Rollup merge of rust-lang#119726 - NCGThompson:div-overflow-doc, r=Nilstrieb

Tweak Library Integer Division Docs

Improved the documentation and diagnostics related to panicking in the division-like methods in std:

* For signed methods that can overflow, clarified "results in overflow" to "self is -1 and rhs is Self::MIN." This is more concise than saying "results in overflow" and then explaining how it could overflow.
* For floor/ceil_div, corrected the documentation and made it more like the documentation in other methods.
* For signed methods that can overflow, explicitly mention that they are not affected by compiler flags.
* Removed all unused rustc_inherit_overflow_checks attributes. The non-division-like operations will never overflow.
* Added track_caller attributes to all methods that can panic. The panic messages will always be correct. For example, division methods all have / before %.
* Edited the saturating_div documentation to be consistent with similar methods.

Author: matthiaskrgr

library/core/src/num/int_macros.rs

@@ -1643,6 +1643,10 @@ macro_rules! int_impl {
         /// Saturating integer division. Computes `self / rhs`, saturating at the
         /// numeric bounds instead of overflowing.
         ///
+        /// # Panics
+        ///
+        /// This function will panic if `rhs` is 0.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -1653,11 +1657,6 @@ macro_rules! int_impl {
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.saturating_div(-1), ", stringify!($SelfT), "::MAX);")]
         ///
         /// ```
-        ///
-        /// ```should_panic
-        #[doc = concat!("let _ = 1", stringify!($SelfT), ".saturating_div(0);")]
-        ///
-        /// ```
         #[stable(feature = "saturating_div", since = "1.58.0")]
         #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
         #[must_use = "this returns the result of the operation, \
@@ -2435,6 +2434,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
+        #[track_caller]
         pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
             if unlikely!(rhs == -1) {
                 (0, self == Self::MIN)
@@ -2674,7 +2674,8 @@ macro_rules! int_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `rhs` is 0 or the division results in overflow.
+        /// This function will panic if `rhs` is 0 or if `self` is -1 and `rhs` is
+        /// `Self::MIN`. This behavior is not affected by the `overflow-checks` flag.
         ///
         /// # Examples
         ///
@@ -2694,7 +2695,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn div_euclid(self, rhs: Self) -> Self {
             let q = self / rhs;
             if self % rhs < 0 {
@@ -2712,7 +2713,8 @@ macro_rules! int_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `rhs` is 0 or the division results in overflow.
+        /// This function will panic if `rhs` is 0 or if `self` is -1 and `rhs` is
+        /// `Self::MIN`. This behavior is not affected by the `overflow-checks` flag.
         ///
         /// # Examples
         ///
@@ -2733,7 +2735,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn rem_euclid(self, rhs: Self) -> Self {
             let r = self % rhs;
             if r < 0 {
@@ -2755,12 +2757,8 @@ macro_rules! int_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `rhs` is zero.
-        ///
-        /// ## Overflow behavior
-        ///
-        /// On overflow, this function will panic if overflow checks are enabled (default in debug
-        /// mode) and wrap if overflow checks are disabled (default in release mode).
+        /// This function will panic if `rhs` is 0 or if `self` is -1 and `rhs` is
+        /// `Self::MIN`. This behavior is not affected by the `overflow-checks` flag.
         ///
         /// # Examples
         ///
@@ -2780,7 +2778,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn div_floor(self, rhs: Self) -> Self {
             let d = self / rhs;
             let r = self % rhs;
@@ -2795,12 +2793,8 @@ macro_rules! int_impl {
         ///
         /// # Panics
         ///
-        /// This function will panic if `rhs` is zero.
-        ///
-        /// ## Overflow behavior
-        ///
-        /// On overflow, this function will panic if overflow checks are enabled (default in debug
-        /// mode) and wrap if overflow checks are disabled (default in release mode).
+        /// This function will panic if `rhs` is 0 or if `self` is -1 and `rhs` is
+        /// `Self::MIN`. This behavior is not affected by the `overflow-checks` flag.
         ///
         /// # Examples
         ///
@@ -2820,7 +2814,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn div_ceil(self, rhs: Self) -> Self {
             let d = self / rhs;
             let r = self % rhs;

library/core/src/num/uint_macros.rs

@@ -1531,6 +1531,10 @@ macro_rules! uint_impl {
         /// Saturating integer division. Computes `self / rhs`, saturating at the
         /// numeric bounds instead of overflowing.
         ///
+        /// # Panics
+        ///
+        /// This function will panic if `rhs` is 0.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -1539,16 +1543,12 @@ macro_rules! uint_impl {
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
         ///
         /// ```
-        ///
-        /// ```should_panic
-        #[doc = concat!("let _ = 1", stringify!($SelfT), ".saturating_div(0);")]
-        ///
-        /// ```
         #[stable(feature = "saturating_div", since = "1.58.0")]
         #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
+        #[track_caller]
         pub const fn saturating_div(self, rhs: Self) -> Self {
             // on unsigned types, there is no overflow in integer division
             self.wrapping_div(rhs)
@@ -1683,6 +1683,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[track_caller]
         pub const fn wrapping_div(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -1712,6 +1713,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[track_caller]
         pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -1739,6 +1741,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[track_caller]
         pub const fn wrapping_rem(self, rhs: Self) -> Self {
             self % rhs
         }
@@ -1769,6 +1772,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[track_caller]
         pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
             self % rhs
         }
@@ -2151,6 +2155,7 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[track_caller]
         pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
             (self / rhs, false)
         }
@@ -2181,6 +2186,7 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[track_caller]
         pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
             (self / rhs, false)
         }
@@ -2208,6 +2214,7 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[track_caller]
         pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
             (self % rhs, false)
         }
@@ -2238,6 +2245,7 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[track_caller]
         pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
             (self % rhs, false)
         }
@@ -2473,7 +2481,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn div_euclid(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -2502,7 +2510,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn rem_euclid(self, rhs: Self) -> Self {
             self % rhs
         }
@@ -2527,6 +2535,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[track_caller]
         pub const fn div_floor(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -2537,11 +2546,6 @@ macro_rules! uint_impl {
         ///
         /// This function will panic if `rhs` is zero.
         ///
-        /// ## Overflow behavior
-        ///
-        /// On overflow, this function will panic if overflow checks are enabled (default in debug
-        /// mode) and wrap if overflow checks are disabled (default in release mode).
-        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -2554,7 +2558,7 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline]
-        #[rustc_inherit_overflow_checks]
+        #[track_caller]
         pub const fn div_ceil(self, rhs: Self) -> Self {
             let d = self / rhs;
             let r = self % rhs;