A pool can invoke destructors when it is cleared. Might take a bit of overhead (if the pool is to support arbitrary classes), but you could retain the fast pointer-bump allocation.

Not Rust, C++, but in case anybody wants an example: https://github.com/eclipse/omr/commit/fd99ca42fdbed76cc00e68...

TR::Region is the slab allocator used by the JIT in OpenJ9/OMR. The linked commit adds functionality for calling destructors of arbitrary types allocated in the Region.

Interesting, thanks. Seems to require use of a common base class though, i.e. to use a class with this pool, you have to inherit from Destructable, or else create a subclass that does. Seems ugly. Perhaps that's the only way it can be done in C++ though.

It does create an object with that base class for the allocator but returns an object of the type you want from the allocator, using a template (Region::Instance<T>). So the API user only sees the types it's interested in.