By default, rebase will take all commits from the branch that is to be
rebased which are missing in upstream. The new --first-parent option
allows to just follow the first parent and thus completely ignore
merges.
Additionally, when used together with --preserve-merges (which is the
more useful use-case) it will no longer rebase the commits from the
merged-in branches, but instead redo the merge with the original
parents.
That means that:
---H------I topicB
/ \ \
| D---E---F--G topicA
|/
A---B---C master
does no longer become:
-H'--------I'
/ \ \
D'---E'---F'---G' topicA
/
A---B---C master
\
H---I topicB
but instead:
A---B---C master
\ \
\ D'---E'---F'---G' topicA
\ / /
---------H---------I topicB
Signed-off-by: Björn Steinbrink <B.Steinbrink@xxxxxx>
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index e4326d3..0b5f4b6 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -10,7 +10,7 @@ SYNOPSIS
[verse]
'git-rebase' [-i | --interactive] [-v | --verbose] [-m | --merge]
[-C<n>] [ --whitespace=<option>] [-p | --preserve-merges]
- [--onto <newbase>] <upstream> [<branch>]
+ [--first-parent] [--onto <newbase>] <upstream> [<branch>]
'git-rebase' --continue | --skip | --abort
DESCRIPTION
@@ -166,6 +166,52 @@ This is useful if F and G were flawed in some way, or should not be
part of topicA. Note that the argument to --onto and the <upstream>
parameter can be any valid commit-ish.
+If you have a branch that contains merges which you want to preserve, you
+can use the --preserve-merges option. By default, this will duplicate all
+merged commits on top of <upstream> (or <newbase>) and try to redo the
+merges using the new commits. Given this situation:
+
+------------
+ ---H------I topicB
+ / \ \
+ | D---E---F--G topicA
+ |/
+ A---B---C master
+------------
+
+then the command
+
+ git rebase -i --preserve-merges master topicA
+
+would result in
+
+------------
+ -H'--------I'
+ / \ \
+ D'---E'---F'---G' topicA
+ /
+ A---B---C master
+ \
+ H---I topicB
+------------
+
+If you pass --first-parent in addition to --preserve-merges, the commits
+from the merged-in branches won't be duplicated.
+
+So the command
+
+ git rebase -i --preserve-merges --first-parent master topicA
+
+would instead result in
+
+------------
+ A---B---C master
+ \ \
+ \ D'---E'---F'---G' topicA
+ \ / /
+ ---------H---------I topicB
+------------
+
In case of conflict, git-rebase will stop at the first problematic commit
and leave conflict markers in the tree. You can use git diff to locate
the markers (<<<<<<) and make edits to resolve the conflict. For each
@@ -246,6 +292,13 @@ OPTIONS
Instead of ignoring merges, try to recreate them. This option
only works in interactive mode.
+\--first-parent::
+ Only follow the first parent commits in merge commits when looking
+ for the commits that are to be rebased. This is most useful with -p
+ as it will cause rebase to recreate the merges against the original
+ branches instead of rebasing those branches as well. This option
+ only works in interactive mode.
+
include::merge-strategies.txt[]
NOTES
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index e63e1c9..38b070e 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -22,6 +22,7 @@ DONE="$DOTEST"/done
MSG="$DOTEST"/message
SQUASH_MSG="$DOTEST"/message-squash
REWRITTEN="$DOTEST"/rewritten
+FIRST_PARENT=
PRESERVE_MERGES=
STRATEGY=
VERBOSE=
@@ -143,14 +144,20 @@ pick_one_preserving_merges () {
preserve=f
new_p=$(cat "$REWRITTEN"/$p)
test $p != $new_p && fast_forward=f
- case "$new_parents" in
- *$new_p*)
- ;; # do nothing; that parent is already there
- *)
- new_parents="$new_parents $new_p"
- ;;
- esac
+ elif test t = "$FIRST_PARENT"
+ then
+ new_p=$p
+ else
+ continue
fi
+
+ case "$new_parents" in
+ *$new_p*)
+ ;; # do nothing; that parent is already there
+ *)
+ new_parents="$new_parents $new_p"
+ ;;
+ esac
done
case $fast_forward in
t)
@@ -412,6 +419,9 @@ do
-p|--preserve-merges)
PRESERVE_MERGES=t
;;
+ --first-parent)
+ FIRST_PARENT=t
+ ;;
-i|--interactive)
# yeah, we know
;;
@@ -481,6 +491,10 @@ do
else
MERGES_OPTION=--no-merges
fi
+ if test t = "$FIRST_PARENT"
+ then
+ MERGES_OPTION="--first-parent $MERGES_OPTION"
+ fi
SHORTUPSTREAM=$(git rev-parse --short $UPSTREAM)
SHORTHEAD=$(git rev-parse --short $HEAD)
--
1.5.3.4.456.g072a
-
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