Use MaybeUninit instead of ManuallyDrop to inhibit the validity invariant of the storage type #3
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``` assertion failed: Some(InlineArray::<usize, [Box<()>; 2]>::new()).is_some() assertion failed: Some(RingBuffer::<Box<()>>::new()).is_some() assertion failed: Some(Chunk::<Box<()>>::new()).is_some() assertion failed: Some(SparseChunk::<Box<()>>::new()).is_some() ```
… calls where straightforward This also takes care of returning early if needs_drop returns false
It is undecided whether the Rust language should make this UB, so manipulating raw pointers works either way.
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This is brilliant, and, more importantly, seems to pass the im-rs stress tests. Thanks! |
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Oops I meant to mention: this raises the minimum Rust version to 1.36 |
This was referenced Nov 15, 2019
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Nov 19, 2019
bump im-rc version This bumps im-rc to a version that includes (transitively) the soundness fix in bodil/sized-chunks#3. * [im-rc changelog](https://github.com/bodil/im-rs/blob/master/CHANGELOG.md#1400---2019-11-19)
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This fixes the tests added in the first commit, which failed previously:
Box<_>contains a pointer that is known not to be null, soOption<Box<_>>can be stored on a single pointer with null representingNone. This also works for structs that contain aBoxfield, even withinManuallyDrop, so writing zero to that memory location is incorrect. WithMaybeUninithowever, it is correct for any byte of the memory representation to be zero (or not initialized) so the enum layout optimization does not use niches found withinMaybeUninit.Also some less important drive-by changes in the latter two commits, let me know if you’d prefer having them separately or not having them.