Import the 2021 prelude in the core crate

Author: dpaoliello

crates/core_simd/src/lib.rs

@@ -45,10 +45,6 @@
 #![unstable(feature = "portable_simd", issue = "86656")]
 //! Portable SIMD module.
 
-#[prelude_import]
-#[allow(unused_imports)]
-use core::prelude::v1::*;
-
 #[path = "mod.rs"]
 mod core_simd;
 pub use self::core_simd::simd;

crates/core_simd/src/vector.rs

@@ -4,7 +4,6 @@ use crate::simd::{
     ptr::{SimdConstPtr, SimdMutPtr},
     LaneCount, Mask, MaskElement, SupportedLaneCount, Swizzle,
 };
-use core::convert::{TryFrom, TryInto};
 
 /// A SIMD vector with the shape of `[T; N]` but the operations of `T`.
 ///