Auto merge of #134830 - matthiaskrgr:rollup-7hdjojz, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #133663 (Add a compiler intrinsic to back `bigint_helper_methods`)
 - #134798 (Make `ty::Error` implement all auto traits)
 - #134808 (compiletest: Remove empty 'expected' files when blessing)
 - #134809 (Add `--no-capture`/`--nocapture` as bootstrap arguments)
 - #134826 (Add spastorino to users_on_vacation)
 - #134828 (Add clubby789 back to bootstrap review rotation)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -340,6 +340,37 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                     self.const_i32(cache_type),
                 ])
             }
+            sym::carrying_mul_add => {
+                let (size, signed) = fn_args.type_at(0).int_size_and_signed(self.tcx);
+
+                let wide_llty = self.type_ix(size.bits() * 2);
+                let args = args.as_array().unwrap();
+                let [a, b, c, d] = args.map(|a| self.intcast(a.immediate(), wide_llty, signed));
+
+                let wide = if signed {
+                    let prod = self.unchecked_smul(a, b);
+                    let acc = self.unchecked_sadd(prod, c);
+                    self.unchecked_sadd(acc, d)
+                } else {
+                    let prod = self.unchecked_umul(a, b);
+                    let acc = self.unchecked_uadd(prod, c);
+                    self.unchecked_uadd(acc, d)
+                };
+
+                let narrow_llty = self.type_ix(size.bits());
+                let low = self.trunc(wide, narrow_llty);
+                let bits_const = self.const_uint(wide_llty, size.bits());
+                // No need for ashr when signed; LLVM changes it to lshr anyway.
+                let high = self.lshr(wide, bits_const);
+                // FIXME: could be `trunc nuw`, even for signed.
+                let high = self.trunc(high, narrow_llty);
+
+                let pair_llty = self.type_struct(&[narrow_llty, narrow_llty], false);
+                let pair = self.const_poison(pair_llty);
+                let pair = self.insert_value(pair, low, 0);
+                let pair = self.insert_value(pair, high, 1);
+                pair
+            }
             sym::ctlz
             | sym::ctlz_nonzero
             | sym::cttz

compiler/rustc_codegen_llvm/src/lib.rs

@@ -17,6 +17,7 @@
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
+#![feature(slice_as_array)]
 #![feature(try_blocks)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -94,6 +94,7 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -
         | sym::add_with_overflow
         | sym::sub_with_overflow
         | sym::mul_with_overflow
+        | sym::carrying_mul_add
         | sym::wrapping_add
         | sym::wrapping_sub
         | sym::wrapping_mul
@@ -436,6 +437,10 @@ pub fn check_intrinsic_type(
                 (1, 0, vec![param(0), param(0)], Ty::new_tup(tcx, &[param(0), tcx.types.bool]))
             }
 
+            sym::carrying_mul_add => {
+                (2, 0, vec![param(0); 4], Ty::new_tup(tcx, &[param(1), param(0)]))
+            }
+
             sym::ptr_guaranteed_cmp => (
                 1,
                 0,

compiler/rustc_span/src/symbol.rs

@@ -555,6 +555,7 @@ symbols! {
         call_ref_future,
         caller_location,
         capture_disjoint_fields,
+        carrying_mul_add,
         catch_unwind,
         cause,
         cdylib,

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -819,7 +819,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         candidates.vec.push(AutoImplCandidate)
                     }
                 }
-                ty::Error(_) => {} // do not add an auto trait impl for `ty::Error` for now.
+                ty::Error(_) => {
+                    candidates.vec.push(AutoImplCandidate);
+                }
             }
         }
     }

library/core/src/intrinsics/fallback.rs

@@ -0,0 +1,111 @@
+#![unstable(
+    feature = "core_intrinsics_fallbacks",
+    reason = "The fallbacks will never be stable, as they exist only to be called \
+              by the fallback MIR, but they're exported so they can be tested on \
+              platforms where the fallback MIR isn't actually used",
+    issue = "none"
+)]
+#![allow(missing_docs)]
+
+#[const_trait]
+pub trait CarryingMulAdd: Copy + 'static {
+    type Unsigned: Copy + 'static;
+    fn carrying_mul_add(
+        self,
+        multiplicand: Self,
+        addend: Self,
+        carry: Self,
+    ) -> (Self::Unsigned, Self);
+}
+
+macro_rules! impl_carrying_mul_add_by_widening {
+    ($($t:ident $u:ident $w:ident,)+) => {$(
+        #[rustc_const_unstable(feature = "core_intrinsics_fallbacks", issue = "none")]
+        impl const CarryingMulAdd for $t {
+            type Unsigned = $u;
+            #[inline]
+            fn carrying_mul_add(self, a: Self, b: Self, c: Self) -> ($u, $t) {
+                let wide = (self as $w) * (a as $w) + (b as $w) + (c as $w);
+                (wide as _, (wide >> Self::BITS) as _)
+            }
+        }
+    )+};
+}
+impl_carrying_mul_add_by_widening! {
+    u8 u8 u16,
+    u16 u16 u32,
+    u32 u32 u64,
+    u64 u64 u128,
+    usize usize UDoubleSize,
+    i8 u8 i16,
+    i16 u16 i32,
+    i32 u32 i64,
+    i64 u64 i128,
+    isize usize UDoubleSize,
+}
+
+#[cfg(target_pointer_width = "16")]
+type UDoubleSize = u32;
+#[cfg(target_pointer_width = "32")]
+type UDoubleSize = u64;
+#[cfg(target_pointer_width = "64")]
+type UDoubleSize = u128;
+
+#[inline]
+const fn wide_mul_u128(a: u128, b: u128) -> (u128, u128) {
+    #[inline]
+    const fn to_low_high(x: u128) -> [u128; 2] {
+        const MASK: u128 = u64::MAX as _;
+        [x & MASK, x >> 64]
+    }
+    #[inline]
+    const fn from_low_high(x: [u128; 2]) -> u128 {
+        x[0] | (x[1] << 64)
+    }
+    #[inline]
+    const fn scalar_mul(low_high: [u128; 2], k: u128) -> [u128; 3] {
+        let [x, c] = to_low_high(k * low_high[0]);
+        let [y, z] = to_low_high(k * low_high[1] + c);
+        [x, y, z]
+    }
+    let a = to_low_high(a);
+    let b = to_low_high(b);
+    let low = scalar_mul(a, b[0]);
+    let high = scalar_mul(a, b[1]);
+    let r0 = low[0];
+    let [r1, c] = to_low_high(low[1] + high[0]);
+    let [r2, c] = to_low_high(low[2] + high[1] + c);
+    let r3 = high[2] + c;
+    (from_low_high([r0, r1]), from_low_high([r2, r3]))
+}
+
+#[rustc_const_unstable(feature = "core_intrinsics_fallbacks", issue = "none")]
+impl const CarryingMulAdd for u128 {
+    type Unsigned = u128;
+    #[inline]
+    fn carrying_mul_add(self, b: u128, c: u128, d: u128) -> (u128, u128) {
+        let (low, mut high) = wide_mul_u128(self, b);
+        let (low, carry) = u128::overflowing_add(low, c);
+        high += carry as u128;
+        let (low, carry) = u128::overflowing_add(low, d);
+        high += carry as u128;
+        (low, high)
+    }
+}
+
+#[rustc_const_unstable(feature = "core_intrinsics_fallbacks", issue = "none")]
+impl const CarryingMulAdd for i128 {
+    type Unsigned = u128;
+    #[inline]
+    fn carrying_mul_add(self, b: i128, c: i128, d: i128) -> (u128, i128) {
+        let (low, high) = wide_mul_u128(self as u128, b as u128);
+        let mut high = high as i128;
+        high = high.wrapping_add(i128::wrapping_mul(self >> 127, b));
+        high = high.wrapping_add(i128::wrapping_mul(self, b >> 127));
+        let (low, carry) = u128::overflowing_add(low, c as u128);
+        high = high.wrapping_add((carry as i128) + (c >> 127));
+        let (low, carry) = u128::overflowing_add(low, d as u128);
+        high = high.wrapping_add((carry as i128) + (d >> 127));
+        (low, high)
+    }
+}

