diff options
author | Junio C Hamano <gitster@pobox.com> | 2010-04-03 23:28:44 +0400 |
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committer | Junio C Hamano <gitster@pobox.com> | 2010-04-03 23:28:44 +0400 |
commit | 9234b003726556e0d3d0ea8ade97dc9f7bd50a6e (patch) | |
tree | 194e8895d8a2e7c7dba0f5e6ab9108231aaae711 /Documentation | |
parent | 7b1cb5c40ebb57c5a26f1335807be24dba8d4518 (diff) | |
parent | b499549401cb2b1f6c30d09681380fd519938eb0 (diff) |
Merge branch 'mb/rebase-i-no-ff'
* mb/rebase-i-no-ff:
Teach rebase the --no-ff option.
Conflicts:
git-rebase--interactive.sh
t/t3404-rebase-interactive.sh
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/git-rebase.txt | 23 | ||||
-rw-r--r-- | Documentation/howto/revert-a-faulty-merge.txt | 90 |
2 files changed, 111 insertions, 2 deletions
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt index 823f2a4638..0d07b1b207 100644 --- a/Documentation/git-rebase.txt +++ b/Documentation/git-rebase.txt @@ -274,9 +274,16 @@ which makes little sense. -f:: --force-rebase:: Force the rebase even if the current branch is a descendant - of the commit you are rebasing onto. Normally the command will + of the commit you are rebasing onto. Normally non-interactive rebase will exit with the message "Current branch is up to date" in such a situation. + Incompatible with the --interactive option. ++ +You may find this (or --no-ff with an interactive rebase) helpful after +reverting a topic branch merge, as this option recreates the topic branch with +fresh commits so it can be remerged successfully without needing to "revert +the reversion" (see the +link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). --ignore-whitespace:: --whitespace=<option>:: @@ -316,7 +323,19 @@ which makes little sense. commit to be modified, and change the action of the moved commit from `pick` to `squash` (or `fixup`). + -This option is only valid when '--interactive' option is used. +This option is only valid when the '--interactive' option is used. + +--no-ff:: + With --interactive, cherry-pick all rebased commits instead of + fast-forwarding over the unchanged ones. This ensures that the + entire history of the rebased branch is composed of new commits. ++ +Without --interactive, this is a synonym for --force-rebase. ++ +You may find this helpful after reverting a topic branch merge, as this option +recreates the topic branch with fresh commits so it can be remerged +successfully without needing to "revert the reversion" (see the +link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). include::merge-strategies.txt[] diff --git a/Documentation/howto/revert-a-faulty-merge.txt b/Documentation/howto/revert-a-faulty-merge.txt index 3b4a390005..ff5c0bc27a 100644 --- a/Documentation/howto/revert-a-faulty-merge.txt +++ b/Documentation/howto/revert-a-faulty-merge.txt @@ -142,6 +142,8 @@ different resolution strategies: revert of a merge was rebuilt from scratch (i.e. rebasing and fixing, as you seem to have interpreted), then re-merging the result without doing anything else fancy would be the right thing to do. + (See the ADDENDUM below for how to rebuild a branch from scratch + without changing its original branching-off point.) However, there are things to keep in mind when reverting a merge (and reverting such a revert). @@ -177,3 +179,91 @@ the answer is: "oops, I really shouldn't have merged it, because it wasn't ready yet, and I really need to undo _all_ of the merge"). So then you really should revert the merge, but when you want to re-do the merge, you now need to do it by reverting the revert. + +ADDENDUM + +Sometimes you have to rewrite one of a topic branch's commits *and* you can't +change the topic's branching-off point. Consider the following situation: + + P---o---o---M---x---x---W---x + \ / + A---B---C + +where commit W reverted commit M because it turned out that commit B was wrong +and needs to be rewritten, but you need the rewritten topic to still branch +from commit P (perhaps P is a branching-off point for yet another branch, and +you want be able to merge the topic into both branches). + +The natural thing to do in this case is to checkout the A-B-C branch and use +"rebase -i P" to change commit B. However this does not rewrite commit A, +because "rebase -i" by default fast-forwards over any initial commits selected +with the "pick" command. So you end up with this: + + P---o---o---M---x---x---W---x + \ / + A---B---C <-- old branch + \ + B'---C' <-- naively rewritten branch + +To merge A-B'-C' into the mainline branch you would still have to first revert +commit W in order to pick up the changes in A, but then it's likely that the +changes in B' will conflict with the original B changes re-introduced by the +reversion of W. + +However, you can avoid these problems if you recreate the entire branch, +including commit A: + + A'---B'---C' <-- completely rewritten branch + / + P---o---o---M---x---x---W---x + \ / + A---B---C + +You can merge A'-B'-C' into the mainline branch without worrying about first +reverting W. Mainline's history would look like this: + + A'---B'---C'------------------ + / \ + P---o---o---M---x---x---W---x---M2 + \ / + A---B---C + +But if you don't actually need to change commit A, then you need some way to +recreate it as a new commit with the same changes in it. The rebase commmand's +--no-ff option provides a way to do this: + + $ git rebase [-i] --no-ff P + +The --no-ff option creates a new branch A'-B'-C' with all-new commits (all the +SHA IDs will be different) even if in the interactive case you only actually +modify commit B. You can then merge this new branch directly into the mainline +branch and be sure you'll get all of the branch's changes. + +You can also use --no-ff in cases where you just add extra commits to the topic +to fix it up. Let's revisit the situation discussed at the start of this howto: + + P---o---o---M---x---x---W---x + \ / + A---B---C----------------D---E <-- fixed-up topic branch + +At this point, you can use --no-ff to recreate the topic branch: + + $ git checkout E + $ git rebase --no-ff P + +yielding + + A'---B'---C'------------D'---E' <-- recreated topic branch + / + P---o---o---M---x---x---W---x + \ / + A---B---C----------------D---E + +You can merge the recreated branch into the mainline without reverting commit W, +and mainline's history will look like this: + + A'---B'---C'------------D'---E' + / \ + P---o---o---M---x---x---W---x---M2 + \ / + A---B---C |