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Diffstat (limited to 'src/zeroable.rs')
| -rw-r--r-- | src/zeroable.rs | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/src/zeroable.rs b/src/zeroable.rs new file mode 100644 index 0000000..5f19b98 --- /dev/null +++ b/src/zeroable.rs @@ -0,0 +1,235 @@ +use super::*;
+
+/// Trait for types that can be safely created with
+/// [`zeroed`](core::mem::zeroed).
+///
+/// An all-zeroes value may or may not be the same value as the
+/// [Default](core::default::Default) value of the type.
+///
+/// ## Safety
+///
+/// * Your type must be inhabited (eg: no
+/// [Infallible](core::convert::Infallible)).
+/// * Your type must be allowed to be an "all zeroes" bit pattern (eg: no
+/// [`NonNull<T>`](core::ptr::NonNull)).
+///
+/// ## Features
+///
+/// Some `impl`s are feature gated due to the MSRV policy:
+///
+/// * `MaybeUninit<T>` was not available in 1.34.0, but is available under the
+/// `zeroable_maybe_uninit` feature flag.
+/// * `Atomic*` types require Rust 1.60.0 or later to work on certain platforms, but is available
+/// under the `zeroable_atomics` feature flag.
+/// * `[T; N]` for arbitrary `N` requires the `min_const_generics` feature flag.
+pub unsafe trait Zeroable: Sized {
+ /// Calls [`zeroed`](core::mem::zeroed).
+ ///
+ /// This is a trait method so that you can write `MyType::zeroed()` in your
+ /// code. It is a contract of this trait that if you implement it on your type
+ /// you **must not** override this method.
+ #[inline]
+ fn zeroed() -> Self {
+ unsafe { core::mem::zeroed() }
+ }
+}
+unsafe impl Zeroable for () {}
+unsafe impl Zeroable for bool {}
+unsafe impl Zeroable for char {}
+unsafe impl Zeroable for u8 {}
+unsafe impl Zeroable for i8 {}
+unsafe impl Zeroable for u16 {}
+unsafe impl Zeroable for i16 {}
+unsafe impl Zeroable for u32 {}
+unsafe impl Zeroable for i32 {}
+unsafe impl Zeroable for u64 {}
+unsafe impl Zeroable for i64 {}
+unsafe impl Zeroable for usize {}
+unsafe impl Zeroable for isize {}
+unsafe impl Zeroable for u128 {}
+unsafe impl Zeroable for i128 {}
+unsafe impl Zeroable for f32 {}
+unsafe impl Zeroable for f64 {}
+unsafe impl<T: Zeroable> Zeroable for Wrapping<T> {}
+unsafe impl<T: Zeroable> Zeroable for core::cmp::Reverse<T> {}
+
+// Note: we can't implement this for all `T: ?Sized` types because it would
+// create NULL pointers for vtables.
+// Maybe one day this could be changed to be implemented for
+// `T: ?Sized where <T as core::ptr::Pointee>::Metadata: Zeroable`.
+unsafe impl<T> Zeroable for *mut T {}
+unsafe impl<T> Zeroable for *const T {}
+unsafe impl<T> Zeroable for *mut [T] {}
+unsafe impl<T> Zeroable for *const [T] {}
+unsafe impl Zeroable for *mut str {}
+unsafe impl Zeroable for *const str {}
+
+unsafe impl<T: ?Sized> Zeroable for PhantomData<T> {}
+unsafe impl Zeroable for PhantomPinned {}
+unsafe impl<T: Zeroable> Zeroable for ManuallyDrop<T> {}
+unsafe impl<T: Zeroable> Zeroable for core::cell::UnsafeCell<T> {}
+unsafe impl<T: Zeroable> Zeroable for core::cell::Cell<T> {}
+
+#[cfg(feature = "zeroable_atomics")]
+mod atomic_impls {
+ use super::Zeroable;
+
+ #[cfg(target_has_atomic = "8")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicBool {}
+ #[cfg(target_has_atomic = "8")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicU8 {}
+ #[cfg(target_has_atomic = "8")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicI8 {}
+
+ #[cfg(target_has_atomic = "16")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicU16 {}
+ #[cfg(target_has_atomic = "16")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicI16 {}
+
+ #[cfg(target_has_atomic = "32")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicU32 {}
+ #[cfg(target_has_atomic = "32")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicI32 {}
+
+ #[cfg(target_has_atomic = "64")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicU64 {}
+ #[cfg(target_has_atomic = "64")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicI64 {}
+
+ #[cfg(target_has_atomic = "ptr")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicUsize {}
+ #[cfg(target_has_atomic = "ptr")]
+ unsafe impl Zeroable for core::sync::atomic::AtomicIsize {}
