[GSoC][PATCHl 0/6] rebase -i: support more options

> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index db6ca9bd7d..3c195ddc73 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> ...
> @@ -511,6 +523,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>  	argc = parse_options(argc, argv, NULL, options,
>  			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);

> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> new file mode 100755
> index 0000000000..e617d3150e
> --- /dev/null
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -0,0 +1,65 @@
> ...
> +
> +	git checkout --orphan master &&
> +	cat >file <<-EOF &&
> +	line 1
> +	        line 2
> +	line 3
> +	EOF

>
> Rohit Ashiwal <rohit.ashiwal265@gmail.com> writes:
>
> > diff --git a/builtin/rebase.c b/builtin/rebase.c
> > index db6ca9bd7d..3c195ddc73 100644
> > --- a/builtin/rebase.c
> > +++ b/builtin/rebase.c
> > ...
> > @@ -511,6 +523,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
> >       argc = parse_options(argc, argv, NULL, options,
> >                       builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
>
> Curious.  Did you rebase onto an older codebase?  I think the round
> currently queued in my tree already has c0e78f7e46 which merged the
> jk/unused-params-final-batch topic that updated this call to
> parse_options() to pass prefix.  Perhaps you want to fetch from me
> what has been on 'pu' (it should be "log master..10827432") and
> compare what you had?  Unless there is no compelling reason not to,
> it would be a good idea to base the reroll on the same commit as
> the commit on which the previous version has been queued, which in
> this case is 9c9b961d ("The sixth batch", 2019-07-19).

> > diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> > new file mode 100755
> > index 0000000000..e617d3150e
> > --- /dev/null
> > +++ b/t/t3433-rebase-options-compatibility.sh
> > @@ -0,0 +1,65 @@
> > ...
> > +
> > +     git checkout --orphan master &&
> > +     cat >file <<-EOF &&
> > +     line 1
> > +             line 2
> > +     line 3
> > +     EOF
>
> The second line triggers "indent with spaces" whitespace error; you
> can protect these spaces in the leading indent like so:
>
>         sed -e "s/^|//" <<-\EOF &&
>         |line 1
>         |        line 2
>         |line 3
>         EOF
>
> Also make it a habit to always quote the EOF token that begins the
> here document (i.e. <<-\EOF) when the here document does not need
> variable interpolation.  I suspect (but I did not read all of the
> tests) that there may be many other instances of here document in
> this patch that can use the same improvement.

> There are two backends available for rebasing, viz, the am and the
> interactive. Naturally, there shall be some features that are
> implemented in one but not in the other. One such flag is
> --ignore-whitespace which indicates merge mechanism to treat lines
> with only whitespace changes as unchanged. Wire the interactive
> rebase to also understand the --ignore-whitespace flag by
> translating it to -Xignore-space-change.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 10 +++-
>   builtin/rebase.c                        | 26 ++++++++--
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 65 +++++++++++++++++++++++++
>   4 files changed, 95 insertions(+), 7 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 5e4e927647..85404fea52 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -371,8 +371,13 @@ If either <upstream> or --root is given on the command line, then the
>   default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   
>   --ignore-whitespace::
> +	This flag is either passed to the 'git apply' program
> +	(see linkgit:git-apply[1]), or to 'git merge' program
> +	(see linkgit:git-merge[1]) as `-Xignore-space-change`,
> +	depending on which backend is selected by other options.

