Auto merge of #121454 - reitermarkus:generic-nonzero-library, r=dtolnay

Use generic `NonZero` everywhere in `library`.

Tracking issue: #120257

Use generic `NonZero` everywhere (except stable examples).

r? `@dtolnay`

Author: bors

library/alloc/src/ffi/c_str.rs

@@ -11,7 +11,7 @@ use core::borrow::Borrow;
 use core::ffi::{c_char, CStr};
 use core::fmt;
 use core::mem;
-use core::num::NonZeroU8;
+use core::num::NonZero;
 use core::ops;
 use core::ptr;
 use core::slice;
@@ -795,22 +795,22 @@ impl From<Box<CStr>> for CString {
 }
 
 #[stable(feature = "cstring_from_vec_of_nonzerou8", since = "1.43.0")]
-impl From<Vec<NonZeroU8>> for CString {
-    /// Converts a <code>[Vec]<[NonZeroU8]></code> into a [`CString`] without
+impl From<Vec<NonZero<u8>>> for CString {
+    /// Converts a <code>[Vec]<[NonZero]<[u8]>></code> into a [`CString`] without
     /// copying nor checking for inner nul bytes.
     #[inline]
-    fn from(v: Vec<NonZeroU8>) -> CString {
+    fn from(v: Vec<NonZero<u8>>) -> CString {
         unsafe {
-            // Transmute `Vec<NonZeroU8>` to `Vec<u8>`.
+            // Transmute `Vec<NonZero<u8>>` to `Vec<u8>`.
             let v: Vec<u8> = {
                 // SAFETY:
-                //   - transmuting between `NonZeroU8` and `u8` is sound;
-                //   - `alloc::Layout<NonZeroU8> == alloc::Layout<u8>`.
-                let (ptr, len, cap): (*mut NonZeroU8, _, _) = Vec::into_raw_parts(v);
+                //   - transmuting between `NonZero<u8>` and `u8` is sound;
+                //   - `alloc::Layout<NonZero<u8>> == alloc::Layout<u8>`.
+                let (ptr, len, cap): (*mut NonZero<u8>, _, _) = Vec::into_raw_parts(v);
                 Vec::from_raw_parts(ptr.cast::<u8>(), len, cap)
             };
             // SAFETY: `v` cannot contain nul bytes, given the type-level
-            // invariant of `NonZeroU8`.
+            // invariant of `NonZero<u8>`.
             Self::_from_vec_unchecked(v)
         }
     }

library/alloc/src/vec/is_zero.rs

@@ -1,4 +1,4 @@
-use core::num::{Saturating, Wrapping};
+use core::num::{NonZero, Saturating, Wrapping};
 
 use crate::boxed::Box;
 
@@ -69,7 +69,7 @@ unsafe impl<T: IsZero, const N: usize> IsZero for [T; N] {
 }
 
 // This is recursive macro.
-macro_rules! impl_for_tuples {
+macro_rules! impl_is_zero_tuples {
     // Stopper
     () => {
         // No use for implementing for empty tuple because it is ZST.
@@ -88,11 +88,11 @@ macro_rules! impl_for_tuples {
             }
         }
 
-        impl_for_tuples!($($rest),*);
+        impl_is_zero_tuples!($($rest),*);
     }
 }
 
-impl_for_tuples!(A, B, C, D, E, F, G, H);
+impl_is_zero_tuples!(A, B, C, D, E, F, G, H);
 
 // `Option<&T>` and `Option<Box<T>>` are guaranteed to represent `None` as null.
 // For fat pointers, the bytes that would be the pointer metadata in the `Some`
@@ -115,16 +115,15 @@ unsafe impl<T: ?Sized> IsZero for Option<Box<T>> {
     }
 }
 
-// `Option<num::NonZeroU32>` and similar have a representation guarantee that
+// `Option<NonZero<u32>>` and similar have a representation guarantee that
 // they're the same size as the corresponding `u32` type, as well as a guarantee
-// that transmuting between `NonZeroU32` and `Option<num::NonZeroU32>` works.
+// that transmuting between `NonZero<u32>` and `Option<NonZero<u32>>` works.
 // While the documentation officially makes it UB to transmute from `None`,
 // we're the standard library so we can make extra inferences, and we know that
 // the only niche available to represent `None` is the one that's all zeros.
-
-macro_rules! impl_is_zero_option_of_nonzero {
-    ($($t:ident,)+) => {$(
-        unsafe impl IsZero for Option<core::num::$t> {
+macro_rules! impl_is_zero_option_of_nonzero_int {
+    ($($t:ty),+ $(,)?) => {$(
+        unsafe impl IsZero for Option<NonZero<$t>> {
             #[inline]
             fn is_zero(&self) -> bool {
                 self.is_none()
@@ -133,23 +132,10 @@ macro_rules! impl_is_zero_option_of_nonzero {
     )+};
 }
 