+
+ #[cfg(target_has_atomic = "ptr")]
+ unsafe impl<T> Zeroable for core::sync::atomic::AtomicPtr<T> {}
+}
+
+#[cfg(feature = "zeroable_maybe_uninit")]
+unsafe impl<T> Zeroable for core::mem::MaybeUninit<T> {}
+
+unsafe impl<A: Zeroable> Zeroable for (A,) {}
+unsafe impl<A: Zeroable, B: Zeroable> Zeroable for (A, B) {}
+unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable> Zeroable for (A, B, C) {}
+unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable> Zeroable
+ for (A, B, C, D)
+{
+}
+unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable, E: Zeroable>
+ Zeroable for (A, B, C, D, E)
+{
+}
+unsafe impl<
+ A: Zeroable,
+ B: Zeroable,
+ C: Zeroable,
+ D: Zeroable,
+ E: Zeroable,
+ F: Zeroable,
+ > Zeroable for (A, B, C, D, E, F)
+{
+}
+unsafe impl<
+ A: Zeroable,
+ B: Zeroable,
+ C: Zeroable,
+ D: Zeroable,
+ E: Zeroable,
+ F: Zeroable,
+ G: Zeroable,
+ > Zeroable for (A, B, C, D, E, F, G)
+{
+}
+unsafe impl<
+ A: Zeroable,
+ B: Zeroable,
+ C: Zeroable,
+ D: Zeroable,
+ E: Zeroable,
+ F: Zeroable,
+ G: Zeroable,
+ H: Zeroable,
+ > Zeroable for (A, B, C, D, E, F, G, H)
+{
+}
+
+#[cfg(feature = "min_const_generics")]
+unsafe impl<T, const N: usize> Zeroable for [T; N] where T: Zeroable {}
+
+#[cfg(not(feature = "min_const_generics"))]
+impl_unsafe_marker_for_array!(
+ Zeroable, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
+ 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 48, 64, 96, 128, 256,
+ 512, 1024, 2048, 4096
+);
+
+#[cfg(all(target_arch = "wasm32", feature = "wasm_simd"))]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for wasm32::{v128}
+);
+
+#[cfg(all(target_arch = "aarch64", feature = "aarch64_simd"))]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for aarch64::{
+ float32x2_t, float32x2x2_t, float32x2x3_t, float32x2x4_t, float32x4_t,
+ float32x4x2_t, float32x4x3_t, float32x4x4_t, float64x1_t, float64x1x2_t,
+ float64x1x3_t, float64x1x4_t, float64x2_t, float64x2x2_t, float64x2x3_t,
+ float64x2x4_t, int16x4_t, int16x4x2_t, int16x4x3_t, int16x4x4_t, int16x8_t,
+ int16x8x2_t, int16x8x3_t, int16x8x4_t, int32x2_t, int32x2x2_t, int32x2x3_t,
+ int32x2x4_t, int32x4_t, int32x4x2_t, int32x4x3_t, int32x4x4_t, int64x1_t,
+ int64x1x2_t, int64x1x3_t, int64x1x4_t, int64x2_t, int64x2x2_t, int64x2x3_t,
+ int64x2x4_t, int8x16_t, int8x16x2_t, int8x16x3_t, int8x16x4_t, int8x8_t,
+ int8x8x2_t, int8x8x3_t, int8x8x4_t, poly16x4_t, poly16x4x2_t, poly16x4x3_t,
+ poly16x4x4_t, poly16x8_t, poly16x8x2_t, poly16x8x3_t, poly16x8x4_t,
+ poly64x1_t, poly64x1x2_t, poly64x1x3_t, poly64x1x4_t, poly64x2_t,
+ poly64x2x2_t, poly64x2x3_t, poly64x2x4_t, poly8x16_t, poly8x16x2_t,
+ poly8x16x3_t, poly8x16x4_t, poly8x8_t, poly8x8x2_t, poly8x8x3_t, poly8x8x4_t,
+ uint16x4_t, uint16x4x2_t, uint16x4x3_t, uint16x4x4_t, uint16x8_t,
+ uint16x8x2_t, uint16x8x3_t, uint16x8x4_t, uint32x2_t, uint32x2x2_t,
+ uint32x2x3_t, uint32x2x4_t, uint32x4_t, uint32x4x2_t, uint32x4x3_t,
+ uint32x4x4_t, uint64x1_t, uint64x1x2_t, uint64x1x3_t, uint64x1x4_t,
+ uint64x2_t, uint64x2x2_t, uint64x2x3_t, uint64x2x4_t, uint8x16_t,
+ uint8x16x2_t, uint8x16x3_t, uint8x16x4_t, uint8x8_t, uint8x8x2_t,
+ uint8x8x3_t, uint8x8x4_t,
+ }
+);
+
+#[cfg(target_arch = "x86")]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for x86::{
+ __m128i, __m128, __m128d,
+ __m256i, __m256, __m256d,
+ }
+);
+
+#[cfg(target_arch = "x86_64")]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for x86_64::{
+ __m128i, __m128, __m128d,
+ __m256i, __m256, __m256d,
+ }
+);
+
+#[cfg(feature = "nightly_portable_simd")]
+unsafe impl<T, const N: usize> Zeroable for core::simd::Simd<T, N>
+where
+ T: core::simd::SimdElement + Zeroable,
+ core::simd::LaneCount<N>: core::simd::SupportedLaneCount,
+{
+}
+
+#[cfg(all(target_arch = "x86", feature = "nightly_stdsimd"))]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for x86::{
+ __m128bh, __m256bh, __m512,
+ __m512bh, __m512d, __m512i,
+ }
+);
+
+#[cfg(all(target_arch = "x86_64", feature = "nightly_stdsimd"))]
+impl_unsafe_marker_for_simd!(
+ unsafe impl Zeroable for x86_64::{
+ __m128bh, __m256bh, __m512,
+ __m512bh, __m512d, __m512i,
+ }
+);
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