Add copy_unsafe feature

rkyv/Cargo.toml

@@ -28,6 +28,7 @@ archive_be = ["rend", "rkyv_derive/archive_be"]
 archive_le = ["rend", "rkyv_derive/archive_le"]
 const_generics = []
 copy = []
+copy_unsafe = []
 size_64 = []
 std = ["bytecheck/std", "seahash", "rend/std"]
 strict = ["rkyv_derive/strict"]

rkyv/src/copy.rs

@@ -36,7 +36,6 @@ use core::sync::atomic::{
 /// This trait is similar to `Copy` in that it's automatically implemented for all types composed
 /// entirely of other `ArchiveCopy` types. `Copy` is necessary, but not sufficient for `ArchiveCopy`
 /// as some `Copy` type representations may vary from platform to platform.
-#[rustc_unsafe_specialization_marker]
 pub auto trait ArchiveCopy {}
 
 // (), PhantomData, PhantomPinned, bool, i8, u8, NonZeroI8, and NonZeroU8 are always ArchiveCopy
@@ -112,7 +111,6 @@ impl !ArchiveCopy for crate::RawRelPtr {}
 ///
 /// These types are always safe to `memcpy` around because they will never contain uninitialized
 /// padding.
-#[rustc_unsafe_specialization_marker]
 pub unsafe trait ArchiveCopySafe: ArchiveCopy + Sized {}
 
 // (), PhantomData, PhantomPinned, bool, i8, u8, NonZeroI8, and NonZeroU8 are always ArchiveCopySafe
@@ -178,3 +176,25 @@ macro_rules! impl_tuple {
 impl_tuple!(T, T, T, T, T, T, T, T, T, T, T,);
 
 unsafe impl<T: ArchiveCopySafe, const N: usize> ArchiveCopySafe for [T; N] {}
+
+/// Types that are may be copy optimized.
+///
+/// By default, only [`ArchiveCopySafe`] types may be copy optimized. By enabling the `copy_unsafe`
+/// feature, all types that are [`ArchiveCopy`] may be copy optimized.
+#[cfg(not(feature = "copy_unsafe"))]
+#[rustc_unsafe_specialization_marker]
+pub trait ArchiveCopyOptimize: ArchiveCopySafe {}
+
+#[cfg(not(feature = "copy_unsafe"))]
+impl<T: ArchiveCopySafe> ArchiveCopyOptimize for T {}
+
+/// Types that are may be copy optimized.
+///
+/// By default, only [`ArchiveCopySafe`] types may be copy optimized. By enabling the `copy_unsafe`
+/// feature, all types that are [`ArchiveCopy`] may be copy optimized.
+#[cfg(feature = "copy_unsafe")]
+#[rustc_unsafe_specialization_marker]
+pub trait ArchiveCopyOptimize: ArchiveCopy {}
+
+#[cfg(feature = "copy_unsafe")]
+impl<T: ArchiveCopy> ArchiveCopyOptimize for T {}

rkyv/src/core_impl/mod.rs

@@ -6,7 +6,7 @@ use crate::{
     Deserialize, DeserializeUnsized, Fallible, FixedUsize, Serialize, SerializeUnsized,
 };
 #[cfg(feature = "copy")]
-use crate::copy::ArchiveCopySafe;
+use crate::copy::ArchiveCopyOptimize;
 use core::{
     alloc, cmp,
     hash::{Hash, Hasher},
@@ -302,7 +302,7 @@ impl<T: Archive<Resolver = ()> + Serialize<S>, S: Serializer + ?Sized> Serialize
 }
 
 #[cfg(all(not(feature = "std"), feature = "copy"))]
-impl<T: Archive<Resolver = ()> + Serialize<S> + crate::copy::ArchiveCopySafe, S: Serializer + ?Sized> SerializeUnsized<S> for [T] {
+impl<T: Archive<Resolver = ()> + Serialize<S> + crate::copy::ArchiveCopyOptimize, S: Serializer + ?Sized> SerializeUnsized<S> for [T] {
     #[inline]
     fn serialize_unsized(&self, serializer: &mut S) -> Result<usize, S::Error> {
         if self.is_empty() || core::mem::size_of::<T::Archived>() == 0 {
@@ -358,7 +358,7 @@ impl<T: Serialize<S>, S: Serializer + ?Sized> SerializeUnsized<S> for [T] {
 }
 
 #[cfg(all(feature = "std", feature = "copy"))]
-impl<T: Serialize<S> + crate::copy::ArchiveCopySafe, S: Serializer + ?Sized> SerializeUnsized<S> for [T] {
+impl<T: Serialize<S> + crate::copy::ArchiveCopyOptimize, S: Serializer + ?Sized> SerializeUnsized<S> for [T] {
     #[inline]
     fn serialize_unsized(&self, serializer: &mut S) -> Result<usize, S::Error> {
         if self.is_empty() || core::mem::size_of::<T::Archived>() == 0 {
@@ -411,7 +411,7 @@ impl<T: Deserialize<U, D>, U, D: Deserializer + ?Sized>
 }
 
 #[cfg(feature = "copy")]
-impl<T: Deserialize<U, D>, U: ArchiveCopySafe, D: Deserializer + ?Sized>
+impl<T: Deserialize<U, D>, U: ArchiveCopyOptimize, D: Deserializer + ?Sized>
     DeserializeUnsized<[U], D> for [T]
 {
     #[inline]

rkyv_test/Cargo.toml

@@ -22,6 +22,7 @@ archive_be = ["rkyv/archive_be"]
 archive_le = ["rkyv/archive_le"]
 const_generics = ["rkyv/const_generics"]
 copy = ["rkyv/copy"]
+copy_unsafe = ["rkyv/copy_unsafe"]
 size_64 = ["rkyv/size_64"]
 std = ["rkyv/std"]
 strict = ["rkyv/strict"]