-impl_is_zero_option_of_nonzero!(
-    NonZeroU8,
-    NonZeroU16,
-    NonZeroU32,
-    NonZeroU64,
-    NonZeroU128,
-    NonZeroI8,
-    NonZeroI16,
-    NonZeroI32,
-    NonZeroI64,
-    NonZeroI128,
-    NonZeroUsize,
-    NonZeroIsize,
-);
-
-macro_rules! impl_is_zero_option_of_num {
-    ($($t:ty,)+) => {$(
+impl_is_zero_option_of_nonzero_int!(u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
+
+macro_rules! impl_is_zero_option_of_int {
+    ($($t:ty),+ $(,)?) => {$(
         unsafe impl IsZero for Option<$t> {
             #[inline]
             fn is_zero(&self) -> bool {
@@ -163,7 +149,7 @@ macro_rules! impl_is_zero_option_of_num {
     )+};
 }
 
-impl_is_zero_option_of_num!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, usize, isize,);
+impl_is_zero_option_of_int!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, usize, isize);
 
 unsafe impl<T: IsZero> IsZero for Wrapping<T> {
     #[inline]
@@ -179,8 +165,8 @@ unsafe impl<T: IsZero> IsZero for Saturating<T> {
     }
 }
 
-macro_rules! impl_for_optional_bool {
-    ($($t:ty,)+) => {$(
+macro_rules! impl_is_zero_option_of_bool {
+    ($($t:ty),+ $(,)?) => {$(
         unsafe impl IsZero for $t {
             #[inline]
             fn is_zero(&self) -> bool {
@@ -194,9 +180,10 @@ macro_rules! impl_for_optional_bool {
         }
     )+};
 }
-impl_for_optional_bool! {
+
+impl_is_zero_option_of_bool! {
     Option<bool>,
     Option<Option<bool>>,
     Option<Option<Option<bool>>>,
-    // Could go further, but not worth the metadata overhead
+    // Could go further, but not worth the metadata overhead.
 }

library/core/src/array/mod.rs

@@ -511,7 +511,7 @@ impl<T, const N: usize> [T; N] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(array_try_map)]
+    /// #![feature(array_try_map, generic_nonzero)]
     /// let a = ["1", "2", "3"];
     /// let b = a.try_map(|v| v.parse::<u32>()).unwrap().map(|v| v + 1);
     /// assert_eq!(b, [2, 3, 4]);
@@ -520,12 +520,12 @@ impl<T, const N: usize> [T; N] {
     /// let b = a.try_map(|v| v.parse::<u32>());
     /// assert!(b.is_err());
     ///
-    /// use std::num::NonZeroU32;
+    /// use std::num::NonZero;
     /// let z = [1, 2, 0, 3, 4];
-    /// assert_eq!(z.try_map(NonZeroU32::new), None);
+    /// assert_eq!(z.try_map(NonZero::new), None);
     /// let a = [1, 2, 3];
-    /// let b = a.try_map(NonZeroU32::new);
-    /// let c = b.map(|x| x.map(NonZeroU32::get));
+    /// let b = a.try_map(NonZero::new);
+    /// let c = b.map(|x| x.map(NonZero::get));
     /// assert_eq!(c, Some(a));
     /// ```
     #[unstable(feature = "array_try_map", issue = "79711")]

library/core/src/cmp/bytewise.rs

@@ -1,5 +1,4 @@
-use crate::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
-use crate::num::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};
+use crate::num::NonZero;
 
