I have a project using this to provide the bit functions on C++17. I am working toward updating it to C++20, and when I did so, I realized all the extensions were no longer defined. It looks like when <bit> is used instead of the nonstd implementation for the standard features, it also disables all the extensions. Switching back with bit_CONFIG_SELECT_BIT works, but I would have expected the extensions to be available regardless of which implementation is used for the standard bit functions.