Hi David,
On 2013-11-04, David Roe <roed.m...@gmail.com> wrote:
> Even if you
> decide you don't want some code that you introduced, you should introduce a
> new commit that deletes the code rather than removing old commits and
> force-pushing your branch.
Good example.
So, what simple and easy-to-use command does git offer to create a
"negative commit"? That's to say, if I have commits A-B-C and want to
"remove" B, how can I make git create a commit D for me such that
A-B-C-D results in the same code as A-C?
If the creation of D is more complicated than changing the "apply"
information on trac (for patches in the old workflow, I mean), I still
don't see why I should do so, from the point of view of "avoid dull work".
Anyway, I think it is a good idea to have a concrete
example. I created a test repository, created ticket/123,
ticket/456 and an identical copy ticket/456new of ticke/456.
The commits are
- A: Introduces file bla
- B: Introduces file blaB
- C: Changes file bla
- X: Changes file bla on top of commit C
Branches master and ticket/123 is A-B-C, branches ticket/456 and
ticket/456new are A-B-C-X
Result on ticket/123 = master
git log --oneline
202a495 Commit C
c7edaa0 Commit B
3c00aaf Commit A
ls
bla blaB
Then, I changed ticket/123 by
git reset --hard HEAD~2
followed by
git cherry-pick master
The result was
git log --oneline
e7d13cf Commit C
3c00aaf Commit A
ls
bla
Then, I tested two ways to rebase ticket/456 resp ticket/456new with
respect to the changed branch ticket/123.
First way:
git checkout ticket/456
git merge ticket/123
<resolve merge conflicts>
which resulted in
git log --oneline
063383d Merge branch 'ticket/123' into ticket/456
e7d13cf Commit C
007abaf Commit X
202a495 Commit C
c7edaa0 Commit B
3c00aaf Commit A
and
ls
bla blaB
This is certainly not what we want.
Second way:
git rebase ticket/123 ticket/456new
<it simply worked, no conflicts!>
which resulted in
git log --oneline
3816d11 Commit X
9f83a92 Commit B
e7d13cf Commit C
3c00aaf Commit A
and
ls
bla blaB
This is also certainly not what we want.
Question to the git experts:
- Is there an easy git command that creates a new commit reverting the
effects of a specified old commit (or series of old commits)?
If there isn't, I think it is a good argument for using patches and
mercurial queues. If you have patches A,B,C,X corresponding to the commits
above, then removing B simply amounts to hg qdelete B.
Best regards,
Simon
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