When working in projects where having nice commits matters it's quite
common that developers end up reordering commits a lot. Tihs is
typically done via interactive rebases, where they can then rearrange
commits in the instruction sheet.
Still, this operation is a frequent-enough operation to provide a more
direct of doing this imperatively. As such, introduce a new "reorder"
subcommand where users can reorder a commit A to come after or before
another commit B:
$ git log --oneline
a978f73 fifth
57594ee fourth
04eb1c4 third
d535e30 second
bf7438d first
$ git history reorder :/fourth --before=:/second
$ git log --oneline
1610fe0 fifth
444f97d third
2f90797 second
b0ae659 fourth
bf7438d first
$ git history reorder :/fourth --after=:/second
$ git log --oneline
c48729d fifth
f44a46e third
26693b8 fourth
8cb4171 second
bf7438d first
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
Documentation/git-history.adoc | 32 ++++++
builtin/history.c | 135 +++++++++++++++++++++++++
t/meson.build | 1 +
t/t3451-history-reorder.sh | 218 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 386 insertions(+)
diff --git a/Documentation/git-history.adoc b/Documentation/git-history.adoc
index 3012445ddc..6e8b4e1326 100644
--- a/Documentation/git-history.adoc
+++ b/Documentation/git-history.adoc
@@ -9,6 +9,7 @@ SYNOPSIS
--------
[synopsis]
git history drop [<options>] <revision>
+git history reorder [<options>] <revision> --(before|after)=<revision>
DESCRIPTION
-----------
@@ -40,6 +41,12 @@ Dropping the root commit converts the child of that commit into the new
root commit. It is invalid to drop a root commit that does not have any
child commits, as that would lead to an empty branch.
+reorder <revision> (--before=<revision>|--after=<revision>)::
+ Reorder the commit so that it becomes either the parent
+ (`--before=`) or child (`--after=`) of the other specified
+ commit. The commits must be related to one another and must be
+ reachable from the current `HEAD` commit.
+
EXAMPLES
--------
@@ -56,6 +63,31 @@ b1bc1bd third
e098c27 first
----------
+* Reorder a commit.
++
+----------
+$ git log --oneline
+a978f73 fifth
+57594ee fourth
+04eb1c4 third
+d535e30 second
+bf7438d first
+$ git history reorder :/fourth --before=:/second
+$ git log --oneline
+1610fe0 fifth
+444f97d third
+2f90797 second
+b0ae659 fourth
+bf7438d first
+$ git history reorder :/fourth --after=:/second
+$ git log --oneline
+c48729d fifth
+f44a46e third
+26693b8 fourth
+8cb4171 second
+bf7438d first
+----------
+
CONFIGURATION
-------------
diff --git a/builtin/history.c b/builtin/history.c
index 183ab9d5f7..de6073f557 100644
--- a/builtin/history.c
+++ b/builtin/history.c
@@ -83,6 +83,33 @@ static int collect_commits(struct repository *repo,
return ret;
}
+static void replace_commits(struct strvec *commits,
+ const struct object_id *commit_to_replace,
+ const struct object_id *replacements,
+ size_t replacements_nr)
+{
+ char commit_to_replace_oid[GIT_MAX_HEXSZ + 1];
+ struct strvec replacement_oids = STRVEC_INIT;
+ bool found = false;
+ size_t i;
+
+ oid_to_hex_r(commit_to_replace_oid, commit_to_replace);
+ for (i = 0; i < replacements_nr; i++)
+ strvec_push(&replacement_oids, oid_to_hex(&replacements[i]));
+
+ for (i = 0; i < commits->nr; i++) {
+ if (strcmp(commits->v[i], commit_to_replace_oid))
+ continue;
+ strvec_splice(commits, i, 1, replacement_oids.v, replacement_oids.nr);
+ found = true;
+ break;
+ }
+ if (!found)
+ BUG("could not find commit to replace");