> +
>   --whitespace=<option>::
> -	These flag are passed to the 'git apply' program
> +	This flag is passed to the 'git apply' program
>   	(see linkgit:git-apply[1]) that applies the patch.
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -520,7 +525,6 @@ The following options:
>    * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
> - * --ignore-whitespace
>    * -C
>   
>   are incompatible with the following options:
> @@ -543,6 +547,8 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --interactive
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
> + * --preserve-merges and --ignore-whitespace
> + * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
>   
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index db6ca9bd7d..3c195ddc73 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -79,6 +79,7 @@ struct rebase_options {
>   	int allow_rerere_autoupdate;
>   	int keep_empty;
>   	int autosquash;
> +	int ignore_whitespace;
>   	char *gpg_sign_opt;
>   	int autostash;
>   	char *cmd;
> @@ -97,7 +98,7 @@ struct rebase_options {
>   		.git_format_patch_opt = STRBUF_INIT	\
>   	}
>   
> -static struct replay_opts get_replay_opts(const struct rebase_options *opts)
> +static struct replay_opts get_replay_opts(struct rebase_options *opts)
>   {
>   	struct replay_opts replay = REPLAY_OPTS_INIT;
>   
> @@ -114,6 +115,17 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)

>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
> +
> +	if (opts->ignore_whitespace) {
> +		struct strbuf buf = STRBUF_INIT;
> +
> +		if (opts->strategy_opts)
> +			strbuf_addstr(&buf, opts->strategy_opts);
> +
> +		strbuf_addstr(&buf, " --ignore-space-change");
> +		free(opts->strategy_opts);
> +		opts->strategy_opts = strbuf_detach(&buf, NULL);
> +	}

>   	if (opts->strategy_opts)
>   		parse_strategy_opts(&replay, opts->strategy_opts);
>   
> @@ -511,6 +523,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   	argc = parse_options(argc, argv, NULL, options,
>   			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
>   
> +	opts.strategy_opts = xstrdup_or_null(opts.strategy_opts);
> +
>   	if (!is_null_oid(&squash_onto))
>   		opts.squash_onto = &squash_onto;
>   
> @@ -954,6 +968,8 @@ static int run_am(struct rebase_options *opts)
>   	am.git_cmd = 1;
>   	argv_array_push(&am.args, "am");
>   
> +	if (opts->ignore_whitespace)
> +		argv_array_push(&am.args, "--ignore-whitespace");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1401,9 +1417,6 @@ 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, "ignore-whitespace", &options.git_am_opts,
> -				  NULL, N_("passed to 'git am'"),
> -				  PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
>   				  &options.git_am_opts, NULL,
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
> @@ -1411,6 +1424,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
> +		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> +			 N_("ignore changes in whitespace")),
>   		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
>   				  N_("action"), N_("passed to 'git apply'"), 0),
>   		OPT_BIT('f', "force-rebase", &options.flags,
> @@ -1821,6 +1836,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   	}
>   
>   	if (options.rebase_merges) {
> +		if (options.ignore_whitespace)
> +			die(_("cannot combine '--rebase-merges' with "
> +			      "'--ignore-whitespace'"));
>   		if (strategy_options.nr)
>   			die(_("cannot combine '--rebase-merges' with "
>   			      "'--strategy-option'"));
> diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> index a5868ea152..4342f79eea 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 --ignore-whitespace
>   test_rebase_am_only --committer-date-is-author-date
>   test_rebase_am_only -C4
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> new file mode 100755
> index 0000000000..e617d3150e
> --- /dev/null
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -0,0 +1,65 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2019 Rohit Ashiwal
> +#
> +
> +test_description='tests to ensure compatibility between am and interactive backends'
> +
> +. ./test-lib.sh
> +
> +# 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.
> +test_expect_success 'setup' '
> +	git checkout -b topic &&
> +	q_to_tab >file <<-EOF &&
> +	line 1
> +	Qline 2
> +	line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	cat >file <<-EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	git commit -am "update file" &&
> +	git tag side &&
> +
> +	git checkout --orphan master &&
> +	cat >file <<-EOF &&
> +	line 1
> +	        line 2
> +	line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	git tag main
> +'
> +
> +test_expect_success '--ignore-whitespace works with am backend' '
> +	cat >expect <<-EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase main side &&
> +	git rebase --abort &&
> +	git rebase --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_expect_success '--ignore-whitespace works with interactive backend' '
> +	cat >expect <<-EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase --merge main side &&
> +	git rebase --abort &&
> +	git rebase --merge --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_done
> 

> 
> [...]
> >   --ignore-whitespace::
> > +	This flag is either passed to the 'git apply' program
> > +	(see linkgit:git-apply[1]), or to 'git merge' program
> > +	(see linkgit:git-merge[1]) as `-Xignore-space-change`,
> > +	depending on which backend is selected by other options.
> 
> I think it would be better to document the effect of this option rather
> than the implementation detail. It is confusing at the moment as it
> talks about 'git merge' but we don't allow this option with merges.

