From 23d033e17788d828aad233ff7c55652ac310d0b8 Mon Sep 17 00:00:00 2001
From: AlexApps99 <alex.apps99@gmail.com>
Date: Fri, 22 Oct 2021 10:03:18 +1300
Subject: [PATCH 01/12] Added const versions of common numeric operations

# Conflicts:
#	library/core/src/lib.rs
---
 library/core/src/internal_macros.rs |  68 +++++++++++++++
 library/core/src/lib.rs             |   1 +
 library/core/src/num/nonzero.rs     |  21 +++--
 library/core/src/num/wrapping.rs    | 128 +++++++++++++++++-----------
 library/core/src/ops/arith.rs       |  65 ++++++++------
 library/core/src/ops/bit.rs         |  55 +++++++-----
 6 files changed, 232 insertions(+), 106 deletions(-)

diff --git a/library/core/src/internal_macros.rs b/library/core/src/internal_macros.rs
index be12f90464084..b5c1bf6897c18 100644
--- a/library/core/src/internal_macros.rs
+++ b/library/core/src/internal_macros.rs
@@ -5,6 +5,22 @@ macro_rules! forward_ref_unop {
         forward_ref_unop!(impl $imp, $method for $t,
                 #[stable(feature = "rust1", since = "1.0.0")]);
     };
+    (impl const $imp:ident, $method:ident for $t:ty) => {
+        forward_ref_unop!(impl const $imp, $method for $t,
+                #[stable(feature = "rust1", since = "1.0.0")]);
+    };
+    (impl const $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => {
+        #[$attr]
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const $imp for &$t {
+            type Output = <$t as $imp>::Output;
+
+            #[inline]
+            fn $method(self) -> <$t as $imp>::Output {
+                $imp::$method(*self)
+            }
+        }
+    };
     (impl $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => {
         #[$attr]
         impl $imp for &$t {
@@ -25,6 +41,44 @@ macro_rules! forward_ref_binop {
         forward_ref_binop!(impl $imp, $method for $t, $u,
                 #[stable(feature = "rust1", since = "1.0.0")]);
     };
+    (impl const $imp:ident, $method:ident for $t:ty, $u:ty) => {
+        forward_ref_binop!(impl const $imp, $method for $t, $u,
+                #[stable(feature = "rust1", since = "1.0.0")]);
+    };
+    (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
+        #[$attr]
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl<'a> const $imp<$u> for &'a $t {
+            type Output = <$t as $imp<$u>>::Output;
+
+            #[inline]
+            fn $method(self, other: $u) -> <$t as $imp<$u>>::Output {
+                $imp::$method(*self, other)
+            }
+        }
+
+        #[$attr]
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const $imp<&$u> for $t {
+            type Output = <$t as $imp<$u>>::Output;
+
+            #[inline]
+            fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output {
+                $imp::$method(self, *other)
+            }
+        }
+
+        #[$attr]
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const $imp<&$u> for &$t {
+            type Output = <$t as $imp<$u>>::Output;
+
+            #[inline]
+            fn $method(self, other: &$u) -> <$t as $imp<$u>>::Output {
+                $imp::$method(*self, *other)
+            }
+        }
+    };
     (impl $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
         #[$attr]
         impl<'a> $imp<$u> for &'a $t {
@@ -65,6 +119,20 @@ macro_rules! forward_ref_op_assign {
         forward_ref_op_assign!(impl $imp, $method for $t, $u,
                 #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]);
     };
+    (impl const $imp:ident, $method:ident for $t:ty, $u:ty) => {
+        forward_ref_op_assign!(impl const $imp, $method for $t, $u,
+                #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]);
+    };
+    (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
+        #[$attr]
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const $imp<&$u> for $t {
+            #[inline]
+            fn $method(&mut self, other: &$u) {
+                $imp::$method(self, *other);
+            }
+        }
+    };
     (impl $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
         #[$attr]
         impl $imp<&$u> for $t {
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 58a170401e7c1..87857873dfd88 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -116,6 +116,7 @@
 #![feature(const_maybe_uninit_as_ptr)]
 #![feature(const_maybe_uninit_assume_init)]
 #![feature(const_num_from_num)]
+#![feature(const_ops)]
 #![feature(const_option)]
 #![feature(const_pin)]
 #![feature(const_replace)]
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 9b1a4de5d8037..7708094e1fcea 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -92,7 +92,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "nonzero_bitor", since = "1.45.0")]
-            impl BitOr for $Ty {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const BitOr for $Ty {
                 type Output = Self;
                 #[inline]
                 fn bitor(self, rhs: Self) -> Self::Output {
@@ -103,7 +104,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "nonzero_bitor", since = "1.45.0")]
-            impl BitOr<$Int> for $Ty {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const BitOr<$Int> for $Ty {
                 type Output = Self;
                 #[inline]
                 fn bitor(self, rhs: $Int) -> Self::Output {
@@ -115,7 +117,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "nonzero_bitor", since = "1.45.0")]
-            impl BitOr<$Ty> for $Int {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const BitOr<$Ty> for $Int {
                 type Output = $Ty;
                 #[inline]
                 fn bitor(self, rhs: $Ty) -> Self::Output {
@@ -127,7 +130,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "nonzero_bitor", since = "1.45.0")]
-            impl BitOrAssign for $Ty {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const BitOrAssign for $Ty {
                 #[inline]
                 fn bitor_assign(&mut self, rhs: Self) {
                     *self = *self | rhs;
@@ -135,7 +139,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "nonzero_bitor", since = "1.45.0")]
-            impl BitOrAssign<$Int> for $Ty {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const BitOrAssign<$Int> for $Ty {
                 #[inline]
                 fn bitor_assign(&mut self, rhs: $Int) {
                     *self = *self | rhs;
@@ -257,7 +262,8 @@ macro_rules! nonzero_integers_div {
     ( $( $Ty: ident($Int: ty); )+ ) => {
         $(
             #[stable(feature = "nonzero_div", since = "1.51.0")]
-            impl Div<$Ty> for $Int {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const Div<$Ty> for $Int {
                 type Output = $Int;
                 /// This operation rounds towards zero,
                 /// truncating any fractional part of the exact result, and cannot panic.
@@ -270,7 +276,8 @@ macro_rules! nonzero_integers_div {
             }
 