+
+ strvec_clear(&replacement_oids);
+}
+
static int apply_commits(struct repository *repo,
const struct strvec *commits,
struct commit *head,
@@ -291,6 +318,112 @@ static int cmd_history_drop(int argc,
return ret;
}
+static int cmd_history_reorder(int argc,
+ const char **argv,
+ const char *prefix,
+ struct repository *repo)
+{
+ const char * const usage[] = {
+ N_("git history reorder [<options>] <revision> (--before=<commit>|--after=<commit>)"),
+ NULL,
+ };
+ const char *before = NULL, *after = NULL;
+ struct option options[] = {
+ OPT_STRING(0, "before", &before, N_("commit"), N_("reorder before this commit")),
+ OPT_STRING(0, "after", &after, N_("commit"), N_("reorder after this commit")),
+ OPT_END(),
+ };
+ struct commit *commit_to_reorder, *head, *anchor, *old;
+ struct strvec commits = STRVEC_INIT;
+ struct object_id replacement[2];
+ struct commit_list *list = NULL;
+ int ret;
+
+ argc = parse_options(argc, argv, prefix, options, usage, 0);
+ if (argc != 1)
+ die(_("command expects a single revision"));
+ if (!before && !after)
+ die(_("exactly one option of 'before' or 'after' must be given"));
+ die_for_incompatible_opt2(!!before, "before", !!after, "after");
+
+ repo_config(repo, git_default_config, NULL);
+
+ commit_to_reorder = lookup_commit_reference_by_name(argv[0]);
+ if (!commit_to_reorder)
+ die(_("commit to be reordered cannot be found: %s"), argv[0]);
+ if (commit_to_reorder->parents && commit_to_reorder->parents->next)
+ die(_("commit to be reordered must not be a merge commit"));
+
+ anchor = lookup_commit_reference_by_name(before ? before : after);
+ if (!commit_to_reorder)
+ die(_("anchor commit cannot be found: %s"), before ? before : after);
+
+ if (oideq(&commit_to_reorder->object.oid, &anchor->object.oid))
+ die(_("commit to reorder and anchor must not be the same"));
+
+ head = lookup_commit_reference_by_name("HEAD");
+ if (!head)
+ die(_("could not resolve HEAD to a commit"));
+
+ commit_list_append(commit_to_reorder, &list);
+ if (!repo_is_descendant_of(repo, commit_to_reorder, list))
+ die(_("reordered commit must be reachable from current HEAD commit"));
+
+ /*
+ * There is no requirement for the user to have either one of the
+ * provided commits be the parent or child. We thus have to figure out
+ * ourselves which one is which.
+ */
+ if (repo_is_descendant_of(repo, anchor, list))
+ old = commit_to_reorder;
+ else
+ old = anchor;
+
+ /*
+ * Select the whole range of commits, including the boundary commit
+ * itself. In case the old commit is the root commit we simply pass no
+ * boundary.
+ */
+ ret = collect_commits(repo, old->parents ? old->parents->item : NULL,
+ head, &commits);
+ if (ret < 0)
+ goto out;
+
+ /*
+ * Perform the reordering of commits in the strvec. This is done by:
+ *
+ * - Deleting the to-be-reordered commit from the range of commits.
+ *
+ * - Replacing the anchor commit with the anchor commit plus the
+ * to-be-reordered commit.
+ */
+ if (before) {
+ replacement[0] = commit_to_reorder->object.oid;
+ replacement[1] = anchor->object.oid;
+ } else {
+ replacement[0] = anchor->object.oid;
+ replacement[1] = commit_to_reorder->object.oid;
+ }
+ replace_commits(&commits, &commit_to_reorder->object.oid, NULL, 0);
+ replace_commits(&commits, &anchor->object.oid, replacement, ARRAY_SIZE(replacement));
+
+ /*
+ * And now we pick commits in the new order on top of either the root
+ * commit or on top the old commit's parent.
