1 use 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. 25 pub 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] zeroed() -> Self32 fn zeroed() -> Self { 33 unsafe { core::mem::zeroed() } 34 } 35 } 36 unsafe impl Zeroable for () {} 37 unsafe impl Zeroable for bool {} 38 unsafe impl Zeroable for char {} 39 unsafe impl Zeroable for u8 {} 40 unsafe impl Zeroable for i8 {} 41 unsafe impl Zeroable for u16 {} 42 unsafe impl Zeroable for i16 {} 43 unsafe impl Zeroable for u32 {} 44 unsafe impl Zeroable for i32 {} 45 unsafe impl Zeroable for u64 {} 46 unsafe impl Zeroable for i64 {} 47 unsafe impl Zeroable for usize {} 48 unsafe impl Zeroable for isize {} 49 unsafe impl Zeroable for u128 {} 50 unsafe impl Zeroable for i128 {} 51 #[cfg(feature = "nightly_float")] 52 unsafe impl Zeroable for f16 {} 53 unsafe impl Zeroable for f32 {} 54 unsafe impl Zeroable for f64 {} 55 #[cfg(feature = "nightly_float")] 56 unsafe impl Zeroable for f128 {} 57 unsafe impl<T: Zeroable> Zeroable for Wrapping<T> {} 58 unsafe impl<T: Zeroable> Zeroable for core::cmp::Reverse<T> {} 59 60 // Note: we can't implement this for all `T: ?Sized` types because it would 61 // create NULL pointers for vtables. 62 // Maybe one day this could be changed to be implemented for 63 // `T: ?Sized where <T as core::ptr::Pointee>::Metadata: Zeroable`. 64 unsafe impl<T> Zeroable for *mut T {} 65 unsafe impl<T> Zeroable for *const T {} 66 unsafe impl<T> Zeroable for *mut [T] {} 67 unsafe impl<T> Zeroable for *const [T] {} 68 unsafe impl Zeroable for *mut str {} 69 unsafe impl Zeroable for *const str {} 70 71 unsafe impl<T: ?Sized> Zeroable for PhantomData<T> {} 72 unsafe impl Zeroable for PhantomPinned {} 73 unsafe impl<T: Zeroable> Zeroable for core::mem::ManuallyDrop<T> {} 74 unsafe impl<T: Zeroable> Zeroable for core::cell::UnsafeCell<T> {} 75 unsafe impl<T: Zeroable> Zeroable for core::cell::Cell<T> {} 76 77 #[cfg(feature = "zeroable_atomics")] 78 #[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "zeroable_atomics")))] 79 mod atomic_impls { 80 use super::Zeroable; 81 82 #[cfg(target_has_atomic = "8")] 83 unsafe impl Zeroable for core::sync::atomic::AtomicBool {} 84 #[cfg(target_has_atomic = "8")] 85 unsafe impl Zeroable for core::sync::atomic::AtomicU8 {} 86 #[cfg(target_has_atomic = "8")] 87 unsafe impl Zeroable for core::sync::atomic::AtomicI8 {} 88 89 #[cfg(target_has_atomic = "16")] 90 unsafe impl Zeroable for core::sync::atomic::AtomicU16 {} 91 #[cfg(target_has_atomic = "16")] 92 unsafe impl Zeroable for core::sync::atomic::AtomicI16 {} 93 94 #[cfg(target_has_atomic = "32")] 95 unsafe impl Zeroable for core::sync::atomic::AtomicU32 {} 96 #[cfg(target_has_atomic = "32")] 97 unsafe impl Zeroable for core::sync::atomic::AtomicI32 {} 98 99 #[cfg(target_has_atomic = "64")] 100 unsafe impl Zeroable for core::sync::atomic::AtomicU64 {} 101 #[cfg(target_has_atomic = "64")] 102 unsafe impl Zeroable for core::sync::atomic::AtomicI64 {} 103 104 #[cfg(target_has_atomic = "ptr")] 105 unsafe impl Zeroable for core::sync::atomic::AtomicUsize {} 106 #[cfg(target_has_atomic = "ptr")] 107 unsafe impl Zeroable for core::sync::atomic::AtomicIsize {} 108 109 #[cfg(target_has_atomic = "ptr")] 110 unsafe impl<T> Zeroable for core::sync::atomic::AtomicPtr<T> {} 111 } 112 113 #[cfg(feature = "zeroable_maybe_uninit")] 114 #[cfg_attr( 115 feature = "nightly_docs", 116 doc(cfg(feature = "zeroable_maybe_uninit")) 117 )] 118 unsafe impl<T> Zeroable for core::mem::MaybeUninit<T> {} 119 120 unsafe impl<A: Zeroable> Zeroable for (A,) {} 121 unsafe impl<A: Zeroable, B: Zeroable> Zeroable for (A, B) {} 122 unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable> Zeroable for (A, B, C) {} 123 unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable> Zeroable 124 for (A, B, C, D) 125 { 126 } 127 unsafe impl<A: Zeroable, B: Zeroable, C: Zeroable, D: Zeroable, E: Zeroable> 128 Zeroable for (A, B, C, D, E) 129 { 130 } 131 unsafe impl< 