bytemuck/
zeroable.rs

1use super::*;
2
3/// Trait for types that can be safely created with
4/// [`zeroed`](core::mem::zeroed).
5///
6/// An all-zeroes value may or may not be the same value as the
7/// [Default](core::default::Default) value of the type.
8///
9/// ## Safety
10///
11/// * Your type must be inhabited (eg: no
12///   [Infallible](core::convert::Infallible)).
13/// * Your type must be allowed to be an "all zeroes" bit pattern (eg: no
14///   [`NonNull<T>`](core::ptr::NonNull)).
15///
16/// ## Features
17///
18/// Some `impl`s are feature gated due to the MSRV policy:
19///
20/// * `MaybeUninit<T>` was not available in 1.34.0, but is available under the
21///   `zeroable_maybe_uninit` feature flag.
22/// * `Atomic*` types require Rust 1.60.0 or later to work on certain platforms,
23///   but is available under the `zeroable_atomics` feature flag.
24/// * `[T; N]` for arbitrary `N` requires the `min_const_generics` feature flag.
25pub unsafe trait Zeroable: Sized {
26  /// Calls [`zeroed`](core::mem::zeroed).
27  ///
28  /// This is a trait method so that you can write `MyType::zeroed()` in your
29  /// code. It is a contract of this trait that if you implement it on your type
30  /// you **must not** override this method.
31  #[inline]
32  fn zeroed() -> Self {
33    unsafe { core::mem::zeroed() }
34  }
35}
36unsafe impl Zeroable for () {}
37unsafe impl Zeroable for bool {}
38unsafe impl Zeroable for char {}
39unsafe impl Zeroable for u8 {}
40unsafe impl Zeroable for i8 {}
41unsafe impl Zeroable for u16 {}
42unsafe impl Zeroable for i16 {}
43unsafe impl Zeroable for u32 {}
44unsafe impl Zeroable for i32 {}
45unsafe impl Zeroable for u64 {}
46unsafe impl Zeroable for i64 {}
47unsafe impl Zeroable for usize {}
48unsafe impl Zeroable for isize {}
49unsafe impl Zeroable for u128 {}
50unsafe impl Zeroable for i128 {}
51#[cfg(feature = "nightly_float")]
52unsafe impl Zeroable for f16 {}
53unsafe impl Zeroable for f32 {}
54unsafe impl Zeroable for f64 {}
55#[cfg(feature = "nightly_float")]
56unsafe impl Zeroable for f128 {}
57unsafe impl<T: Zeroable> Zeroable for Wrapping<T> {}
58unsafe impl<T: Zeroable> Zeroable for core::cmp::Reverse<T> {}
59#[cfg(feature = "pod_saturating")]
60unsafe impl<T: Zeroable> Zeroable for core::num::Saturating<T> {}
61
62// Note: we can't implement this for all `T: ?Sized` types because it would
63// create NULL pointers for vtables.
64// Maybe one day this could be changed to be implemented for
65// `T: ?Sized where <T as core::ptr::Pointee>::Metadata: Zeroable`.
