rebase -i: introduce --rebase-merges=[no-]rebase-cousins

When running `git rebase --rebase-merges` non-interactively with an
ancestor of HEAD as <upstream> (or leaving the todo list unmodified),
we would ideally recreate the exact same commits as before the rebase.

However, if there are commits in the commit range <upstream>.. that do not
have <upstream> as direct ancestor (i.e. if `git log <upstream>..` would
show commits that are omitted by `git log --ancestry-path <upstream>..`),
this is currently not the case: we would turn them into commits that have
<upstream> as direct ancestor.

Let's illustrate that with a diagram:

C
/   \
A - B - E - F
\   /
D

Currently, after running `git rebase -i --rebase-merges B`, the new branch
structure would be (pay particular attention to the commit `D`):

--- 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`.

This is unintuitive behavior. Even worse, when recreating branch
structure, most use cases would appear to want cousins *not* to be
rebased onto the new base commit. For example, Git for Windows (the
heaviest user of the Git garden shears, which served as the blueprint
for --rebase-merges) frequently merges branches from `next` early, and
these branches certainly do *not* want to be rebased. 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 let's not rebase them by default. For hypothetical
use cases where cousins *do* need to be rebased, `git rebase
--rebase=merges=rebase-cousins` needs to be used.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 7f1756f1ebaceeec39c65e087cb0f4af200e4a84..fe681d6928197d0f7402196cd5ef8afa980b0c57 100644 (file)
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -380,7 +380,7 @@ rebase.instructionFormat.  A customized instruction format will automatically
 have the long commit hash prepended to the format.
 
 -r::
 have the long commit hash prepended to the format.
 
 -r::

---rebase-merges::
+--rebase-merges[=(rebase-cousins|no-rebase-cousins)]::

        By default, a rebase will simply drop merge commits from the todo
        list, and put the rebased commits into a single, linear branch.
        With `--rebase-merges`, the rebase will instead try to preserve
        By default, a rebase will simply drop merge commits from the todo
        list, and put the rebased commits into a single, linear branch.
        With `--rebase-merges`, the rebase will instead try to preserve


@@ -389,9 +389,16 @@ have the long commit hash prepended to the format.
        manual amendments in these merge commits will have to be
        resolved/re-applied manually.
 +
        manual amendments in these merge commits will have to be
        resolved/re-applied manually.
 +

-This mode is similar in spirit to `--preserve-merges`, but in contrast to
-that option works well in interactive rebases: commits can be reordered,
-inserted and dropped at will.
+By default, or when `no-rebase-cousins` was specified, commits which do not
+have `<upstream>` as direct ancestor will keep their original branch point,
+i.e. commits that would be excluded by gitlink:git-log[1]'s
+`--ancestry-path` option will keep their original ancestry by default. If
+the `rebase-cousins` mode is turned on, such commits are instead rebased
+onto `<upstream>` (or `<onto>`, if specified).
++
+The `--rebase-merges` mode is similar in spirit to `--preserve-merges`, but
+in contrast to that option works well in interactive rebases: commits can be
+reordered, inserted and dropped at will.

 +
 It is currently only possible to recreate the merge commits using the
 `recursive` merge strategy; Different merge strategies can be used only via
 +
 It is currently only possible to recreate the merge commits using the
 `recursive` merge strategy; Different merge strategies can be used only via

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 781782e72720927cc3dfcc6afe7aad7bd5b40146..f7c2a5fdc815a892b99d6561d73d953740bf789a 100644 (file)
--- 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, rebase_merges = 0;
 {
        struct replay_opts opts = REPLAY_OPTS_INIT;
        unsigned flags = 0, keep_empty = 0, rebase_merges = 0;

-       int abbreviate_commands = 0;
+       int abbreviate_commands = 0, rebase_cousins = -1;

        enum {
                CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
                CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,
        enum {
                CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
                CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,


@@ -25,6 +25,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
                OPT_BOOL(0, "allow-empty-message", &opts.allow_empty_message,
                        N_("allow commits with empty messages")),
                OPT_BOOL(0, "rebase-merges", &rebase_merges, N_("rebase merge commits")),
                OPT_BOOL(0, "allow-empty-message", &opts.allow_empty_message,
                        N_("allow commits with empty messages")),
                OPT_BOOL(0, "rebase-merges", &rebase_merges, N_("rebase merge commits")),

+               OPT_BOOL(0, "rebase-cousins", &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"),
                OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
                                CONTINUE),
                OPT_CMDMODE(0, "abort", &command, N_("abort rebase"),


@@ -59,8 +61,13 @@ 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 |= rebase_merges ? TODO_LIST_REBASE_MERGES : 0;
        flags |= keep_empty ? TODO_LIST_KEEP_EMPTY : 0;
        flags |= abbreviate_commands ? TODO_LIST_ABBREVIATE_CMDS : 0;
        flags |= rebase_merges ? TODO_LIST_REBASE_MERGES : 0;

+       flags |= rebase_cousins > 0 ? TODO_LIST_REBASE_COUSINS : 0;

        flags |= command == SHORTEN_OIDS ? TODO_LIST_SHORTEN_IDS : 0;
 
        flags |= command == SHORTEN_OIDS ? TODO_LIST_SHORTEN_IDS : 0;
 