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  8 +++-
>   builtin/rebase.c                        | 20 +++++++---
>   sequencer.c                             | 52 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 91 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 85404fea52..83c5bbe06c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -383,8 +383,12 @@ default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This implies --force-rebase.
> +
>   --ignore-date::
> -	These flags are passed to 'git am' to easily change the dates
> +	This flag is passed to 'git am' to change the author date
>   	of the rebased commits (see linkgit:git-am[1]).
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -522,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -548,6 +551,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 3c195ddc73..41fe9ebff8 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ 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;
> @@ -113,6 +114,8 @@ static struct replay_opts get_replay_opts(struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	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;
>   
> @@ -532,6 +535,9 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> +	if (opts.committer_date_is_author_date)
> +		opts.flags |= REBASE_FORCE;
> +
>   	return !!run_rebase_interactive(&opts, command);
>   }
>   
> @@ -970,6 +976,8 @@ 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);
> @@ -1417,9 +1425,9 @@ 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"),
> @@ -1686,10 +1694,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	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"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index a2d7b0925e..65adf79222 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -876,6 +877,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}
> +
>   /* Read author-script and return an ident line (author <email> timestamp) */
>   static const char *read_author_ident(struct strbuf *buf)
>   {
> @@ -904,6 +916,18 @@ static const char *read_author_ident(struct strbuf *buf)
>   	return buf->buf;
>   }
>   
> +static int setenv_committer_date_to_author_date(void)
> +{
> +	int res = 1;

> +	char *date = read_author_date_or_null();
> +
> +	if (date)
> +		res = setenv("GIT_COMMITTER_DATE", date, 1);
> +
> +	free(date);
> +	return res;
> +}
> +
>   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"
> @@ -961,6 +985,9 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> +	if (opts->committer_date_is_author_date &&
> +	    setenv_committer_date_to_author_date())
> +		return 1;

>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>   		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>   		const char *author = NULL;
> @@ -1397,7 +1424,9 @@ static int try_to_commit(struct repository *r,
>   
>   	if (parse_head(r, &current_head))
>   		return -1;
> -
> +	if (!(flags & AMEND_MSG) && opts->committer_date_is_author_date &&
> +	    setenv_committer_date_to_author_date())
> +		return -1;

>   	if (flags & AMEND_MSG) {
>   		const char *exclude_gpgsig[] = { "gpgsig", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1418,6 +1447,17 @@ static int try_to_commit(struct repository *r,
>   			res = error(_("unable to parse commit author"));
>   			goto out;
>   		}
> +		if (opts->committer_date_is_author_date) {
> +			char *date;
> +			int len = strlen(author);
> +			char *idx = memchr(author, '>', len);

> +
> +			++idx;
> +			date = malloc(author + len - idx);
> +			memcpy(date, idx, author + len - idx);
> +			setenv("GIT_COMMITTER_DATE", date, 1);
> +			free(date);

> @@ -2538,6 +2578,11 @@ 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;
>   
> @@ -2620,6 +2665,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3708,7 +3755,8 @@ 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 0c494b83d4..e6cba468db 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index e617d3150e..ceab48a831 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git rebase -f HEAD^ &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%at" >authortime &&
> +	git show HEAD --pretty="format:%ct" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git rebase -f HEAD^ &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%at" >authortime &&
> +	git show HEAD --pretty="format:%ct" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
>   test_done
> 

