6bc 100644
--- a/src/test/run-pass/issue-23433.rs
+++ b/src/test/run-pass/issue-23433.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Don't fail if we encounter a NonZero<*T> where T is an unsized type
+// Don't fail if we encounter a NonNull<T> where T is an unsized type
 
 use std::ptr::NonNull;
 
diff --git a/src/test/ui/print_type_sizes/niche-filling.rs b/src/test/ui/print_type_sizes/niche-filling.rs
index 7f234e243e926..875883a2cca7f 100644
--- a/src/test/ui/print_type_sizes/niche-filling.rs
+++ b/src/test/ui/print_type_sizes/niche-filling.rs
@@ -14,7 +14,7 @@
 // This file illustrates how niche-filling enums are handled,
 // modelled after cases like `Option<&u32>`, `Option<bool>` and such.
 //
-// It uses NonZero directly, rather than `&_` or `Unique<_>`, because
+// It uses NonZeroU32 rather than `&_` or `Unique<_>`, because
 // the test is not set up to deal with target-dependent pointer width.
 //
 // It avoids using u64/i64 because on some targets that is only 4-byte
@@ -25,8 +25,7 @@
 #![feature(nonzero)]
 #![allow(dead_code)]
 
-extern crate core;
-use core::nonzero::{NonZero, Zeroable};
+use std::num::NonZeroU32;
 
 pub enum MyOption<T> { None, Some(T) }
 
@@ -36,7 +35,7 @@ impl<T> Default for MyOption<T> {
 
 pub enum EmbeddedDiscr {
     None,
-    Record { pre: u8, val: NonZero<u32>, post: u16 },
+    Record { pre: u8, val: NonZeroU32, post: u16 },
 }
 
 impl Default for EmbeddedDiscr {
@@ -44,32 +43,24 @@ impl Default for EmbeddedDiscr {
 }
 
 #[derive(Default)]
-pub struct IndirectNonZero<T: Zeroable + One> {
+pub struct IndirectNonZero {
     pre: u8,
-    nested: NestedNonZero<T>,
+    nested: NestedNonZero,
     post: u16,
 }
 
-pub struct NestedNonZero<T: Zeroable> {
+pub struct NestedNonZero {
     pre: u8,
-    val: NonZero<T>,
+    val: NonZeroU32,
     post: u16,
 }
 
-impl<T: Zeroable+One> Default for NestedNonZero<T> {
+impl Default for NestedNonZero {
     fn default() -> Self {
-        NestedNonZero { pre: 0, val: NonZero::new(T::one()).unwrap(), post: 0 }
+        NestedNonZero { pre: 0, val: NonZeroU32::new(1).unwrap(), post: 0 }
     }
 }
 
-pub trait One {
-    fn one() -> Self;
-}
-
-impl One for u32 {
-    fn one() -> Self { 1 }
-}
-
 pub enum Enum4<A, B, C, D> {
     One(A),
     Two(B),
@@ -79,9 +70,9 @@ pub enum Enum4<A, B, C, D> {
 
