A while a go Philippe reported [1] that he was surprised 'git rebase --keep-base' removed commits that had been cherry-picked upstream even though to branch was not being rebased. I think it is also surprising if '--keep-base' changes the base of the branch without '--fork-point' being explicitly given on the command line. This series therefore changes the default behavior of '--keep-base' to imply '--reapply-cherry-picks' and '--no-fork-point' so that the base of the branch is unchanged and no commits are removed. Thanks to everyone who commented for their reviews, the changes since V1 are: * Patch 1: new patch to tighten a couple of existing tests * Patch 2: reworded commit message in response to Junio's comments * Patch 3: fixed a typo in the commit message spotted by Elijah and tidied code formatting * Patch 4: new patch to rename a variable suggested by Junio * Patch 5: clarified commit message and removed some redundant code spotted by Junio * Patch 6: improved --reapply-cherry-picks documentation to mention --keep-base and vice-versa suggested by Philippe * Patch 7: expanded the commit message and documentation in response to Junio's comments [1] https://lore.kernel.org/git/0EA8C067-5805-40A7-857A-55C2633B8570@xxxxxxxxx/ Phillip Wood (7): t3416: tighten two tests t3416: set $EDITOR in subshell rebase: store orig_head as a commit rebase: rename merge_base to branch_base rebase: factor out branch_base calculation rebase --keep-base: imply --reapply-cherry-picks rebase --keep-base: imply --no-fork-point Documentation/git-rebase.txt | 32 ++++---- builtin/rebase.c | 129 ++++++++++++++++++------------- t/t3416-rebase-onto-threedots.sh | 62 +++++++++++---- t/t3431-rebase-fork-point.sh | 2 +- 4 files changed, 142 insertions(+), 83 deletions(-) base-commit: afa70145a25e81faa685dc0b465e52b45d2444bd Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1323%2Fphillipwood%2Fwip%2Frebase--keep-base-tweaks-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1323/phillipwood/wip/rebase--keep-base-tweaks-v2 Pull-Request: https://github.com/gitgitgadget/git/pull/1323 Range-diff vs v1: -: ----------- > 1: 12fb0ac6d5d t3416: tighten two tests 1: c1d91a2b190 ! 2: d6f2f716c77 t3416: set $EDITOR in subshell @@ Metadata ## Commit message ## t3416: set $EDITOR in subshell - As $EDITOR is exported setting it in one test affects all subsequent - tests. Avoid this by always setting it in a subshell and remove a - couple of unnecessary call to set_fake_editor. + As $EDITOR is exported, setting it in one test affects all subsequent + tests. Avoid this by always setting it in a subshell. Also remove a + couple of unnecessary call to set_fake_editor where the editor does + not change the todo list. Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> @@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --onto main...' git rev-parse HEAD^1 >actual && git rev-parse C^0 >expect && test_cmp expect actual -@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --onto main...side' ' +@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase --onto main...side requires a single merge-base' ' git checkout side && git reset --hard K && - set_fake_editor && - test_must_fail git rebase -i --onto main...side J + test_must_fail git rebase -i --onto main...side J 2>err && + grep "need exactly one merge base" err ' - @@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --keep-base main from topic' ' git checkout topic && git reset --hard G && @@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --keep-base mai git rev-parse C >base.expect && git merge-base main HEAD >base.actual && test_cmp base.expect base.actual && -@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --keep-base main from side' ' +@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase --keep-base requires a single merge base' ' git checkout side && git reset --hard K && - set_fake_editor && - test_must_fail git rebase -i --keep-base main + test_must_fail git rebase -i --keep-base main 2>err && + grep "need exactly one merge base with branch" err ' +# This must be the last test in this file 2: cced4a48360 ! 3: 9daee95d434 rebase: store orig_head as a commit @@ Commit message rebase: store orig_head as a commit Using a struct commit rather than a struct oid to hold orig_head means - that we error out straight away if branch being rebased does not point - to a commit. It also simplifies the code than handles finding the - merge base and fork point as it not longer has to convert from an oid - to a commit. + that we error out straight away if the branch being rebased does not + point to a commit. It also simplifies the code that handles finding + the merge base and fork point as it no longer has to convert from an + oid to a commit. Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix - get_fork_point(options.upstream_name, head); - } + get_fork_point(options.upstream_name, options.orig_head); -+ if (repo_read_index(the_repository) < 0) die(_("could not read index")); -: ----------- > 4: cca933a5f1d rebase: rename merge_base to branch_base 3: 019158db9d2 ! 