[any] [basic_any] This seems like a little pearl in Boost 1.77, but it's a bit underdocumented?

From: Viktor Sehr (viktor.sehr_at_[hidden])
Date: 2021-08-20 11:23:36

I just discovered basic_any which is a very nice addition for me. However
it's a bit under-documented for the moment.

For example:
- I assume it's stack-allocated, does it allocate on the heap if assigned
an object larger than the stack (like small_vector) or is this not allowed
(like static_vector)?

- An idea would also be to add a flag which breaks compilation if an object
larger than the OptimizeForSize argument is assigned?

- (For detail) If allocated on the stack, are the first bytes of the
basic_any the same as the contained object?

/Viktor