 #[start]
 fn start(_: isize, _: *const *const u8) -> isize {
-    let _x: MyOption<NonZero<u32>> = Default::default();
+    let _x: MyOption<NonZeroU32> = Default::default();
     let _y: EmbeddedDiscr = Default::default();
-    let _z: MyOption<IndirectNonZero<u32>> = Default::default();
+    let _z: MyOption<IndirectNonZero> = Default::default();
     let _a: MyOption<bool> = Default::default();
     let _b: MyOption<char> = Default::default();
     let _c: MyOption<std::cmp::Ordering> = Default::default();
diff --git a/src/test/ui/print_type_sizes/niche-filling.stdout b/src/test/ui/print_type_sizes/niche-filling.stdout
index 0f53e7722dd51..79f9ef5a231d3 100644
--- a/src/test/ui/print_type_sizes/niche-filling.stdout
+++ b/src/test/ui/print_type_sizes/niche-filling.stdout
@@ -1,9 +1,9 @@
-print-type-size type: `IndirectNonZero<u32>`: 12 bytes, alignment: 4 bytes
+print-type-size type: `IndirectNonZero`: 12 bytes, alignment: 4 bytes
 print-type-size     field `.nested`: 8 bytes
 print-type-size     field `.post`: 2 bytes
 print-type-size     field `.pre`: 1 bytes
 print-type-size     end padding: 1 bytes
-print-type-size type: `MyOption<IndirectNonZero<u32>>`: 12 bytes, alignment: 4 bytes
+print-type-size type: `MyOption<IndirectNonZero>`: 12 bytes, alignment: 4 bytes
 print-type-size     variant `None`: 0 bytes
 print-type-size     variant `Some`: 12 bytes
 print-type-size         field `.0`: 12 bytes
@@ -14,7 +14,7 @@ print-type-size         field `.val`: 4 bytes
 print-type-size         field `.post`: 2 bytes
 print-type-size         field `.pre`: 1 bytes
 print-type-size     end padding: 1 bytes
-print-type-size type: `NestedNonZero<u32>`: 8 bytes, alignment: 4 bytes
+print-type-size type: `NestedNonZero`: 8 bytes, alignment: 4 bytes
 print-type-size     field `.val`: 4 bytes
 print-type-size     field `.post`: 2 bytes
 print-type-size     field `.pre`: 1 bytes
@@ -32,12 +32,14 @@ print-type-size type: `MyOption<char>`: 4 bytes, alignment: 4 bytes
 print-type-size     variant `None`: 0 bytes
 print-type-size     variant `Some`: 4 bytes
 print-type-size         field `.0`: 4 bytes
-print-type-size type: `MyOption<core::nonzero::NonZero<u32>>`: 4 bytes, alignment: 4 bytes
+print-type-size type: `MyOption<std::num::NonZeroU32>`: 4 bytes, alignment: 4 bytes
 print-type-size     variant `None`: 0 bytes
 print-type-size     variant `Some`: 4 bytes
 print-type-size         field `.0`: 4 bytes
 print-type-size type: `core::nonzero::NonZero<u32>`: 4 bytes, alignment: 4 bytes
 print-type-size     field `.0`: 4 bytes
+print-type-size type: `std::num::NonZeroU32`: 4 bytes, alignment: 4 bytes
+print-type-size     field `.0`: 4 bytes
 print-type-size type: `Enum4<(), (), (), MyOption<u8>>`: 2 bytes, alignment: 1 bytes
 print-type-size     variant `One`: 0 bytes
 print-type-size         field `.0`: 0 bytes

From 22f7a0295828c0d75b5487d89343e722b406dd5f Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 11:14:35 +0100
Subject: [PATCH 4/8] Deprecate core::nonzero in favor of ptr::NonNull and
 num::NonZero*

---
 src/libcore/nonzero.rs |  5 ++++-
 src/libcore/num/mod.rs |  4 +++-
 src/libcore/ptr.rs     | 11 +++++++++--
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/libcore/nonzero.rs b/src/libcore/nonzero.rs
index c6a1dab561757..59aaef9d66a00 100644
--- a/src/libcore/nonzero.rs
+++ b/src/libcore/nonzero.rs
@@ -10,8 +10,11 @@
 
 //! Exposes the NonZero lang item which provides optimization hints.
 #![unstable(feature = "nonzero",
-            reason = "needs an RFC to flesh out the design",
+            reason = "deprecated",
             issue = "27730")]
+#![rustc_deprecated(reason = "use `std::ptr::NonNull` or `std::num::NonZero*` instead",
+                    since = "1.26.0")]
+#![allow(deprecated)]
 
 use ops::CoerceUnsized;
 
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index d3556ef742b53..84f6ab9b76498 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -15,7 +15,7 @@
 use convert::{Infallible, TryFrom};
 use fmt;
 use intrinsics;
-use nonzero::NonZero;
+#[allow(deprecated)] use nonzero::NonZero;
 use ops;
 use str::FromStr;
 
@@ -46,9 +46,11 @@ macro_rules! nonzero_integers {
             /// assert_eq!(size_of::<Option<std::num::NonZeroU32>>(), size_of::<u32>());
             /// ```
             #[$stability]
+            #[allow(deprecated)]
             #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
             pub struct $Ty(NonZero<$Int>);
 
+            #[allow(deprecated)]
             impl $Ty {
                 /// Create a non-zero without checking the value.
                 ///
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 6270e5892b3a0..834a2ed09f77a 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -23,7 +23,7 @@ use fmt;
 use hash;
 use marker::{PhantomData, Unsize};
 use mem;
-use nonzero::NonZero;
+#[allow(deprecated)] use nonzero::NonZero;
 
 use cmp::Ordering::{self, Less, Equal, Greater};
 
