Merging Bit, Enum and Set fields in MySql

I kn开发者_运维百科ow up to eight Bit fields are merged into one byte to save space, but what if I have a couple of Bit fields and an Enum or a Set field? Are they internally merged too? I'm asking because I'm going to have a lot of rows in my table and I want to avoid overhead as much as possible.

According to the reference, SET fields use one byte minimum so those are out for any kind of merging.

Update: ENUM is out, too: They take at least one byte as well. Reference