> ...
> I think it would be better to handle committer_date_is_author_date in
> a single place in this function, not have two implementations one of
> ...
> git has a high level api for manipulation author/committer information
> in ident.c, it would be best to use that. In any case code like this
> should be using strbuf's rather than malloc
> ...
> Do the committer_date_is_author_date check after the end of this if.
>
> Best Wishes
>
> Phillip

> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   sequencer.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index 65adf79222..d24a6fd585 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -1417,7 +1417,7 @@ static int try_to_commit(struct repository *r,
>   	struct commit_extra_header *extra = NULL;
>   	struct strbuf err = STRBUF_INIT;
>   	struct strbuf commit_msg = STRBUF_INIT;
> -	char *amend_author = NULL;
> +	char *author_to_free = NULL;
>   	const char *hook_commit = NULL;
>   	enum commit_msg_cleanup_mode cleanup;
>   	int res = 0;
> @@ -1441,7 +1441,7 @@ static int try_to_commit(struct repository *r,
>   			strbuf_addstr(msg, orig_message);
>   			hook_commit = "HEAD";
>   		}
> -		author = amend_author = get_author(message);
> +		author = author_to_free = get_author(message);
>   		unuse_commit_buffer(current_head, message);
>   		if (!author) {
>   			res = error(_("unable to parse commit author"));
> @@ -1526,7 +1526,7 @@ static int try_to_commit(struct repository *r,
>   	free_commit_extra_headers(extra);
>   	strbuf_release(&err);
>   	strbuf_release(&commit_msg);
> -	free(amend_author);
> +	free(author_to_free);
>   
>   	return res;
>   }
> 

> @@ -1046,6 +1066,8 @@ static int run_git_commit(struct repository *r,
>  		argv_array_push(&cmd.args, "--amend");
>  	if (opts->gpg_sign)
>  		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
>  	if (defmsg)
>  		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>  	else if (!(flags & EDIT_MSG))

> On Tue, 6 Aug 2019, Rohit Ashiwal wrote:
>
>> @@ -1046,6 +1066,8 @@ static int run_git_commit(struct repository *r,
>>  		argv_array_push(&cmd.args, "--amend");
>>  	if (opts->gpg_sign)
>>  		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>> +	if (opts->ignore_date)
>> +		argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
>>  	if (defmsg)
>>  		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>>  	else if (!(flags & EDIT_MSG))
>
> I need this patch to make the code _at least_ compile on Windows again
> (I don't know whether it breaks the test suite yet):
>
> -- snipsnap --
> Subject: [PATCH] fixup! rebase -i: support --ignore-date
>
> It is a mistake to believe that the return value of `time()` is always
> an `unsigned long`.

> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  sequencer.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index 539c0ef601b..a4c932d3407 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -1070,7 +1070,8 @@ static int run_git_commit(struct repository *r,
>  	if (opts->gpg_sign)
>  		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>  	if (opts->ignore_date)
> -		argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
> +		argv_array_pushf(&cmd.args, "--date=%"PRIuMAX,
> +				 (uintmax_t)time(NULL));
>  	if (defmsg)
>  		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>  	else if (!(flags & EDIT_MSG))
> @@ -3642,7 +3643,8 @@ static int do_merge(struct repository *r,
>  			argv_array_push(&cmd.args, opts->gpg_sign);
>  		if (opts->ignore_date)
>  			argv_array_pushf(&cmd.args,
> -					 "GIT_AUTHOR_DATE=%ld", time(NULL));
> +					 "GIT_AUTHOR_DATE=%"PRIuMAX,
> +					 (uintmax_t)time(NULL));
>
>  		/* Add the tips to be merged */
>  		for (j = to_merge; j; j = j->next)
> --
> 2.22.0.windows.1.6.g271c090e89