 /// Types where `==` & `!=` are equivalent to comparing their underlying bytes.
 ///
@@ -36,37 +35,37 @@ is_bytewise_comparable!(bool, char, super::Ordering);
 // SAFETY: Similarly, the `NonZero` type has a niche, but no undef and no pointers,
 // and they compare like their underlying numeric type.
 is_bytewise_comparable!(
-    NonZeroU8,
-    NonZeroU16,
-    NonZeroU32,
-    NonZeroU64,
-    NonZeroU128,
-    NonZeroUsize,
-    NonZeroI8,
-    NonZeroI16,
-    NonZeroI32,
-    NonZeroI64,
-    NonZeroI128,
-    NonZeroIsize,
+    NonZero<u8>,
+    NonZero<u16>,
+    NonZero<u32>,
+    NonZero<u64>,
+    NonZero<u128>,
+    NonZero<usize>,
+    NonZero<i8>,
+    NonZero<i16>,
+    NonZero<i32>,
+    NonZero<i64>,
+    NonZero<i128>,
+    NonZero<isize>,
 );
 
 // SAFETY: The `NonZero` type has the "null" optimization guaranteed, and thus
 // are also safe to equality-compare bitwise inside an `Option`.
 // The way `PartialOrd` is defined for `Option` means that this wouldn't work
 // for `<` or `>` on the signed types, but since we only do `==` it's fine.
 is_bytewise_comparable!(
-    Option<NonZeroU8>,
-    Option<NonZeroU16>,
-    Option<NonZeroU32>,
-    Option<NonZeroU64>,
-    Option<NonZeroU128>,
-    Option<NonZeroUsize>,
-    Option<NonZeroI8>,
-    Option<NonZeroI16>,
-    Option<NonZeroI32>,
-    Option<NonZeroI64>,
-    Option<NonZeroI128>,
-    Option<NonZeroIsize>,
+    Option<NonZero<u8>>,
+    Option<NonZero<u16>>,
+    Option<NonZero<u32>>,
+    Option<NonZero<u64>>,
+    Option<NonZero<u128>>,
+    Option<NonZero<usize>>,
+    Option<NonZero<i8>>,
+    Option<NonZero<i16>>,
+    Option<NonZero<i32>>,
+    Option<NonZero<i64>>,
+    Option<NonZero<i128>>,
+    Option<NonZero<isize>>,
 );
 
 macro_rules! is_bytewise_comparable_array_length {

library/core/src/iter/traits/double_ended.rs

@@ -100,7 +100,7 @@ pub trait DoubleEndedIterator: Iterator {
     /// to `n` times until [`None`] is encountered.
     ///
     /// `advance_back_by(n)` will return `Ok(())` if the iterator successfully advances by
-    /// `n` elements, or a `Err(NonZeroUsize)` with value `k` if [`None`] is encountered, where `k`
+    /// `n` elements, or a `Err(NonZero<usize>)` with value `k` if [`None`] is encountered, where `k`
     /// is remaining number of steps that could not be advanced because the iterator ran out.
     /// If `self` is empty and `n` is non-zero, then this returns `Err(n)`.
     /// Otherwise, `k` is always less than `n`.
@@ -118,16 +118,16 @@ pub trait DoubleEndedIterator: Iterator {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(iter_advance_by)]
-    /// use std::num::NonZeroUsize;
+    /// #![feature(generic_nonzero, iter_advance_by)]
+    /// use std::num::NonZero;
     ///
     /// let a = [3, 4, 5, 6];
     /// let mut iter = a.iter();
     ///
     /// assert_eq!(iter.advance_back_by(2), Ok(()));
     /// assert_eq!(iter.next_back(), Some(&4));
     /// assert_eq!(iter.advance_back_by(0), Ok(()));
-    /// assert_eq!(iter.advance_back_by(100), Err(NonZeroUsize::new(99).unwrap())); // only `&3` was skipped
+    /// assert_eq!(iter.advance_back_by(100), Err(NonZero::new(99).unwrap())); // only `&3` was skipped
     /// ```
     ///
     /// [`Ok(())`]: Ok