             #[stable(feature = "nonzero_div", since = "1.51.0")]
-            impl Rem<$Ty> for $Int {
+            #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+            impl const Rem<$Ty> for $Int {
                 type Output = $Int;
                 /// This operation satisfies `n % d == n - (n / d) * d`, and cannot panic.
                 #[inline]
diff --git a/library/core/src/num/wrapping.rs b/library/core/src/num/wrapping.rs
index f387bd5b41cc4..a0e42c51e4517 100644
--- a/library/core/src/num/wrapping.rs
+++ b/library/core/src/num/wrapping.rs
@@ -87,7 +87,8 @@ impl<T: fmt::UpperHex> fmt::UpperHex for Wrapping<T> {
 macro_rules! sh_impl_signed {
     ($t:ident, $f:ident) => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shl<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shl<$f> for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -99,20 +100,22 @@ macro_rules! sh_impl_signed {
                 }
             }
         }
-        forward_ref_binop! { impl Shl, shl for Wrapping<$t>, $f,
+        forward_ref_binop! { impl const Shl, shl for Wrapping<$t>, $f,
         #[stable(feature = "wrapping_ref_ops", since = "1.39.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShlAssign<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShlAssign<$f> for Wrapping<$t> {
             #[inline]
             fn shl_assign(&mut self, other: $f) {
                 *self = *self << other;
             }
         }
-        forward_ref_op_assign! { impl ShlAssign, shl_assign for Wrapping<$t>, $f }
+        forward_ref_op_assign! { impl const ShlAssign, shl_assign for Wrapping<$t>, $f }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shr<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shr<$f> for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -124,24 +127,26 @@ macro_rules! sh_impl_signed {
                 }
             }
         }
-        forward_ref_binop! { impl Shr, shr for Wrapping<$t>, $f,
+        forward_ref_binop! { impl const Shr, shr for Wrapping<$t>, $f,
         #[stable(feature = "wrapping_ref_ops", since = "1.39.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShrAssign<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShrAssign<$f> for Wrapping<$t> {
             #[inline]
             fn shr_assign(&mut self, other: $f) {
                 *self = *self >> other;
             }
         }
-        forward_ref_op_assign! { impl ShrAssign, shr_assign for Wrapping<$t>, $f }
+        forward_ref_op_assign! { impl const ShrAssign, shr_assign for Wrapping<$t>, $f }
     };
 }
 
 macro_rules! sh_impl_unsigned {
     ($t:ident, $f:ident) => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shl<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shl<$f> for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -149,20 +154,22 @@ macro_rules! sh_impl_unsigned {
                 Wrapping(self.0.wrapping_shl((other & self::shift_max::$t as $f) as u32))
             }
         }
-        forward_ref_binop! { impl Shl, shl for Wrapping<$t>, $f,
+        forward_ref_binop! { impl const Shl, shl for Wrapping<$t>, $f,
         #[stable(feature = "wrapping_ref_ops", since = "1.39.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShlAssign<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShlAssign<$f> for Wrapping<$t> {
             #[inline]
             fn shl_assign(&mut self, other: $f) {
                 *self = *self << other;
             }
         }
-        forward_ref_op_assign! { impl ShlAssign, shl_assign for Wrapping<$t>, $f }
+        forward_ref_op_assign! { impl const ShlAssign, shl_assign for Wrapping<$t>, $f }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shr<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shr<$f> for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -170,17 +177,18 @@ macro_rules! sh_impl_unsigned {
                 Wrapping(self.0.wrapping_shr((other & self::shift_max::$t as $f) as u32))
             }
         }
-        forward_ref_binop! { impl Shr, shr for Wrapping<$t>, $f,
+        forward_ref_binop! { impl const Shr, shr for Wrapping<$t>, $f,
         #[stable(feature = "wrapping_ref_ops", since = "1.39.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShrAssign<$f> for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShrAssign<$f> for Wrapping<$t> {
             #[inline]
             fn shr_assign(&mut self, other: $f) {
                 *self = *self >> other;
             }
         }
-        forward_ref_op_assign! { impl ShrAssign, shr_assign for Wrapping<$t>, $f }
+        forward_ref_op_assign! { impl const ShrAssign, shr_assign for Wrapping<$t>, $f }
     };
 }
 
@@ -209,7 +217,8 @@ sh_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize }
 macro_rules! wrapping_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Add for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Add for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -217,20 +226,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0.wrapping_add(other.0))
             }
         }
-        forward_ref_binop! { impl Add, add for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const Add, add for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl AddAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const AddAssign for Wrapping<$t> {
             #[inline]
             fn add_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self + other;
             }
         }
-        forward_ref_op_assign! { impl AddAssign, add_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const AddAssign, add_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Sub for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Sub for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -238,20 +249,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0.wrapping_sub(other.0))
             }
         }
-        forward_ref_binop! { impl Sub, sub for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const Sub, sub for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl SubAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const SubAssign for Wrapping<$t> {
             #[inline]
             fn sub_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self - other;
             }
         }
-        forward_ref_op_assign! { impl SubAssign, sub_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const SubAssign, sub_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Mul for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Mul for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -263,16 +276,18 @@ macro_rules! wrapping_impl {
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl MulAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const MulAssign for Wrapping<$t> {
             #[inline]
             fn mul_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self * other;
             }
         }
-        forward_ref_op_assign! { impl MulAssign, mul_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const MulAssign, mul_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_div", since = "1.3.0")]
-        impl Div for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Div for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -280,20 +295,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0.wrapping_div(other.0))
             }
         }
-        forward_ref_binop! { impl Div, div for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const Div, div for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl DivAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const DivAssign for Wrapping<$t> {
             #[inline]
             fn div_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self / other;
             }
         }
-        forward_ref_op_assign! { impl DivAssign, div_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const DivAssign, div_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_impls", since = "1.7.0")]
-        impl Rem for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Rem for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -301,20 +318,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0.wrapping_rem(other.0))
             }
         }
-        forward_ref_binop! { impl Rem, rem for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const Rem, rem for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl RemAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const RemAssign for Wrapping<$t> {
             #[inline]
             fn rem_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self % other;
             }
         }
-        forward_ref_op_assign! { impl RemAssign, rem_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const RemAssign, rem_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Not for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Not for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -322,11 +341,12 @@ macro_rules! wrapping_impl {
                 Wrapping(!self.0)
             }
         }
-        forward_ref_unop! { impl Not, not for Wrapping<$t>,
+        forward_ref_unop! { impl const Not, not for Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitXor for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitXor for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -334,20 +354,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0 ^ other.0)
             }
         }
-        forward_ref_binop! { impl BitXor, bitxor for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const BitXor, bitxor for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitXorAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitXorAssign for Wrapping<$t> {
             #[inline]
             fn bitxor_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self ^ other;
             }
         }
-        forward_ref_op_assign! { impl BitXorAssign, bitxor_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const BitXorAssign, bitxor_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitOr for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitOr for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -355,20 +377,22 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0 | other.0)
             }
         }
-        forward_ref_binop! { impl BitOr, bitor for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const BitOr, bitor for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitOrAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitOrAssign for Wrapping<$t> {
             #[inline]
             fn bitor_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self | other;
             }
         }
-        forward_ref_op_assign! { impl BitOrAssign, bitor_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const BitOrAssign, bitor_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitAnd for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitAnd for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline]
@@ -376,27 +400,29 @@ macro_rules! wrapping_impl {
                 Wrapping(self.0 & other.0)
             }
         }
-        forward_ref_binop! { impl BitAnd, bitand for Wrapping<$t>, Wrapping<$t>,
+        forward_ref_binop! { impl const BitAnd, bitand for Wrapping<$t>, Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitAndAssign for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitAndAssign for Wrapping<$t> {
             #[inline]
             fn bitand_assign(&mut self, other: Wrapping<$t>) {
                 *self = *self & other;
             }
         }
-        forward_ref_op_assign! { impl BitAndAssign, bitand_assign for Wrapping<$t>, Wrapping<$t> }
+        forward_ref_op_assign! { impl const BitAndAssign, bitand_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_neg", since = "1.10.0")]
-        impl Neg for Wrapping<$t> {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Neg for Wrapping<$t> {
             type Output = Self;
             #[inline]
             fn neg(self) -> Self {
                 Wrapping(0) - self
             }
         }
-        forward_ref_unop! { impl Neg, neg for Wrapping<$t>,
+        forward_ref_unop! { impl const Neg, neg for Wrapping<$t>,
                 #[stable(feature = "wrapping_ref", since = "1.14.0")] }
 
