Custom allocator for DenseMap

Hi all,

I’m curious, is there a reason why DenseMap doesn’t templatize a custom Allocator? I’m
in the process of switching all my uses of std::unordered_map and a custom-rolled hash
map implementation to StringMap and DenseMap. StringMap allows the injection of an
allocator, but not DenseMap.

Aside from subclassing DenseMapBase and implementing grow/shrink functionality similar
to DenseMap, is there a simpler solution to injecting custom allocation and deallocation
into a DenseMap?