Core: consider dive-number on sorting

A user reports a problem when dives have the same time but different
numbers. The dives appear sorted randomly (effectively they are sorted
by an internal unique-id).

Try to sort by number for dives at the same date in this case.

Fixes #2086

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

CHANGELOG.md

@@ -1,5 +1,6 @@
 - Import: Small enhancements on Suunto SDE import
 - Desktop: Add import dive site menu option and site selection dialog
+- Core: Sort dives by number if at the same date
 - Core: fix bug in get_distance() to correctly compute spherical distance
 - Desktop: For videos, add save data export as subtitle file
 - Desktop: make dive sites 1st class citizens with their own dive site table

core/divelist.c

@@ -779,7 +779,7 @@ struct dive *last_selected_dive()
  * After editing a key used in this sort-function, the order of
  * the dives must be re-astablished.
  * Currently, this does a lexicographic sort on the
- * (start-time, trip-time, id) tuple.
+ * (start-time, trip-time, number, id) tuple.
  * trip-time is defined such that dives that do not belong to
  * a trip are sorted *after* dives that do. Thus, in the default
  * chronologically-descending sort order, they are shown *before*.
@@ -804,6 +804,10 @@ static int comp_dives(const struct dive *a, const struct dive *b)
 		if (trip_date(a->divetrip) > trip_date(b->divetrip))
 			return 1;
 	}
+	if (a->number < b->number)
+		return -1;
+	if (a->number > b->number)
+		return 1;
 	if (a->id < b->id)
 		return -1;
 	if (a->id > b->id)