     )*)
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index a0577b287ce24..e954742938910 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -92,7 +92,8 @@ pub trait Add<Rhs = Self> {
 macro_rules! add_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Add for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Add for $t {
             type Output = $t;
 
             #[inline]
@@ -100,7 +101,7 @@ macro_rules! add_impl {
             fn add(self, other: $t) -> $t { self + other }
         }
 
-        forward_ref_binop! { impl Add, add for $t, $t }
+        forward_ref_binop! { impl const Add, add for $t, $t }
     )*)
 }
 
@@ -198,7 +199,8 @@ pub trait Sub<Rhs = Self> {
 macro_rules! sub_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Sub for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Sub for $t {
             type Output = $t;
 
             #[inline]
@@ -206,7 +208,7 @@ macro_rules! sub_impl {
             fn sub(self, other: $t) -> $t { self - other }
         }
 
-        forward_ref_binop! { impl Sub, sub for $t, $t }
+        forward_ref_binop! { impl const Sub, sub for $t, $t }
     )*)
 }
 
@@ -326,7 +328,8 @@ pub trait Mul<Rhs = Self> {
 macro_rules! mul_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Mul for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Mul for $t {
             type Output = $t;
 
             #[inline]
@@ -334,7 +337,7 @@ macro_rules! mul_impl {
             fn mul(self, other: $t) -> $t { self * other }
         }
 
-        forward_ref_binop! { impl Mul, mul for $t, $t }
+        forward_ref_binop! { impl const Mul, mul for $t, $t }
     )*)
 }
 
@@ -464,14 +467,15 @@ macro_rules! div_impl_integer {
         ///
         #[doc = $panic]
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Div for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Div for $t {
             type Output = $t;
 
             #[inline]
             fn div(self, other: $t) -> $t { self / other }
         }
 
-        forward_ref_binop! { impl Div, div for $t, $t }
+        forward_ref_binop! { impl const Div, div for $t, $t }
     )*)*)
 }
 
@@ -483,14 +487,15 @@ div_impl_integer! {
 macro_rules! div_impl_float {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Div for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Div for $t {
             type Output = $t;
 
             #[inline]
             fn div(self, other: $t) -> $t { self / other }
         }
 
-        forward_ref_binop! { impl Div, div for $t, $t }
+        forward_ref_binop! { impl const Div, div for $t, $t }
     )*)
 }
 
@@ -564,14 +569,15 @@ macro_rules! rem_impl_integer {
         ///
         #[doc = $panic]
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Rem for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Rem for $t {
             type Output = $t;
 
             #[inline]
             fn rem(self, other: $t) -> $t { self % other }
         }
 
-        forward_ref_binop! { impl Rem, rem for $t, $t }
+        forward_ref_binop! { impl const Rem, rem for $t, $t }
     )*)*)
 }
 
@@ -598,14 +604,15 @@ macro_rules! rem_impl_float {
         /// assert_eq!(x % y, remainder);
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Rem for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Rem for $t {
             type Output = $t;
 
             #[inline]
             fn rem(self, other: $t) -> $t { self % other }
         }
 
-        forward_ref_binop! { impl Rem, rem for $t, $t }
+        forward_ref_binop! { impl const Rem, rem for $t, $t }
     )*)
 }
 
@@ -671,7 +678,8 @@ pub trait Neg {
 macro_rules! neg_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Neg for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Neg for $t {
             type Output = $t;
 
             #[inline]
@@ -679,7 +687,7 @@ macro_rules! neg_impl {
             fn neg(self) -> $t { -self }
         }
 
-        forward_ref_unop! { impl Neg, neg for $t }
+        forward_ref_unop! { impl const Neg, neg for $t }
     )*)
 }
 
@@ -739,13 +747,14 @@ pub trait AddAssign<Rhs = Self> {
 macro_rules! add_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl AddAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const AddAssign for $t {
             #[inline]
             #[rustc_inherit_overflow_checks]
             fn add_assign(&mut self, other: $t) { *self += other }
         }
 
-        forward_ref_op_assign! { impl AddAssign, add_assign for $t, $t }
+        forward_ref_op_assign! { impl const AddAssign, add_assign for $t, $t }
     )+)
 }
 
@@ -805,13 +814,14 @@ pub trait SubAssign<Rhs = Self> {
 macro_rules! sub_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl SubAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const SubAssign for $t {
             #[inline]
             #[rustc_inherit_overflow_checks]
             fn sub_assign(&mut self, other: $t) { *self -= other }
         }
 
-        forward_ref_op_assign! { impl SubAssign, sub_assign for $t, $t }
+        forward_ref_op_assign! { impl const SubAssign, sub_assign for $t, $t }
     )+)
 }
 
@@ -862,13 +872,14 @@ pub trait MulAssign<Rhs = Self> {
 macro_rules! mul_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl MulAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const MulAssign for $t {
             #[inline]
             #[rustc_inherit_overflow_checks]
             fn mul_assign(&mut self, other: $t) { *self *= other }
         }
 