>
> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
> > On Tue, 6 Aug 2019, Rohit Ashiwal wrote:
> >
> >> @@ -1046,6 +1066,8 @@ static int run_git_commit(struct repository *r,
> >>              argv_array_push(&cmd.args, "--amend");
> >>      if (opts->gpg_sign)
> >>              argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> >> +    if (opts->ignore_date)
> >> +            argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
> >>      if (defmsg)
> >>              argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
> >>      else if (!(flags & EDIT_MSG))
> >
> > I need this patch to make the code _at least_ compile on Windows again
> > (I don't know whether it breaks the test suite yet):
> >
> > -- snipsnap --
> > Subject: [PATCH] fixup! rebase -i: support --ignore-date
> >
> > It is a mistake to believe that the return value of `time()` is always
> > an `unsigned long`.
>
> Good catch.  We can at least expect it to be some integral type ;-)
>
> With or without this fix-up, I think the patch is still not quite
> right.  Output from time() formatted as an integer is a string of
> digits, and the side that reads that string and interprets it as a
> timestamp does so by calling parse_date(); it is up to that function
> to decide what datestring format it is in, and it does not
> necessarily take it as seconds since epoch.  It is safer to force
> the "seconds since epoch" interpretation by writing the timestamp
> string like so:
>
>         argv_array_pushf(&args, "--date=@%ld", time(NULL));
>
> See 14ac2864 ("commit: accept more date formats for "--date"",
> 2014-05-01), which gives a good hint on how to do this right, and
> 2c733fb2 ("parse_date(): '@' prefix forces git-timestamp",
> 2012-02-02) for a backstory.
>
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >  sequencer.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/sequencer.c b/sequencer.c
> > index 539c0ef601b..a4c932d3407 100644
> > --- a/sequencer.c
> > +++ b/sequencer.c
> > @@ -1070,7 +1070,8 @@ static int run_git_commit(struct repository *r,
> >       if (opts->gpg_sign)
> >               argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> >       if (opts->ignore_date)
> > -             argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
> > +             argv_array_pushf(&cmd.args, "--date=%"PRIuMAX,
> > +                              (uintmax_t)time(NULL));
> >       if (defmsg)
> >               argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
> >       else if (!(flags & EDIT_MSG))
> > @@ -3642,7 +3643,8 @@ static int do_merge(struct repository *r,
> >                       argv_array_push(&cmd.args, opts->gpg_sign);
> >               if (opts->ignore_date)
> >                       argv_array_pushf(&cmd.args,
> > -                                      "GIT_AUTHOR_DATE=%ld", time(NULL));
> > +                                      "GIT_AUTHOR_DATE=%"PRIuMAX,
> > +                                      (uintmax_t)time(NULL));
> >
> >               /* Add the tips to be merged */
> >               for (j = to_merge; j; j = j->next)
> > --
> > 2.22.0.windows.1.6.g271c090e89

> rebase am already has this flag to "lie" about the author date
> by changing it to the committer (current) date. Let's add the same
> for interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  6 ++--
>   builtin/rebase.c                        | 17 +++++----
>   sequencer.c                             | 48 ++++++++++++++++++++++---
>   sequencer.h                             |  1 +
>   t/t3433-rebase-options-compatibility.sh | 16 +++++++++
>   5 files changed, 74 insertions(+), 14 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 83c5bbe06c..a5cdf8518b 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -388,8 +388,8 @@ See also INCOMPATIBLE OPTIONS below.
>   	as the committer date. This implies --force-rebase.
>   
>   --ignore-date::
> -	This flag is passed to 'git am' to change the author date
> -	of the rebased commits (see linkgit:git-am[1]).
> +	Lie about the author date by re-setting it to the value
> +	same as committer (current) date. This implies --force-rebase.