library/core/src/intrinsics/mod.rs

@@ -68,6 +68,7 @@ use crate::marker::{DiscriminantKind, Tuple};
 use crate::mem::SizedTypeProperties;
 use crate::{ptr, ub_checks};
 
+pub mod fallback;
 pub mod mir;
 pub mod simd;
 
@@ -3305,6 +3306,34 @@ pub const fn mul_with_overflow<T: Copy>(_x: T, _y: T) -> (T, bool) {
     unimplemented!()
 }
 
+/// Performs full-width multiplication and addition with a carry:
+/// `multiplier * multiplicand + addend + carry`.
+///
+/// This is possible without any overflow.  For `uN`:
+///    MAX * MAX + MAX + MAX
+/// => (2ⁿ-1) × (2ⁿ-1) + (2ⁿ-1) + (2ⁿ-1)
+/// => (2²ⁿ - 2ⁿ⁺¹ + 1) + (2ⁿ⁺¹ - 2)
+/// => 2²ⁿ - 1
+///
+/// For `iN`, the upper bound is MIN * MIN + MAX + MAX => 2²ⁿ⁻² + 2ⁿ - 2,
+/// and the lower bound is MAX * MIN + MIN + MIN => -2²ⁿ⁻² - 2ⁿ + 2ⁿ⁺¹.
+///
+/// This currently supports unsigned integers *only*, no signed ones.
+/// The stabilized versions of this intrinsic are available on integers.
+#[unstable(feature = "core_intrinsics", issue = "none")]
+#[rustc_const_unstable(feature = "const_carrying_mul_add", issue = "85532")]
+#[rustc_nounwind]
+#[cfg_attr(not(bootstrap), rustc_intrinsic)]
+#[cfg_attr(not(bootstrap), miri::intrinsic_fallback_is_spec)]
+pub const fn carrying_mul_add<T: ~const fallback::CarryingMulAdd<Unsigned = U>, U>(
+    multiplier: T,
+    multiplicand: T,
+    addend: T,
+    carry: T,
+) -> (U, T) {
+    multiplier.carrying_mul_add(multiplicand, addend, carry)
+}
+
 /// Performs an exact division, resulting in undefined behavior where
 /// `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`
 ///

library/core/src/lib.rs

@@ -110,6 +110,7 @@
 #![cfg_attr(bootstrap, feature(do_not_recommend))]
 #![feature(array_ptr_get)]
 #![feature(asm_experimental_arch)]
+#![feature(const_carrying_mul_add)]
 #![feature(const_eval_select)]
 #![feature(const_typed_swap)]
 #![feature(core_intrinsics)]

library/core/src/num/mod.rs

@@ -228,134 +228,6 @@ macro_rules! midpoint_impl {
     };
 }
 
-macro_rules! widening_impl {
-    ($SelfT:ty, $WideT:ty, $BITS:literal, unsigned) => {
-        /// Calculates the complete product `self * rhs` without the possibility to overflow.
-        ///
-        /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
-        /// of the result as two separate values, in that order.
-        ///
-        /// If you also need to add a carry to the wide result, then you want
-        /// [`Self::carrying_mul`] instead.
-        ///
-        /// # Examples
-        ///
-        /// Basic usage:
-        ///
-        /// Please note that this example is shared between integer types.
-        /// Which explains why `u32` is used here.
-        ///
-        /// ```
-        /// #![feature(bigint_helper_methods)]
-        /// assert_eq!(5u32.widening_mul(2), (10, 0));
-        /// assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));
-        /// ```
-        #[unstable(feature = "bigint_helper_methods", issue = "85532")]
-        #[must_use = "this returns the result of the operation, \
-                      without modifying the original"]
-        #[inline]
-        pub const fn widening_mul(self, rhs: Self) -> (Self, Self) {
-            // note: longer-term this should be done via an intrinsic,
-            //   but for now we can deal without an impl for u128/i128
-            // SAFETY: overflow will be contained within the wider types
-            let wide = unsafe { (self as $WideT).unchecked_mul(rhs as $WideT) };
-            (wide as $SelfT, (wide >> $BITS) as $SelfT)
-        }
-
-        /// Calculates the "full multiplication" `self * rhs + carry`
-        /// without the possibility to overflow.
-        ///
-        /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
-        /// of the result as two separate values, in that order.
-        ///
-        /// Performs "long multiplication" which takes in an extra amount to add, and may return an
-        /// additional amount of overflow. This allows for chaining together multiple
-        /// multiplications to create "big integers" which represent larger values.
-        ///
-        /// If you don't need the `carry`, then you can use [`Self::widening_mul`] instead.
-        ///
-        /// # Examples
-        ///
-        /// Basic usage:
-        ///
-        /// Please note that this example is shared between integer types.
-        /// Which explains why `u32` is used here.
-        ///
-        /// ```
-        /// #![feature(bigint_helper_methods)]
-        /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
-        /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
-        /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
-        /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
-        #[doc = concat!("assert_eq!(",
-            stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
-            "(0, ", stringify!($SelfT), "::MAX));"
-        )]
-        /// ```
-        ///
-        /// This is the core operation needed for scalar multiplication when
-        /// implementing it for wider-than-native types.
-        ///
-        /// ```
-        /// #![feature(bigint_helper_methods)]
-        /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
-        ///     let mut carry = 0;
-        ///     for d in little_endian_digits.iter_mut() {
-        ///         (*d, carry) = d.carrying_mul(multiplicand, carry);
-        ///     }
-        ///     if carry != 0 {
-        ///         little_endian_digits.push(carry);
-        ///     }
-        /// }
-        ///
-        /// let mut v = vec![10, 20];
-        /// scalar_mul_eq(&mut v, 3);
-        /// assert_eq!(v, [30, 60]);
-        ///
-        /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
-        /// let mut v = vec![0x4321, 0x8765];
-        /// scalar_mul_eq(&mut v, 0xFEED);
-        /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
-        /// ```
-        ///
-        /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
-        /// except that it gives the value of the overflow instead of just whether one happened:
-        ///
-        /// ```
-        /// #![feature(bigint_helper_methods)]
-        /// let r = u8::carrying_mul(7, 13, 0);
-        /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
-        /// let r = u8::carrying_mul(13, 42, 0);
-        /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
-        /// ```
-        ///
-        /// The value of the first field in the returned tuple matches what you'd get
-        /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
-        /// [`wrapping_add`](Self::wrapping_add) methods:
-        ///
-        /// ```
-        /// #![feature(bigint_helper_methods)]
-        /// assert_eq!(
-        ///     789_u16.carrying_mul(456, 123).0,
-        ///     789_u16.wrapping_mul(456).wrapping_add(123),
-        /// );
-        /// ```
-        #[unstable(feature = "bigint_helper_methods", issue = "85532")]
-        #[must_use = "this returns the result of the operation, \
-                      without modifying the original"]
-        #[inline]
-        pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
-            // note: longer-term this should be done via an intrinsic,
-            //   but for now we can deal without an impl for u128/i128
-            // SAFETY: overflow will be contained within the wider types
-            let wide = unsafe {
-                (self as $WideT).unchecked_mul(rhs as $WideT).unchecked_add(carry as $WideT)
-            };
-            (wide as $SelfT, (wide >> $BITS) as $SelfT)
-        }
-    };
-}
-
 impl i8 {
     int_impl! {
         Self = i8,
@@ -576,7 +448,6 @@ impl u8 {
         from_xe_bytes_doc = u8_xe_bytes_doc!(),
         bound_condition = "",
     }
-    widening_impl! { u8, u16, 8, unsigned }
     midpoint_impl! { u8, u16, unsigned }
 