-        forward_ref_op_assign! { impl MulAssign, mul_assign for $t, $t }
+        forward_ref_op_assign! { impl const MulAssign, mul_assign for $t, $t }
     )+)
 }
 
@@ -919,12 +930,13 @@ pub trait DivAssign<Rhs = Self> {
 macro_rules! div_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl DivAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const DivAssign for $t {
             #[inline]
             fn div_assign(&mut self, other: $t) { *self /= other }
         }
 
-        forward_ref_op_assign! { impl DivAssign, div_assign for $t, $t }
+        forward_ref_op_assign! { impl const DivAssign, div_assign for $t, $t }
     )+)
 }
 
@@ -979,12 +991,13 @@ pub trait RemAssign<Rhs = Self> {
 macro_rules! rem_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl RemAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const RemAssign for $t {
             #[inline]
             fn rem_assign(&mut self, other: $t) { *self %= other }
         }
 
-        forward_ref_op_assign! { impl RemAssign, rem_assign for $t, $t }
+        forward_ref_op_assign! { impl const RemAssign, rem_assign for $t, $t }
     )+)
 }
 
diff --git a/library/core/src/ops/bit.rs b/library/core/src/ops/bit.rs
index 92f45ac9e7ea9..255f6cb7933a2 100644
--- a/library/core/src/ops/bit.rs
+++ b/library/core/src/ops/bit.rs
@@ -54,14 +54,15 @@ pub trait Not {
 macro_rules! not_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Not for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Not for $t {
             type Output = $t;
 
             #[inline]
             fn not(self) -> $t { !self }
         }
 
-        forward_ref_unop! { impl Not, not for $t }
+        forward_ref_unop! { impl const Not, not for $t }
     )*)
 }
 
@@ -154,14 +155,15 @@ pub trait BitAnd<Rhs = Self> {
 macro_rules! bitand_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitAnd for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitAnd for $t {
             type Output = $t;
 
             #[inline]
             fn bitand(self, rhs: $t) -> $t { self & rhs }
         }
 
-        forward_ref_binop! { impl BitAnd, bitand for $t, $t }
+        forward_ref_binop! { impl const BitAnd, bitand for $t, $t }
     )*)
 }
 
@@ -254,14 +256,15 @@ pub trait BitOr<Rhs = Self> {
 macro_rules! bitor_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitOr for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitOr for $t {
             type Output = $t;
 
             #[inline]
             fn bitor(self, rhs: $t) -> $t { self | rhs }
         }
 
-        forward_ref_binop! { impl BitOr, bitor for $t, $t }
+        forward_ref_binop! { impl const BitOr, bitor for $t, $t }
     )*)
 }
 
@@ -354,14 +357,15 @@ pub trait BitXor<Rhs = Self> {
 macro_rules! bitxor_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl BitXor for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitXor for $t {
             type Output = $t;
 
             #[inline]
             fn bitxor(self, other: $t) -> $t { self ^ other }
         }
 
-        forward_ref_binop! { impl BitXor, bitxor for $t, $t }
+        forward_ref_binop! { impl const BitXor, bitxor for $t, $t }
     )*)
 }
 
@@ -451,7 +455,8 @@ pub trait Shl<Rhs = Self> {
 macro_rules! shl_impl {
     ($t:ty, $f:ty) => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shl<$f> for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shl<$f> for $t {
             type Output = $t;
 
             #[inline]
@@ -461,7 +466,7 @@ macro_rules! shl_impl {
             }
         }
 
-        forward_ref_binop! { impl Shl, shl for $t, $f }
+        forward_ref_binop! { impl const Shl, shl for $t, $f }
     };
 }
 
@@ -569,7 +574,8 @@ pub trait Shr<Rhs = Self> {
 macro_rules! shr_impl {
     ($t:ty, $f:ty) => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl Shr<$f> for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const Shr<$f> for $t {
             type Output = $t;
 
             #[inline]
@@ -579,7 +585,7 @@ macro_rules! shr_impl {
             }
         }
 
-        forward_ref_binop! { impl Shr, shr for $t, $f }
+        forward_ref_binop! { impl const Shr, shr for $t, $f }
     };
 }
 
@@ -704,12 +710,13 @@ pub trait BitAndAssign<Rhs = Self> {
 macro_rules! bitand_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitAndAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitAndAssign for $t {
             #[inline]
             fn bitand_assign(&mut self, other: $t) { *self &= other }
         }
 
-        forward_ref_op_assign! { impl BitAndAssign, bitand_assign for $t, $t }
+        forward_ref_op_assign! { impl const BitAndAssign, bitand_assign for $t, $t }
     )+)
 }
 
@@ -775,12 +782,13 @@ pub trait BitOrAssign<Rhs = Self> {
 macro_rules! bitor_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitOrAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitOrAssign for $t {
             #[inline]
             fn bitor_assign(&mut self, other: $t) { *self |= other }
         }
 
-        forward_ref_op_assign! { impl BitOrAssign, bitor_assign for $t, $t }
+        forward_ref_op_assign! { impl const BitOrAssign, bitor_assign for $t, $t }
     )+)
 }
 
@@ -846,12 +854,13 @@ pub trait BitXorAssign<Rhs = Self> {
 macro_rules! bitxor_assign_impl {
     ($($t:ty)+) => ($(
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl BitXorAssign for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const BitXorAssign for $t {
             #[inline]
             fn bitxor_assign(&mut self, other: $t) { *self ^= other }
         }
 
-        forward_ref_op_assign! { impl BitXorAssign, bitxor_assign for $t, $t }
+        forward_ref_op_assign! { impl const BitXorAssign, bitxor_assign for $t, $t }
     )+)
 }
 
@@ -907,7 +916,8 @@ pub trait ShlAssign<Rhs = Self> {
 macro_rules! shl_assign_impl {
     ($t:ty, $f:ty) => {
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShlAssign<$f> for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShlAssign<$f> for $t {
             #[inline]
             #[rustc_inherit_overflow_checks]
             fn shl_assign(&mut self, other: $f) {
@@ -915,7 +925,7 @@ macro_rules! shl_assign_impl {
             }
         }
 
-        forward_ref_op_assign! { impl ShlAssign, shl_assign for $t, $f }
+        forward_ref_op_assign! { impl const ShlAssign, shl_assign for $t, $f }
     };
 }
 
