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 ALL stable Rust versions (MSRV: Rust 1.0.0).
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
. -
Rust 1.6.x - 1.20.x: No Drop protection: now,
MaybeUninit
is basically likestd::mem::uninitialized()
. -
Rust 1.0.x - 1.5.x: No support for
no_std
(it got stabilized in 1.6.0).