This one is a bit tricky to explain, so let's try with a diagram:
C
/ \
A - B - E - F
\ /
D
To illustrate what this new mode is all about, let's consider what
happens upon `git rebase -i --recreate-merges B`, in particular to
the commit `D`. In the default mode, the new branch structure is:
--- C' --
/ \
A - B ------ E' - F'
\ /
D'
This is not really preserving the branch topology from before! The
reason is that the commit `D` does not have `B` as ancestor, and
therefore it gets rebased onto `B`.
However, when recreating branch structure, there are legitimate use
cases where one might want to preserve the branch points of commits that
do not descend from the <upstream> commit that was passed to the rebase
command, e.g. when a branch from core Git's `next` was merged into Git
for Windows' master we will not want to rebase those commits on top of a
Windows-specific commit. In the example above, the desired outcome would
look like this:
--- C' --
/ \
A - B ------ E' - F'
\ /
-- D' --
Let's introduce the term "cousins" for such commits ("D" in the
example), and the "no-rebase-cousins" mode of the merge-recreating
rebase, to help those use cases.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
Documentation/git-rebase.txt | 7 ++++++-
builtin/rebase--helper.c | 9 ++++++++-
git-rebase--interactive.sh | 1 +
git-rebase.sh | 12 +++++++++++-
sequencer.c | 4 ++++
sequencer.h | 8 ++++++++
t/t3430-rebase-recreate-merges.sh | 23 +++++++++++++++++++++++
7 files changed, 61 insertions(+), 3 deletions(-)
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 1d061373288..ac07a5c3fc9 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -368,10 +368,15 @@ The commit list format can be changed by setting the configuration option
rebase.instructionFormat. A customized instruction format will automatically
have the long commit hash prepended to the format.
---recreate-merges::
+--recreate-merges[=(rebase-cousins|no-rebase-cousins)]::
Recreate merge commits instead of flattening the history by replaying
merges. Merge conflict resolutions or manual amendments to merge
commits are not preserved.
++
+By default, or when `rebase-cousins` was specified, commits which do not have
+`<upstream>` as direct ancestor are rebased onto `<upstream>` (or `<onto>`,
+if specified). If the `rebase-cousins` mode is turned off, such commits will
+retain their original branch point.
-p::
--preserve-merges::
diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index a34ab5c0655..ef08fef4d14 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -13,7 +13,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
{
struct replay_opts opts = REPLAY_OPTS_INIT;
unsigned flags = 0, keep_empty = 0, recreate_merges = 0;
- int abbreviate_commands = 0;
+ int abbreviate_commands = 0, no_rebase_cousins = -1;
enum {
CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,
@@ -23,6 +23,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
OPT_BOOL(0, "keep-empty", &keep_empty, N_("keep empty commits")),
OPT_BOOL(0, "recreate-merges", &recreate_merges, N_("recreate merge commits")),
+ OPT_BOOL(0, "no-rebase-cousins", &no_rebase_cousins,
+ N_("keep original branch points of cousins")),
OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
CONTINUE),
OPT_CMDMODE(0, "abort", &command, N_("abort rebase"),
@@ -57,8 +59,13 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
flags |= keep_empty ? TODO_LIST_KEEP_EMPTY : 0;
flags |= abbreviate_commands ? TODO_LIST_ABBREVIATE_CMDS : 0;
flags |= recreate_merges ? TODO_LIST_RECREATE_MERGES : 0;
+ flags |= no_rebase_cousins > 0 ? TODO_LIST_NO_REBASE_COUSINS : 0;
flags |= command == SHORTEN_OIDS ? TODO_LIST_SHORTEN_IDS : 0;
+ if (no_rebase_cousins >= 0&& !recreate_merges)
+ warning(_("--[no-]rebase-cousins has no effect without "
+ "--recreate-merges"));
+
if (command == CONTINUE && argc == 1)
return !!sequencer_continue(&opts);
if (command == ABORT && argc == 1)
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 3459ec5a018..23184c77e88 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -901,6 +901,7 @@ if test t != "$preserve_merges"
