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
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
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 {}
#[cfg(feature = "nightly_float")]
unsafe impl Zeroable for f16 {}
unsafe impl Zeroable for f32 {}
unsafe impl Zeroable for f64 {}
#[cfg(feature = "nightly_float")]
unsafe impl Zeroable for f128 {}
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 core::mem::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")]
#[cfg_attr(feature = "nightly_docs", doc(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")]
#[cfg_attr(
  feature = "nightly_docs",
  doc(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")]
#[cfg_attr(feature = "nightly_docs", doc(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
);

impl_unsafe_marker_for_simd!(
  #[cfg(all(target_arch = "wasm32", feature = "wasm_simd"))]
  unsafe impl Zeroable for wasm32::{v128}
);

impl_unsafe_marker_for_simd!(
  #[cfg(all(target_arch = "aarch64", feature = "aarch64_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,
  }
);

impl_unsafe_marker_for_simd!(
  #[cfg(target_arch = "x86")]
  unsafe impl Zeroable for x86::{
    __m128i, __m128, __m128d,
    __m256i, __m256, __m256d,
  }
);

impl_unsafe_marker_for_simd!(
  #[cfg(target_arch = "x86_64")]
    unsafe impl Zeroable for x86_64::{
        __m128i, __m128, __m128d,
        __m256i, __m256, __m256d,
    }
);

#[cfg(feature = "nightly_portable_simd")]
#[cfg_attr(
  feature = "nightly_docs",
  doc(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,
{
}

impl_unsafe_marker_for_simd!(
  #[cfg(all(target_arch = "x86", feature = "nightly_stdsimd"))]
  unsafe impl Zeroable for x86::{
    __m128bh, __m256bh, __m512,
    __m512bh, __m512d, __m512i,
  }
);

impl_unsafe_marker_for_simd!(
  #[cfg(all(target_arch = "x86_64", feature = "nightly_stdsimd"))]
  unsafe impl Zeroable for x86_64::{
    __m128bh, __m256bh, __m512,
    __m512bh, __m512d, __m512i,
  }
);