[pcwalton]

Some sort of pointer tagging system, like 128-bit pointers where the upper word is a unique generation ID, might be the simplest approach to eliminate security problems from use-after-free, but it's going to have some amount of runtime overhead (though new hardware features may help to reduce it).

Alternately, use a GC.

[azakai]

Another option is something like Type-After-Type (make allocations use type-specific regions, so use-after-free is still fully type safe at least):

https://download.vusec.net/papers/tat_acsac18.pdf

[pcwalton]

Yes, something like that may work. Note that this approach also has time and memory overhead quoted in the paper. There's no free lunch.