library/core/src/iter/traits/iterator.rs

@@ -304,7 +304,7 @@ pub trait Iterator {
     /// times until [`None`] is encountered.
     ///
     /// `advance_by(n)` will return `Ok(())` if the iterator successfully advances by
-    /// `n` elements, or a `Err(NonZeroUsize)` with value `k` if [`None`] is encountered,
+    /// `n` elements, or a `Err(NonZero<usize>)` with value `k` if [`None`] is encountered,
     /// where `k` is remaining number of steps that could not be advanced because the iterator ran out.
     /// If `self` is empty and `n` is non-zero, then this returns `Err(n)`.
     /// Otherwise, `k` is always less than `n`.
@@ -319,16 +319,16 @@ pub trait Iterator {
     /// # Examples
     ///
     /// ```
-    /// #![feature(iter_advance_by)]
-    /// use std::num::NonZeroUsize;
+    /// #![feature(generic_nonzero, iter_advance_by)]
+    /// use std::num::NonZero;
     ///
     /// let a = [1, 2, 3, 4];
     /// let mut iter = a.iter();
     ///
     /// assert_eq!(iter.advance_by(2), Ok(()));
     /// assert_eq!(iter.next(), Some(&3));
     /// assert_eq!(iter.advance_by(0), Ok(()));
-    /// assert_eq!(iter.advance_by(100), Err(NonZeroUsize::new(99).unwrap())); // only `&4` was skipped
+    /// assert_eq!(iter.advance_by(100), Err(NonZero::new(99).unwrap())); // only `&4` was skipped
     /// ```
     #[inline]
     #[unstable(feature = "iter_advance_by", reason = "recently added", issue = "77404")]
@@ -2967,17 +2967,18 @@ pub trait Iterator {
     /// assert!(result.is_err());
     /// ```
     ///
-    /// This also supports other types which implement `Try`, not just `Result`.
+    /// This also supports other types which implement [`Try`], not just [`Result`].
+    ///
     /// ```
-    /// #![feature(try_find)]
+    /// #![feature(generic_nonzero, try_find)]
+    /// use std::num::NonZero;
     ///
-    /// use std::num::NonZeroU32;
-    /// let a = [3, 5, 7, 4, 9, 0, 11];
-    /// let result = a.iter().try_find(|&&x| NonZeroU32::new(x).map(|y| y.is_power_of_two()));
+    /// let a = [3, 5, 7, 4, 9, 0, 11u32];
+    /// let result = a.iter().try_find(|&&x| NonZero::new(x).map(|y| y.is_power_of_two()));
     /// assert_eq!(result, Some(Some(&4)));
-    /// let result = a.iter().take(3).try_find(|&&x| NonZeroU32::new(x).map(|y| y.is_power_of_two()));
+    /// let result = a.iter().take(3).try_find(|&&x| NonZero::new(x).map(|y| y.is_power_of_two()));
     /// assert_eq!(result, Some(None));
-    /// let result = a.iter().rev().try_find(|&&x| NonZeroU32::new(x).map(|y| y.is_power_of_two()));
+    /// let result = a.iter().rev().try_find(|&&x| NonZero::new(x).map(|y| y.is_power_of_two()));
     /// assert_eq!(result, None);
     /// ```
     #[inline]

library/core/src/num/nonzero.rs

@@ -23,7 +23,7 @@ mod private {
 
 /// A marker trait for primitive types which can be zero.
 ///
-/// This is an implementation detail for [`NonZero<T>`](NonZero) which may disappear or be replaced at any time.
+/// This is an implementation detail for <code>[NonZero]\<T></code> which may disappear or be replaced at any time.
 #[unstable(
     feature = "nonzero_internals",
     reason = "implementation detail which may disappear or be replaced at any time",
@@ -507,18 +507,16 @@ macro_rules! nonzero_integer {
             /// Basic usage:
             ///
             /// ```
-            /// #![feature(non_zero_count_ones)]
+            /// #![feature(generic_nonzero, non_zero_count_ones)]
             /// # fn main() { test().unwrap(); }
             /// # fn test() -> Option<()> {
             /// # use std::num::*;
             /// #
-            /// let one = NonZeroU32::new(1)?;
-            /// let three = NonZeroU32::new(3)?;
-            #[doc = concat!("let a = ", stringify!($Ty), "::new(0b100_0000)?;")]
-            #[doc = concat!("let b = ", stringify!($Ty), "::new(0b100_0011)?;")]
+            #[doc = concat!("let a = NonZero::<", stringify!($Int), ">::new(0b100_0000)?;")]
+            #[doc = concat!("let b = NonZero::<", stringify!($Int), ">::new(0b100_0011)?;")]
             ///
-            /// assert_eq!(a.count_ones(), one);
-            /// assert_eq!(b.count_ones(), three);
+            /// assert_eq!(a.count_ones(), NonZero::new(1)?);
+            /// assert_eq!(b.count_ones(), NonZero::new(3)?);
             /// # Some(())
             /// # }
             /// ```
@@ -530,7 +528,7 @@ macro_rules! nonzero_integer {
             #[must_use = "this returns the result of the operation, \
                         without modifying the original"]
             #[inline(always)]
-            pub const fn count_ones(self) -> NonZeroU32 {
+            pub const fn count_ones(self) -> NonZero<u32> {
                 // SAFETY:
                 // `self` is non-zero, which means it has at least one bit set, which means
                 // that the result of `count_ones` is non-zero.