>   +
>   See also INCOMPATIBLE OPTIONS below.
>   
> @@ -526,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --ignore-date
>    * --whitespace
>    * -C
>   
> @@ -552,6 +551,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
>    * --preserve-merges and --committer-date-is-author-date
> + * --preserve-merges and --ignore-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 41fe9ebff8..7f464fc9ba 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -83,6 +83,7 @@ struct rebase_options {
>   	char *gpg_sign_opt;
>   	int autostash;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   	char *cmd;
>   	int allow_empty_message;
>   	int rebase_merges, rebase_cousins;
> @@ -116,6 +117,7 @@ static struct replay_opts get_replay_opts(struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.committer_date_is_author_date =
>   					opts->committer_date_is_author_date;
> +	replay.ignore_date = opts->ignore_date;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
>   
> @@ -535,7 +537,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> -	if (opts.committer_date_is_author_date)
> +	if (opts.committer_date_is_author_date ||
> +	    opts.ignore_date)
>   		opts.flags |= REBASE_FORCE;
>   
>   	return !!run_rebase_interactive(&opts, command);
> @@ -978,6 +981,8 @@ static int run_am(struct rebase_options *opts)
>   		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->ignore_date)
> +		argv_array_push(&opts->git_am_opts, "--ignore-date");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1428,8 +1433,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		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_BOOL(0, "ignore-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
>   		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> @@ -1694,13 +1699,13 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> -	if (options.committer_date_is_author_date)
> +	if (options.committer_date_is_author_date ||
> +	    options.ignore_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, "--ignore-date") ||
> -		    !strcmp(option, "--whitespace=fix") ||
> +		if (!strcmp(option, "--whitespace=fix") ||
>   		    !strcmp(option, "--whitespace=strip"))
>   			options.flags |= REBASE_FORCE;
>   		else if (skip_prefix(option, "-C", &p)) {
> diff --git a/sequencer.c b/sequencer.c
> index d24a6fd585..c882dc5d5f 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -148,6 +148,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
>    */
>   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_ignore_date, "rebase-merge/ignore_date")
>   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")
> @@ -928,6 +929,17 @@ static int setenv_committer_date_to_author_date(void)
>   	return res;
>   }
>   
> +static void ignore_author_date(const char **author)
> +{
> +	struct strbuf new_author = STRBUF_INIT;
> +	char *idx = memchr(*author, '>', strlen(*author));

> +
> +	strbuf_add(&new_author, *author, idx - *author);
> +	strbuf_addstr(&new_author, "> ");
> +	datestamp(&new_author);
> +	*author = strbuf_detach(&new_author, NULL);
> +}
> +
>   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"
> @@ -985,7 +997,7 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> -	if (opts->committer_date_is_author_date &&
> +	if (opts->committer_date_is_author_date && !opts->ignore_date &&
>   	    setenv_committer_date_to_author_date())
>   		return 1;

>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
> @@ -1013,10 +1025,18 @@ static int run_git_commit(struct repository *r,
>   
>   		if (res <= 0)
>   			res = error_errno(_("could not read '%s'"), defmsg);
> -		else
> +		else {
> +			if (opts->ignore_date) {
> +				if (!author)
> +					BUG("ignore-date can only be used with "
> +					    "rebase -i, which must set the "

> +					    "author before committing the tree");
> +				ignore_author_date(&author);
> +			}
>   			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>   					  NULL, &root_commit, author,
>   					  opts->gpg_sign);
> +		}
>   
>   		strbuf_release(&msg);
>   		strbuf_release(&script);
> @@ -1046,6 +1066,8 @@ static int run_git_commit(struct repository *r,
>   		argv_array_push(&cmd.args, "--amend");
>   	if (opts->gpg_sign)
>   		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));

>   	if (defmsg)
>   		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>   	else if (!(flags & EDIT_MSG))
> @@ -1425,7 +1447,7 @@ static int try_to_commit(struct repository *r,
>   	if (parse_head(r, &current_head))
>   		return -1;
>   	if (!(flags & AMEND_MSG) && opts->committer_date_is_author_date &&
> -	    setenv_committer_date_to_author_date())
> +	    !opts->ignore_date && setenv_committer_date_to_author_date())
>   		return -1;
>   	if (flags & AMEND_MSG) {
>   		const char *exclude_gpgsig[] = { "gpgsig", NULL };
> @@ -1447,7 +1469,7 @@ static int try_to_commit(struct repository *r,
>   			res = error(_("unable to parse commit author"));
>   			goto out;
>   		}
> -		if (opts->committer_date_is_author_date) {
> +		if (opts->committer_date_is_author_date && !opts->ignore_date) {

