> IOW, the example is not related to https://timsong-cpp.github.io/cppwp/n4868/over.ics.rank#3.3, you need multiple `f`s to start to care about that bullet.

Actually, this should not be new to you, here is your 10 y.o. question https://stackoverflow.com/questions/11555950/distinguishing-between-user-defined-conversion-sequences-by-the-initial-standard