README.md
1# maybe-uninit
2
3Quite often, uses of `std::mem::uninitialized()` end up in unsound code.
4Therefore, the `MaybeUninit` union has been added to `std::mem` and `std::mem::uninitialized()` is being deprecated.
5However, `MaybeUninit` has been added quite recently.
6Sometimes you might want to support older versions of Rust as well.
7Here is where `maybe-uninit` comes in: it supports stable Rust versions starting with 1.20.0.
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9Sadly, a feature-complete implementation of `MaybeUninit` is not possible on stable Rust.
10Therefore, the library offers the guarantees of `MaybeUninit` in a staged fashion:
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12* Rust 1.36.0 onward: `MaybeUninit` implementation of Rust stable is being re-exported
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14* Rust 1.22.x - 1.35.0: No panicing on uninhabited types,
15 unsoundness when used with types like `bool` or enums.
16 However, there is protection from accidentially `Drop`ing e.g. during unwind!
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18* Rust 1.20.x - 1.21.x: No support for Copy/Clone of `MaybeUninit<T>`,
19 even if `T` impls `Copy` or even `Clone`.
20