diff options
| -rw-r--r-- | Documentation/git-rebase.txt | 23 | ||||
| -rw-r--r-- | Documentation/howto/revert-a-faulty-merge.txt | 90 | ||||
| -rwxr-xr-x | git-rebase--interactive.sh | 8 | ||||
| -rwxr-xr-x | git-rebase.sh | 4 | ||||
| -rwxr-xr-x | t/t3404-rebase-interactive.sh | 36 |
5 files changed, 152 insertions, 9 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 diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh index 2ff211cbaa..b817c4a76e 100755 --- a/git-rebase--interactive.sh +++ b/git-rebase--interactive.sh @@ -20,6 +20,7 @@ v,verbose display a diffstat of what changed upstream onto= rebase onto given branch instead of upstream p,preserve-merges try to recreate merges instead of ignoring them s,strategy= use the given merge strategy +no-ff cherry-pick all commits, even if unchanged m,merge always used (no-op) i,interactive always used (no-op) Actions: @@ -110,6 +111,7 @@ VERBOSE= OK_TO_SKIP_PRE_REBASE= REBASE_ROOT= AUTOSQUASH= +NEVER_FF= GIT_CHERRY_PICK_HELP=" After resolving the conflicts, mark the corrected paths with 'git add <paths>', and @@ -232,6 +234,7 @@ do_with_author () { pick_one () { ff=--ff case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac + case "$NEVER_FF" in '') ;; ?*) ff= ;; esac output git rev-parse --verify $sha1 || die "Invalid commit name: $sha1" test -d "$REWRITTEN" && pick_one_preserving_merges "$@" && return @@ -782,6 +785,9 @@ first and then run 'git rebase --continue' again." -i) # yeah, we know ;; + --no-ff) + NEVER_FF=t + ;; --root) REBASE_ROOT=t ;; @@ -965,7 +971,7 @@ EOF has_action "$TODO" || die_abort "Nothing to do" - test -d "$REWRITTEN" || skip_unnecessary_picks + test -d "$REWRITTEN" || test -n "$NEVER_FF" || skip_unnecessary_picks git update-ref ORIG_HEAD $HEAD output git checkout $ONTO && do_rest diff --git a/git-rebase.sh b/git-rebase.sh index e0eb9568f3..44f5c65fdb 100755 --- a/git-rebase.sh +++ b/git-rebase.sh @@ -3,7 +3,7 @@ # Copyright (c) 2005 Junio C Hamano. # -USAGE='[--interactive | -i] [-v] [--force-rebase | -f] [--onto <newbase>] [<upstream>|--root] [<branch>] [--quiet | -q]' +USAGE='[--interactive | -i] [-v] [--force-rebase | -f] [--no-ff] [--onto <newbase>] [<upstream>|--root] [<branch>] [--quiet | -q]' LONG_USAGE='git-rebase replaces <branch> with a new branch of the same name. When the --onto option is provided the new branch starts out with a HEAD equal to <newbase>, otherwise it is equal to <upstream> @@ -353,7 +353,7 @@ do --root) rebase_root=t ;; - -f|--f|--fo|--for|--forc|force|--force-r|--force-re|--force-reb|--force-reba|--force-rebas|--force-rebase) + -f|--f|--fo|--for|--forc|force|--force-r|--force-re|--force-reb|--force-reba|--force-rebas|--force-rebase|--no-ff) force_rebase=t ;; --rerere-autoupdate|--no-rerere-autoupdate) diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh index b0b43c6d32..f20ea38411 100755 --- a/t/t3404-rebase-interactive.sh +++ b/t/t3404-rebase-interactive.sh @@ -22,12 +22,18 @@ set_fake_editor # | \ # | F - G - H (branch1) # | \ -# \ I (branch2) -# \ -# J - K - L - M (no-conflict-branch) +# |\ I (branch2) +# | \ +# | J - K - L - M (no-conflict-branch) +# \ +# N - O - P (no-ff-branch) # # where A, B, D and G all touch file1, and one, two, three, four all # touch file "conflict". +# +# WARNING: Modifications to the initial repository can change the SHA ID used +# in the expect2 file for the 'stop on conflicting pick' test. + test_expect_success 'setup' ' test_commit A file1 && @@ -50,6 +56,11 @@ test_expect_success 'setup' ' for n in J K L M do test_commit $n file$n + done && + git checkout -b no-ff-branch A && + for n in N O P + do + test_commit $n file$n done ' @@ -113,7 +124,7 @@ cat > expect2 << EOF D ======= G ->>>>>>> 51047de... G +>>>>>>> 5d18e54... G EOF test_expect_success 'stop on conflicting pick' ' @@ -586,4 +597,21 @@ test_expect_success 'rebase while detaching HEAD' ' test_must_fail git symbolic-ref HEAD ' +test_tick # Ensure that the rebased commits get a different timestamp. +test_expect_success 'always cherry-pick with --no-ff' ' + git checkout no-ff-branch && + git tag original-no-ff-branch && + git rebase -i --no-ff A && + touch empty && + for p in 0 1 2 + do + test ! $(git rev-parse HEAD~$p) = $(git rev-parse original-no-ff-branch~$p) && + git diff HEAD~$p original-no-ff-branch~$p > out && + test_cmp empty out + done && + test $(git rev-parse HEAD~3) = $(git rev-parse original-no-ff-branch~3) && + git diff HEAD~3 original-no-ff-branch~3 > out && + test_cmp empty out +' + test_done |