From e34c698dbdc101f495b74f365124f0aea1c02e8c Mon Sep 17 00:00:00 2001
From: Nikolai Vazquez <hello@nikolaivazquez.com>
Date: Sun, 20 Mar 2022 18:29:12 -0400
Subject: [PATCH 1/3] Create `NonZero` trait with primitive associated type

This enables getting the primitive integer type for a nonzero type
through a type alias.
---
 library/core/src/lib.rs         |  8 ++++++++
 library/core/src/num/nonzero.rs | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 1ab7481b7baae..048f8f0223b65 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -422,3 +422,11 @@ pub mod simd {
 }
 
 include!("primitive_docs.rs");
+
+mod sealed {
+    /// This trait being unreachable from outside the crate
+    /// prevents outside implementations of our extension traits.
+    /// This allows adding more trait methods in the future.
+    #[unstable(feature = "sealed", issue = "none")]
+    pub trait Sealed {}
+}
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 5bdd78aa2dea4..2a5083f86d097 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -6,7 +6,32 @@ use crate::str::FromStr;
 
 use super::from_str_radix;
 use super::{IntErrorKind, ParseIntError};
-use crate::intrinsics;
+use crate::{intrinsics, sealed::Sealed};
+
+/// A number that is known not to equal zero.
+///
+/// # Safety
+///
+/// Implementors of this trait must not have a memory representation for zero.
+pub unsafe trait NonZero: Sealed {
+    /// The primitive scalar type.
+    ///
+    /// # Examples
+    ///
+    /// ## Type Aliases
+    ///
+    /// When referring to an integer type through an alias, this can be used to
+    /// state its primitive type.
+    ///
+    /// ```
+    /// use std::num::{NonZero, NonZeroU32};
+    ///
+    /// type NonZeroInt = NonZeroU32;
+    ///
+    /// let n: <NonZeroInt as NonZero>::Scalar = 1;
+    /// ```
+    type Scalar;
+}
 
 macro_rules! impl_nonzero_fmt {
     ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
@@ -41,6 +66,12 @@ macro_rules! nonzero_integers {
             #[rustc_nonnull_optimization_guaranteed]
             pub struct $Ty($Int);
 
+            impl Sealed for $Ty {}
+
+            unsafe impl NonZero for $Ty {
+                type Scalar = $Int;
+            }
+
             impl $Ty {
                 /// Creates a non-zero without checking whether the value is non-zero.
                 /// This results in undefined behaviour if the value is zero.

From 545f836cbcf700d513c7ccdce2bcca63cb93e01b Mon Sep 17 00:00:00 2001
From: Nikolai Vazquez <hello@nikolaivazquez.com>
Date: Sun, 20 Mar 2022 18:38:10 -0400
Subject: [PATCH 2/3] Add stability attributes

---
 library/core/src/num/nonzero.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 2a5083f86d097..a3ee74990a10c 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -13,6 +13,7 @@ use crate::{intrinsics, sealed::Sealed};
 /// # Safety
 ///
 /// Implementors of this trait must not have a memory representation for zero.
+#[unstable(feature = "nonzero_trait", issue = "none")]
 pub unsafe trait NonZero: Sealed {
     /// The primitive scalar type.
     ///
@@ -66,8 +67,10 @@ macro_rules! nonzero_integers {
             #[rustc_nonnull_optimization_guaranteed]
             pub struct $Ty($Int);
 
+            #[unstable(feature = "sealed", issue = "none")]
             impl Sealed for $Ty {}
 
+            #[unstable(feature = "nonzero_trait", issue = "none")]
             unsafe impl NonZero for $Ty {
                 type Scalar = $Int;
             }

From f062242aca44b45aadc003b269d3d71d804739b9 Mon Sep 17 00:00:00 2001
From: Nikolai Vazquez <hello@nikolaivazquez.com>
Date: Sun, 20 Mar 2022 18:44:34 -0400
Subject: [PATCH 3/3] Add tracking issue

---
 library/core/src/num/nonzero.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index a3ee74990a10c..533258ef00196 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -13,7 +13,7 @@ use crate::{intrinsics, sealed::Sealed};
 /// # Safety
 ///
 /// Implementors of this trait must not have a memory representation for zero.
-#[unstable(feature = "nonzero_trait", issue = "none")]
+#[unstable(feature = "nonzero_trait", issue = "95157")]
 pub unsafe trait NonZero: Sealed {
     /// The primitive scalar type.
     ///
@@ -70,7 +70,7 @@ macro_rules! nonzero_integers {
             #[unstable(feature = "sealed", issue = "none")]
             impl Sealed for $Ty {}
 
-            #[unstable(feature = "nonzero_trait", issue = "none")]
+            #[unstable(feature = "nonzero_trait", issue = "95157")]
             unsafe impl NonZero for $Ty {
                 type Scalar = $Int;
             }