     /// Checks if the value is within the ASCII range.
@@ -1192,7 +1063,6 @@ impl u16 {
         from_xe_bytes_doc = "",
         bound_condition = "",
     }
-    widening_impl! { u16, u32, 16, unsigned }
     midpoint_impl! { u16, u32, unsigned }
 
     /// Checks if the value is a Unicode surrogate code point, which are disallowed values for [`char`].
@@ -1240,7 +1110,6 @@ impl u32 {
         from_xe_bytes_doc = "",
         bound_condition = "",
     }
-    widening_impl! { u32, u64, 32, unsigned }
     midpoint_impl! { u32, u64, unsigned }
 }
 
@@ -1264,7 +1133,6 @@ impl u64 {
         from_xe_bytes_doc = "",
         bound_condition = "",
     }
-    widening_impl! { u64, u128, 64, unsigned }
     midpoint_impl! { u64, u128, unsigned }
 }
 
@@ -1314,7 +1182,6 @@ impl usize {
         from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
         bound_condition = " on 16-bit targets",
     }
-    widening_impl! { usize, u32, 16, unsigned }
     midpoint_impl! { usize, u32, unsigned }
 }
 
@@ -1339,7 +1206,6 @@ impl usize {
         from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
         bound_condition = " on 32-bit targets",
     }
-    widening_impl! { usize, u64, 32, unsigned }
     midpoint_impl! { usize, u64, unsigned }
 }
 
@@ -1364,7 +1230,6 @@ impl usize {
         from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
         bound_condition = " on 64-bit targets",
     }
-    widening_impl! { usize, u128, 64, unsigned }
     midpoint_impl! { usize, u128, unsigned }
 }
 

library/core/src/num/uint_macros.rs

@@ -3347,6 +3347,122 @@ macro_rules! uint_impl {
             unsafe { mem::transmute(bytes) }
         }
 
+        /// Calculates the complete product `self * rhs` without the possibility to overflow.
+        ///
+        /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
+        /// of the result as two separate values, in that order.
+        ///
+        /// If you also need to add a carry to the wide result, then you want
+        /// [`Self::carrying_mul`] instead.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// Please note that this example is shared between integer types.
+        /// Which explains why `u32` is used here.
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// assert_eq!(5u32.widening_mul(2), (10, 0));
+        /// assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));
+        /// ```
+        #[unstable(feature = "bigint_helper_methods", issue = "85532")]
+        #[rustc_const_unstable(feature = "bigint_helper_methods", issue = "85532")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn widening_mul(self, rhs: Self) -> (Self, Self) {
+            Self::carrying_mul(self, rhs, 0)
+        }
+
+        /// Calculates the "full multiplication" `self * rhs + carry`
+        /// without the possibility to overflow.
+        ///
+        /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
+        /// of the result as two separate values, in that order.
+        ///
+        /// Performs "long multiplication" which takes in an extra amount to add, and may return an
+        /// additional amount of overflow. This allows for chaining together multiple
+        /// multiplications to create "big integers" which represent larger values.
+        ///
+        /// If you don't need the `carry`, then you can use [`Self::widening_mul`] instead.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// Please note that this example is shared between integer types.
+        /// Which explains why `u32` is used here.
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
+        /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
+        /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
+        /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
+        #[doc = concat!("assert_eq!(",
+            stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
+            "(0, ", stringify!($SelfT), "::MAX));"
+        )]
+        /// ```
+        ///
+        /// This is the core operation needed for scalar multiplication when
+        /// implementing it for wider-than-native types.
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
+        ///     let mut carry = 0;
+        ///     for d in little_endian_digits.iter_mut() {
+        ///         (*d, carry) = d.carrying_mul(multiplicand, carry);
+        ///     }
+        ///     if carry != 0 {
+        ///         little_endian_digits.push(carry);
+        ///     }
+        /// }
+        ///
+        /// let mut v = vec![10, 20];
+        /// scalar_mul_eq(&mut v, 3);
+        /// assert_eq!(v, [30, 60]);
+        ///
+        /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
+        /// let mut v = vec![0x4321, 0x8765];
+        /// scalar_mul_eq(&mut v, 0xFEED);
+        /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
+        /// ```
+        ///
+        /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
+        /// except that it gives the value of the overflow instead of just whether one happened:
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// let r = u8::carrying_mul(7, 13, 0);
+        /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
+        /// let r = u8::carrying_mul(13, 42, 0);
+        /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
+        /// ```
+        ///
+        /// The value of the first field in the returned tuple matches what you'd get
+        /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
+        /// [`wrapping_add`](Self::wrapping_add) methods:
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// assert_eq!(
+        ///     789_u16.carrying_mul(456, 123).0,
+        ///     789_u16.wrapping_mul(456).wrapping_add(123),
+        /// );
+        /// ```
+        #[unstable(feature = "bigint_helper_methods", issue = "85532")]
+        #[rustc_const_unstable(feature = "bigint_helper_methods", issue = "85532")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
+            intrinsics::carrying_mul_add(self, rhs, 0, carry)
+        }
+
         /// New code should prefer to use
         #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
         ///