library/core/src/option.rs

@@ -558,6 +558,7 @@ use crate::panicking::{panic, panic_str};
 use crate::pin::Pin;
 use crate::{
     cmp, convert, hint, mem,
+    num::NonZero,
     ops::{self, ControlFlow, Deref, DerefMut},
     slice,
 };
@@ -2194,18 +2195,18 @@ macro_rules! non_zero_option {
 }
 
 non_zero_option! {
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU8;
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU16;
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU32;
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU64;
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU128;
-    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroUsize;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI8;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI16;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI32;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI64;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI128;
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroIsize;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<u8>;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<u16>;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<u32>;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<u64>;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<u128>;
+    #[stable(feature = "nonzero", since = "1.28.0")] NonZero<usize>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<i8>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<i16>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<i32>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<i64>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<i128>;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZero<isize>;
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]

library/core/src/primitive_docs.rs

@@ -1577,8 +1577,7 @@ mod prim_ref {}
 /// - Any two types with size 0 and alignment 1 are ABI-compatible.
 /// - A `repr(transparent)` type `T` is ABI-compatible with its unique non-trivial field, i.e., the
 ///   unique field that doesn't have size 0 and alignment 1 (if there is such a field).
-/// - `i32` is ABI-compatible with `NonZeroI32`, and similar for all other integer types with their
-///   matching `NonZero*` type.
+/// - `i32` is ABI-compatible with `NonZero<i32>`, and similar for all other integer types.
 /// - If `T` is guaranteed to be subject to the [null pointer
 ///   optimization](option/index.html#representation), then `T` and `Option<T>` are ABI-compatible.
 ///
@@ -1613,9 +1612,9 @@ mod prim_ref {}
 /// type in the function pointer to the type at the function declaration, and the return value is
 /// [`transmute`d][mem::transmute] from the type in the declaration to the type in the
 /// pointer. All the usual caveats and concerns around transmutation apply; for instance, if the
-/// function expects a `NonZeroI32` and the function pointer uses the ABI-compatible type
-/// `Option<NonZeroI32>`, and the value used for the argument is `None`, then this call is Undefined
-/// Behavior since transmuting `None::<NonZeroI32>` to `NonZeroI32` violates the non-zero
+/// function expects a `NonZero<i32>` and the function pointer uses the ABI-compatible type
+/// `Option<NonZero<i32>>`, and the value used for the argument is `None`, then this call is Undefined
+/// Behavior since transmuting `None::<NonZero<i32>>` to `NonZero<i32>` violates the non-zero
 /// requirement.
 ///
 /// #### Requirements concerning target features

library/core/src/ptr/alignment.rs

@@ -1,5 +1,5 @@
 use crate::convert::{TryFrom, TryInto};
-use crate::num::{NonZero, NonZeroUsize};
+use crate::num::NonZero;
 use crate::{cmp, fmt, hash, mem, num};
 
 /// A type storing a `usize` which is a power of two, and thus
@@ -87,19 +87,19 @@ impl Alignment {
         unsafe { mem::transmute::<usize, Alignment>(align) }
     }
 
-    /// Returns the alignment as a [`usize`]
+    /// Returns the alignment as a [`usize`].
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
     pub const fn as_usize(self) -> usize {
         self.0 as usize
     }
 
-    /// Returns the alignment as a [`NonZeroUsize`]
+    /// Returns the alignment as a <code>[NonZero]<[usize]></code>.
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
-    pub const fn as_nonzero(self) -> NonZeroUsize {
+    pub const fn as_nonzero(self) -> NonZero<usize> {
         // SAFETY: All the discriminants are non-zero.
         unsafe { NonZero::new_unchecked(self.as_usize()) }
     }
@@ -164,11 +164,11 @@ impl fmt::Debug for Alignment {
 }
 
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
-impl TryFrom<NonZeroUsize> for Alignment {
+impl TryFrom<NonZero<usize>> for Alignment {
     type Error = num::TryFromIntError;
 