@@ -2285,6 +2285,7 @@ impl<T: ?Sized> PartialOrd for *mut T {
 #[unstable(feature = "ptr_internals", issue = "0",
            reason = "use NonNull instead and consider PhantomData<T> \
                      (if you also use #[may_dangle]), Send, and/or Sync")]
+#[allow(deprecated)]
 pub struct Unique<T: ?Sized> {
     pointer: NonZero<*const T>,
     // NOTE: this marker has no consequences for variance, but is necessary
@@ -2332,6 +2333,7 @@ impl<T: Sized> Unique<T> {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
+#[allow(deprecated)]
 impl<T: ?Sized> Unique<T> {
     /// Creates a new `Unique`.
     ///
@@ -2392,6 +2394,7 @@ impl<T: ?Sized> fmt::Pointer for Unique<T> {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
+#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> {
     fn from(reference: &'a mut T) -> Self {
         Unique { pointer: NonZero::from(reference), _marker: PhantomData }
@@ -2399,6 +2402,7 @@ impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> {
 }
 
 #[unstable(feature = "ptr_internals", issue = "0")]
+#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for Unique<T> {
     fn from(reference: &'a T) -> Self {
         Unique { pointer: NonZero::from(reference), _marker: PhantomData }
@@ -2436,7 +2440,7 @@ pub type Shared<T> = NonNull<T>;
 /// provide a public API that follows the normal shared XOR mutable rules of Rust.
 #[stable(feature = "nonnull", since = "1.25.0")]
 pub struct NonNull<T: ?Sized> {
-    pointer: NonZero<*const T>,
+    #[allow(deprecated)] pointer: NonZero<*const T>,
 }
 
 /// `NonNull` pointers are not `Send` because the data they reference may be aliased.
@@ -2463,6 +2467,7 @@ impl<T: Sized> NonNull<T> {
     }
 }
 
+#[allow(deprecated)]
 impl<T: ?Sized> NonNull<T> {
     /// Creates a new `NonNull`.
     ///
@@ -2581,6 +2586,7 @@ impl<T: ?Sized> From<Unique<T>> for NonNull<T> {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
+#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> {
     fn from(reference: &'a mut T) -> Self {
         NonNull { pointer: NonZero::from(reference) }
@@ -2588,6 +2594,7 @@ impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
+#[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for NonNull<T> {
     fn from(reference: &'a T) -> Self {
         NonNull { pointer: NonZero::from(reference) }

From 6d682c9adc12c5aee1bac37afa15f01b420be8ee Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 11:45:44 +0100
Subject: [PATCH 5/8] Stop using deprecated NonZero APIs

These will eventually be removed
(though the NonZero<T> lang item will likely stay).
---
 src/libcore/ptr.rs | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 834a2ed09f77a..4ab0ceb796773 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -2341,17 +2341,21 @@ impl<T: ?Sized> Unique<T> {
     ///
     /// `ptr` must be non-null.
     pub const unsafe fn new_unchecked(ptr: *mut T) -> Self {
-        Unique { pointer: NonZero::new_unchecked(ptr), _marker: PhantomData }
+        Unique { pointer: NonZero(ptr as _), _marker: PhantomData }
     }
 
     /// Creates a new `Unique` if `ptr` is non-null.
     pub fn new(ptr: *mut T) -> Option<Self> {
-        NonZero::new(ptr as *const T).map(|nz| Unique { pointer: nz, _marker: PhantomData })
+        if !ptr.is_null() {
+            Some(Unique { pointer: NonZero(ptr as _), _marker: PhantomData })
+        } else {
+            None
+        }
     }
 
     /// Acquires the underlying `*mut` pointer.
     pub fn as_ptr(self) -> *mut T {
-        self.pointer.get() as *mut T
+        self.pointer.0 as *mut T
     }
 
     /// Dereferences the content.
@@ -2397,7 +2401,7 @@ impl<T: ?Sized> fmt::Pointer for Unique<T> {
 #[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> {
     fn from(reference: &'a mut T) -> Self {
-        Unique { pointer: NonZero::from(reference), _marker: PhantomData }
+        Unique { pointer: NonZero(reference as _), _marker: PhantomData }
     }
 }
 
@@ -2405,7 +2409,7 @@ impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> {
 #[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for Unique<T> {
     fn from(reference: &'a T) -> Self {
-        Unique { pointer: NonZero::from(reference), _marker: PhantomData }
+        Unique { pointer: NonZero(reference as _), _marker: PhantomData }
     }
 }
 
