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.