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ArrayVec is undefined behavior when storing types with invalid bit patterns #105
Description
Initially in an ArrayVec the memory is uninitialized: https://github.com/bluss/arrayvec/blob/master/src/lib.rs#L80.
This simply is UB in Rust for any types with invalid bit patterns (most notably references). Just creating an uninitialized value with these bit patterns is UB.
Even perfectly fine code that never actually reads or uses the uninitialized memory still has undefined behavior. I ran into this myself: https://stackoverflow.com/questions/52348277/vector-is-empty-after-cloning-struct-with-uninitialized-member.
Activity
bluss commentedon Oct 27, 2018
Thanks, this is something that has clarified a lot in recent versions of Rust, and we should be able to use MaybeUninitialized soon.
bluss commentedon Nov 25, 2018
See also #97 and related issues and prs
bluss commentedon Jul 10, 2019
Closed by #127 with the caveat, that Rust 1.36 or later is required.