@@ -989,7 +999,8 @@ pub trait ShrAssign<Rhs = Self> {
 macro_rules! shr_assign_impl {
     ($t:ty, $f:ty) => {
         #[stable(feature = "op_assign_traits", since = "1.8.0")]
-        impl ShrAssign<$f> for $t {
+        #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
+        impl const ShrAssign<$f> for $t {
             #[inline]
             #[rustc_inherit_overflow_checks]
             fn shr_assign(&mut self, other: $f) {
@@ -997,7 +1008,7 @@ macro_rules! shr_assign_impl {
             }
         }
 
-        forward_ref_op_assign! { impl ShrAssign, shr_assign for $t, $f }
+        forward_ref_op_assign! { impl const ShrAssign, shr_assign for $t, $f }
     };
 }
 

From 361c978fbd41535f3c7fd0b2f956d4e1ee4aeefd Mon Sep 17 00:00:00 2001
From: AlexApps99 <alex.apps99@gmail.com>
Date: Thu, 21 Oct 2021 12:26:26 +1300
Subject: [PATCH 02/12] Added docs to internal_macro const

---
 library/core/src/internal_macros.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/library/core/src/internal_macros.rs b/library/core/src/internal_macros.rs
index b5c1bf6897c18..9c6acfb1e8c94 100644
--- a/library/core/src/internal_macros.rs
+++ b/library/core/src/internal_macros.rs
@@ -9,6 +9,7 @@ macro_rules! forward_ref_unop {
         forward_ref_unop!(impl const $imp, $method for $t,
                 #[stable(feature = "rust1", since = "1.0.0")]);
     };
+    // Equivalent to the non-const version, with the addition of `rustc_const_unstable`
     (impl const $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => {
         #[$attr]
         #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
@@ -45,6 +46,7 @@ macro_rules! forward_ref_binop {
         forward_ref_binop!(impl const $imp, $method for $t, $u,
                 #[stable(feature = "rust1", since = "1.0.0")]);
     };
+    // Equivalent to the non-const version, with the addition of `rustc_const_unstable`
     (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
         #[$attr]
         #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
@@ -123,6 +125,7 @@ macro_rules! forward_ref_op_assign {
         forward_ref_op_assign!(impl const $imp, $method for $t, $u,
                 #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]);
     };
+    // Equivalent to the non-const version, with the addition of `rustc_const_unstable`
     (impl const $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
         #[$attr]
         #[rustc_const_unstable(feature = "const_ops", issue = "90080")]

From 29a4e4a009a32094e85bb9867432d45a2e0edacd Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Thu, 28 Oct 2021 11:51:00 +0200
Subject: [PATCH 03/12] Fix incorrect doc link

---
 library/core/src/str/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 607a0179ff4b9..7939ea3bb7fb2 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -1663,7 +1663,7 @@ impl str {
     /// If the pattern allows a reverse search but its results might differ
     /// from a forward search, the [`rmatch_indices`] method can be used.
     ///
-    /// [`rmatch_indices`]: str::match_indices
+    /// [`rmatch_indices`]: str::rmatch_indices
     ///
     /// # Examples
     ///

From 991a296ce7617443c021c164644e2791890849bc Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Thu, 28 Oct 2021 17:15:25 +0300
Subject: [PATCH 04/12] Make `core::slice::from_raw_parts[_mut]` const

---
 library/core/src/lib.rs       |  1 +
 library/core/src/slice/raw.rs | 55 ++++++++++++++++++++++++++---------
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 36496193d0370..da537262f6bd5 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -105,6 +105,7 @@
 #![feature(const_caller_location)]
 #![feature(const_cell_into_inner)]
 #![feature(const_discriminant)]
+#![cfg_attr(not(bootstrap), feature(const_eval_select))]
 #![feature(const_float_bits_conv)]
 #![feature(const_float_classify)]
 #![feature(const_fmt_arguments_new)]
diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index ad38aaf9f8300..6653c998fa2ba 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -1,8 +1,6 @@
 //! Free functions to create `&[T]` and `&mut [T]`.
 
 use crate::array;
-use crate::intrinsics::is_aligned_and_not_null;
-use crate::mem;
 use crate::ptr;
 
 /// Forms a slice from a pointer and a length.
@@ -85,12 +83,10 @@ use crate::ptr;
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
-    debug_assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
-    debug_assert!(
-        mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
-        "attempt to create slice covering at least half the address space"
-    );
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
+    debug_check_data_len(data, len);
+
     // SAFETY: the caller must uphold the safety contract for `from_raw_parts`.
     unsafe { &*ptr::slice_from_raw_parts(data, len) }
 }
@@ -126,16 +122,47 @@ pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
-    debug_assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
-    debug_assert!(
-        mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
-        "attempt to create slice covering at least half the address space"
-    );
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
+    debug_check_data_len(data as _, len);
+
     // SAFETY: the caller must uphold the safety contract for `from_raw_parts_mut`.
     unsafe { &mut *ptr::slice_from_raw_parts_mut(data, len) }
 }
 
+// In debug builds checks that `data` pointer is aligned and non-null and that slice with given `len` would cover less than half the address space
+#[cfg(all(not(bootstrap), debug_assertions))]
+#[unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+const fn debug_check_data_len<T>(data: *const T, len: usize) {
+    fn rt_check<T>(data: *const T) {
+        use crate::intrinsics::is_aligned_and_not_null;
+
+        assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
+    }
+
+    const fn ctfe_check<T>(_data: *const T) {
+        // It's impossible to check alignment in const fn.
+        //
+        // CTFE engine checks that the pointer is aligned and not null.
+    }
+
+    // SAFETY:
+    // - `calling from_raw_parts[_mut]` with arguments that fail to fulfil checks made here is UB, so unless UB is already triggered this is noop
+    // - CTFE makes the same checks as `rt_check`, so behavior change is not observable due to compilation error
+    unsafe {
+        crate::intrinsics::const_eval_select((data,), ctfe_check, rt_check);
+    }
+
+    assert!(
+        crate::mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
+        "attempt to create slice covering at least half the address space"
+    );
+}
+
+#[cfg(not(all(not(bootstrap), debug_assertions)))]
+const fn debug_check_data_len<T>(_data: *const T, _len: usize) {}
+
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
 #[rustc_const_unstable(feature = "const_slice_from_ref", issue = "90206")]

From 04cb19692c8bf15fb1cc02872fdd209228db6329 Mon Sep 17 00:00:00 2001
From: b-naber <bn263@gmx.de>
Date: Fri, 29 Oct 2021 12:32:06 +0200
Subject: [PATCH 05/12] don't mutably borrow inner infcx in all of
 ConstInferUnifier::consts