132 A: Zeroable, 133 B: Zeroable, 134 C: Zeroable, 135 D: Zeroable, 136 E: Zeroable, 137 F: Zeroable, 138 > Zeroable for (A, B, C, D, E, F) 139 { 140 } 141 unsafe impl< 142 A: Zeroable, 143 B: Zeroable, 144 C: Zeroable, 145 D: Zeroable, 146 E: Zeroable, 147 F: Zeroable, 148 G: Zeroable, 149 > Zeroable for (A, B, C, D, E, F, G) 150 { 151 } 152 unsafe impl< 153 A: Zeroable, 154 B: Zeroable, 155 C: Zeroable, 156 D: Zeroable, 157 E: Zeroable, 158 F: Zeroable, 159 G: Zeroable, 160 H: Zeroable, 161 > Zeroable for (A, B, C, D, E, F, G, H) 162 { 163 } 164 165 #[cfg(feature = "min_const_generics")] 166 #[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "min_const_generics")))] 167 unsafe impl<T, const N: usize> Zeroable for [T; N] where T: Zeroable {} 168 169 #[cfg(not(feature = "min_const_generics"))] 170 impl_unsafe_marker_for_array!( 171 Zeroable, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 172 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 48, 64, 96, 128, 256, 173 512, 1024, 2048, 4096 174 ); 175 176 impl_unsafe_marker_for_simd!( 177 #[cfg(all(target_arch = "wasm32", feature = "wasm_simd"))] 178 unsafe impl Zeroable for wasm32::{v128} 179 ); 180 181 impl_unsafe_marker_for_simd!( 182 #[cfg(all(target_arch = "aarch64", feature = "aarch64_simd"))] 183 unsafe impl Zeroable for aarch64::{ 184 float32x2_t, float32x2x2_t, float32x2x3_t, float32x2x4_t, float32x4_t, 185 float32x4x2_t, float32x4x3_t, float32x4x4_t, float64x1_t, float64x1x2_t, 186 float64x1x3_t, float64x1x4_t, float64x2_t, float64x2x2_t, float64x2x3_t, 187 float64x2x4_t, int16x4_t, int16x4x2_t, int16x4x3_t, int16x4x4_t, int16x8_t, 188 int16x8x2_t, int16x8x3_t, int16x8x4_t, int32x2_t, int32x2x2_t, int32x2x3_t, 189 int32x2x4_t, int32x4_t, int32x4x2_t, int32x4x3_t, int32x4x4_t, int64x1_t, 190 int64x1x2_t, int64x1x3_t, int64x1x4_t, int64x2_t, int64x2x2_t, int64x2x3_t, 191 int64x2x4_t, int8x16_t, int8x16x2_t, int8x16x3_t, int8x16x4_t, int8x8_t, 192 int8x8x2_t, int8x8x3_t, int8x8x4_t, poly16x4_t, poly16x4x2_t, poly16x4x3_t, 193 poly16x4x4_t, poly16x8_t, poly16x8x2_t, poly16x8x3_t, poly16x8x4_t, 194 poly64x1_t, poly64x1x2_t, poly64x1x3_t, poly64x1x4_t, poly64x2_t, 195 poly64x2x2_t, poly64x2x3_t, poly64x2x4_t, poly8x16_t, poly8x16x2_t, 196 poly8x16x3_t, poly8x16x4_t, poly8x8_t, poly8x8x2_t, poly8x8x3_t, poly8x8x4_t, 197 uint16x4_t, uint16x4x2_t, uint16x4x3_t, uint16x4x4_t, uint16x8_t, 198 uint16x8x2_t, uint16x8x3_t, uint16x8x4_t, uint32x2_t, uint32x2x2_t, 199 uint32x2x3_t, uint32x2x4_t, uint32x4_t, uint32x4x2_t, uint32x4x3_t, 200 uint32x4x4_t, uint64x1_t, uint64x1x2_t, uint64x1x3_t, uint64x1x4_t, 201 uint64x2_t, uint64x2x2_t, uint64x2x3_t, uint64x2x4_t, uint8x16_t, 202 uint8x16x2_t, uint8x16x3_t, uint8x16x4_t, uint8x8_t, uint8x8x2_t, 203 uint8x8x3_t, uint8x8x4_t, 204 } 205 ); 206 207 impl_unsafe_marker_for_simd!( 208 #[cfg(target_arch = "x86")] 209 unsafe impl Zeroable for x86::{ 210 __m128i, __m128, __m128d, 211 __m256i, __m256, __m256d, 212 } 213 ); 214 215 impl_unsafe_marker_for_simd!( 216 #[cfg(target_arch = "x86_64")] 217 unsafe impl Zeroable for x86_64::{ 218 __m128i, __m128, __m128d, 219 __m256i, __m256, __m256d, 220 } 221 ); 222 223 #[cfg(feature = "nightly_portable_simd")] 224 #[cfg_attr( 225 feature = "nightly_docs", 226 doc(cfg(feature = "nightly_portable_simd")) 227 )] 228 unsafe impl<T, const N: usize> Zeroable for core::simd::Simd<T, N> 229 where 230 T: core::simd::SimdElement + Zeroable, 231 core::simd::LaneCount<N>: core::simd::SupportedLaneCount, 232 { 233 } 234 235 impl_unsafe_marker_for_simd!( 236 #[cfg(all(target_arch = "x86", feature = "nightly_stdsimd"))] 237 unsafe impl Zeroable for x86::{ 238 __m128bh, __m256bh, __m512, 239 __m512bh, __m512d, __m512i, 240 } 241 ); 242 243 impl_unsafe_marker_for_simd!( 244 #[cfg(all(target_arch = "x86_64", feature = "nightly_stdsimd"))] 245 unsafe impl Zeroable for x86_64::{ 246 __m128bh, __m256bh, __m512, 247 __m512bh, __m512d, __m512i, 248 } 249 ); 250