@@ -2476,19 +2480,23 @@ impl<T: ?Sized> NonNull<T> {
     /// `ptr` must be non-null.
     #[stable(feature = "nonnull", since = "1.25.0")]
     pub const unsafe fn new_unchecked(ptr: *mut T) -> Self {
-        NonNull { pointer: NonZero::new_unchecked(ptr) }
+        NonNull { pointer: NonZero(ptr as _) }
     }
 
     /// Creates a new `NonNull` if `ptr` is non-null.
     #[stable(feature = "nonnull", since = "1.25.0")]
     pub fn new(ptr: *mut T) -> Option<Self> {
-        NonZero::new(ptr as *const T).map(|nz| NonNull { pointer: nz })
+        if !ptr.is_null() {
+            Some(NonNull { pointer: NonZero(ptr as _) })
+        } else {
+            None
+        }
     }
 
     /// Acquires the underlying `*mut` pointer.
     #[stable(feature = "nonnull", since = "1.25.0")]
     pub fn as_ptr(self) -> *mut T {
-        self.pointer.get() as *mut T
+        self.pointer.0 as *mut T
     }
 
     /// Dereferences the content.
@@ -2589,7 +2597,7 @@ impl<T: ?Sized> From<Unique<T>> for NonNull<T> {
 #[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> {
     fn from(reference: &'a mut T) -> Self {
-        NonNull { pointer: NonZero::from(reference) }
+        NonNull { pointer: NonZero(reference as _) }
     }
 }
 
@@ -2597,6 +2605,6 @@ impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> {
 #[allow(deprecated)]
 impl<'a, T: ?Sized> From<&'a T> for NonNull<T> {
     fn from(reference: &'a T) -> Self {
-        NonNull { pointer: NonZero::from(reference) }
+        NonNull { pointer: NonZero(reference as _) }
     }
 }

From 7cf1f18cb9209156108e3871e11cb5d63f7f1cf1 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 16 Feb 2018 19:28:13 +0100
Subject: [PATCH 6/8] Test NonZero in a const item in a pattern.

(This was buggy before https://github.com/rust-lang/rust/pull/46882)
---
 src/libcore/tests/nonzero.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/libcore/tests/nonzero.rs b/src/libcore/tests/nonzero.rs
index 9eaf7529dd3cf..8d39298bac3d1 100644
--- a/src/libcore/tests/nonzero.rs
+++ b/src/libcore/tests/nonzero.rs
@@ -98,3 +98,26 @@ fn test_match_option_string() {
         None => panic!("unexpected None while matching on Some(String { ... })")
     }
 }
+
+mod atom {
+    use core::num::NonZeroU32;
+
+    #[derive(PartialEq, Eq)]
+    pub struct Atom {
+        index: NonZeroU32, // private
+    }
+    pub const FOO_ATOM: Atom = Atom { index: unsafe { NonZeroU32::new_unchecked(7) } };
+}
+
+macro_rules! atom {
+    ("foo") => { atom::FOO_ATOM }
+}
+
+#[test]
+fn test_match_nonzero_const_pattern() {
+    match atom!("foo") {
+        // Using as a pattern is supported by the compiler:
+        atom!("foo") => {}
+        _ => panic!("Expected the const item as a pattern to match.")
+    }
+}

From 73c053786dde55059932b9ebcd4a40edf89eae15 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Thu, 8 Mar 2018 16:55:51 +0100
Subject: [PATCH 7/8] Remove deprecated unstable ptr::Shared type alias.

It has been deprecated for about one release cycle.
---
 src/libcore/cell.rs | 5 ++---
 src/libcore/ptr.rs  | 5 -----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/src/libcore/cell.rs b/src/libcore/cell.rs
index 36618e86968b5..c8ee166fee3e9 100644
--- a/src/libcore/cell.rs
+++ b/src/libcore/cell.rs
@@ -146,13 +146,12 @@
 //!
 //! ```
 //! #![feature(core_intrinsics)]
-//! #![feature(shared)]
 //! use std::cell::Cell;
-//! use std::ptr::Shared;
+//! use std::ptr::NonNull;
 //! use std::intrinsics::abort;
 //!
 //! struct Rc<T: ?Sized> {
-//!     ptr: Shared<RcBox<T>>
+//!     ptr: NonNull<RcBox<T>>
 //! }
 //!
 //! struct RcBox<T: ?Sized> {
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 4ab0ceb796773..cebd5989e96cd 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -2420,11 +2420,6 @@ impl<'a, T: ?Sized> From<NonNull<T>> for Unique<T> {
     }
 }
 
