Remove shared_array!
#318
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Remove shared_array!
#318
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While I was fixing #317 I found this macro and concluded it was both irredeemable and unnecessary. Using |
nnethercote
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It's wildly unsound, as far as I can tell. - The use of `UnsafeCell`/`unsafe impl Send`/`unsafe impl Sync` is very dodgy. - The use of `MaybeUninit<[T; N]>` is completely wrong. It should be `[<MaybeUninit<T>; N>]`, which allows for partial initialization. - The examples don't use `write`/`assume_init` with `MaybeUninit`, which is UB. The alternative is to use `#[address_space(shared) static mut [MaybeUninit<T>; N]` directly instead. That avoids all the unsoundness, and is more ergonomic because you don't have to work with a raw pointer, and is clearer because details aren't hidden within the macro. I moved (with some modifications) the comments on `shared_array` to the `address_space` proc macro because there were some useful details in there.
This was non-obvious to me, and took a minute to work out.
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LegNeato
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Nov 26, 2025
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It's wildly unsound, as far as I can tell.
UnsafeCell/unsafe impl Send/unsafe impl Syncis very dodgy.MaybeUninit<[T; N]>is completely wrong. It should be[<MaybeUninit<T>; N>], which allows for partial initialization.write/assume_initwithMaybeUninit, which is UB.The alternative is to use
#[address_space(shared) static mut [MaybeUninit<T>; N]directly instead. That avoids all the unsoundness, and is more ergonomic because you don't have to work with a raw pointer, and is clearer because details aren't hidden within the macro.I moved (with some modifications) the comments on
shared_arrayto theaddress_spaceproc macro because there were some useful details in there.