library/core/tests/intrinsics.rs

@@ -125,3 +125,71 @@ fn test_three_way_compare_in_const_contexts() {
     assert_eq!(SIGNED_EQUAL, Equal);
     assert_eq!(SIGNED_GREATER, Greater);
 }
+
+fn fallback_cma<T: core::intrinsics::fallback::CarryingMulAdd>(
+    a: T,
+    b: T,
+    c: T,
+    d: T,
+) -> (T::Unsigned, T) {
+    a.carrying_mul_add(b, c, d)
+}
+
+#[test]
+fn carrying_mul_add_fallback_u32() {
+    let r = fallback_cma::<u32>(0x9e37_79b9, 0x7f4a_7c15, 0xf39c_c060, 0x5ced_c834);
+    assert_eq!(r, (0x2087_20c1, 0x4eab_8e1d));
+    let r = fallback_cma::<u32>(0x1082_276b, 0xf3a2_7251, 0xf86c_6a11, 0xd0c1_8e95);
+    assert_eq!(r, (0x7aa0_1781, 0x0fb6_0528));
+}
+
+#[test]
+fn carrying_mul_add_fallback_i32() {
+    let r = fallback_cma::<i32>(-1, -1, -1, -1);
+    assert_eq!(r, (u32::MAX, -1));
+    let r = fallback_cma::<i32>(1, -1, 1, 1);
+    assert_eq!(r, (1, 0));
+}
+
+#[test]
+fn carrying_mul_add_fallback_u128() {
+    assert_eq!(fallback_cma::<u128>(u128::MAX, u128::MAX, 0, 0), (1, u128::MAX - 1));
+    assert_eq!(fallback_cma::<u128>(1, 1, 1, 1), (3, 0));
+    assert_eq!(fallback_cma::<u128>(0, 0, u128::MAX, u128::MAX), (u128::MAX - 1, 1));
+    assert_eq!(
+        fallback_cma::<u128>(u128::MAX, u128::MAX, u128::MAX, u128::MAX),
+        (u128::MAX, u128::MAX),
+    );
+
+    let r = fallback_cma::<u128>(
+        0x243f6a8885a308d313198a2e03707344,
+        0xa4093822299f31d0082efa98ec4e6c89,
+        0x452821e638d01377be5466cf34e90c6c,
+        0xc0ac29b7c97c50dd3f84d5b5b5470917,
+    );
+    assert_eq!(r, (0x8050ec20ed554e40338d277e00b674e7, 0x1739ee6cea07da409182d003859b59d8));
+    let r = fallback_cma::<u128>(
+        0x9216d5d98979fb1bd1310ba698dfb5ac,
+        0x2ffd72dbd01adfb7b8e1afed6a267e96,
+        0xba7c9045f12c7f9924a19947b3916cf7,
+        0x0801f2e2858efc16636920d871574e69,
+    );
+    assert_eq!(r, (0x185525545fdb2fefb502a3a602efd628, 0x1b62d35fe3bff6b566f99667ef7ebfd6));
+}
+
+#[test]
+fn carrying_mul_add_fallback_i128() {
+    assert_eq!(fallback_cma::<i128>(-1, -1, 0, 0), (1, 0));
+    let r = fallback_cma::<i128>(-1, -1, -1, -1);
+    assert_eq!(r, (u128::MAX, -1));
+    let r = fallback_cma::<i128>(1, -1, 1, 1);
+    assert_eq!(r, (1, 0));
+    assert_eq!(
+        fallback_cma::<i128>(i128::MAX, i128::MAX, i128::MAX, i128::MAX),
+        (u128::MAX, i128::MAX / 2),
+    );
+    assert_eq!(
+        fallback_cma::<i128>(i128::MIN, i128::MIN, i128::MAX, i128::MAX),
+        (u128::MAX - 1, -(i128::MIN / 2)),
+    );
+}

library/core/tests/lib.rs

@@ -19,6 +19,7 @@
 #![feature(const_swap_nonoverlapping)]
 #![feature(const_trait_impl)]
 #![feature(core_intrinsics)]
+#![feature(core_intrinsics_fallbacks)]
 #![feature(core_io_borrowed_buf)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]

src/bootstrap/src/core/build_steps/test.rs

@@ -1829,6 +1829,10 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             cmd.arg("--force-rerun");
         }
 
+        if builder.config.cmd.no_capture() {
+            cmd.arg("--no-capture");
+        }
+
         let compare_mode =
             builder.config.cmd.compare_mode().or_else(|| {
                 if builder.config.test_compare_mode { self.compare_mode } else { None }

src/bootstrap/src/core/builder/tests.rs

@@ -637,6 +637,7 @@ mod dist {
             run: None,
             only_modified: false,
             extra_checks: None,
+            no_capture: false,
         };
 
         let build = Build::new(config);
@@ -702,6 +703,7 @@ mod dist {
             run: None,
             only_modified: false,
             extra_checks: None,
+            no_capture: false,
         };
         // Make sure rustfmt binary not being found isn't an error.
         config.channel = "beta".to_string();

src/bootstrap/src/core/config/flags.rs

@@ -388,6 +388,9 @@ pub enum Subcommand {
         /// enable this to generate a Rustfix coverage file, which is saved in
         /// `/<build_base>/rustfix_missing_coverage.txt`
         rustfix_coverage: bool,
+        #[arg(long)]
+        /// don't capture stdout/stderr of tests
+        no_capture: bool,
     },
     /// Build and run some test suites *in Miri*
     Miri {
@@ -563,6 +566,13 @@ impl Subcommand {
         }
     }
 
