For example:

enum Animal {
  Spider {
    iHateSnakes: bool,
  },
  ...
}

...

match pet {
  Animal::Spider { iHateSnakes } =>
  ...

This gives you a warning that iHateSnakes should be snake case in the match arm. But at that point you don't really have much choice about it. Variable name warnings should be where the variable is named, and it isn't really named there. (Maybe there's some syntax like { i_hate_snakes @ iHateSnakes } but who is going to bother with that?)

This issue has been assigned to @jumbatm via this comment.