From 853099f49c4680bf1f46802cb4f6a153717574dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gabriel=20Bj=C3=B8rnager=20Jensen?= <gabriel@achernar.io>
Date: Tue, 14 Oct 2025 20:54:40 +0200
Subject: [PATCH] Implement 'bit' and 'set_bit' for integral types;

---
 library/core/src/num/int_macros.rs            | 59 ++++++++++++++++++
 library/core/src/num/uint_macros.rs           | 61 +++++++++++++++++++
 tests/ui/const-generics/issues/issue-86820.rs |  2 +-
 3 files changed, 121 insertions(+), 1 deletion(-)

diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index c3460a6409069..28fd9e1013c97 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs
@@ -56,6 +56,65 @@ macro_rules! int_impl {
         #[stable(feature = "int_bits_const", since = "1.53.0")]
         pub const BITS: u32 = <$UnsignedT>::BITS;
 
+        /// Tests the value of a specific bit.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// #![feature(get_set_bit)]
+        ///
+        #[doc = concat!("let n = 0b1000001", stringify!($SelfT), ";")]
+        ///
+        /// assert!(n.bit(0));
+        /// assert!(!n.bit(1));
+        /// assert!(!n.bit(2));
+        /// assert!(!n.bit(3));
+        /// assert!(!n.bit(4));
+        /// assert!(!n.bit(5));
+        /// assert!(n.bit(6));
+        /// ```
+        #[unstable(feature = "get_set_bit", issue = "147702")]
+        #[rustc_const_unstable(feature = "get_set_bit", issue = "147702")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        #[track_caller]
+        pub const fn bit(self, index: u32) -> bool {
+            self & (1 as $SelfT) << index != (0 as $SelfT)
+        }
+
+        /// Sets the value of a specific bit.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// #![feature(get_set_bit)]
+        ///
+        #[doc = concat!("let mut n = 0b1010101", stringify!($SelfT), ";")]
+        ///
+        /// n = n.set_bit(0, false);
+        /// n = n.set_bit(1, true);
+        /// n = n.set_bit(2, false);
+        /// n = n.set_bit(3, true);
+        /// n = n.set_bit(4, false);
+        /// n = n.set_bit(5, true);
+        /// n = n.set_bit(6, false);
+        ///
+        /// assert_eq!(n, 0b0101010);
+        /// ```
+        #[unstable(feature = "get_set_bit", issue = "147702")]
+        #[rustc_const_unstable(feature = "get_set_bit", issue = "147702")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        #[track_caller]
+        pub const fn set_bit(mut self, index: u32, value: bool) -> Self {
+            self &= !((1 as $SelfT) << index);
+            self |= (value as $SelfT) << index;
+
+            self
+        }
+
         /// Returns the number of ones in the binary representation of `self`.
         ///
         /// # Examples
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index b5b768cf677aa..13077e98dbb40 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -57,6 +57,67 @@ macro_rules! uint_impl {
         #[stable(feature = "int_bits_const", since = "1.53.0")]
         pub const BITS: u32 = Self::MAX.count_ones();
 
+        /// Tests the value of a specific bit.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// #![feature(get_set_bit)]
+        ///
+        #[doc = concat!("let n = 0b10000001", stringify!($SelfT), ";")]
+        ///
+        /// assert!(n.bit(0));
+        /// assert!(!n.bit(1));
+        /// assert!(!n.bit(2));
+        /// assert!(!n.bit(3));
+        /// assert!(!n.bit(4));
+        /// assert!(!n.bit(5));
+        /// assert!(!n.bit(6));
+        /// assert!(n.bit(7));
+        /// ```
+        #[unstable(feature = "get_set_bit", issue = "147702")]
+        #[rustc_const_unstable(feature = "get_set_bit", issue = "147702")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        #[track_caller]
+        pub const fn bit(self, index: u32) -> bool {
+            self & (1 as $SelfT) << index != (0 as $SelfT)
+        }
+
+        /// Sets the value of a specific bit.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// #![feature(get_set_bit)]
+        ///
+        #[doc = concat!("let mut n = 0b01010101", stringify!($SelfT), ";")]
+        ///
+        /// n = n.set_bit(0, false);
+        /// n = n.set_bit(1, true);
+        /// n = n.set_bit(2, false);
+        /// n = n.set_bit(3, true);
+        /// n = n.set_bit(4, false);
+        /// n = n.set_bit(5, true);
+        /// n = n.set_bit(6, false);
+        /// n = n.set_bit(7, true);
+        ///
+        /// assert_eq!(n, 0b10101010);
+        /// ```
+        #[unstable(feature = "get_set_bit", issue = "147702")]
+        #[rustc_const_unstable(feature = "get_set_bit", issue = "147702")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        #[track_caller]
+        pub const fn set_bit(mut self, index: u32, value: bool) -> Self {
+            self &= !((1 as $SelfT) << index);
+            self |= (value as $SelfT) << index;
+
+            self
+        }
+
         /// Returns the number of ones in the binary representation of `self`.
         ///
         /// # Examples
diff --git a/tests/ui/const-generics/issues/issue-86820.rs b/tests/ui/const-generics/issues/issue-86820.rs
index ae4bd943fd415..d20432ce27a4f 100644
--- a/tests/ui/const-generics/issues/issue-86820.rs
+++ b/tests/ui/const-generics/issues/issue-86820.rs
@@ -5,7 +5,7 @@ use std::ops::BitAnd;
 
 const C: fn() = || is_set();
 fn is_set() {
-    0xffu8.bit::<0>();
+    Bits::bit::<0>(0xffu8);
 }
 
 trait Bits {