hi-lock-regexp-history

hi-lock-regexp-history is a variable defined in `hi-lock.el'.
Its value is

nil

• This variable is an alias for `regexp-history'.
• This variable is obsolete since 23.1;
  use `regexp-history' instead.

Documentation:
History list for some commands that read regular expressions.

Maximum length of the history list is determined by the value
of `history-length', which see.