66unsafe impl<T> Zeroable for *mut T {}
67unsafe impl<T> Zeroable for *const T {}
68unsafe impl<T> Zeroable for *mut [T] {}
69unsafe impl<T> Zeroable for *const [T] {}
70unsafe impl Zeroable for *mut str {}
71unsafe impl Zeroable for *const str {}
72
73unsafe impl<T: ?Sized> Zeroable for PhantomData<T> {}
74unsafe impl Zeroable for PhantomPinned {}
75unsafe impl<T: Zeroable> Zeroable for core::mem::ManuallyDrop<T> {}
76unsafe impl<T: Zeroable> Zeroable for core::cell::UnsafeCell<T> {}
77unsafe impl<T: Zeroable> Zeroable for core::cell::Cell<T> {}
78
79#[cfg(feature = "zeroable_atomics")]
80#[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "zeroable_atomics")))]
81mod atomic_impls {
82  use super::Zeroable;
83
84  #[cfg(target_has_atomic = "8")]
85  unsafe impl Zeroable for core::sync::atomic::AtomicBool {}
86  #[cfg(target_has_atomic = "8")]
87  unsafe impl Zeroable for core::sync::atomic::AtomicU8 {}
88  #[cfg(target_has_atomic = "8")]
89  unsafe impl Zeroable for core::sync::atomic::AtomicI8 {}
90
91  #[cfg(target_has_atomic = "16")]
92  unsafe impl Zeroable for core::sync::atomic::AtomicU16 {}
93  #[cfg(target_has_atomic = "16")]
94  unsafe impl Zeroable for core::sync::atomic::AtomicI16 {}
95
96  #[cfg(target_has_atomic = "32")]
97  unsafe impl Zeroable for core::sync::atomic::AtomicU32 {}
98  #[cfg(target_has_atomic = "32")]
99  unsafe impl Zeroable for core::sync::atomic::AtomicI32 {}
100
101  #[cfg(target_has_atomic = "64")]
102  unsafe impl Zeroable for core::sync::atomic::AtomicU64 {}
103  #[cfg(target_has_atomic = "64")]
104  unsafe impl Zeroable for core::sync::atomic::AtomicI64 {}
105
106  #[cfg(target_has_atomic = "ptr")]
107  unsafe impl Zeroable for core::sync::atomic::AtomicUsize {}
108  #[cfg(target_has_atomic = "ptr")]
109  unsafe impl Zeroable for core::sync::atomic::AtomicIsize {}
110
111  #[cfg(target_has_atomic = "ptr")]
112  unsafe impl<T> Zeroable for core::sync::atomic::AtomicPtr<T> {}
113}
114
115#[cfg(feature = "zeroable_maybe_uninit")]
116#[cfg_attr(
117  feature = "nightly_docs",
118  doc(cfg(feature = "zeroable_maybe_uninit"))
119)]
120unsafe impl<T> Zeroable for core::mem::MaybeUninit<T> {}
121
122unsafe impl<A: Zeroable> Zeroable for (A,) {}
123unsafe impl<A: Zeroable, B: Zeroable> Zeroable for (A, B) {}
124unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable> Zeroable for (A, B, C) {}
125unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable> Zeroable
126  for (A, B, C, D)
127{
128}
129unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable, E: Zeroable>
130  Zeroable for (A, B, C, D, E)
131{
132}
133unsafe impl<
134    A: Zeroable,
135    B: Zeroable,
136    C: Zeroable,
137    D: Zeroable,
138    E: Zeroable,
139    F: Zeroable,
140  > Zeroable for (A, B, C, D, E, F)
141{
142}
143unsafe impl<
144    A: Zeroable,
145    B: Zeroable,
146    C: Zeroable,
147    D: Zeroable,
148    E: Zeroable,
149    F: Zeroable,
150    G: Zeroable,
151  > Zeroable for (A, B, C, D, E, F, G)
152{
153}
154unsafe impl<
155    A: Zeroable,
156    B: Zeroable,
157    C: Zeroable,
158    D: Zeroable,
159    E: Zeroable,
160    F: Zeroable,
161    G: Zeroable,
162    H: Zeroable,
163  > Zeroable for (A, B, C, D, E, F, G, H)
164{
165}
166
167#[cfg(feature = "min_const_generics")]
168#[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "min_const_generics")))]
169unsafe impl<T, const N: usize> Zeroable for [T; N] where T: Zeroable {}
170
171#[cfg(not(feature = "min_const_generics"))]
172impl_unsafe_marker_for_array!(
173  Zeroable, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
