Add ?Sized bound to some SIMD intrinsics.

Author: JamieCunliffe

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -623,6 +623,7 @@ pub fn check_intrinsic_type(
             sym::simd_cast
             | sym::simd_as
             | sym::simd_cast_ptr
+            | sym::simd_reinterpret
             | sym::simd_expose_addr
             | sym::simd_from_exposed_addr => (2, 0, vec![param(0)], param(1)),
             sym::simd_bitmask => (2, 0, vec![param(0)], param(1)),

library/core/src/intrinsics/simd.rs

@@ -122,7 +122,7 @@ extern "rust-intrinsic" {
     /// * Not be infinite
     /// * Be representable in the return type, after truncating off its fractional part
     #[rustc_nounwind]
-    pub fn simd_cast<T, U>(x: T) -> U;
+    pub fn simd_cast<T: ?Sized, U: ?Sized>(x: T) -> U;
 
     /// Numerically cast a vector, elementwise.
     ///
@@ -138,6 +138,10 @@ extern "rust-intrinsic" {
     #[rustc_nounwind]
     pub fn simd_as<T, U>(x: T) -> U;
 
+    #[cfg(not(bootstrap))]
+    #[rustc_nounwind]
+    pub fn simd_reinterpret<Src: ?Sized, Dst: ?Sized>(src: Src) -> Dst;
+
     /// Elementwise negation of a vector.
     ///
     /// `T` must be a vector of integer or floating-point primitive types.
@@ -500,7 +504,7 @@ extern "rust-intrinsic" {
     /// # Safety
     /// `mask` must only contain `0` and `!0`.
     #[rustc_nounwind]
-    pub fn simd_select<M, T>(mask: M, if_true: T, if_false: T) -> T;
+    pub fn simd_select<M: ?Sized, T: ?Sized>(mask: M, if_true: T, if_false: T) -> T;
 
     /// Select elements from a bitmask.
     ///