Christian Couder [off-list ref] writes:
Ok, I will try to group knobs like that, but the comments tend to
break the groups.
By keeping the comment on a single field short, and reserve comment
occupying its own line(s) to comment on group, you can do
/* These control what gets looked at and modified */
int apply; /* this is not a dry-run */
int check_index; /* preimage must match the indexed version */
int cached; /* apply to the index only */
/* These control cosmetic aspect of the output */
int diffstat; /* show diffstat */
int numstat; /* numerical stat */
int summary; /* report creation, deletion, etc. */