>   			char *date;
>   			int len = strlen(author);
>   			char *idx = memchr(author, '>', len);
> @@ -1507,6 +1529,11 @@ static int try_to_commit(struct repository *r,
>   
>   	reset_ident_date();
>   
> +	if (opts->ignore_date) {
> +		ignore_author_date(&author);
> +		free(author_to_free);
> +		author_to_free = (char *)author;
> +	}
>   	if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
>   				 oid, author, opts->gpg_sign, extra)) {
>   		res = error(_("failed to write commit object"));
> @@ -2583,6 +2610,11 @@ static int read_populate_opts(struct replay_opts *opts)
>   			opts->committer_date_is_author_date = 1;
>   		}
>   
> +		if (file_exists(rebase_path_ignore_date())) {
> +			opts->allow_ff = 0;
> +			opts->ignore_date = 1;
> +		}
> +
>   		if (file_exists(rebase_path_reschedule_failed_exec()))
>   			opts->reschedule_failed_exec = 1;
>   
> @@ -2667,6 +2699,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_signoff(), "--signoff\n");
>   	if (opts->committer_date_is_author_date)
>   		write_file(rebase_path_cdate_is_adate(), "%s", "");
> +	if (opts->ignore_date)
> +		write_file(rebase_path_ignore_date(), "%s", "");
>   	if (opts->reschedule_failed_exec)
>   		write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>   
> @@ -3484,6 +3518,9 @@ static int do_merge(struct repository *r,
>   		argv_array_push(&cmd.args, git_path_merge_msg(r));
>   		if (opts->gpg_sign)
>   			argv_array_push(&cmd.args, opts->gpg_sign);
> +		if (opts->ignore_date)
> +			argv_array_pushf(&cmd.args,
> +					 "GIT_AUTHOR_DATE=%ld", time(NULL));
>   
>   		/* Add the tips to be merged */
>   		for (j = to_merge; j; j = j->next)
> @@ -3756,7 +3793,8 @@ static int pick_commits(struct repository *r,
>   	if (opts->allow_ff)
>   		assert(!(opts->signoff || opts->no_commit ||
>   				opts->record_origin || opts->edit ||
> -				opts->committer_date_is_author_date));
> +				opts->committer_date_is_author_date ||
> +				opts->ignore_date));
>   	if (read_and_refresh_cache(r, opts))
>   		return -1;
>   
> diff --git a/sequencer.h b/sequencer.h
> index e6cba468db..73d0515a3e 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -44,6 +44,7 @@ struct replay_opts {
>   	int quiet;
>   	int reschedule_failed_exec;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   
>   	int mainline;
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index ceab48a831..95d99c4b7b 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -81,4 +81,20 @@ test_expect_success '--committer-date-is-author-date works with interactive back
>   	test_cmp authortime committertime
>   '
>   
> +# Checking for +0000 in author time is enough since default
> +# timezone is UTC, but the timezone used while committing
> +# sets to +0530.

> +test_expect_success '--ignore-date works with am backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
> +
> +test_expect_success '--ignore-date works with interactive backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date -i HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
>   test_done
> 

> On 06/08/2019 18:36, Rohit Ashiwal wrote:
>> rebase am already has this flag to "lie" about the author date
>> by changing it to the committer (current) date. Let's add the same
>> for interactive machinery.
>>
>> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
>> ---

>>   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"
>> @@ -985,7 +997,7 @@ static int run_git_commit(struct repository *r,
>>   {
>>       struct child_process cmd = CHILD_PROCESS_INIT;
>> -    if (opts->committer_date_is_author_date &&
>> +    if (opts->committer_date_is_author_date && !opts->ignore_date &&
>>           setenv_committer_date_to_author_date())
>>           return 1;
> 
> We read the author script again just below, can set the committer date 
> there by parsing the author string, that would mean you could use the 
> same function that works on an author string in try_to_commit() (this 
> comment should be on patch 3 I think)