+    pub fn no_capture(&self) -> bool {
+        match *self {
+            Subcommand::Test { no_capture, .. } => no_capture,
+            _ => false,
+        }
+    }
+
     pub fn rustfix_coverage(&self) -> bool {
         match *self {
             Subcommand::Test { rustfix_coverage, .. } => rustfix_coverage,

src/bootstrap/src/utils/change_tracker.rs

@@ -315,4 +315,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "`build.vendor` is now enabled by default for dist/tarball sources when 'vendor' directory and '.cargo/config.toml' file are present.",
     },
+    ChangeInfo {
+        change_id: 134809,
+        severity: ChangeSeverity::Warning,
+        summary: "compiletest now takes `--no-capture` instead of `--nocapture`; bootstrap now accepts `--no-capture` as an argument to test commands directly",
+    },
 ];

src/etc/completions/x.fish

@@ -319,6 +319,7 @@ complete -c x -n "__fish_x_using_subcommand test" -l bless -d 'whether to automa
 complete -c x -n "__fish_x_using_subcommand test" -l force-rerun -d 'rerun tests even if the inputs are unchanged'
 complete -c x -n "__fish_x_using_subcommand test" -l only-modified -d 'only run tests that result has been changed'
 complete -c x -n "__fish_x_using_subcommand test" -l rustfix-coverage -d 'enable this to generate a Rustfix coverage file, which is saved in `/<build_base>/rustfix_missing_coverage.txt`'
+complete -c x -n "__fish_x_using_subcommand test" -l no-capture -d 'don\'t capture stdout/stderr of tests'
 complete -c x -n "__fish_x_using_subcommand test" -s v -l verbose -d 'use verbose output (-vv for very verbose)'
 complete -c x -n "__fish_x_using_subcommand test" -s i -l incremental -d 'use incremental compilation'
 complete -c x -n "__fish_x_using_subcommand test" -l include-default-paths -d 'include default paths in addition to the provided ones'

src/etc/completions/x.ps1

@@ -366,6 +366,7 @@ Register-ArgumentCompleter -Native -CommandName 'x' -ScriptBlock {
             [CompletionResult]::new('--force-rerun', '--force-rerun', [CompletionResultType]::ParameterName, 'rerun tests even if the inputs are unchanged')
             [CompletionResult]::new('--only-modified', '--only-modified', [CompletionResultType]::ParameterName, 'only run tests that result has been changed')
             [CompletionResult]::new('--rustfix-coverage', '--rustfix-coverage', [CompletionResultType]::ParameterName, 'enable this to generate a Rustfix coverage file, which is saved in `/<build_base>/rustfix_missing_coverage.txt`')
+            [CompletionResult]::new('--no-capture', '--no-capture', [CompletionResultType]::ParameterName, 'don''t capture stdout/stderr of tests')
             [CompletionResult]::new('-v', '-v', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
             [CompletionResult]::new('--verbose', '--verbose', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
             [CompletionResult]::new('-i', '-i', [CompletionResultType]::ParameterName, 'use incremental compilation')

src/etc/completions/x.py.fish

@@ -319,6 +319,7 @@ complete -c x.py -n "__fish_x.py_using_subcommand test" -l bless -d 'whether to
 complete -c x.py -n "__fish_x.py_using_subcommand test" -l force-rerun -d 'rerun tests even if the inputs are unchanged'
 complete -c x.py -n "__fish_x.py_using_subcommand test" -l only-modified -d 'only run tests that result has been changed'
 complete -c x.py -n "__fish_x.py_using_subcommand test" -l rustfix-coverage -d 'enable this to generate a Rustfix coverage file, which is saved in `/<build_base>/rustfix_missing_coverage.txt`'
+complete -c x.py -n "__fish_x.py_using_subcommand test" -l no-capture -d 'don\'t capture stdout/stderr of tests'
 complete -c x.py -n "__fish_x.py_using_subcommand test" -s v -l verbose -d 'use verbose output (-vv for very verbose)'
 complete -c x.py -n "__fish_x.py_using_subcommand test" -s i -l incremental -d 'use incremental compilation'
 complete -c x.py -n "__fish_x.py_using_subcommand test" -l include-default-paths -d 'include default paths in addition to the provided ones'

src/etc/completions/x.py.ps1

@@ -366,6 +366,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--force-rerun', '--force-rerun', [CompletionResultType]::ParameterName, 'rerun tests even if the inputs are unchanged')
             [CompletionResult]::new('--only-modified', '--only-modified', [CompletionResultType]::ParameterName, 'only run tests that result has been changed')
             [CompletionResult]::new('--rustfix-coverage', '--rustfix-coverage', [CompletionResultType]::ParameterName, 'enable this to generate a Rustfix coverage file, which is saved in `/<build_base>/rustfix_missing_coverage.txt`')
+            [CompletionResult]::new('--no-capture', '--no-capture', [CompletionResultType]::ParameterName, 'don''t capture stdout/stderr of tests')
             [CompletionResult]::new('-v', '-v', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
             [CompletionResult]::new('--verbose', '--verbose', [CompletionResultType]::ParameterName, 'use verbose output (-vv for very verbose)')
             [CompletionResult]::new('-i', '-i', [CompletionResultType]::ParameterName, 'use incremental compilation')

src/etc/completions/x.py.sh

@@ -3119,7 +3119,7 @@ _x.py() {
             return 0
             ;;
         x.py__test)
-            opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --no-capture --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0

src/etc/completions/x.py.zsh

@@ -365,6 +365,7 @@ _arguments "${_arguments_options[@]}" : \
 '--force-rerun[rerun tests even if the inputs are unchanged]' \
 '--only-modified[only run tests that result has been changed]' \
 '--rustfix-coverage[enable this to generate a Rustfix coverage file, which is saved in \`/<build_base>/rustfix_missing_coverage.txt\`]' \
+'--no-capture[don'\''t capture stdout/stderr of tests]' \
 '*-v[use verbose output (-vv for very verbose)]' \
 '*--verbose[use verbose output (-vv for very verbose)]' \
 '-i[use incremental compilation]' \

src/etc/completions/x.sh

@@ -3119,7 +3119,7 @@ _x() {
             return 0
             ;;
         x__test)
-            opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --no-fail-fast --test-args --compiletest-rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --no-capture --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0

src/etc/completions/x.zsh

@@ -365,6 +365,7 @@ _arguments "${_arguments_options[@]}" : \
 '--force-rerun[rerun tests even if the inputs are unchanged]' \
 '--only-modified[only run tests that result has been changed]' \
 '--rustfix-coverage[enable this to generate a Rustfix coverage file, which is saved in \`/<build_base>/rustfix_missing_coverage.txt\`]' \
+'--no-capture[don'\''t capture stdout/stderr of tests]' \
 '*-v[use verbose output (-vv for very verbose)]' \
 '*--verbose[use verbose output (-vv for very verbose)]' \
 '-i[use incremental compilation]' \

src/tools/compiletest/src/lib.rs

@@ -159,7 +159,9 @@ pub fn parse_config(args: Vec<String>) -> Config {
         )
         .optflag("", "force-rerun", "rerun tests even if the inputs are unchanged")
         .optflag("", "only-modified", "only run tests that result been modified")
+        // FIXME: Temporarily retained so we can point users to `--no-capture`
         .optflag("", "nocapture", "")
+        .optflag("", "no-capture", "don't capture stdout/stderr of tests")
         .optflag("", "profiler-runtime", "is the profiler runtime enabled for this target")
         .optflag("h", "help", "show this message")
         .reqopt("", "channel", "current Rust channel", "CHANNEL")
@@ -288,6 +290,10 @@ pub fn parse_config(args: Vec<String>) -> Config {
             );
         })
     });
+    if matches.opt_present("nocapture") {
+        panic!("`--nocapture` is deprecated; please use `--no-capture`");
+    }
+
     Config {
         bless: matches.opt_present("bless"),
         compile_lib_path: make_absolute(opt_path(matches, "compile-lib-path")),
@@ -385,7 +391,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         target_cfgs: OnceLock::new(),
         builtin_cfg_names: OnceLock::new(),
 