     #[inline]
-    fn try_from(align: NonZeroUsize) -> Result<Alignment, Self::Error> {
+    fn try_from(align: NonZero<usize>) -> Result<Alignment, Self::Error> {
         align.get().try_into()
     }
 }
@@ -184,9 +184,9 @@ impl TryFrom<usize> for Alignment {
 }
 
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
-impl From<Alignment> for NonZeroUsize {
+impl From<Alignment> for NonZero<usize> {
     #[inline]
-    fn from(align: Alignment) -> NonZeroUsize {
+    fn from(align: Alignment) -> NonZero<usize> {
         align.as_nonzero()
     }
 }

library/core/src/ptr/non_null.rs

@@ -5,7 +5,7 @@ use crate::intrinsics;
 use crate::intrinsics::assert_unsafe_precondition;
 use crate::marker::Unsize;
 use crate::mem::{MaybeUninit, SizedTypeProperties};
-use crate::num::{NonZero, NonZeroUsize};
+use crate::num::NonZero;
 use crate::ops::{CoerceUnsized, DispatchFromDyn};
 use crate::ptr;
 use crate::ptr::Unique;
@@ -291,7 +291,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn addr(self) -> NonZeroUsize {
+    pub fn addr(self) -> NonZero<usize> {
         // SAFETY: The pointer is guaranteed by the type to be non-null,
         // meaning that the address will be non-zero.
         unsafe { NonZero::new_unchecked(self.pointer.addr()) }
@@ -306,7 +306,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn with_addr(self, addr: NonZeroUsize) -> Self {
+    pub fn with_addr(self, addr: NonZero<usize>) -> Self {
         // SAFETY: The result of `ptr::from::with_addr` is non-null because `addr` is guaranteed to be non-zero.
         unsafe { NonNull::new_unchecked(self.pointer.with_addr(addr.get()) as *mut _) }
     }
@@ -320,7 +320,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self {
+    pub fn map_addr(self, f: impl FnOnce(NonZero<usize>) -> NonZero<usize>) -> Self {
         self.with_addr(f(self.addr()))
     }
 

library/core/src/str/iter.rs

@@ -5,10 +5,10 @@ use crate::fmt::{self, Write};
 use crate::iter::{Chain, FlatMap, Flatten};
 use crate::iter::{Copied, Filter, FusedIterator, Map, TrustedLen};
 use crate::iter::{TrustedRandomAccess, TrustedRandomAccessNoCoerce};
+use crate::num::NonZero;
 use crate::ops::Try;
 use crate::option;
 use crate::slice::{self, Split as SliceSplit};
-use core::num::{NonZero, NonZeroUsize};
 
 use super::from_utf8_unchecked;
 use super::pattern::Pattern;
@@ -51,7 +51,7 @@ impl<'a> Iterator for Chars<'a> {
     }
 
     #[inline]
-    fn advance_by(&mut self, mut remainder: usize) -> Result<(), NonZeroUsize> {
+    fn advance_by(&mut self, mut remainder: usize) -> Result<(), NonZero<usize>> {
         const CHUNK_SIZE: usize = 32;
 
         if remainder >= CHUNK_SIZE {

library/proc_macro/src/bridge/symbol.rs

@@ -136,7 +136,7 @@ thread_local! {
         arena: arena::Arena::new(),
         names: fxhash::FxHashMap::default(),
         strings: Vec::new(),
-        // Start with a base of 1 to make sure that `NonZeroU32` works.
+        // Start with a base of 1 to make sure that `NonZero<u32>` works.
         sym_base: NonZero::new(1).unwrap(),
     });
 }

library/std/src/io/error/repr_bitpacked.rs

@@ -73,7 +73,7 @@
 //! union Repr {
 //!     // holds integer (Simple/Os) variants, and
 //!     // provides access to the tag bits.
-//!     bits: NonZeroU64,
+//!     bits: NonZero<u64>,
 //!     // Tag is 0, so this is stored untagged.
 //!     msg: &'static SimpleMessage,
 //!     // Tagged (offset) `Box<Custom>` pointer.
@@ -93,7 +93,7 @@
 //!    `io::Result<()>` and `io::Result<usize>` larger, which defeats part of
 //!    the motivation of this bitpacking.
 //!
-//! Storing everything in a `NonZeroUsize` (or some other integer) would be a
+//! Storing everything in a `NonZero<usize>` (or some other integer) would be a
 //! bit more traditional for pointer tagging, but it would lose provenance
 //! information, couldn't be constructed from a `const fn`, and would probably
 //! run into other issues as well.

