The crate gained quite a bit of interface since last time. I'm not quite sure
how I feel about this at the moment but understanding definitely suffered
from it.

Of most concern is definitely TransparentWrapper which relies on the
internal implementation detail that the layout of a pointer type itself does
not change for transparent wrappers. This premise seems a very unlikely to be
invalidated from changes but nevertheless departs with only relying on
stabilized and fully RFCed properties.

Other than that, no critical changes and a continued trend of being cautious.
Notably the implementation of Contiguous guards against bad implementations
despite being unsafe to implement, the offset_of macro is completely
safe(!)—a welcome change for such macros—and there are MIRI tests in CI.

The test suite could be a lot bigger but some tests are obviously foiled by
MIRI rejecting some sound and UB-free code that relies on alignment checks,
to avoid those incidentally succeeding in unsound code.