AFAIK tagged-index-handles are typically used for this (where the tag is a generation-counter to detect 'dangling handles'), which more or less side-steps the b

AFAIK tagged-index-handles are typically used for this (where the tag is a generation-counter to detect 'dangling handles'), which more or less side-steps the borrow checker restrictions (e.g. see https://floooh.github.io/2018/06/17/handles-vs-pointers.html https://floooh.github.io/2018/06/17/handles-vs-pointers.html).