Auto merge of #80962 - jhpratt:const_int_fn-stabilization, r=dtolnay

Stabilize remaining integer methods as `const fn` This pull request stabilizes the following methods as `const fn`: - `i*::checked_div` - `i*::checked_div_euclid` - `i*::checked_rem` - `i*::checked_rem_euclid` - `i*::div_euclid` - `i*::overflowing_div` - `i*::overflowing_div_euclid` - `i*::overflowing_rem` - `i*::overflowing_rem_euclid` - `i*::rem_euclid` - `i*::wrapping_div` - `i*::wrapping_div_euclid` - `i*::wrapping_rem` - `i*::wrapping_rem_euclid` - `u*::checked_div` - `u*::checked_div_euclid` - `u*::checked_rem` - `u*::checked_rem_euclid` - `u*::div_euclid` - `u*::overflowing_div` - `u*::overflowing_div_euclid` - `u*::overflowing_rem` - `u*::overflowing_rem_euclid` - `u*::rem_euclid` - `u*::wrapping_div` - `u*::wrapping_div_euclid` - `u*::wrapping_rem` - `u*::wrapping_rem_euclid` These can all be implemented on the current stable (1.49). There are two unstable details: const likely/unlikely and unchecked division/remainder. Both of these are for optimizations, and are in no way required to make the methods function; there is no exposure of these details publicly. Per comments below, it seems best practice is to stabilize the intrinsics. As such, `intrinsics::unchecked_div` and `intrinsics::unchecked_rem` have been stabilized as `const` as part of this pull request as well. The methods themselves remain unstable. I believe part of the reason these were not stabilized previously was the behavior around division by 0 and modulo 0. After testing on nightly, the diagnostic for something like `const _: i8 = 5i8 % 0i8;` is similar to that of `const _: i8 = 5i8.rem_euclid(0i8);` (assuming the appropriate feature flag is enabled). As such, I believe these methods are ready to be stabilized as `const fn`. This pull request represents the final methods mentioned in #53718. As such, this PR closes #53718. `@rustbot` modify labels to +A-const-fn, +T-libs
rust-lang · Feb 8, 2021 · 4940dd4 · 4940dd4
2 parents 0b7a598 + f55029a
commit 4940dd4
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diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
@@ -1586,15 +1586,15 @@ extern "rust-intrinsic" {
     /// Safe wrappers for this intrinsic are available on the integer
     /// primitives via the `checked_div` method. For example,
     /// [`u32::checked_div`]
-    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
+    #[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.51.0")]
     pub fn unchecked_div<T: Copy>(x: T, y: T) -> T;
     /// Returns the remainder of an unchecked division, resulting in
     /// undefined behavior when `y == 0` or `x == T::MIN && y == -1`
     ///
     /// Safe wrappers for this intrinsic are available on the integer
     /// primitives via the `checked_rem` method. For example,
     /// [`u32::checked_rem`]
-    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
+    #[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.51.0")]
     pub fn unchecked_rem<T: Copy>(x: T, y: T) -> T;
 
     /// Performs an unchecked left shift, resulting in undefined behavior when

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -73,11 +73,8 @@
 #![feature(const_discriminant)]
 #![feature(const_cell_into_inner)]
 #![feature(const_intrinsic_copy)]
-#![feature(const_checked_int_methods)]
-#![feature(const_euclidean_int_methods)]
 #![feature(const_float_classify)]
 #![feature(const_float_bits_conv)]
-#![feature(const_overflowing_int_methods)]
 #![feature(const_int_unchecked_arith)]
 #![feature(const_mut_refs)]
 #![feature(const_cttz)]

diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
@@ -513,7 +513,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!((1", stringify!($SelfT), ").checked_div(0), None);")]
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
-        #[rustc_const_unstable(feature = "const_checked_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -539,7 +539,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!((1", stringify!($SelfT), ").checked_div_euclid(0), None);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -565,7 +565,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.checked_rem(-1), None);")]
         /// ```
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_checked_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -591,7 +591,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.checked_rem_euclid(-1), None);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -949,7 +949,7 @@ macro_rules! int_impl {
         /// assert_eq!((-128i8).wrapping_div(-1), -128);
         /// ```
         #[stable(feature = "num_wrapping", since = "1.2.0")]
-        #[rustc_const_unstable(feature = "const_wrapping_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -977,7 +977,7 @@ macro_rules! int_impl {
         /// assert_eq!((-128i8).wrapping_div_euclid(-1), -128);
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1005,7 +1005,7 @@ macro_rules! int_impl {
         /// assert_eq!((-128i8).wrapping_rem(-1), 0);
         /// ```
         #[stable(feature = "num_wrapping", since = "1.2.0")]
-        #[rustc_const_unstable(feature = "const_wrapping_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1032,7 +1032,7 @@ macro_rules! int_impl {
         /// assert_eq!((-128i8).wrapping_rem_euclid(-1), 0);
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1299,7 +1299,7 @@ macro_rules! int_impl {
         /// ```
         #[inline]
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_overflowing_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
@@ -1329,7 +1329,7 @@ macro_rules! int_impl {
         /// ```
         #[inline]
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
@@ -1360,7 +1360,7 @@ macro_rules! int_impl {
         /// ```
         #[inline]
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_overflowing_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
@@ -1390,7 +1390,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.overflowing_rem_euclid(-1), (0, true));")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1615,7 +1615,7 @@ macro_rules! int_impl {
         /// assert_eq!((-a).div_euclid(-b), 2); // -7 >= -4 * 2
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1653,7 +1653,7 @@ macro_rules! int_impl {
         /// assert_eq!((-a).rem_euclid(-b), 1);
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]

diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
@@ -522,7 +522,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
-        #[rustc_const_unstable(feature = "const_checked_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -548,7 +548,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -573,7 +573,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
         /// ```
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_checked_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -599,7 +599,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -876,7 +876,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
         /// ```
         #[stable(feature = "num_wrapping", since = "1.2.0")]
-        #[rustc_const_unstable(feature = "const_wrapping_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -901,7 +901,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -924,7 +924,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
         /// ```
         #[stable(feature = "num_wrapping", since = "1.2.0")]
-        #[rustc_const_unstable(feature = "const_wrapping_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -950,7 +950,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1185,7 +1185,7 @@ macro_rules! uint_impl {
         /// ```
         #[inline]
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_overflowing_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
@@ -1215,7 +1215,7 @@ macro_rules! uint_impl {
         /// ```
         #[inline]
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
@@ -1242,7 +1242,7 @@ macro_rules! uint_impl {
         /// ```
         #[inline]
         #[stable(feature = "wrapping", since = "1.7.0")]
-        #[rustc_const_unstable(feature = "const_overflowing_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
@@ -1272,7 +1272,7 @@ macro_rules! uint_impl {
         /// ```
         #[inline]
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
@@ -1456,7 +1456,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
@@ -1484,7 +1484,7 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
         /// ```
         #[stable(feature = "euclidean_division", since = "1.38.0")]
-        #[rustc_const_unstable(feature = "const_euclidean_int_methods", issue = "53718")]
+        #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.51.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]

diff --git a/src/test/ui/consts/const-int-arithmetic.rs b/src/test/ui/consts/const-int-arithmetic.rs
@@ -1,10 +1,5 @@
 // run-pass
 
-#![feature(const_checked_int_methods)]
-#![feature(const_euclidean_int_methods)]
-#![feature(const_overflowing_int_methods)]
-#![feature(const_wrapping_int_methods)]
-
 macro_rules! suite {
     ($(
         $fn:ident -> $ty:ty { $( $label:ident : $expr:expr, $result:expr; )* }