On Thu, May 26 2022, Junio C Hamano wrote:
> When this option is in use, the first line of the pre-filled editor
> buffer becomes a comment line that tells the user to say _why_. If
> the user exits the editor without touching this line by mistake,
> what we prepare to become the first line of the body, i.e. "This
> reverts commit 8fa7f667 (do this and that, 2022-04-25)", ends up to
> be the title of the resulting commit. This behaviour is designed to
> help such a user to identify such a revert in "git log --oneline"
> easily so that it can be further reworded with "git rebase -i" later.
This is a good trade-off, and means that the --no-edit case is also
preserved. However...
> @@ -2167,14 +2184,20 @@ static int do_pick_commit(struct repository *r,
> base_label = msg.label;
> next = parent;
> next_label = msg.parent_label;
> - strbuf_addstr(&msgbuf, "Revert \"");
> - strbuf_addstr(&msgbuf, msg.subject);
> - strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
> - strbuf_addstr(&msgbuf, oid_to_hex(&commit->object.oid));
> + if (opts->commit_use_reference) {
> + strbuf_addstr(&msgbuf,
> + "# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***");
> + } else {
> + strbuf_addstr(&msgbuf, "Revert \"");
> + strbuf_addstr(&msgbuf, msg.subject);
> + strbuf_addstr(&msgbuf, "\"");
> + }
> + strbuf_addstr(&msgbuf, "\n\nThis reverts commit ");
> + refer_to_commit(opts, &msgbuf, commit);
>
> if (commit->parents && commit->parents->next) {
> strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
> - strbuf_addstr(&msgbuf, oid_to_hex(&parent->object.oid));
> + refer_to_commit(opts, &msgbuf, parent);
> }
...the way this is implemented means that we end up with a much more
verbose subject line in the case of reverts, which doesn't seem to be
intended (or at least not called out in the commit message).
I think a good solution to that would be to e.g. emit:
# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***
Reverts commit <git reference>
This revert of a merge reverts changes made to <git reference 2>.
Instead of what you have, which is:
# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***
This reverts commit <git reference>, reversing
changes made to <git reference 2>.
It's sharing a bit less code between the two, but I think the message is
suffering for it now.
I.e. the "Revert <reference>" change to "This reverts commit
<reference>" doesn't per-se seem intentional, but just a side-effect of
the optional "reference" revert's default "subject" line piggy-backing
on the non-"reference" body.
> +test_expect_success 'identification of reverted commit (default)' '
> + test_commit to-ident &&
> + test_when_finished "git reset --hard to-ident" &&
> + git checkout --detach to-ident &&
> + git revert --no-edit HEAD &&
> + git cat-file commit HEAD >actual.raw &&
> + grep "^This reverts " actual.raw >actual &&
> + echo "This reverts commit $(git rev-parse HEAD^)." >expect &&
This pattern hides git exit codes & segfaults (I don't remember if I
mentioned that in a previous round, I think so...).
> +test_expect_success 'identification of reverted commit (--reference)' '
> + git checkout --detach to-ident &&
> + git revert --reference --no-edit HEAD &&
> + git cat-file commit HEAD >actual.raw &&
> + grep "^This reverts " actual.raw >actual &&
> + echo "This reverts commit $(git show -s --pretty=reference HEAD^)." >expect &&
> + test_cmp expect actual
> +'
> +
> +test_expect_success 'identification of reverted commit (revert.reference)' '
> + git checkout --detach to-ident &&
> + git -c revert.reference=true revert --no-edit HEAD &&
> + git cat-file commit HEAD >actual.raw &&
> + grep "^This reverts " actual.raw >actual &&
> + echo "This reverts commit $(git show -s --pretty=reference HEAD^)." >expect &&
> + test_cmp expect actual
Also (probably mentioned) I'd find this much easier to read/review if it
was using test_cmp, now you need to carefully parse the code to see what
the outputs are like exactly, but if we compared the full output...
