All are fair points, I was being a bit cavalier with the facts. I'll also add that many if not all modern malloc() implementations actually allocate somewhat larger amounts of memory than your request, to respect various alignment requirements and/or to avoid excessive fragmentation - even when not using pure slab allocations.

I do think the C++ bookkeeping from new[]/delete[] however has few if any similar caveats - the runtime really needs exactly the kind of information you also need in your code; the only caveat I can imagine is that it might omit this information for types that don't need destruction, such as `int`, but I don't know if this is a plausible optimization in realistic use cases that are not trivial.