Re: [RFC/PATCH] fetch: bigger forced-update warnings

Jeff King [off-list ref] writes:

Subject: fetch: bigger forced-update warnings

The default fetch refspec allows forced-updates. We already
print "forced update" in the status table, but it's easy to
miss. Let's make the warning a little more prominent.

Some branches are expected to rewind, so the prominent
warning would be annoying. However, git doesn't know what
the expectation is for a particular branch. We can have it
guess by peeking at the lost couple of reflog entries. If we

s/lost/last/

see all fast forwards, then a new forced-update is probably
noteworthy. If we see something that force-updates all the
time, it's probably boring and not worth displaying the big
warning (we keep the status table "forced update" note, of
course).

Signed-off-by: Jeff King <redacted>

This is slightly offtopic, but I have been wondering if this approach do
the right thing for "git pull". Wouldn't the underlying "git fetch" give a
warning, and then the calling "git pull" go ahead and make a merge,
scrolling the warning away with the merge/update summary diffstat? That
would be a larger change if "git pull" needs to stash away the warning
message, do its thing and then spit out the warning later.

+static int forced_update_is_uncommon(const char *ref)
+{
+	struct update_counts uc;
+	memset(&uc, 0, sizeof(&uc));
+	if (for_each_recent_reflog_ent(ref, count_updates, 4096, &uc) < 0)
+		for_each_reflog_ent(ref, count_updates, &uc);
+	return uc.fastforward && uc.forced <= 1; /* 1 for the one we just did */
+}

Looks sensible.