+       if (rebase_cousins >= 0 && !rebase_merges)
+               warning(_("--[no-]rebase-cousins has no effect without "
+                         "--rebase-merges"));
+

        if (command == CONTINUE && argc == 1)
                return !!sequencer_continue(&opts);
        if (command == ABORT && argc == 1)
        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 e29da6343392d59f1999c486137b12bbb50e7382..cbf44f864828cca964693bea6a701ce882afd6eb 100644 (file)
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -971,6 +971,7 @@ git_rebase__interactive () {
 
        git rebase--helper --make-script ${keep_empty:+--keep-empty} \
                ${rebase_merges:+--rebase-merges} \
 
        git rebase--helper --make-script ${keep_empty:+--keep-empty} \
                ${rebase_merges:+--rebase-merges} \

+               ${rebase_cousins:+--rebase-cousins} \

                $revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
        die "$(gettext "Could not generate todo list")"
 
                $revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
        die "$(gettext "Could not generate todo list")"
 

diff --git a/git-rebase.sh b/git-rebase.sh
index a553f969d118f561dc30df581f3990b73942510f..40be59ecc4704da05a0e153f1709d4af2c62cd18 100755 (executable)
--- 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
 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

-r,rebase-merges!   try to rebase merges instead of skipping them
+r,rebase-merges?   try to rebase 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
 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


@@ -91,6 +91,7 @@ state_dir=
 # One of {'', continue, skip, abort}, as parsed from command line
 action=
 rebase_merges=
 # One of {'', continue, skip, abort}, as parsed from command line
 action=
 rebase_merges=

+rebase_cousins=

 preserve_merges=
 autosquash=
 keep_empty=
 preserve_merges=
 autosquash=
 keep_empty=


@@ -286,6 +287,15 @@ do
                rebase_merges=t
                test -z "$interactive_rebase" && interactive_rebase=implied
                ;;
                rebase_merges=t
                test -z "$interactive_rebase" && interactive_rebase=implied
                ;;

+       --rebase-merges=*)
+               rebase_merges=t
+               case "${1#*=}" in
+               rebase-cousins) rebase_cousins=t;;
+               no-rebase-cousins) rebase_cousins=;;
+               *) die "Unknown mode: $1";;
+               esac
+               test -z "$interactive_rebase" && interactive_rebase=implied
+               ;;

        --preserve-merges)
                preserve_merges=t
                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 afa155c28290ad069e0e2fef64e9447526f8c78f..e2f83942843ec5aec866d4029d26abbba0a8713f 100644 (file)
--- a/sequencer.c
+++ b/sequencer.c
@@ -3578,6 +3578,7 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                                   unsigned flags)
 {
        int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
                                   unsigned flags)
 {
        int keep_empty = flags & TODO_LIST_KEEP_EMPTY;

+       int rebase_cousins = flags & TODO_LIST_REBASE_COUSINS;

        struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
        struct strbuf label = STRBUF_INIT;
        struct commit_list *commits = NULL, **tail = &commits, *iter;
        struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
        struct strbuf label = STRBUF_INIT;
        struct commit_list *commits = NULL, **tail = &commits, *iter;


@@ -3755,6 +3756,9 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                                           &commit->object.oid);
                        if (entry)
                                to = entry->string;
                                           &commit->object.oid);
                        if (entry)
                                to = entry->string;

+                       else if (!rebase_cousins)
+                               to = label_oid(&commit->object.oid, NULL,
+                                              &state);

 
                        if (!to || !strcmp(to, "onto"))
                                fprintf(out, "%s onto\n", cmd_reset);
 
                        if (!to || !strcmp(to, "onto"))
                                fprintf(out, "%s onto\n", cmd_reset);

diff --git a/sequencer.h b/sequencer.h
index 6bc4da17243b19fb1a7b5b7f2bc445feb0af0149..d9570d92b11d15e6046e4b8473cb5f8a450ea64f 100644 (file)
--- a/sequencer.h
+++ b/sequencer.h
@@ -60,6 +60,12 @@ 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_REBASE_MERGES (1U << 3)
 #define TODO_LIST_SHORTEN_IDS (1U << 1)
 #define TODO_LIST_ABBREVIATE_CMDS (1U << 2)
 #define TODO_LIST_REBASE_MERGES (1U << 3)

+/*
+ * When rebasing merges, commits that do have the base commit as ancestor
+ * ("cousins") are *not* rebased onto the new base by default. If those
+ * commits should be rebased onto the new base, this flag needs to be passed.
+ */
+#define TODO_LIST_REBASE_COUSINS (1U << 4)

 int sequencer_make_script(FILE *out, int argc, const char **argv,
                          unsigned flags);
 
 int sequencer_make_script(FILE *out, int argc, const char **argv,
                          unsigned flags);
 

diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
index 1628c8dcc20a4df7a5007efae1ca97a03068b948..3d4dfdf7bec7db74eb41bd7606c13629f6abc370 100755 (executable)
--- a/t/t3430-rebase-merges.sh
+++ b/t/t3430-rebase-merges.sh
@@ -176,6 +176,24 @@ test_expect_success 'with a branch tip that was cherry-picked already' '
        EOF
 '
 
        EOF
 '
 

+test_expect_success 'do not rebase cousins unless asked for' '
+       git checkout -b cousins master &&
+       before="$(git rev-parse --verify HEAD)" &&
+       test_tick &&
+       git rebase -r HEAD^ &&
+       test_cmp_rev HEAD $before &&
+       test_tick &&
+       git rebase --rebase-merges=rebase-cousins 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 &&
 test_expect_success 'refs/rewritten/* is worktree-local' '
        git worktree add wt &&
        cat >wt/script-from-scratch <<-\EOF &&