---
 compiler/rustc_infer/src/infer/combine.rs | 29 ++++++++++++++++-------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index 3f54247ecef21..09bfb3290f4ca 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -866,6 +866,7 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
         Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
     }
 
+    #[tracing::instrument(level = "debug", skip(self))]
     fn tys(&mut self, t: Ty<'tcx>, _t: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         debug_assert_eq!(t, _t);
         debug!("ConstInferUnifier: t={:?}", t);
@@ -941,6 +942,7 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
         }
     }
 
+    #[tracing::instrument(level = "debug", skip(self))]
     fn consts(
         &mut self,
         c: &'tcx ty::Const<'tcx>,
@@ -951,29 +953,38 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
 
         match c.val {
             ty::ConstKind::Infer(InferConst::Var(vid)) => {
-                let mut inner = self.infcx.inner.borrow_mut();
-                let variable_table = &mut inner.const_unification_table();
-
                 // Check if the current unification would end up
                 // unifying `target_vid` with a const which contains
                 // an inference variable which is unioned with `target_vid`.
                 //
                 // Not doing so can easily result in stack overflows.
-                if variable_table.unioned(self.target_vid, vid) {
+                if self
+                    .infcx
+                    .inner
+                    .borrow_mut()
+                    .const_unification_table()
+                    .unioned(self.target_vid, vid)
+                {
                     return Err(TypeError::CyclicConst(c));
                 }
 
-                let var_value = variable_table.probe_value(vid);
+                let var_value =
+                    self.infcx.inner.borrow_mut().const_unification_table().probe_value(vid);
                 match var_value.val {
                     ConstVariableValue::Known { value: u } => self.consts(u, u),
                     ConstVariableValue::Unknown { universe } => {
                         if self.for_universe.can_name(universe) {
                             Ok(c)
                         } else {
-                            let new_var_id = variable_table.new_key(ConstVarValue {
-                                origin: var_value.origin,
-                                val: ConstVariableValue::Unknown { universe: self.for_universe },
-                            });
+                            let new_var_id =
+                                self.infcx.inner.borrow_mut().const_unification_table().new_key(
+                                    ConstVarValue {
+                                        origin: var_value.origin,
+                                        val: ConstVariableValue::Unknown {
+                                            universe: self.for_universe,
+                                        },
+                                    },
+                                );
                             Ok(self.tcx().mk_const_var(new_var_id, c.ty))
                         }
                     }

From a39c50b64caca297b3e98ebf7cdb68c96ca0f3c1 Mon Sep 17 00:00:00 2001
From: b-naber <bn263@gmx.de>
Date: Fri, 29 Oct 2021 12:38:28 +0200
Subject: [PATCH 06/12] add test

---
 .../ui/const-generics/issues/issue-89304.rs   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 src/test/ui/const-generics/issues/issue-89304.rs

diff --git a/src/test/ui/const-generics/issues/issue-89304.rs b/src/test/ui/const-generics/issues/issue-89304.rs
new file mode 100644
index 0000000000000..d544d637cc490
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-89304.rs
@@ -0,0 +1,20 @@
+// check-pass
+
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+struct GenericStruct<const T: usize> { val: i64 }
+
+impl<const T: usize> From<GenericStruct<T>> for GenericStruct<{T + 1}> {
+    fn from(other: GenericStruct<T>) -> Self {
+        Self { val: other.val }
+    }
+}
+
+impl<const T: usize> From<GenericStruct<{T + 1}>> for GenericStruct<T> {
+    fn from(other: GenericStruct<{T + 1}>) -> Self {
+        Self { val: other.val }
+    }
+}
+
+fn main() {}

From 87fbf3c5aaff62cb70cf95ccfd756f4f147e8fea Mon Sep 17 00:00:00 2001
From: b-naber <bn263@gmx.de>
Date: Fri, 29 Oct 2021 13:14:44 +0200
Subject: [PATCH 07/12] ignore type flags insertion in
 default_anon_const_substs if error occurred

---
 compiler/rustc_typeck/src/collect/type_of.rs      |  3 ++-
 src/test/ui/const-generics/issues/issue-88997.rs  | 14 ++++++++++++++
 .../ui/const-generics/issues/issue-88997.stderr   | 15 +++++++++++++++
 src/test/ui/const-generics/issues/issue-90364.rs  |  9 +++++++++
 .../ui/const-generics/issues/issue-90364.stderr   |  9 +++++++++
 5 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/const-generics/issues/issue-88997.rs
 create mode 100644 src/test/ui/const-generics/issues/issue-88997.stderr
 create mode 100644 src/test/ui/const-generics/issues/issue-90364.rs
 create mode 100644 src/test/ui/const-generics/issues/issue-90364.stderr

diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_typeck/src/collect/type_of.rs
index cee3679d0a052..96211be8cdcf7 100644
--- a/compiler/rustc_typeck/src/collect/type_of.rs
+++ b/compiler/rustc_typeck/src/collect/type_of.rs
@@ -292,7 +292,8 @@ pub(super) fn default_anon_const_substs(tcx: TyCtxt<'_>, def_id: DefId) -> Subst
     // Getting this wrong can lead to ICE and unsoundness, so we assert it here.
     for arg in substs.iter() {
         let allowed_flags = ty::TypeFlags::MAY_NEED_DEFAULT_CONST_SUBSTS
-            | ty::TypeFlags::STILL_FURTHER_SPECIALIZABLE;
+            | ty::TypeFlags::STILL_FURTHER_SPECIALIZABLE
+            | ty::TypeFlags::HAS_ERROR;
         assert!(!arg.has_type_flags(!allowed_flags));
     }
     substs
diff --git a/src/test/ui/const-generics/issues/issue-88997.rs b/src/test/ui/const-generics/issues/issue-88997.rs
new file mode 100644
index 0000000000000..7666a514101da
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-88997.rs
@@ -0,0 +1,14 @@
+#![allow(incomplete_features)]
+#![feature(generic_const_exprs)]
+
+struct ConstAssert<const COND: bool>;
+trait True {}
+impl True for ConstAssert<true> {}
+
+struct Range<T: PartialOrd, const MIN: T, const MAX: T>(T)
+//~^ ERROR the type of const parameters must not depend on other generic parameters
+//~| ERROR the type of const parameters must not depend on other generic parameters
+where
+    ConstAssert<{ MIN <= MAX }>: True;
+
+fn main() {}
diff --git a/src/test/ui/const-generics/issues/issue-88997.stderr b/src/test/ui/const-generics/issues/issue-88997.stderr
new file mode 100644
index 0000000000000..505ba0da23214
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-88997.stderr
@@ -0,0 +1,15 @@
+error[E0770]: the type of const parameters must not depend on other generic parameters
+  --> $DIR/issue-88997.rs:8:40
+   |
+LL | struct Range<T: PartialOrd, const MIN: T, const MAX: T>(T)
+   |                                        ^ the type must not depend on the parameter `T`
+
+error[E0770]: the type of const parameters must not depend on other generic parameters
+  --> $DIR/issue-88997.rs:8:54
+   |
+LL | struct Range<T: PartialOrd, const MIN: T, const MAX: T>(T)
+   |                                                      ^ the type must not depend on the parameter `T`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0770`.
diff --git a/src/test/ui/const-generics/issues/issue-90364.rs b/src/test/ui/const-generics/issues/issue-90364.rs
new file mode 100644
index 0000000000000..b11b07b5023b2
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-90364.rs
@@ -0,0 +1,9 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+pub struct Foo<T, const H: T>(T)
+//~^ ERROR the type of const parameters must not depend on other generic parameters
+where
+    [(); 1]:;
+
+fn main() {}
diff --git a/src/test/ui/const-generics/issues/issue-90364.stderr b/src/test/ui/const-generics/issues/issue-90364.stderr
new file mode 100644
index 0000000000000..e85bd136ef6dc
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-90364.stderr
@@ -0,0 +1,9 @@
+error[E0770]: the type of const parameters must not depend on other generic parameters
+  --> $DIR/issue-90364.rs:4:28
+   |
+LL | pub struct Foo<T, const H: T>(T)
+   |                            ^ the type must not depend on the parameter `T`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0770`.