+ */
+ ret = apply_commits(repo, &commits, head,
+ old->parents ? old->parents->item : NULL, "reorder");
+ if (ret < 0)
+ goto out;
+
+ ret = 0;
+
+out:
+ free_commit_list(list);
+ strvec_clear(&commits);
+ return ret;
+}
+
int cmd_history(int argc,
const char **argv,
const char *prefix,
@@ -298,11 +431,13 @@ int cmd_history(int argc,
{
const char * const usage[] = {
N_("git history drop [<options>] <revision>"),
+ N_("git history reorder [<options>] <revision> --(before|after)=<revision>"),
NULL,
};
parse_opt_subcommand_fn *fn = NULL;
struct option options[] = {
OPT_SUBCOMMAND("drop", &fn, cmd_history_drop),
+ OPT_SUBCOMMAND("reorder", &fn, cmd_history_reorder),
OPT_END(),
};
diff --git a/t/meson.build b/t/meson.build
index 859c388987..8eded9ec1b 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -377,6 +377,7 @@ integration_tests = [
't3437-rebase-fixup-options.sh',
't3438-rebase-broken-files.sh',
't3450-history-drop.sh',
+ 't3451-history-reorder.sh',
't3500-cherry.sh',
't3501-revert-cherry-pick.sh',
't3502-cherry-pick-merge.sh',
diff --git a/t/t3451-history-reorder.sh b/t/t3451-history-reorder.sh
new file mode 100755
index 0000000000..cc311ba190
--- /dev/null
+++ b/t/t3451-history-reorder.sh
@@ -0,0 +1,218 @@
+#!/bin/sh
+
+test_description='tests for git-history reorder subcommand'
+
+. ./test-lib.sh
+
+test_expect_success 'reorder refuses to work with merge commits' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit base &&
+ git branch branch &&
+ test_commit ours &&
+ git switch branch &&
+ test_commit theirs &&
+ git switch - &&
+ git merge theirs &&
+ test_must_fail git history reorder HEAD --before=HEAD~ 2>err &&
+ test_grep "commit to be reordered must not be a merge commit" err &&
+ test_must_fail git history reorder HEAD~ --after=HEAD 2>err &&
+ test_grep "cannot rearrange commit history with merges" err
+ )
+'
+
+test_expect_success 'reorder requires exactly one of --before or --after' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_must_fail git history reorder HEAD 2>err &&
+ test_grep "exactly one option of ${SQ}before${SQ} or ${SQ}after${SQ} must be given" err &&
+ test_must_fail git history reorder HEAD --before=a --after=b 2>err &&
+ test_grep "options ${SQ}before${SQ} and ${SQ}after${SQ} cannot be used together" err
+ )
+'
+
+test_expect_success 'reorder refuses to reorder commit with itself' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_must_fail git history reorder HEAD --after=HEAD 2>err &&
+ test_grep "commit to reorder and anchor must not be the same" err
+ )
+'
+
+test_expect_success '--before can move commit back in history' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ test_commit fourth &&
+ test_commit fifth &&
+ git history reorder :/fourth --before=:/second &&
+ cat >expect <<-EOF &&
+ fifth
+ third
+ second
+ fourth
+ first
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success '--before can move commit forward in history' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ test_commit fourth &&
+ test_commit fifth &&
+ git history reorder :/second --before=:/fourth &&
+ cat >expect <<-EOF &&
+ fifth
+ fourth
+ second
+ third
+ first
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success '--before can make a commit a root commit' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ git history reorder :/third --before=:/first &&
+ cat >expect <<-EOF &&
+ second
+ first
+ third
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success '--after can move commit back in history' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ test_commit fourth &&
+ test_commit fifth &&
+ git history reorder :/fourth --after=:/second &&
+ cat >expect <<-EOF &&
+ fifth
+ third
+ fourth
+ second
+ first
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success '--after can move commit forward in history' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ test_commit fourth &&
+ test_commit fifth &&
+ git history reorder :/second --after=:/fourth &&
+ cat >expect <<-EOF &&
+ fifth
+ second
+ fourth
+ third
+ first
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success '--after can make commit the tip' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ test_commit first &&
+ test_commit second &&
+ test_commit third &&
+ git history reorder :/first --after=:/third &&
+ cat >expect <<-EOF &&
+ first
+ third
+ second
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual
+ )
+'
+
+test_expect_success 'conflicts are detected' '
+ test_when_finished "rm -rf repo" &&
+ git init repo &&
+ (
+ cd repo &&
+ echo base >file &&
+ git add file &&
+ git commit -m base &&
+ echo "first edit" >file &&
+ git commit -am "first edit" &&
+ echo "second edit" >file &&
+ git commit -am "second edit" &&
+
+ git symbolic-ref HEAD >expect-head &&
+ test_must_fail git history reorder HEAD --before=HEAD~ &&
+ test_must_fail git symbolic-ref HEAD &&
+ echo "second edit" >file &&
+ git add file &&
+ test_must_fail git cherry-pick --continue &&
+ echo "first edit" >file &&
+ git add file &&
+ git cherry-pick --continue &&
+
+ cat >expect <<-EOF &&
+ first edit
+ second edit
+ base
+ EOF
+ git log --format=%s >actual &&
+ test_cmp expect actual &&
+
+ git symbolic-ref HEAD >actual-head &&
+ test_cmp expect-head actual-head
+ )
+'
+
+test_done
--
2.51.0.261.g7ce5a0a67e.dirty
