Rollup merge of #136511 - joshtriplett:nonzero-cast-signed-unsigned, r=dtolnay

Add `cast_signed` and `cast_unsigned` methods for `NonZero` types

Requested in https://github.com/rust-lang/rust/issues/125882 .

Note that this keeps the same names as the methods currently present on other
integer types. If we want to rename them, we can rename them all at the same
time.

1 files changed, 64 insertions, 2 deletions

diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 61e83ebfad7..a115acf42b1 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -474,6 +474,7 @@ macro_rules! nonzero_integer {
         #[$stability:meta]
         Self = $Ty:ident,
         Primitive = $signedness:ident $Int:ident,
+        SignedPrimitive = $Sint:ty,
         UnsignedPrimitive = $Uint:ty,
 
         // Used in doc comments.
@@ -905,6 +906,7 @@ macro_rules! nonzero_integer {
 
             nonzero_integer_signedness_dependent_methods! {
                 Primitive = $signedness $Int,
+                SignedPrimitive = $Sint,
                 UnsignedPrimitive = $Uint,
             }
 
@@ -1128,6 +1130,7 @@ macro_rules! nonzero_integer {
     (
         Self = $Ty:ident,
         Primitive = unsigned $Int:ident,
+        SignedPrimitive = $Sint:ident,
         rot = $rot:literal,
         rot_op = $rot_op:literal,
         rot_result = $rot_result:literal,
@@ -1140,6 +1143,7 @@ macro_rules! nonzero_integer {
             #[stable(feature = "nonzero", since = "1.28.0")]
             Self = $Ty,
             Primitive = unsigned $Int,
+            SignedPrimitive = $Sint,
             UnsignedPrimitive = $Int,
             rot = $rot,
             rot_op = $rot_op,
@@ -1154,7 +1158,7 @@ macro_rules! nonzero_integer {
     (
         Self = $Ty:ident,
         Primitive = signed $Int:ident,
-        UnsignedPrimitive = $UInt:ident,
+        UnsignedPrimitive = $Uint:ident,
         rot = $rot:literal,
         rot_op = $rot_op:literal,
         rot_result = $rot_result:literal,
@@ -1166,7 +1170,8 @@ macro_rules! nonzero_integer {
             #[stable(feature = "signed_nonzero", since = "1.34.0")]
             Self = $Ty,
             Primitive = signed $Int,
-            UnsignedPrimitive = $UInt,
+            SignedPrimitive = $Int,
+            UnsignedPrimitive = $Uint,
             rot = $rot,
             rot_op = $rot_op,
             rot_result = $rot_result,
@@ -1286,6 +1291,7 @@ macro_rules! nonzero_integer_signedness_dependent_methods {
     // Associated items for unsigned nonzero types only.
     (
         Primitive = unsigned $Int:ident,
+        SignedPrimitive = $Sint:ty,
         UnsignedPrimitive = $Uint:ty,
     ) => {
         /// The smallest value that can be represented by this non-zero
@@ -1620,11 +1626,35 @@ macro_rules! nonzero_integer_signedness_dependent_methods {
             // results will be sqrt(1), which is 1, so a result can't be zero.
             unsafe { Self::new_unchecked(result) }
         }
+
+        /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(integer_sign_cast)]
+        /// # use std::num::NonZero;
+        ///
+        #[doc = concat!("let n = NonZero::<", stringify!($Int), ">::MAX;")]
+        ///
+        #[doc = concat!("assert_eq!(n.cast_signed(), NonZero::new(-1", stringify!($Sint), ").unwrap());")]
+        /// ```
+        #[unstable(feature = "integer_sign_cast", issue = "125882")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline(always)]
+        pub const fn cast_signed(self) -> NonZero<$Sint> {
+            // SAFETY: `self.get()` can't be zero
+            unsafe { NonZero::new_unchecked(self.get().cast_signed()) }
+        }
     };
 
     // Associated items for signed nonzero types only.
     (
         Primitive = signed $Int:ident,
+        SignedPrimitive = $Sint:ty,
         UnsignedPrimitive = $Uint:ty,
     ) => {
         /// The smallest value that can be represented by this non-zero
@@ -2035,12 +2065,37 @@ macro_rules! nonzero_integer_signedness_dependent_methods {
             // SAFETY: negation of nonzero cannot yield zero values.
             unsafe { Self::new_unchecked(result) }
         }
+
+        /// Returns the bit pattern of `self` reinterpreted as an unsigned integer of the same size.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(integer_sign_cast)]
+        /// # use std::num::NonZero;
+        ///
+        #[doc = concat!("let n = NonZero::new(-1", stringify!($Int), ").unwrap();")]
+        ///
+        #[doc = concat!("assert_eq!(n.cast_unsigned(), NonZero::<", stringify!($Uint), ">::MAX);")]
+        /// ```
+        #[unstable(feature = "integer_sign_cast", issue = "125882")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline(always)]
+        pub const fn cast_unsigned(self) -> NonZero<$Uint> {
+            // SAFETY: `self.get()` can't be zero
+            unsafe { NonZero::new_unchecked(self.get().cast_unsigned()) }
+        }
+
     };
 }
 
 nonzero_integer! {
     Self = NonZeroU8,
     Primitive = unsigned u8,
+    SignedPrimitive = i8,
     rot = 2,
     rot_op = "0x82",
     rot_result = "0xa",
@@ -2052,6 +2107,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroU16,
     Primitive = unsigned u16,
+    SignedPrimitive = i16,
     rot = 4,
     rot_op = "0xa003",
     rot_result = "0x3a",
@@ -2063,6 +2119,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroU32,
     Primitive = unsigned u32,
+    SignedPrimitive = i32,
     rot = 8,
     rot_op = "0x10000b3",
     rot_result = "0xb301",
@@ -2074,6 +2131,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroU64,
     Primitive = unsigned u64,
+    SignedPrimitive = i64,
     rot = 12,
     rot_op = "0xaa00000000006e1",
     rot_result = "0x6e10aa",
@@ -2085,6 +2143,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroU128,
     Primitive = unsigned u128,
+    SignedPrimitive = i128,
     rot = 16,
     rot_op = "0x13f40000000000000000000000004f76",
     rot_result = "0x4f7613f4",
@@ -2097,6 +2156,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroUsize,
     Primitive = unsigned usize,
+    SignedPrimitive = isize,
     rot = 4,
     rot_op = "0xa003",
     rot_result = "0x3a",
@@ -2109,6 +2169,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroUsize,
     Primitive = unsigned usize,
+    SignedPrimitive = isize,
     rot = 8,
     rot_op = "0x10000b3",
     rot_result = "0xb301",
@@ -2121,6 +2182,7 @@ nonzero_integer! {
 nonzero_integer! {
     Self = NonZeroUsize,
     Primitive = unsigned usize,
+    SignedPrimitive = isize,
     rot = 12,
     rot_op = "0xaa00000000006e1",
     rot_result = "0x6e10aa",