5: fc45b996d34 rebase: factor out merge_base calculation @@ Metadata Author: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> ## Commit message ## - rebase: factor out merge_base calculation + rebase: factor out branch_base calculation - Separate out calculating the merge base between onto and head from the - check for whether we can fast-forward or not. This means we can skip - the fast-forward checks when the rebase is forced and avoid - calculating the merge-base twice when --keep-base is given. + Separate out calculating the merge base between 'onto' and 'HEAD' from + the check for whether we can fast-forward or not. This means we can skip + the fast-forward checks when the rebase is forced and avoid calculating + the merge-base between 'HEAD' and 'onto' when --keep-base is given. Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> - --- - Note the unnecessary braces around "if (keep_base)" are added here - reduce the churn on the next commit. ## builtin/rebase.c ## @@ builtin/rebase.c: static int can_fast_forward(struct commit *onto, struct commit *upstream, @@ builtin/rebase.c: static int can_fast_forward(struct commit *onto, struct commit - merge_bases = get_merge_bases(onto, head); - if (!merge_bases || merge_bases->next) { -- oidcpy(merge_base, null_oid()); -+ if (is_null_oid(merge_base)) +- oidcpy(branch_base, null_oid()); ++ if (is_null_oid(branch_base)) goto done; - } -- oidcpy(merge_base, &merge_bases->item->object.oid); - if (!oideq(merge_base, &onto->object.oid)) +- oidcpy(branch_base, &merge_bases->item->object.oid); + if (!oideq(branch_base, &onto->object.oid)) goto done; +@@ builtin/rebase.c: static int can_fast_forward(struct commit *onto, struct commit *upstream, + if (!upstream) + goto done; + +- free_commit_list(merge_bases); + merge_bases = get_merge_bases(upstream, head); + if (!merge_bases || merge_bases->next) + goto done; @@ builtin/rebase.c: done: return res && is_linear_history(onto, head); } -+static void fill_merge_base(struct rebase_options *options, -+ struct object_id *merge_base) ++static void fill_branch_base(struct rebase_options *options, ++ struct object_id *branch_base) +{ + struct commit_list *merge_bases = NULL; + + merge_bases = get_merge_bases(options->onto, options->orig_head); + if (!merge_bases || merge_bases->next) -+ oidcpy(merge_base, null_oid()); ++ oidcpy(branch_base, null_oid()); + else -+ oidcpy(merge_base, &merge_bases->item->object.oid); ++ oidcpy(branch_base, &merge_bases->item->object.oid); + + free_commit_list(merge_bases); +} @@ builtin/rebase.c: done: { struct rebase_options *opts = opt->value; @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix) + if (!options.onto) die(_("Does not point to a valid commit '%s'"), options.onto_name); ++ fill_branch_base(&options, &branch_base); } - -+ if (keep_base) { -+ oidcpy(&merge_base, &options.onto->object.oid); -+ } else { -+ fill_merge_base(&options, &merge_base); -+ } if (options.fork_point > 0) options.restrict_revision = get_fork_point(options.upstream_name, options.orig_head); @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix * in which case we could fast-forward without replacing the commits * with new commits recreated by replaying their changes. - * -- * Note that can_fast_forward() initializes merge_base, so we have to +- * Note that can_fast_forward() initializes branch_base, so we have to - * call it before checking allow_preemptive_ff. */ - if (can_fast_forward(options.onto, options.upstream, options.restrict_revision, -- options.orig_head, &merge_base) && +- options.orig_head, &branch_base) && - allow_preemptive_ff) { + if (allow_preemptive_ff && + can_fast_forward(options.onto, options.upstream, options.restrict_revision, -+ options.orig_head, &merge_base)) { ++ options.orig_head, &branch_base)) { int flag; if (!(options.flags & REBASE_FORCE)) { 4: 9cd4c372ee4 ! 6: faad7eaf0d6 rebase --keep-base: imply --reapply-cherry-picks @@ Documentation/git-rebase.txt: leave out at most one of A and B, in which case it + This option is useful in the case where one is developing a feature on top of an upstream branch. While the feature is being worked on, the + upstream branch may advance and it may not be the best idea to keep +-rebasing on top of the upstream but to keep the base commit as-is. ++rebasing on top of the upstream but to keep the base commit as-is. As ++the base commit is unchanged this option implies `--reapply-cherry-picks` ++to avoid losing commits. + + + Although both this option and `--fork-point` find the merge base between + `<upstream>` and `<branch>`, this option uses the merge base as the _starting +@@ Documentation/git-rebase.txt: See also INCOMPATIBLE OPTIONS below. + Note that commits which start empty are kept (unless `--no-keep-empty` + is specified), and commits which are clean cherry-picks (as determined + by `git log --cherry-mark ...