From: Phillip Wood <redacted>

As part of the on-going effort to retire the apply rebase backend teach
the merge backend how to handle --committer-date-is-author-date.

Original-patch-by: Rohit Ashiwal [off-list ref]
Signed-off-by: Phillip Wood <redacted>
---
 Documentation/git-rebase.txt           | 10 +++--
 builtin/rebase.c                       | 16 ++++---
 sequencer.c                            | 60 +++++++++++++++++++++++++-
 sequencer.h                            |  1 +
 t/t3422-rebase-incompatible-options.sh |  1 -
 t/t3436-rebase-more-options.sh         | 56 ++++++++++++++++++++++++
 6 files changed, 133 insertions(+), 11 deletions(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index d060c143e6..8c62645b8c 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt

@@ -438,9 +438,13 @@ when merging.
 See also INCOMPATIBLE OPTIONS below.

 --committer-date-is-author-date::
+       Instead of using the current time as the committer date, use
+       the author date of the commit being rebased as the committer
+       date. This option implies --force-rebase.
+
 --ignore-date::
-       These flags are passed to 'git am' to easily change the dates
-       of the rebased commits (see linkgit:git-am[1]).
+       This flag is passed to 'git am' to change the author date
+       of each rebased commit (see linkgit:git-am[1]).
 +
 See also INCOMPATIBLE OPTIONS below.

@@ -578,7 +582,6 @@ INCOMPATIBLE OPTIONS
 The following options:

  * --apply
- * --committer-date-is-author-date
  * --ignore-date
  * --whitespace
  * -C

@@ -606,6 +609,7 @@ In addition, the following pairs of options are incompatible:
  * --preserve-merges and --rebase-merges
  * --preserve-merges and --empty=
  * --preserve-merges and --ignore-whitespace
+ * --preserve-merges and --committer-date-is-author-date
  * --keep-base and --onto
  * --keep-base and --root

diff --git a/builtin/rebase.c b/builtin/rebase.c
index 5d8e117276..357cd6acf3 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c

@@ -89,6 +89,7 @@ struct rebase_options {
        int ignore_whitespace;
        char *gpg_sign_opt;
        int autostash;
+       int committer_date_is_author_date;
        char *cmd;
        int allow_empty_message;
        int rebase_merges, rebase_cousins;

@@ -126,6 +127,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
        replay.quiet = !(opts->flags & REBASE_NO_QUIET);
        replay.verbose = opts->flags & REBASE_VERBOSE;
        replay.reschedule_failed_exec = opts->reschedule_failed_exec;
+       replay.committer_date_is_author_date =
+                                       opts->committer_date_is_author_date;
        replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
        replay.strategy = opts->strategy;

@@ -1003,6 +1006,8 @@ static int run_am(struct rebase_options *opts)

        if (opts->ignore_whitespace)
                argv_array_push(&am.args, "--ignore-whitespace");
+       if (opts->committer_date_is_author_date)
+               argv_array_push(&opts->git_am_opts, "--committer-date-is-author-date");
        if (opts->action && !strcmp("continue", opts->action)) {
                argv_array_push(&am.args, "--resolved");
                argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);

@@ -1507,9 +1512,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                        PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
                OPT_BOOL(0, "signoff", &options.signoff,
                         N_("add a Signed-off-by: line to each commit")),
-               OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
-                                 &options.git_am_opts, NULL,
-                                 N_("passed to 'git am'"), PARSE_OPT_NOARG),
+               OPT_BOOL(0, "committer-date-is-author-date",
+                        &options.committer_date_is_author_date,
+                        N_("make committer date match author date")),
                OPT_PASSTHRU_ARGV(0, "ignore-date", &options.git_am_opts, NULL,
                                  N_("passed to 'git am'"), PARSE_OPT_NOARG),
                OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),

@@ -1804,11 +1809,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
            options.autosquash) {
                allow_preemptive_ff = 0;
        }
+       if (options.committer_date_is_author_date)
+               options.flags |= REBASE_FORCE;

        for (i = 0; i < options.git_am_opts.argc; i++) {
                const char *option = options.git_am_opts.argv[i], *p;
-               if (!strcmp(option, "--committer-date-is-author-date") ||
-                   !strcmp(option, "--ignore-date") ||
+               if (!strcmp(option, "--ignore-date") ||
                    !strcmp(option, "--whitespace=fix") ||
                    !strcmp(option, "--whitespace=strip"))
                        allow_preemptive_ff = 0;

diff --git a/sequencer.c b/sequencer.c
index 6fd2674632..3bb80d7414 100644
--- a/sequencer.c
+++ b/sequencer.c