174  19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 48, 64, 96, 128, 256,
175  512, 1024, 2048, 4096
176);
177
178impl_unsafe_marker_for_simd!(
179  #[cfg(all(target_arch = "wasm32", feature = "wasm_simd"))]
180  unsafe impl Zeroable for wasm32::{v128}
181);
182
183impl_unsafe_marker_for_simd!(
184  #[cfg(all(target_arch = "aarch64", feature = "aarch64_simd"))]
185  unsafe impl Zeroable for aarch64::{
186    float32x2_t, float32x2x2_t, float32x2x3_t, float32x2x4_t, float32x4_t,
187    float32x4x2_t, float32x4x3_t, float32x4x4_t, float64x1_t, float64x1x2_t,
188    float64x1x3_t, float64x1x4_t, float64x2_t, float64x2x2_t, float64x2x3_t,
189    float64x2x4_t, int16x4_t, int16x4x2_t, int16x4x3_t, int16x4x4_t, int16x8_t,
190    int16x8x2_t, int16x8x3_t, int16x8x4_t, int32x2_t, int32x2x2_t, int32x2x3_t,
191    int32x2x4_t, int32x4_t, int32x4x2_t, int32x4x3_t, int32x4x4_t, int64x1_t,
192    int64x1x2_t, int64x1x3_t, int64x1x4_t, int64x2_t, int64x2x2_t, int64x2x3_t,
193    int64x2x4_t, int8x16_t, int8x16x2_t, int8x16x3_t, int8x16x4_t, int8x8_t,
194    int8x8x2_t, int8x8x3_t, int8x8x4_t, poly16x4_t, poly16x4x2_t, poly16x4x3_t,
195    poly16x4x4_t, poly16x8_t, poly16x8x2_t, poly16x8x3_t, poly16x8x4_t,
196    poly64x1_t, poly64x1x2_t, poly64x1x3_t, poly64x1x4_t, poly64x2_t,
197    poly64x2x2_t, poly64x2x3_t, poly64x2x4_t, poly8x16_t, poly8x16x2_t,
198    poly8x16x3_t, poly8x16x4_t, poly8x8_t, poly8x8x2_t, poly8x8x3_t, poly8x8x4_t,
199    uint16x4_t, uint16x4x2_t, uint16x4x3_t, uint16x4x4_t, uint16x8_t,
200    uint16x8x2_t, uint16x8x3_t, uint16x8x4_t, uint32x2_t, uint32x2x2_t,
201    uint32x2x3_t, uint32x2x4_t, uint32x4_t, uint32x4x2_t, uint32x4x3_t,
202    uint32x4x4_t, uint64x1_t, uint64x1x2_t, uint64x1x3_t, uint64x1x4_t,
203    uint64x2_t, uint64x2x2_t, uint64x2x3_t, uint64x2x4_t, uint8x16_t,
204    uint8x16x2_t, uint8x16x3_t, uint8x16x4_t, uint8x8_t, uint8x8x2_t,
205    uint8x8x3_t, uint8x8x4_t,
206  }
207);
208
209impl_unsafe_marker_for_simd!(
210  #[cfg(target_arch = "x86")]
211  unsafe impl Zeroable for x86::{
212    __m128i, __m128, __m128d,
213    __m256i, __m256, __m256d,
214  }
215);
216
217impl_unsafe_marker_for_simd!(
218  #[cfg(target_arch = "x86_64")]
219    unsafe impl Zeroable for x86_64::{
220        __m128i, __m128, __m128d,
221        __m256i, __m256, __m256d,
222    }
223);
224
225#[cfg(feature = "nightly_portable_simd")]
226#[cfg_attr(
227  feature = "nightly_docs",
228  doc(cfg(feature = "nightly_portable_simd"))
229)]
230unsafe impl<T, const N: usize> Zeroable for core::simd::Simd<T, N>
231where
232  T: core::simd::SimdElement + Zeroable,
233  core::simd::LaneCount<N>: core::simd::SupportedLaneCount,
234{
235}
236
237impl_unsafe_marker_for_simd!(
238  #[cfg(all(target_arch = "x86", any(feature = "nightly_stdsimd", feature = "avx512_simd")))]
239  unsafe impl Zeroable for x86::{
240    __m512, __m512d, __m512i
241  }
242);
243
244impl_unsafe_marker_for_simd!(
245  #[cfg(all(target_arch = "x86_64", any(feature = "nightly_stdsimd", feature = "avx512_simd")))]
246  unsafe impl Zeroable for x86_64::{
247    __m512, __m512d, __m512i
248  }
249);
250
251impl_unsafe_marker_for_simd!(
252  #[cfg(all(target_arch = "x86", feature = "nightly_stdsimd"))]
253  unsafe impl Zeroable for x86::{
254    __m128bh, __m256bh, __m512bh
255  }
256);
257
258impl_unsafe_marker_for_simd!(
259  #[cfg(all(target_arch = "x86_64", feature = "nightly_stdsimd"))]
260  unsafe impl Zeroable for x86_64::{
261    __m128bh, __m256bh, __m512bh
262  }
263);
bytemuck/zeroable.rs

bytemuck/
zeroable.rs