library/std/src/process.rs

@@ -111,7 +111,7 @@ use crate::ffi::OsStr;
 use crate::fmt;
 use crate::fs;
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
-use crate::num::NonZeroI32;
+use crate::num::NonZero;
 use crate::path::Path;
 use crate::str;
 use crate::sys::pipe::{read2, AnonPipe};
@@ -1775,9 +1775,9 @@ impl ExitStatusError {
         self.code_nonzero().map(Into::into)
     }
 
-    /// Reports the exit code, if applicable, from an `ExitStatusError`, as a `NonZero`
+    /// Reports the exit code, if applicable, from an `ExitStatusError`, as a [`NonZero`].
     ///
-    /// This is exactly like [`code()`](Self::code), except that it returns a `NonZeroI32`.
+    /// This is exactly like [`code()`](Self::code), except that it returns a <code>[NonZero]<[i32]></code>.
     ///
     /// Plain `code`, returning a plain integer, is provided because it is often more convenient.
     /// The returned value from `code()` is indeed also nonzero; use `code_nonzero()` when you want
@@ -1786,17 +1786,17 @@ impl ExitStatusError {
     /// # Examples
     ///
     /// ```
-    /// #![feature(exit_status_error)]
+    /// #![feature(exit_status_error, generic_nonzero)]
     /// # if cfg!(unix) {
-    /// use std::num::NonZeroI32;
+    /// use std::num::NonZero;
     /// use std::process::Command;
     ///
     /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
-    /// assert_eq!(bad.code_nonzero().unwrap(), NonZeroI32::try_from(1).unwrap());
+    /// assert_eq!(bad.code_nonzero().unwrap(), NonZero::new(1).unwrap());
     /// # } // cfg!(unix)
     /// ```
     #[must_use]
-    pub fn code_nonzero(&self) -> Option<NonZeroI32> {
+    pub fn code_nonzero(&self) -> Option<NonZero<i32>> {
         self.0.code()
     }
 

library/std/src/thread/mod.rs

@@ -165,7 +165,7 @@ use crate::fmt;
 use crate::io;
 use crate::marker::PhantomData;
 use crate::mem::{self, forget};
-use crate::num::{NonZero, NonZeroU64, NonZeroUsize};
+use crate::num::NonZero;
 use crate::panic;
 use crate::panicking;
 use crate::pin::Pin;
@@ -1222,7 +1222,7 @@ impl ThreadId {
     /// change across Rust versions.
     #[must_use]
     #[unstable(feature = "thread_id_value", issue = "67939")]
-    pub fn as_u64(&self) -> NonZeroU64 {
+    pub fn as_u64(&self) -> NonZero<u64> {
         self.0
     }
 }
@@ -1784,6 +1784,6 @@ fn _assert_sync_and_send() {
 #[doc(alias = "hardware_concurrency")] // Alias for C++ `std::thread::hardware_concurrency`.
 #[doc(alias = "num_cpus")] // Alias for a popular ecosystem crate which provides similar functionality.
 #[stable(feature = "available_parallelism", since = "1.59.0")]
-pub fn available_parallelism() -> io::Result<NonZeroUsize> {
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     imp::available_parallelism()
 }

library/test/src/helpers/concurrency.rs

@@ -1,10 +1,10 @@
 //! Helper module which helps to determine amount of threads to be used
 //! during tests execution.
-use std::{env, num::NonZeroUsize, thread};
+use std::{env, num::NonZero, thread};
 
 pub fn get_concurrency() -> usize {
     if let Ok(value) = env::var("RUST_TEST_THREADS") {
-        match value.parse::<NonZeroUsize>().ok() {
+        match value.parse::<NonZero<usize>>().ok() {
             Some(n) => n.get(),
             _ => panic!("RUST_TEST_THREADS is `{value}`, should be a positive integer."),
         }

library/test/src/lib.rs

@@ -17,6 +17,7 @@
 #![unstable(feature = "test", issue = "50297")]
 #![doc(test(attr(deny(warnings))))]
 #![doc(rust_logo)]
+#![feature(generic_nonzero)]
 #![feature(rustdoc_internals)]
 #![feature(internal_output_capture)]
 #![feature(staged_api)]