Remove some unsafe, update to zerocopy 0.8.0 (#1502)

Author: joshlf

Cargo.toml

@@ -70,7 +70,7 @@ rand_core = { path = "rand_core", version = "=0.9.0-alpha.1", default-features =
 log = { version = "0.4.4", optional = true }
 serde = { version = "1.0.103", features = ["derive"], optional = true }
 rand_chacha = { path = "rand_chacha", version = "=0.9.0-alpha.1", default-features = false, optional = true }
-zerocopy = { version = "0.7.33", default-features = false, features = ["simd"] }
+zerocopy = { version = "0.8.0", default-features = false, features = ["simd"] }
 
 [dev-dependencies]
 rand_pcg = { path = "rand_pcg", version = "=0.9.0-alpha.1" }

rand_core/Cargo.toml

@@ -32,4 +32,4 @@ serde = ["dep:serde"] # enables serde for BlockRng wrapper
 [dependencies]
 serde = { version = "1", features = ["derive"], optional = true }
 getrandom = { version = "0.2", optional = true }
-zerocopy = { version = "0.7.33", default-features = false }
+zerocopy = { version = "0.8.0", default-features = false }

rand_core/src/impls.rs

@@ -19,7 +19,7 @@
 
 use crate::RngCore;
 use core::cmp::min;
-use zerocopy::AsBytes;
+use zerocopy::{Immutable, IntoBytes};
 
 /// Implement `next_u64` via `next_u32`, little-endian order.
 pub fn next_u64_via_u32<R: RngCore + ?Sized>(rng: &mut R) -> u64 {
@@ -53,7 +53,7 @@ pub fn fill_bytes_via_next<R: RngCore + ?Sized>(rng: &mut R, dest: &mut [u8]) {
     }
 }
 
-trait Observable: AsBytes + Copy {
+trait Observable: IntoBytes + Immutable + Copy {
     fn to_le(self) -> Self;
 }
 impl Observable for u32 {

src/rng.rs

@@ -12,8 +12,8 @@
 use crate::distr::uniform::{SampleRange, SampleUniform};
 use crate::distr::{self, Distribution, Standard};
 use core::num::Wrapping;
-use core::{mem, slice};
 use rand_core::RngCore;
+use zerocopy::IntoBytes;
 
 /// User-level interface for RNGs
 ///
@@ -374,12 +374,7 @@ macro_rules! impl_fill {
             #[inline(never)] // in micro benchmarks, this improves performance
             fn fill<R: Rng + ?Sized>(&mut self, rng: &mut R) {
                 if self.len() > 0 {
-                    rng.fill_bytes(unsafe {
-                        slice::from_raw_parts_mut(self.as_mut_ptr()
-                            as *mut u8,
-                            mem::size_of_val(self)
-                        )
-                    });
+                    rng.fill_bytes(self.as_mut_bytes());
                     for x in self {
                         *x = x.to_le();
                     }
@@ -391,12 +386,7 @@ macro_rules! impl_fill {
             #[inline(never)]
             fn fill<R: Rng + ?Sized>(&mut self, rng: &mut R) {
                 if self.len() > 0 {
-                    rng.fill_bytes(unsafe {
-                        slice::from_raw_parts_mut(self.as_mut_ptr()
-                            as *mut u8,
-                            self.len() * mem::size_of::<$t>()
-                        )
-                    });
+                    rng.fill_bytes(self.as_mut_bytes());
                     for x in self {
                     *x = Wrapping(x.0.to_le());
                     }