rust/library/core/src/mem
Yuki Okushi babfdafb10
Rollup merge of #80600 - CoffeeBlend:maybe_uninit_array_assume_init, r=dtolnay
Add `MaybeUninit` method `array_assume_init`

When initialising an array element-by-element, the conversion to the initialised array is done through `mem::transmute`, which is both ugly and does not work with const generics (see #61956). This PR proposes the associated method `array_assume_init`, matching the style of `slice_assume_init_*`:

```rust
unsafe fn array_assume_init<T, const N: usize>(array: [MaybeUninit<T>; N]) -> [T; N];
```

Example:
```rust
let mut array: [MaybeUninit<i32>; 3] = MaybeUninit::uninit_array();
array[0].write(0);
array[1].write(1);
array[2].write(2);

// SAFETY: Now safe as we initialised all elements
let array: [i32; 3] = unsafe {
     MaybeUninit::array_assume_init(array)
};
```

Things I'm unsure about:
* Should this be a method of array instead?
* Should the function be const?
2021-01-12 16:13:24 +09:00
..
manually_drop.rs Don't recommend ManuallyDrop to customize drop order 2020-09-21 14:00:04 +02:00
maybe_uninit.rs Fix implementation 2021-01-12 01:39:10 +01:00
mod.rs Make size_of_val and min_align_of_val intrinsics unsafe 2021-01-04 19:23:55 -08:00