`) are detected and dropped as a +-preliminary step (unless `--reapply-cherry-picks` is passed). ++preliminary step (unless `--reapply-cherry-picks` or `--keep-base` is ++passed). + + + See also INCOMPATIBLE OPTIONS below. + +@@ Documentation/git-rebase.txt: See also INCOMPATIBLE OPTIONS below. + upstream changes, the behavior towards them is controlled by + the `--empty` flag.) + + +-By default (or if `--no-reapply-cherry-picks` is given), these commits +-will be automatically dropped. Because this necessitates reading all +-upstream commits, this can be expensive in repos with a large number +-of upstream commits that need to be read. When using the 'merge' +-backend, warnings will be issued for each dropped commit (unless +-`--quiet` is given). Advice will also be issued unless +-`advice.skippedCherryPicks` is set to false (see linkgit:git-config[1]). ++ ++In the absence of `--keep-base` (or if `--no-reapply-cherry-picks` is ++given), these commits will be automatically dropped. Because this ++necessitates reading all upstream commits, this can be expensive in ++repositories with a large number of upstream commits that need to be ++read. When using the 'merge' backend, warnings will be issued for each ++dropped commit (unless `--quiet` is given). Advice will also be issued ++unless `advice.skippedCherryPicks` is set to false (see ++linkgit:git-config[1]). ++ + + + `--reapply-cherry-picks` allows rebase to forgo reading all upstream + commits, potentially improving performance. ## builtin/rebase.c ## @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix) @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix die(_("options '%s' and '%s' cannot be used together"), "--keep-base", "--root"); } + /* -+ * --keep-base defaults to --reapply-cherry-picks as it is confusing if -+ * commits disappear when using this option. ++ * --keep-base defaults to --reapply-cherry-picks to avoid losing ++ * commits when using this option. + */ + if (options.reapply_cherry_picks < 0) + options.reapply_cherry_picks = keep_base; @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix if (gpg_sign) @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix) + options.onto_name); + fill_branch_base(&options, &branch_base); } - if (keep_base) { - oidcpy(&merge_base, &options.onto->object.oid); -+ if (options.reapply_cherry_picks) -+ options.upstream = options.onto; - } else { - fill_merge_base(&options, &merge_base); - } ++ if (keep_base && options.reapply_cherry_picks) ++ options.upstream = options.onto; ++ + if (options.fork_point > 0) + options.restrict_revision = + get_fork_point(options.upstream_name, options.orig_head); ## t/t3416-rebase-onto-threedots.sh ## -@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase -i --keep-base main from side' ' - test_must_fail git rebase -i --keep-base main +@@ t/t3416-rebase-onto-threedots.sh: test_expect_success 'rebase --keep-base requires a single merge base' ' + grep "need exactly one merge base with branch" err ' +test_expect_success 'rebase --keep-base keeps cherry picks' ' 5: 68bcd10949e ! 7: 6410b101d7f rebase --keep-base: imply --no-fork-point @@ Commit message changes the base of the branch without --fork-point being explicitly given on the command line. + The combination of --keep-base with an explicit --fork-point is still + supported even though --fork-point means we do not keep the same base + if the upstream branch has been rewound. We do this in case anyone is + relying on this behavior which is tested in t3431[1] + + [1] https://lore.kernel.org/git/20200715032014.GA10818@generichostname/ + Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> ## Documentation/git-rebase.txt ## @@ Documentation/git-rebase.txt: leave out at most one of A and B, in which case it + This option is useful in the case where one is developing a feature on top of an upstream branch. While the feature is being worked on, the +@@ Documentation/git-rebase.txt: When `--fork-point` is active, 'fork_point' will be used instead of + <branch>` command (see linkgit:git-merge-base[1]). If 'fork_point' + ends up being empty, the `<upstream>` will be used as a fallback. + + +-If `<upstream>` is given on the command line, then the default is +-`--no-fork-point`, otherwise the default is `--fork-point`. See also +-`rebase.forkpoint` in linkgit:git-config[1]. ++If `<upstream>` or `--keep-base` is given on the command line, then ++the default is `--no-fork-point`, otherwise the default is ++`--fork-point`. See also `rebase.forkpoint` in linkgit:git-config[1]. + + + If your branch was based on `<upstream>` but `<upstream>` was rewound and + your branch contains commits which were dropped, this option can be used ## builtin/rebase.c ## @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix) @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix if (options.root) die(_("options '%s' and '%s' cannot be used together"), "--keep-base", "--root"); + /* -+ * --keep-base ignores config.forkPoint as it is confusing if -+ * the branch base changes when using this option. ++ * --keep-base defaults to --no-fork-point to keep the ++ * base the same. + */ + if (options.fork_point < 0) + options.fork_point = 0; } /* - * --keep-base defaults to --reapply-cherry-picks as it is confusing if + * --keep-base defaults to --reapply-cherry-picks to avoid losing ## t/t3431-rebase-fork-point.sh ## @@ t/t3431-rebase-fork-point.sh: test_rebase () { -- gitgitgadget