-        nocapture: matches.opt_present("nocapture"),
+        nocapture: matches.opt_present("no-capture"),
 
         git_repository: matches.opt_str("git-repository").unwrap(),
         nightly_branch: matches.opt_str("nightly-branch").unwrap(),

src/tools/compiletest/src/runtest.rs

@@ -213,7 +213,7 @@ fn remove_and_create_dir_all(path: &Path) {
     fs::create_dir_all(path).unwrap();
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 struct TestCx<'test> {
     config: &'test Config,
     props: &'test TestProps,
@@ -2318,32 +2318,47 @@ impl<'test> TestCx<'test> {
         match output_kind {
             TestOutput::Compile => {
                 if !self.props.dont_check_compiler_stdout {
-                    errors += self.compare_output(
+                    if self
+                        .compare_output(
+                            stdout_kind,
+                            &normalized_stdout,
+                            &proc_res.stdout,
+                            &expected_stdout,
+                        )
+                        .should_error()
+                    {
+                        errors += 1;
+                    }
+                }
+                if !self.props.dont_check_compiler_stderr {
+                    if self
+                        .compare_output(stderr_kind, &normalized_stderr, &stderr, &expected_stderr)
+                        .should_error()
+                    {
+                        errors += 1;
+                    }
+                }
+            }
+            TestOutput::Run => {
+                if self
+                    .compare_output(
                         stdout_kind,
                         &normalized_stdout,
                         &proc_res.stdout,
                         &expected_stdout,
-                    );
+                    )
+                    .should_error()
+                {
+                    errors += 1;
                 }
-                if !self.props.dont_check_compiler_stderr {
+
-                    errors += self.compare_output(
+                if self
-                        stderr_kind,
+                    .compare_output(stderr_kind, &normalized_stderr, &stderr, &expected_stderr)
-                        &normalized_stderr,
+                    .should_error()
-                        &stderr,
+                {
-                        &expected_stderr,
+                    errors += 1;
-                    );
                 }
             }
-            TestOutput::Run => {
-                errors += self.compare_output(
-                    stdout_kind,
-                    &normalized_stdout,
-                    &proc_res.stdout,
-                    &expected_stdout,
-                );
-                errors +=
-                    self.compare_output(stderr_kind, &normalized_stderr, &stderr, &expected_stderr);
-            }
         }
         errors
     }
@@ -2576,7 +2591,14 @@ impl<'test> TestCx<'test> {
         actual: &str,
         actual_unnormalized: &str,
         expected: &str,
-    ) -> usize {
+    ) -> CompareOutcome {
+        let expected_path =
+            expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
+
+        if self.config.bless && actual.is_empty() && expected_path.exists() {
+            self.delete_file(&expected_path);
+        }
+
         let are_different = match (self.force_color_svg(), expected.find('\n'), actual.find('\n')) {
             // FIXME: We ignore the first line of SVG files
             // because the width parameter is non-deterministic.
@@ -2584,7 +2606,7 @@ impl<'test> TestCx<'test> {
             _ => expected != actual,
         };
         if !are_different {
-            return 0;
+            return CompareOutcome::Same;
         }
 
         // Wrapper tools set by `runner` might provide extra output on failure,
@@ -2600,7 +2622,7 @@ impl<'test> TestCx<'test> {
             used.retain(|line| actual_lines.contains(line));
             // check if `expected` contains a subset of the lines of `actual`
             if used.len() == expected_lines.len() && (expected.is_empty() == actual.is_empty()) {
-                return 0;
+                return CompareOutcome::Same;
             }
             if expected_lines.is_empty() {
                 // if we have no lines to check, force a full overwite
@@ -2626,9 +2648,6 @@ impl<'test> TestCx<'test> {
         }
         println!("Saved the actual {stream} to {actual_path:?}");
 
-        let expected_path =
-            expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
-
         if !self.config.bless {
             if expected.is_empty() {
                 println!("normalized {}:\n{}\n", stream, actual);
@@ -2651,15 +2670,17 @@ impl<'test> TestCx<'test> {
                 self.delete_file(&old);
             }
 
-            if let Err(err) = fs::write(&expected_path, &actual) {
+            if !actual.is_empty() {
-                self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
+                if let Err(err) = fs::write(&expected_path, &actual) {
+                    self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
+                }
+                println!("Blessing the {stream} of {test_name} in {expected_path:?}");
             }
-            println!("Blessing the {stream} of {test_name} in {expected_path:?}");
         }
 
         println!("\nThe actual {0} differed from the expected {0}.", stream);
 
-        if self.config.bless { 0 } else { 1 }
+        if self.config.bless { CompareOutcome::Blessed } else { CompareOutcome::Differed }
     }
 
     /// Returns whether to show the full stderr/stdout.
@@ -2885,3 +2906,21 @@ enum AuxType {
     Dylib,
     ProcMacro,
 }
+
+/// Outcome of comparing a stream to a blessed file,
+/// e.g. `.stderr` and `.fixed`.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+enum CompareOutcome {
+    /// Expected and actual outputs are the same
+    Same,
+    /// Outputs differed but were blessed
+    Blessed,
+    /// Outputs differed and an error should be emitted
+    Differed,
+}
+
+impl CompareOutcome {
+    fn should_error(&self) -> bool {
+        matches!(self, CompareOutcome::Differed)
+    }
+}

src/tools/compiletest/src/runtest/coverage.rs

@@ -39,16 +39,16 @@ impl<'test> TestCx<'test> {
         let expected_coverage_dump = self.load_expected_output(kind);
         let actual_coverage_dump = self.normalize_output(&proc_res.stdout, &[]);
 
-        let coverage_dump_errors = self.compare_output(
+        let coverage_dump_compare_outcome = self.compare_output(
             kind,
             &actual_coverage_dump,
             &proc_res.stdout,
             &expected_coverage_dump,
         );
 
