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Both the name of and the docs for MaybeUninit::uninit_array() make what it actually does somewhat unclear #66845
Description
Basically, based on the name of the function, and also the part of the docs for it that says:
Create a new array of MaybeUninit<T> items, in an uninitialized state.
I initially had the impression that it internally amounted to:
MaybeUninit::<[MaybeUninit<T>; LEN]>::uninit()
and returned an uninitialized array of uninitialized MaybeUninits.
However, after looking at the source, I realized it actually amounts to:
MaybeUninit::<[MaybeUninit<T>; LEN]>::uninit().assume_init()
and returns an initialized array of uninitialized MaybeUninits (which is what I actually needed, so that's good at least!)
Reacted by Luo Jia / Zhouqi Jiang
Activity
hkBst commentedon Feb 7, 2025
IIUC you assumed
MaybeUninit<[MaybeUninit<T>; N]>as output, but the documented output is[MaybeUninit<T>; N]. I don't thinkMaybeUninit<[MaybeUninit<T>; N]>is a useful type as an array really is nothing more than its elements, so if those are uninitialized, then the array is already uninitialized as a whole, since there is nothing else besides the elements.Maybe the "in an uninitialized state" is ambiguous as to whether it refers to the array or the elements though.
Clarify MaybeUninit docs
Clarify MaybeUninit docs
RalfJung commentedon Feb 21, 2025
You don't have to look at the source for that, the type is right there in the docs. :)
Clarify MaybeUninit docs
Rollup merge of rust-lang#134585 - cyrgani:uninit_array, r=Amanieu
Rollup merge of rust-lang#134585 - cyrgani:uninit_array, r=Amanieu
Unrolled build for rust-lang#134585
Rollup merge of rust-lang#134585 - cyrgani:uninit_array, r=Amanieu
Rollup merge of rust-lang#134585 - cyrgani:uninit_array, r=Amanieu