///   '\\' c: matches character c
  /// character-range:
  ///   c: matches character c (c != '\\', '-', ']')
  ///   '\\' c: matches character c
  ///   lo '-' hi: matches character c for lo <= c <= hi
  ///
  /// Implementations must allocate `entries` to hold all names that need to be
  /// returned and return the size of `entries`. Caller takes ownership of
  /// `entries` after the call.
  ///