Only similar by a little bit. Bitset misses the mark in so many ways.

bit_array can be compile time storage (ala bitset) or dynamic at construction time. There is also bit_vector which is entirely dynamic

Critically though, is that the type/library is built on a proxy iterator/pointer that lets you do certain things with STL or the bit algorithms that you cannot otherwise do with bitset.

But back to the bitfields idea. The bit array backing storage is configurable through templates so you will be able to know for certain exactly how much stack or heap your type will take up