Re: [PATCH v3] [GSOC][RFC] format-patch: pass --left-only to range-diff

ZheNing Hu [off-list ref] 于2021年3月14日周日 上午10:16写道：

Junio C Hamano [off-list ref] 于2021年3月14日周日 上午7:23写道：

quoted

Yes, it would be, but that is why you need to educate users what
causes it, and what the right way to avoid unrelated commits from
appearing, and how this --left-only fits in the solution.

If some of the time, "--left-only T1...T2" would give you the same
result as the more strict "B1..T1 B2..T2", that may be why users may
want to use the "--left-only" instead as an easy/lazy alternative.

But I suspect that it would give an incorrect result some of the
time---for example, in the above example, wouldn't one of the
commits labeled as 's' be completely hidden?  And if that is the
case, the end-user documentation would need to warn about it, and
explain that it is a easy/lazy alternative that can produce
incorrect result in the log message.

Thanks, I will try to illustrate these issues in the document.

My another thinking is:
Since `--left-only` inhibits "B1..B2" and "B2..T2" ( let the user
choose the left B1..T1 ), To some extent, `--right-only` can also
add ( let the user choose the right B2..T2 ). A separate `--left-only`
will be strange to the user ( If user call T2...T1 ). Since the
`git rebase --apply` will internal call `git format-patch -k --stdout
--full-index --cherry-pick --right-only ...`, I don't know what to deal
with this `--right-only` yet, because I don't how to teach git to judge
if the `--right-only` is pass from user or `git rebase --apply`, Is there
any good way?  If can solve this problem,  the user can choose the left
or right side of the free choice. (Or users don't need `--right-only?`)

Let me refute my own point just now :`--right-only` can not show "B2..T2",
but "B1..T1", and it may be useful only when user want an inverted "T2...T1".