@@ -149,6 +149,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
  * command-line.
  */
 static GIT_PATH_FUNC(rebase_path_gpg_sign_opt, "rebase-merge/gpg_sign_opt")
+static GIT_PATH_FUNC(rebase_path_cdate_is_adate, "rebase-merge/cdate_is_adate")
 static GIT_PATH_FUNC(rebase_path_orig_head, "rebase-merge/orig-head")
 static GIT_PATH_FUNC(rebase_path_verbose, "rebase-merge/verbose")
 static GIT_PATH_FUNC(rebase_path_quiet, "rebase-merge/quiet")

@@ -872,6 +873,22 @@ static char *get_author(const char *message)
        return NULL;
 }

+static const char *author_date_from_env_array(const struct argv_array *env)
+{
+       int i;
+       const char *date;
+
+       for (i = 0; i < env->argc; i++)
+               if (skip_prefix(env->argv[i],
+                               "GIT_AUTHOR_DATE=", &date))
+                       return date;
+       /*
+        * If GIT_AUTHOR_DATE is missing we should have already errored out when
+        * reading the script
+        */
+       BUG("GIT_AUTHOR_DATE missing from author script");
+}
+
 static const char staged_changes_advice[] =
 N_("you have staged changes in your working tree\n"
 "If these changes are meant to be squashed into the previous commit, run:\n"

@@ -938,6 +955,10 @@ static int run_git_commit(struct repository *r,
                             gpg_opt, gpg_opt);
        }

+       if (opts->committer_date_is_author_date)
+               argv_array_pushf(&cmd.env_array, "GIT_COMMITTER_DATE=%s",
+                                author_date_from_env_array(&cmd.env_array));
+
        argv_array_push(&cmd.args, "commit");

        if (!(flags & VERIFY_MSG))

@@ -1321,7 +1342,6 @@ static int try_to_commit(struct repository *r,

        if (parse_head(r, &current_head))
                return -1;
-
        if (flags & AMEND_MSG) {
                const char *exclude_gpgsig[] = { "gpgsig", "gpgsig-sha256", NULL };
                const char *out_enc = get_commit_output_encoding();

@@ -1349,6 +1369,30 @@ static int try_to_commit(struct repository *r,
                commit_list_insert(current_head, &parents);
        }

+       if (opts->committer_date_is_author_date) {
+               int len = strlen(author);
+               struct ident_split ident;
+               struct strbuf date = STRBUF_INIT;
+
+               if (split_ident_line(&ident, author, len) < 0) {
+                       res = error(_("malformed ident line '%s'"), author);
+                       goto out;
+               }
+               if (!ident.date_begin) {
+                       res = error(_("corrupted author without date information"));
+                       goto out;
+               }
+
+               strbuf_addf(&date, "@%.*s %.*s",
+                           (int)(ident.date_end - ident.date_begin), ident.date_begin,
+                           (int)(ident.tz_end - ident.tz_begin), ident.tz_begin);
+               res = setenv("GIT_COMMITTER_DATE", date.buf, 1);
+               strbuf_release(&date);
+
+               if (res)
+                       goto out;
+       }
+
        if (write_index_as_tree(&tree, r->index, r->index_file, 0, NULL)) {
                res = error(_("git write-tree failed to write a tree"));
                goto out;

@@ -2532,6 +2576,11 @@ static int read_populate_opts(struct replay_opts *opts)
                        opts->signoff = 1;
                }

+               if (file_exists(rebase_path_cdate_is_adate())) {
+                       opts->allow_ff = 0;
+                       opts->committer_date_is_author_date = 1;
+               }
+
                if (file_exists(rebase_path_reschedule_failed_exec()))
                        opts->reschedule_failed_exec = 1;

@@ -2622,6 +2671,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
                write_file(rebase_path_drop_redundant_commits(), "%s", "");
        if (opts->keep_redundant_commits)
                write_file(rebase_path_keep_redundant_commits(), "%s", "");
+       if (opts->committer_date_is_author_date)
+               write_file(rebase_path_cdate_is_adate(), "%s", "");
        if (opts->reschedule_failed_exec)
                write_file(rebase_path_reschedule_failed_exec(), "%s", "");

@@ -3542,6 +3593,10 @@ static int do_merge(struct repository *r,
                        goto leave_merge;
                }

+               if (opts->committer_date_is_author_date)
+                       argv_array_pushf(&cmd.env_array, "GIT_COMMITTER_DATE=%s",
+                                        author_date_from_env_array(&cmd.env_array));
+
                cmd.git_cmd = 1;
                argv_array_push(&cmd.args, "merge");
                argv_array_push(&cmd.args, "-s");

