Document that BytesMut::{reserve,try_reserve} doesn't preserve unused capacity
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Darksonn
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BytesMut::reserve may not preserve memory outside 0..lenBytesMut::{reserve,try_reserve} doesn't preserve unused capacity
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This documents that
BytesMutmay not preserve the memory outside of0..lenafter callingBytesMut::reserve. It may for example discard all of it, and replace it with uninit memory in the fallback case, or even shift it causing a different region of theBytesMutto appear when going through the reclaim optimization.This was encountered in snapview/tungstenite-rs#524 (comment) after #805 was closed, which could have lead to unsound code being merged into
tungstenite.