I tried suggesting this directly on GitHub. Here was the response:<p>&gt; There&#x27;s an old idea of unsafe fields that would come up for datatypes. It can be emulated with a Unsafe&lt;T&gt; wrapper that has unsafe methods to get references to its interior, or to read&#x2F;write. It&#x27;s not widely used, or used at all afaik, since the gains aren&#x27;t that great. People writing unsafe code generally know the issues, and that privacy is the #1 way the abstraction boundary is maintained.<p><a href="https:&#x2F;&#x2F;github.com&#x2F;rust-lang&#x2F;rust&#x2F;issues&#x2F;9883#issuecomment-170716254" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;rust-lang&#x2F;rust&#x2F;issues&#x2F;9883#issuecomment-1...</a><p>Privacy may be the best way to limit unsafety, but C and C++ already have privacy.