Function with contract but not leading to UB, unsafe or not?

[leudz]

Entities can safely be deleted by using AllStorages but all storages have to be iterated over and it prevents any parallelization.

One way to get around this issue is to have a function on Entities. To make this function safe a component counter could be added to Entities but it would mean borrowing Entities to add/remove components and impact performance of many operations (add/remove entities and components).
To avoid the api and performance issue, a function can be implemented without counter.

delete_unchecked would rely on the user to remove all components from the entity before calling it. In case this isn't respected the user could access components they didn't removed with a deleted entity.

The question is: should delete_unchecked be unsafe or not?

I'm not the first person struggling with the issue rust-lang/api-guidelines#179 but currently no consensus has been reached.

[leudz]

Based on this discussion and the ones linked into it, I'm closing this issue with the conclusion that it shouldn't be unsafe but just marked *_unchecked.

If someone has good opposing arguments, I'm open to go back on this decision.