then
git rebase--helper --make-script ${keep_empty:+--keep-empty} \
${recreate_merges:+--recreate-merges} \
+ ${no_rebase_cousins:+--no-rebase-cousins} \
$revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
die "$(gettext "Could not generate todo list")"
else
diff --git a/git-rebase.sh b/git-rebase.sh
index d69bc7d0e0d..3403b1416a8 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -17,7 +17,7 @@ q,quiet! be quiet. implies --no-stat
autostash automatically stash/stash pop before and after
fork-point use 'merge-base --fork-point' to refine upstream
onto=! rebase onto given branch instead of upstream
-recreate-merges! try to recreate merges instead of skipping them
+recreate-merges? try to recreate merges instead of skipping them
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
@@ -88,6 +88,7 @@ state_dir=
# One of {'', continue, skip, abort}, as parsed from command line
action=
recreate_merges=
+no_rebase_cousins=
preserve_merges=
autosquash=
keep_empty=
@@ -268,6 +269,15 @@ do
recreate_merges=t
test -z "$interactive_rebase" && interactive_rebase=implied
;;
+ --recreate-merges=*)
+ recreate_merges=t
+ case "${1#*=}" in
+ rebase-cousins) no_rebase_cousins=;;
+ no-rebase-cousins) no_rebase_cousins=t;;
+ *) die "Unknown mode: $1";;
+ esac
+ test -z "$interactive_rebase" && interactive_rebase=implied
+ ;;
--preserve-merges)
preserve_merges=t
test -z "$interactive_rebase" && interactive_rebase=implied
diff --git a/sequencer.c b/sequencer.c
index b63bfb9a141..2b4e6b12321 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2905,6 +2905,7 @@ static int make_script_with_merges(struct pretty_print_context *pp,
unsigned flags)
{
int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
+ int no_rebase_cousins = flags & TODO_LIST_NO_REBASE_COUSINS;
struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
struct strbuf label = STRBUF_INIT;
struct commit_list *commits = NULL, **tail = &commits, *iter;
@@ -3078,6 +3079,9 @@ static int make_script_with_merges(struct pretty_print_context *pp,
&commit->object.oid);
if (entry)
to = entry->string;
+ else if (no_rebase_cousins)
+ to = label_oid(&commit->object.oid, NULL,
+ &state);
if (!to || !strcmp("onto", to))
fprintf(out, "%s\n", b);
diff --git a/sequencer.h b/sequencer.h
index 11d1ac925ef..9530dba3cba 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -49,6 +49,14 @@ int sequencer_remove_state(struct replay_opts *opts);
#define TODO_LIST_SHORTEN_IDS (1U << 1)
#define TODO_LIST_ABBREVIATE_CMDS (1U << 2)
#define TODO_LIST_RECREATE_MERGES (1U << 3)
+/*
+ * When recreating merges, commits that do have the base commit as ancestor
+ * ("cousins") are rebased onto the new base by default. If those commits
+ * should keep their original branch point, this flag needs to be passed.
+ *
+ * This flag only makes sense when <base> and <onto> are different.
+ */
+#define TODO_LIST_NO_REBASE_COUSINS (1U << 4)
int sequencer_make_script(FILE *out, int argc, const char **argv,
unsigned flags);
diff --git a/t/t3430-rebase-recreate-merges.sh b/t/t3430-rebase-recreate-merges.sh
index 76e615bd7c1..22930e470a4 100755
--- a/t/t3430-rebase-recreate-merges.sh
+++ b/t/t3430-rebase-recreate-merges.sh
@@ -143,6 +143,29 @@ test_expect_success 'with a branch tip that was cherry-picked already' '
EOF
'
+test_expect_success 'rebase cousins unless told not to' '
+ write_script copy-editor.sh <<-\EOF &&
+ cp "$1" "$(git rev-parse --git-path ORIGINAL-TODO)"
+ EOF
+
+ test_config sequence.editor \""$PWD"/copy-editor.sh\" &&
+ git checkout -b cousins master &&
+ before="$(git rev-parse --verify HEAD)" &&
+ test_tick &&
+ git rebase -i --recreate-merges=no-rebase-cousins HEAD^ &&
+ test_cmp_rev HEAD $before &&
+ test_tick &&
+ git rebase -i --recreate-merges HEAD^ &&
+ test_cmp_graph HEAD^.. <<-\EOF
+ * Merge the topic branch '\''onebranch'\''
+ |\
+ | * D
+ | * G
+ |/
+ o H
+ EOF
+'
+
test_expect_success 'refs/rewritten/* is worktree-local' '
git worktree add wt &&
cat >wt/script-from-scratch <<-\EOF &&
--
2.15.1.windows.2.1430.ga56c4f9e2a9