From 60bf2f192678337a7e8dcb5cebf6c17762707466 Mon Sep 17 00:00:00 2001
From: Wesley Wiser <wesleywiser@microsoft.com>
Date: Fri, 29 Oct 2021 11:15:45 -0400
Subject: [PATCH 08/12] Add a few query descriptions

---
 compiler/rustc_middle/src/query/mod.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 6d384f5f3d645..06041bbb02d35 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -687,12 +687,13 @@ rustc_queries! {
         desc { |tcx| "processing `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
-    /// The signature of functions.
+    /// Computes the signature of the function.
     query fn_sig(key: DefId) -> ty::PolyFnSig<'tcx> {
         desc { |tcx| "computing function signature of `{}`", tcx.def_path_str(key) }
         separate_provide_extern
     }
 
+    /// Performs lint checking for the module.
     query lint_mod(key: LocalDefId) -> () {
         desc { |tcx| "linting {}", describe_as_module(key, tcx) }
     }
@@ -702,6 +703,7 @@ rustc_queries! {
         desc { |tcx| "checking attributes in {}", describe_as_module(key, tcx) }
     }
 
+    /// Checks for uses of unstable APIs in the module.
     query check_mod_unstable_api_usage(key: LocalDefId) -> () {
         desc { |tcx| "checking for unstable API usage in {}", describe_as_module(key, tcx) }
     }
@@ -928,6 +930,7 @@ rustc_queries! {
         desc { |tcx| "computing drop scopes for `{}`", tcx.def_path_str(def_id) }
     }
 
+    /// Generates a MIR body for the shim.
     query mir_shims(key: ty::InstanceDef<'tcx>) -> mir::Body<'tcx> {
         storage(ArenaCacheSelector<'tcx>)
         desc { |tcx| "generating MIR shim for `{}`", tcx.def_path_str(key.def_id()) }
@@ -946,11 +949,13 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    /// Gets the span for the definition.
     query def_span(def_id: DefId) -> Span {
         desc { |tcx| "looking up span for `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern
     }
 
+    /// Gets the span for the identifier of the definition.
     query def_ident_span(def_id: DefId) -> Option<Span> {
         desc { |tcx| "looking up span for `{}`'s identifier", tcx.def_path_str(def_id) }
         separate_provide_extern
@@ -1466,6 +1471,8 @@ rustc_queries! {
         desc { "fetching what a dependency looks like" }
         separate_provide_extern
     }
+
+    /// Gets the name of the crate.
     query crate_name(_: CrateNum) -> Symbol {
         eval_always
         desc { "fetching what a crate is named" }

From 0c708311715befda3fcb7592f2324d96d9afeb74 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Thu, 28 Oct 2021 14:44:47 +0200
Subject: [PATCH 09/12] Unify titles in rustdoc book doc attributes chapter

---
 compiler/rustc_passes/src/check_attr.rs        | 2 +-
 src/doc/rustdoc/src/the-doc-attribute.md       | 8 ++++++--
 src/test/rustdoc-ui/invalid-doc-attr.stderr    | 4 ++--
 src/test/ui/attributes/invalid-doc-attr.stderr | 4 ++--
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 92d9e89c3a383..658a4d3eac73d 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -768,7 +768,7 @@ impl CheckAttrVisitor<'tcx> {
                             "not a `use` item",
                         );
                     }
-                    err.note("read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#docno_inlinedocinline for more information")
+                    err.note("read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information")
                         .emit();
                 },
             );
diff --git a/src/doc/rustdoc/src/the-doc-attribute.md b/src/doc/rustdoc/src/the-doc-attribute.md
index 5ee06c5f91711..a75b6d3893128 100644
--- a/src/doc/rustdoc/src/the-doc-attribute.md
+++ b/src/doc/rustdoc/src/the-doc-attribute.md
@@ -153,7 +153,9 @@ example, if you want your doctests to fail if they produce any warnings, you cou
 These forms of the `#[doc]` attribute are used on individual items, to control how
 they are documented.
 
-### `#[doc(no_inline)]`/`#[doc(inline)]`
+### `inline` and `no_inline`
+
+<span id="docno_inlinedocinline"></span>
 
 These attributes are used on `use` statements, and control where the documentation shows
 up. For example, consider this Rust code:
@@ -219,7 +221,9 @@ Now we'll have a `Re-exports` line, and `Bar` will not link to anywhere.
 One special case: In Rust 2018 and later, if you `pub use` one of your dependencies, `rustdoc` will
 not eagerly inline it as a module unless you add `#[doc(inline)]`.
 
