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 --rebase-merges B`, in particular to the commit `D`. So far, the new branch structure would be: --- 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, introducing the new "rebase-cousins" mode for use cases where they should be rebased. Signed-off-by: Johannes Schindelin <johannes.schinde...@gmx.de> --- Documentation/git-rebase.txt | 7 ++++++- builtin/rebase--helper.c | 9 ++++++++- git-rebase--interactive.sh | 1 + git-rebase.sh | 12 +++++++++++- sequencer.c | 4 ++++ sequencer.h | 6 ++++++ t/t3430-rebase-merges.sh | 18 ++++++++++++++++++ 7 files changed, 54 insertions(+), 3 deletions(-) diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt index 936c5619b42..8feadf6e663 100644 --- a/Documentation/git-rebase.txt +++ b/Documentation/git-rebase.txt @@ -379,11 +379,16 @@ rebase.instructionFormat. A customized instruction format will automatically have the long commit hash prepended to the format. -r:: ---rebase-merges:: +--rebase-merges[=(rebase-cousins|no-rebase-cousins)]:: Rebase merge commits instead of flattening the history by replaying merges. Merge conflict resolutions or manual amendments to merge commits are not rebased automatically, but have to be applied manually. ++ +By default, or when `no-rebase-cousins` was specified, commits which do not +have `<upstream>` as direct ancestor will keep their original branch point. +If the `rebase-cousins` mode is turned on, such commits are rebased onto +`<upstream>` (or `<onto>`, if specified). -p:: --preserve-merges:: diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c index 781782e7272..f7c2a5fdc81 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, 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, @@ -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, "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"), @@ -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 |= rebase_cousins > 0 ? TODO_LIST_REBASE_COUSINS : 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) diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh index 7a3daf3e40c..b4ad130e8b1 100644 --- 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} \ + ${rebase_cousins:+--rebase-cousins} \ $revisions ${restrict_revision+^$restrict_revision} >"$todo" || die "$(gettext "Could not generate todo list")" diff --git a/git-rebase.sh b/git-rebase.sh index a64460fd25a..157705d2a72 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 -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 @@ -90,6 +90,7 @@ state_dir= # One of {'', continue, skip, abort}, as parsed from command line action= rebase_merges= +rebase_cousins= preserve_merges= autosquash= keep_empty= @@ -276,6 +277,15 @@ do 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 "$interactive_rebase" && interactive_rebase=implied diff --git a/sequencer.c b/sequencer.c index 60bad5708c6..809df1ce484 100644 --- a/sequencer.c +++ b/sequencer.c @@ -3499,6 +3499,7 @@ static int make_script_with_merges(struct pretty_print_context *pp, unsigned flags) { int keep_empty = flags & TODO_LIST_KEEP_EMPTY; + int rebase_cousins = flags & TODO_LIST_REBASE_COUSINS; struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT; struct strbuf label = STRBUF_INIT; struct commit_list *commits = NULL, **tail = &commits, *iter; @@ -3676,6 +3677,9 @@ static int make_script_with_merges(struct pretty_print_context *pp, &commit->object.oid); if (entry) to = entry->string; + else if (!rebase_cousins) + to = label_oid(&commit->object.oid, NULL, + &state); if (!to || !strcmp(to, "onto")) fprintf(out, "%s onto\n", cmd_reset); diff --git a/sequencer.h b/sequencer.h index 6bc4da17243..d9570d92b11 100644 --- a/sequencer.h +++ b/sequencer.h @@ -60,6 +60,12 @@ int sequencer_remove_state(struct replay_opts *opts); #define TODO_LIST_SHORTEN_IDS (1U << 1) #define TODO_LIST_ABBREVIATE_CMDS (1U << 2) #define TODO_LIST_REBASE_MERGES (1U << 3) +/* + * When rebasing merges, commits that do have the base commit as ancestor + * ("cousins") are *not* rebased onto the new base by default. If those + * commits should be rebased onto the new base, this flag needs to be passed. + */ +#define TODO_LIST_REBASE_COUSINS (1U << 4) int sequencer_make_script(FILE *out, int argc, const char **argv, unsigned flags); diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh index 63faf7c2246..ee006810573 100755 --- a/t/t3430-rebase-merges.sh +++ b/t/t3430-rebase-merges.sh @@ -143,6 +143,24 @@ test_expect_success 'with a branch tip that was cherry-picked already' ' EOF ' +test_expect_success 'do not rebase cousins unless asked for' ' + git checkout -b cousins master && + before="$(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 && -- 2.17.0.windows.1.4.g7e4058d72e3