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maybe-uninit
Quite often, uses of std::mem::uninitialized()
end up in unsound code.
Therefore, the MaybeUninit
union has been added to std::mem
and std::mem::uninitialized()
is being deprecated.
However, MaybeUninit
has been added quite recently.
Sometimes you might want to support older versions of Rust as well.
Here is where maybe-uninit
comes in: it supports stable Rust versions starting with 1.20.0.
Sadly, a feature-complete implementation of MaybeUninit
is not possible on stable Rust.
Therefore, the library offers the guarantees of MaybeUninit
in a staged fashion:
-
Rust 1.36.0 onward:
MaybeUninit
implementation of Rust stable is being re-exported -
Rust 1.22.x - 1.35.0: No panicing on uninhabited types, unsoundness when used with types like
bool
or enums. However, there is protection from accidentiallyDrop
ing e.g. during unwind! -
Rust 1.20.x - 1.21.x: No support for Copy/Clone of
MaybeUninit<T>
, even ifT
implsCopy
or evenClone
.