-### `#[doc(hidden)]`
+### `hidden`
+
+<span id="dochidden"></span>
 
 Any item annotated with `#[doc(hidden)]` will not appear in the documentation, unless
 the `strip-hidden` pass is removed.
diff --git a/src/test/rustdoc-ui/invalid-doc-attr.stderr b/src/test/rustdoc-ui/invalid-doc-attr.stderr
index 595ece2ea7247..55006b2087eb0 100644
--- a/src/test/rustdoc-ui/invalid-doc-attr.stderr
+++ b/src/test/rustdoc-ui/invalid-doc-attr.stderr
@@ -29,7 +29,7 @@ LL | pub fn foo() {}
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
-   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#docno_inlinedocinline for more information
+   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information
 
 error: this attribute can only be applied at the crate level
   --> $DIR/invalid-doc-attr.rs:15:12
@@ -72,7 +72,7 @@ LL |     pub fn baz() {}
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
-   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#docno_inlinedocinline for more information
+   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information
 
 error: aborting due to 6 previous errors
 
diff --git a/src/test/ui/attributes/invalid-doc-attr.stderr b/src/test/ui/attributes/invalid-doc-attr.stderr
index 595ece2ea7247..55006b2087eb0 100644
--- a/src/test/ui/attributes/invalid-doc-attr.stderr
+++ b/src/test/ui/attributes/invalid-doc-attr.stderr
@@ -29,7 +29,7 @@ LL | pub fn foo() {}
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
-   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#docno_inlinedocinline for more information
+   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information
 
 error: this attribute can only be applied at the crate level
   --> $DIR/invalid-doc-attr.rs:15:12
@@ -72,7 +72,7 @@ LL |     pub fn baz() {}
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
-   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#docno_inlinedocinline for more information
+   = note: read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information
 
 error: aborting due to 6 previous errors
 

From 878ac10fe13761664da2d205c64e2a398f469601 Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Fri, 29 Oct 2021 22:45:10 +0300
Subject: [PATCH 10/12] Use proper issue number for
 `feature(const_slice_from_raw_parts)`

---
 library/core/src/slice/raw.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index 6653c998fa2ba..edae555206fbe 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -83,7 +83,7 @@ use crate::ptr;
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
 pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
     debug_check_data_len(data, len);
 
@@ -122,7 +122,7 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
 pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
     debug_check_data_len(data as _, len);
 
@@ -132,8 +132,8 @@ pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a m
 
 // In debug builds checks that `data` pointer is aligned and non-null and that slice with given `len` would cover less than half the address space
 #[cfg(all(not(bootstrap), debug_assertions))]
-#[unstable(feature = "const_slice_from_raw_parts", issue = "none")]
-#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "none")]
+#[unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
+#[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
 const fn debug_check_data_len<T>(data: *const T, len: usize) {
     fn rt_check<T>(data: *const T) {
         use crate::intrinsics::is_aligned_and_not_null;

From afaa54a99d75bc6287d835b1ee33e1b15bda462e Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Fri, 29 Oct 2021 23:45:09 +0300
Subject: [PATCH 11/12] Apply changes proposed in the review

---
 library/core/src/slice/raw.rs | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index edae555206fbe..81bb16d54015e 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -141,17 +141,18 @@ const fn debug_check_data_len<T>(data: *const T, len: usize) {
         assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
     }
 
-    const fn ctfe_check<T>(_data: *const T) {
-        // It's impossible to check alignment in const fn.
-        //
-        // CTFE engine checks that the pointer is aligned and not null.
-    }
+    const fn noop<T>(_: *const T) {}
 
     // SAFETY:
-    // - `calling from_raw_parts[_mut]` with arguments that fail to fulfil checks made here is UB, so unless UB is already triggered this is noop
-    // - CTFE makes the same checks as `rt_check`, so behavior change is not observable due to compilation error
+    //
+    // `rt_check` is just a debug assert to hint users that they are causing UB,
+    // it is not required for safety (the safety must be guatanteed by
+    // the `from_raw_parts[_mut]` caller).
+    //
+    // Since the checks are not required, we ignore them in CTFE as they can't
+    // be done there (alignment does not make much sense there).
     unsafe {
-        crate::intrinsics::const_eval_select((data,), ctfe_check, rt_check);
+        crate::intrinsics::const_eval_select((data,), noop, rt_check);
     }
 
     assert!(

From b6851ba3c9eccfb1def7fdb5e4c64edcad55e612 Mon Sep 17 00:00:00 2001
From: Joshua Nelson <jyn514@gmail.com>
Date: Sat, 30 Oct 2021 02:07:37 +0000
Subject: [PATCH 12/12] Remove unnecessary `macro_use`s in rustdoc

---
 src/librustdoc/html/render/context.rs      | 4 ++--
 src/librustdoc/html/render/mod.rs          | 1 +
 src/librustdoc/html/render/write_shared.rs | 1 +
 src/librustdoc/lib.rs                      | 7 ++-----
 4 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 0e29cc85f9e75..1ce6a5c00be74 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -22,8 +22,7 @@ use super::{
     BASIC_KEYWORDS,
 };
 
-use crate::clean;
-use crate::clean::ExternalCrate;
+use crate::clean::{self, ExternalCrate};
 use crate::config::RenderOptions;
 use crate::docfs::{DocFS, PathError};
 use crate::error::Error;
@@ -35,6 +34,7 @@ use crate::html::format::Buffer;
 use crate::html::markdown::{self, plain_text_summary, ErrorCodes, IdMap};
 use crate::html::{layout, sources};
 use crate::scrape_examples::AllCallLocations;
+use crate::try_err;
 
 /// Major driving force in all rustdoc rendering. This contains information
 /// about where in the tree-like hierarchy rendering is occurring and controls
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 07dea624d7c52..0354b87e7b992 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -77,6 +77,7 @@ use crate::html::highlight;
 use crate::html::markdown::{HeadingOffset, Markdown, MarkdownHtml, MarkdownSummaryLine};
 use crate::html::sources;
 use crate::scrape_examples::CallData;
+use crate::try_none;
 
 /// A pair of name and its optional document.
 crate type NameDoc = (String, Option<String>);
diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index 34f1b4cd68408..27277015cd13f 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -17,6 +17,7 @@ use crate::config::{EmitType, RenderOptions};
 use crate::docfs::PathError;
 use crate::error::Error;
 use crate::html::{layout, static_files};
+use crate::{try_err, try_none};
 
 static FILES_UNVERSIONED: Lazy<FxHashMap<&str, &[u8]>> = Lazy::new(|| {
     map! {
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 93dffc27659c2..b50fbf58bae29 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -103,17 +103,14 @@ macro_rules! map {
     }}
 }
 
-#[macro_use]
-mod externalfiles;
-
 mod clean;
 mod config;
 mod core;
 mod docfs;
+mod doctest;
 mod doctree;
-#[macro_use]
 mod error;
-mod doctest;
+mod externalfiles;
 mod fold;
 mod formats;
 // used by the error-index generator, so it needs to be public