-/// Previous name of `NonNull`.
-#[rustc_deprecated(since = "1.25.0", reason = "renamed to `NonNull`")]
-#[unstable(feature = "shared", issue = "27730")]
-pub type Shared<T> = NonNull<T>;
-
 /// `*mut T` but non-zero and covariant.
 ///
 /// This is often the correct thing to use when building data structures using

From a23f685296b2edd59acc998411340184b958ec82 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Sun, 18 Mar 2018 16:58:38 +0100
Subject: [PATCH 8/8] num::NonZero* types now have their own tracking issue:
 #49137

Fixes #27730
---
 src/libcore/nonzero.rs | 7 +------
 src/libcore/num/mod.rs | 4 ++--
 src/libstd/num.rs      | 4 ++--
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/libcore/nonzero.rs b/src/libcore/nonzero.rs
index 59aaef9d66a00..19836d98844e2 100644
--- a/src/libcore/nonzero.rs
+++ b/src/libcore/nonzero.rs
@@ -9,9 +9,7 @@
 // except according to those terms.
 
 //! Exposes the NonZero lang item which provides optimization hints.
-#![unstable(feature = "nonzero",
-            reason = "deprecated",
-            issue = "27730")]
+#![unstable(feature = "nonzero", reason = "deprecated", issue = "49137")]
 #![rustc_deprecated(reason = "use `std::ptr::NonNull` or `std::num::NonZero*` instead",
                     since = "1.26.0")]
 #![allow(deprecated)]
@@ -70,9 +68,6 @@ pub struct NonZero<T: Zeroable>(pub(crate) T);
 impl<T: Zeroable> NonZero<T> {
     /// Creates an instance of NonZero with the provided value.
     /// You must indeed ensure that the value is actually "non-zero".
-    #[unstable(feature = "nonzero",
-               reason = "needs an RFC to flesh out the design",
-               issue = "27730")]
     #[inline]
     pub const unsafe fn new_unchecked(inner: T) -> Self {
         NonZero(inner)
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 84f6ab9b76498..2ffcb9e95e2d9 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -92,7 +92,7 @@ macro_rules! nonzero_integers {
 }
 
 nonzero_integers! {
-    #[unstable(feature = "nonzero", issue = "27730")]
+    #[unstable(feature = "nonzero", issue = "49137")]
     NonZeroU8(u8); NonZeroI8(i8);
     NonZeroU16(u16); NonZeroI16(i16);
     NonZeroU32(u32); NonZeroI32(i32);
@@ -103,7 +103,7 @@ nonzero_integers! {
 nonzero_integers! {
     // Change this to `#[unstable(feature = "i128", issue = "35118")]`
     // if other NonZero* integer types are stabilizied before 128-bit integers
-    #[unstable(feature = "nonzero", issue = "27730")]
+    #[unstable(feature = "nonzero", issue = "49137")]
     NonZeroU128(u128); NonZeroI128(i128);
 }
 
diff --git a/src/libstd/num.rs b/src/libstd/num.rs
index 5e0406ca2202c..0c618370ac212 100644
--- a/src/libstd/num.rs
+++ b/src/libstd/num.rs
@@ -21,7 +21,7 @@ pub use core::num::{FpCategory, ParseIntError, ParseFloatError, TryFromIntError}
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::Wrapping;
 
-#[unstable(feature = "nonzero", issue = "27730")]
+#[unstable(feature = "nonzero", issue = "49137")]
 pub use core::num::{
     NonZeroU8, NonZeroI8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32,
     NonZeroU64, NonZeroI64, NonZeroUsize, NonZeroIsize,
@@ -29,7 +29,7 @@ pub use core::num::{
 
 // Change this to `#[unstable(feature = "i128", issue = "35118")]`
 // if other NonZero* integer types are stabilizied before 128-bit integers
-#[unstable(feature = "nonzero", issue = "27730")]
+#[unstable(feature = "nonzero", issue = "49137")]
 pub use core::num::{NonZeroU128, NonZeroI128};
 
 #[cfg(test)] use fmt;