Make ZeroVec have a niche via NonNull #4491
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Manishearth
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Dec 23, 2023
Manishearth
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Dec 23, 2023
sffc
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Dec 23, 2023
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| // Safety: `ptr` comes from Vec::as_mut_ptr, which says: | ||
| // "Returns an unsafe mutable pointer to the vector’s buffer, | ||
| // or a dangling raw pointer valid for zero sized reads" | ||
| buf: unsafe { NonNull::new_unchecked(slice) }, |
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Is this safety comment valid? If the vector is empty, is it guaranteed that the dangling pointer is non-null?
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^ @Manishearth you approved the PR but can you confirm my question about the dangling pointer being non-null?
Manishearth
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Dec 23, 2023
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Is this good? Gives us a niche so that
Option<ZeroVec>doesn't add a whole word.