@@ -3819,7 +3874,8 @@ static int pick_commits(struct repository *r,
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
        if (opts->allow_ff)
                assert(!(opts->signoff || opts->no_commit ||
-                               opts->record_origin || opts->edit));
+                               opts->record_origin || opts->edit ||
+                               opts->committer_date_is_author_date));
        if (read_and_refresh_cache(r, opts))
                return -1;

diff --git a/sequencer.h b/sequencer.h
index 0bee85093e..4ab94119ae 100644
--- a/sequencer.h
+++ b/sequencer.h

@@ -45,6 +45,7 @@ struct replay_opts {
        int verbose;
        int quiet;
        int reschedule_failed_exec;
+       int committer_date_is_author_date;

        int mainline;

diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
index 55ca46786d..c8234062c6 100755
--- a/t/t3422-rebase-incompatible-options.sh
+++ b/t/t3422-rebase-incompatible-options.sh

@@ -61,7 +61,6 @@ test_rebase_am_only () {
 }

 test_rebase_am_only --whitespace=fix
-test_rebase_am_only --committer-date-is-author-date
 test_rebase_am_only -C4

 test_expect_success REBASE_P '--preserve-merges incompatible with --signoff' '

diff --git a/t/t3436-rebase-more-options.sh b/t/t3436-rebase-more-options.sh
index fb5e747e86..84b9d5d37f 100755
--- a/t/t3436-rebase-more-options.sh
+++ b/t/t3436-rebase-more-options.sh

@@ -9,6 +9,9 @@ test_description='tests to ensure compatibility between am and interactive backe

 . "$TEST_DIRECTORY"/lib-rebase.sh

+GIT_AUTHOR_DATE="1999-04-02T08:03:20+05:30"
+export GIT_AUTHOR_DATE
+
 # This is a special case in which both am and interactive backends
 # provide the same output. It was done intentionally because
 # both the backends fall short of optimal behaviour.

@@ -28,8 +31,13 @@ test_expect_success 'setup' '
        EOF
        git commit -am "update file" &&
        git tag side &&
+       test_commit commit1 foo foo1 &&
+       test_commit commit2 foo foo2 &&
+       test_commit commit3 foo foo3 &&

        git checkout --orphan master &&
+       git rm --cached foo &&
+       rm foo &&
        sed -e "s/^|//" >file <<-\EOF &&
        |line 1
        |        line 2

@@ -78,6 +86,54 @@ test_expect_success '--ignore-whitespace is remembered when continuing' '
        test_cmp expect file
 '

+test_expect_success '--committer-date-is-author-date works with apply backend' '
+       GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
+       git rebase --apply --committer-date-is-author-date HEAD^ &&
+       git log -1 --pretty="format:%ai" >authortime &&
+       git log -1 --pretty="format:%ci" >committertime &&
+       test_cmp authortime committertime
+'
+
+test_expect_success '--committer-date-is-author-date works with merge backend' '
+       GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
+       git rebase -m --committer-date-is-author-date HEAD^ &&
+       git log -1 --pretty="format:%ai" >authortime &&
+       git log -1 --pretty="format:%ci" >committertime &&
+       test_cmp authortime committertime
+'
+
+test_expect_success '--committer-date-is-author-date works with rebase -r' '
+       git checkout side &&
+       GIT_AUTHOR_DATE="@1234 +0300" git merge --no-ff commit3 &&
+       git rebase -r --root --committer-date-is-author-date &&
+       git log --pretty="format:%ai" >authortime &&
+       git log --pretty="format:%ci" >committertime &&
+       test_cmp authortime committertime
+'
+
+test_expect_success '--committer-date-is-author-date works when forking merge' '
+       git checkout side &&
+       GIT_AUTHOR_DATE="@1234 +0300" git merge --no-ff commit3 &&
+       git rebase -r --root --strategy=resolve --committer-date-is-author-date &&
+       git log --pretty="format:%ai" >authortime &&
+       git log --pretty="format:%ci" >committertime &&
+       test_cmp authortime committertime
+
+'
+
+test_expect_success '--committer-date-is-author-date works when committing conflict resolution' '
+       git checkout commit2 &&
+       GIT_AUTHOR_DATE="@1980 +0000" git commit --amend --only --reset-author &&
+       git log -1 --format=%at HEAD >expect &&
+       test_must_fail git rebase -m --committer-date-is-author-date \
+               --onto HEAD^^ HEAD^ &&
+       echo resolved > foo &&
+       git add foo &&
+       git rebase --continue &&
+       git log -1 --format=%ct HEAD >actual &&
+       test_cmp expect actual
+'
+
 # This must be the last test in this file
 test_expect_success '$EDITOR and friends are unchanged' '
        test_editor_unchanged
--

2.26.2