Safety improvements for repr(stabby) enums
#69
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ABI BREAKING CHANGE
While
stabby::result::Result's actual layout hasn't truly changed, this PR fixes a soundness hole which might still be triggered by exploiting aResultreceived from a binary with the previous representation.stabbytreats this release'sResultas different from that of the previous.Fixing an unsoundness in
stabby::result::Resultwhich infected allrepr(stabby)enumstabby::result::Resultsometimes encodes determinants in structure padding. However, until this PR, rustc was free to treat these paddings as unused data, making reads in these regions UB.Due to this, any
repr(stabby)enum that used these determinants is unsound until this PR is merged.This PR addresses this by ensure Rust treats enums as a blob of memory with the appropriate size and alignment.
A nice side effect of this PR is that Rust previously treated
repr(stabby)enums asimproper_ctypesdue to the determinants being ZSTs, as highlighted by issue #68. This is no longer the case.