-        if coverage_dump_errors > 0 {
+        if coverage_dump_compare_outcome.should_error() {
             self.fatal_proc_rec(
-                &format!("{coverage_dump_errors} errors occurred comparing coverage output."),
+                &format!("an error occurred comparing coverage output."),
                 &proc_res,
             );
         }
@@ -139,16 +139,16 @@ impl<'test> TestCx<'test> {
                 self.fatal_proc_rec(&err, &proc_res);
             });
 
-        let coverage_errors = self.compare_output(
+        let coverage_dump_compare_outcome = self.compare_output(
             kind,
             &normalized_actual_coverage,
             &proc_res.stdout,
             &expected_coverage,
         );
 
-        if coverage_errors > 0 {
+        if coverage_dump_compare_outcome.should_error() {
             self.fatal_proc_rec(
-                &format!("{} errors occurred comparing coverage output.", coverage_errors),
+                &format!("an error occurred comparing coverage output."),
                 &proc_res,
             );
         }

src/tools/compiletest/src/runtest/ui.rs

@@ -100,7 +100,12 @@ impl TestCx<'_> {
                 )
             });
 
-            errors += self.compare_output("fixed", &fixed_code, &fixed_code, &expected_fixed);
+            if self
+                .compare_output("fixed", &fixed_code, &fixed_code, &expected_fixed)
+                .should_error()
+            {
+                errors += 1;
+            }
         } else if !expected_fixed.is_empty() {
             panic!(
                 "the `//@ run-rustfix` directive wasn't found but a `*.fixed` \

tests/codegen/intrinsics/carrying_mul_add.rs

@@ -0,0 +1,137 @@
+//@ revisions: RAW OPT
+//@ compile-flags: -C opt-level=1
+//@[RAW] compile-flags: -C no-prepopulate-passes
+//@[OPT] min-llvm-version: 19
+
+#![crate_type = "lib"]
+#![feature(core_intrinsics)]
+#![feature(core_intrinsics_fallbacks)]
+
+// Note that LLVM seems to sometimes permute the order of arguments to mul and add,
+// so these tests don't check the arguments in the optimized revision.
+
+use std::intrinsics::{carrying_mul_add, fallback};
+
+// The fallbacks are emitted even when they're never used, but optimize out.
+
+// RAW: wide_mul_u128
+// OPT-NOT: wide_mul_u128
+
+// CHECK-LABEL: @cma_u8
+#[no_mangle]
+pub unsafe fn cma_u8(a: u8, b: u8, c: u8, d: u8) -> (u8, u8) {
+    // CHECK: [[A:%.+]] = zext i8 %a to i16
+    // CHECK: [[B:%.+]] = zext i8 %b to i16
+    // CHECK: [[C:%.+]] = zext i8 %c to i16
+    // CHECK: [[D:%.+]] = zext i8 %d to i16
+    // CHECK: [[AB:%.+]] = mul nuw i16
+    // RAW-SAME: [[A]], [[B]]
+    // CHECK: [[ABC:%.+]] = add nuw i16
+    // RAW-SAME: [[AB]], [[C]]
+    // CHECK: [[ABCD:%.+]] = add nuw i16
+    // RAW-SAME: [[ABC]], [[D]]
+    // CHECK: [[LOW:%.+]] = trunc i16 [[ABCD]] to i8
+    // CHECK: [[HIGHW:%.+]] = lshr i16 [[ABCD]], 8
+    // RAW: [[HIGH:%.+]] = trunc i16 [[HIGHW]] to i8
+    // OPT: [[HIGH:%.+]] = trunc nuw i16 [[HIGHW]] to i8
+    // CHECK: [[PAIR0:%.+]] = insertvalue { i8, i8 } poison, i8 [[LOW]], 0
+    // CHECK: [[PAIR1:%.+]] = insertvalue { i8, i8 } [[PAIR0]], i8 [[HIGH]], 1
+    // OPT: ret { i8, i8 } [[PAIR1]]
+    carrying_mul_add(a, b, c, d)
+}
+
+// CHECK-LABEL: @cma_u32
+#[no_mangle]
+pub unsafe fn cma_u32(a: u32, b: u32, c: u32, d: u32) -> (u32, u32) {
+    // CHECK: [[A:%.+]] = zext i32 %a to i64
+    // CHECK: [[B:%.+]] = zext i32 %b to i64
+    // CHECK: [[C:%.+]] = zext i32 %c to i64
+    // CHECK: [[D:%.+]] = zext i32 %d to i64
+    // CHECK: [[AB:%.+]] = mul nuw i64
+    // RAW-SAME: [[A]], [[B]]
+    // CHECK: [[ABC:%.+]] = add nuw i64
+    // RAW-SAME: [[AB]], [[C]]
+    // CHECK: [[ABCD:%.+]] = add nuw i64
+    // RAW-SAME: [[ABC]], [[D]]
+    // CHECK: [[LOW:%.+]] = trunc i64 [[ABCD]] to i32
+    // CHECK: [[HIGHW:%.+]] = lshr i64 [[ABCD]], 32
+    // RAW: [[HIGH:%.+]] = trunc i64 [[HIGHW]] to i32
+    // OPT: [[HIGH:%.+]] = trunc nuw i64 [[HIGHW]] to i32
+    // CHECK: [[PAIR0:%.+]] = insertvalue { i32, i32 } poison, i32 [[LOW]], 0
+    // CHECK: [[PAIR1:%.+]] = insertvalue { i32, i32 } [[PAIR0]], i32 [[HIGH]], 1
+    // OPT: ret { i32, i32 } [[PAIR1]]
+    carrying_mul_add(a, b, c, d)
+}
+
+// CHECK-LABEL: @cma_u128
+// CHECK-SAME: sret{{.+}}dereferenceable(32){{.+}}%_0,{{.+}}%a,{{.+}}%b,{{.+}}%c,{{.+}}%d
+#[no_mangle]
+pub unsafe fn cma_u128(a: u128, b: u128, c: u128, d: u128) -> (u128, u128) {
+    // CHECK: [[A:%.+]] = zext i128 %a to i256
+    // CHECK: [[B:%.+]] = zext i128 %b to i256
+    // CHECK: [[C:%.+]] = zext i128 %c to i256
+    // CHECK: [[D:%.+]] = zext i128 %d to i256
+    // CHECK: [[AB:%.+]] = mul nuw i256
+    // RAW-SAME: [[A]], [[B]]
+    // CHECK: [[ABC:%.+]] = add nuw i256
+    // RAW-SAME: [[AB]], [[C]]
+    // CHECK: [[ABCD:%.+]] = add nuw i256
+    // RAW-SAME: [[ABC]], [[D]]
+    // CHECK: [[LOW:%.+]] = trunc i256 [[ABCD]] to i128
+    // CHECK: [[HIGHW:%.+]] = lshr i256 [[ABCD]], 128
+    // RAW: [[HIGH:%.+]] = trunc i256 [[HIGHW]] to i128
+    // OPT: [[HIGH:%.+]] = trunc nuw i256 [[HIGHW]] to i128
+    // RAW: [[PAIR0:%.+]] = insertvalue { i128, i128 } poison, i128 [[LOW]], 0
+    // RAW: [[PAIR1:%.+]] = insertvalue { i128, i128 } [[PAIR0]], i128 [[HIGH]], 1
+    // OPT: store i128 [[LOW]], ptr %_0
+    // OPT: [[P1:%.+]] = getelementptr inbounds i8, ptr %_0, {{i32|i64}} 16
+    // OPT: store i128 [[HIGH]], ptr [[P1]]
+    // CHECK: ret void
+    carrying_mul_add(a, b, c, d)
+}
+
+// CHECK-LABEL: @cma_i128
+// CHECK-SAME: sret{{.+}}dereferenceable(32){{.+}}%_0,{{.+}}%a,{{.+}}%b,{{.+}}%c,{{.+}}%d
+#[no_mangle]
+pub unsafe fn cma_i128(a: i128, b: i128, c: i128, d: i128) -> (u128, i128) {
+    // CHECK: [[A:%.+]] = sext i128 %a to i256
+    // CHECK: [[B:%.+]] = sext i128 %b to i256
+    // CHECK: [[C:%.+]] = sext i128 %c to i256
+    // CHECK: [[D:%.+]] = sext i128 %d to i256
+    // CHECK: [[AB:%.+]] = mul nsw i256
+    // RAW-SAME: [[A]], [[B]]
+    // CHECK: [[ABC:%.+]] = add nsw i256
+    // RAW-SAME: [[AB]], [[C]]
+    // CHECK: [[ABCD:%.+]] = add nsw i256
+    // RAW-SAME: [[ABC]], [[D]]
+    // CHECK: [[LOW:%.+]] = trunc i256 [[ABCD]] to i128
+    // CHECK: [[HIGHW:%.+]] = lshr i256 [[ABCD]], 128
+    // RAW: [[HIGH:%.+]] = trunc i256 [[HIGHW]] to i128
+    // OPT: [[HIGH:%.+]] = trunc nuw i256 [[HIGHW]] to i128
+    // RAW: [[PAIR0:%.+]] = insertvalue { i128, i128 } poison, i128 [[LOW]], 0
+    // RAW: [[PAIR1:%.+]] = insertvalue { i128, i128 } [[PAIR0]], i128 [[HIGH]], 1
+    // OPT: store i128 [[LOW]], ptr %_0
+    // OPT: [[P1:%.+]] = getelementptr inbounds i8, ptr %_0, {{i32|i64}} 16
+    // OPT: store i128 [[HIGH]], ptr [[P1]]
+    // CHECK: ret void
+    carrying_mul_add(a, b, c, d)
+}
+
+// CHECK-LABEL: @fallback_cma_u32
+#[no_mangle]
+pub unsafe fn fallback_cma_u32(a: u32, b: u32, c: u32, d: u32) -> (u32, u32) {
+    // OPT-DAG: [[A:%.+]] = zext i32 %a to i64
+    // OPT-DAG: [[B:%.+]] = zext i32 %b to i64
+    // OPT-DAG: [[AB:%.+]] = mul nuw i64
+    // OPT-DAG: [[C:%.+]] = zext i32 %c to i64
+    // OPT-DAG: [[ABC:%.+]] = add nuw i64{{.+}}[[C]]
+    // OPT-DAG: [[D:%.+]] = zext i32 %d to i64
+    // OPT-DAG: [[ABCD:%.+]] = add nuw i64{{.+}}[[D]]
+    // OPT-DAG: [[LOW:%.+]] = trunc i64 [[ABCD]] to i32
+    // OPT-DAG: [[HIGHW:%.+]] = lshr i64 [[ABCD]], 32
+    // OPT-DAG: [[HIGH:%.+]] = trunc nuw i64 [[HIGHW]] to i32
+    // OPT-DAG: [[PAIR0:%.+]] = insertvalue { i32, i32 } poison, i32 [[LOW]], 0
+    // OPT-DAG: [[PAIR1:%.+]] = insertvalue { i32, i32 } [[PAIR0]], i32 [[HIGH]], 1
+    // OPT-DAG: ret { i32, i32 } [[PAIR1]]
+    fallback::CarryingMulAdd::carrying_mul_add(a, b, c, d)
+}

tests/ui/consts/error-is-freeze.rs

@@ -0,0 +1,14 @@
+// Make sure we treat the error type as freeze to suppress useless errors.
+
+struct MyStruct {
+    foo: Option<UndefinedType>,
+    //~^ ERROR cannot find type `UndefinedType` in this scope
+}
+impl MyStruct {
+    pub const EMPTY_REF: &'static Self = &Self::EMPTY;
+    pub const EMPTY: Self = Self {
+        foo: None,
+    };
+}
+
+fn main() {}

tests/ui/consts/error-is-freeze.stderr

@@ -0,0 +1,14 @@
+error[E0412]: cannot find type `UndefinedType` in this scope
+  --> $DIR/error-is-freeze.rs:4:17
+   |
+LL |     foo: Option<UndefinedType>,
+   |                 ^^^^^^^^^^^^^ not found in this scope
+   |
+help: you might be missing a type parameter
+   |
+LL | struct MyStruct<UndefinedType> {
+   |                +++++++++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0412`.

tests/ui/impl-trait/auto-trait-contains-err.rs

@@ -1,9 +1,9 @@
-//@ known-bug: #131050
 //@ compile-flags: --edition=2021
 
 use std::future::Future;
 
 fn invalid_future() -> impl Future {}
+//~^ ERROR `()` is not a future
 
 fn create_complex_future() -> impl Future<Output = impl ReturnsSend> {
     async { &|| async { invalid_future().await } }
@@ -21,3 +21,5 @@ where
     R: Send,
 {
 }
+
+fn main() {}

tests/ui/impl-trait/auto-trait-contains-err.stderr

@@ -0,0 +1,11 @@
+error[E0277]: `()` is not a future
+  --> $DIR/auto-trait-contains-err.rs:5:24
+   |
+LL | fn invalid_future() -> impl Future {}
+   |                        ^^^^^^^^^^^ `()` is not a future
+   |
+   = help: the trait `Future` is not implemented for `()`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.

triagebot.toml

@@ -997,6 +997,7 @@ users_on_vacation = [
     "jyn514",
     "celinval",
     "nnethercote",
+    "spastorino",
     "workingjubilee",
 ]
 
@@ -1046,6 +1047,7 @@ bootstrap = [
     "@onur-ozkan",
     "@kobzol",
     "@jieyouxu",
+    "@clubby789",
 ]
 infra-ci = [
     "@Mark-Simulacrum",