> 
>>       if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>> @@ -1013,10 +1025,18 @@ static int run_git_commit(struct repository *r,
>>           if (res <= 0)
>>               res = error_errno(_("could not read '%s'"), defmsg);
>> -        else
>> +        else {
>> +            if (opts->ignore_date) {
>> +                if (!author)
>> +                    BUG("ignore-date can only be used with "
>> +                        "rebase -i, which must set the "
> 
> I know it's only a bug message but it's not just 'rebase -i' but 'rebase 
> -k', 'rebase -m' ... that use this code path, it would be better just to 
> say 'rebase'
> 
>> +                        "author before committing the tree");
>> +                ignore_author_date(&author);
>> +            }
>>               res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>>                         NULL, &root_commit, author,
>>                         opts->gpg_sign);
>> +        }
>>           strbuf_release(&msg);
>>           strbuf_release(&script);
>> @@ -1046,6 +1066,8 @@ static int run_git_commit(struct repository *r,
>>           argv_array_push(&cmd.args, "--amend");
>>       if (opts->gpg_sign)
>>           argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>> +    if (opts->ignore_date)
>> +        argv_array_pushf(&cmd.args, "--date=%ld", time(NULL));
> 
> I think this is racy as it only sets the author date, the committer date 
> may end up being different.
> 
>>       if (defmsg)
>>           argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>>       else if (!(flags & EDIT_MSG))
>> @@ -1425,7 +1447,7 @@ static int try_to_commit(struct repository *r,
>>       if (parse_head(r, &current_head))
>>           return -1;
>>       if (!(flags & AMEND_MSG) && opts->committer_date_is_author_date &&
>> -        setenv_committer_date_to_author_date())
>> +        !opts->ignore_date && setenv_committer_date_to_author_date())
>>           return -1;
>>       if (flags & AMEND_MSG) {
>>           const char *exclude_gpgsig[] = { "gpgsig", NULL };
>> @@ -1447,7 +1469,7 @@ static int try_to_commit(struct repository *r,
>>               res = error(_("unable to parse commit author"));
>>               goto out;
>>           }
>> -        if (opts->committer_date_is_author_date) {
>> +        if (opts->committer_date_is_author_date && !opts->ignore_date) {
> 
> If we only handled committer_date_is_author_date in a single place it 
> wouldn't need to be changed twice in this patch
> 
>>               char *date;
>>               int len = strlen(author);
>>               char *idx = memchr(author, '>', len);
>> @@ -1507,6 +1529,11 @@ static int try_to_commit(struct repository *r,
>>       reset_ident_date();
>> +    if (opts->ignore_date) {
>> +        ignore_author_date(&author);
>> +        free(author_to_free);
>> +        author_to_free = (char *)author;
>> +    }
>>       if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
>>                    oid, author, opts->gpg_sign, extra)) {
>>           res = error(_("failed to write commit object"));
>> @@ -2583,6 +2610,11 @@ static int read_populate_opts(struct 
>> replay_opts *opts)
>>               opts->committer_date_is_author_date = 1;
>>           }
>> +        if (file_exists(rebase_path_ignore_date())) {
>> +            opts->allow_ff = 0;
>> +            opts->ignore_date = 1;
>> +        }
>> +
>>           if (file_exists(rebase_path_reschedule_failed_exec()))
>>               opts->reschedule_failed_exec = 1;
>> @@ -2667,6 +2699,8 @@ int write_basic_state(struct replay_opts *opts, 
>> const char *head_name,
>>           write_file(rebase_path_signoff(), "--signoff\n");
>>       if (opts->committer_date_is_author_date)
>>           write_file(rebase_path_cdate_is_adate(), "%s", "");
>> +    if (opts->ignore_date)
>> +        write_file(rebase_path_ignore_date(), "%s", "");
>>       if (opts->reschedule_failed_exec)
>>           write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>> @@ -3484,6 +3518,9 @@ static int do_merge(struct repository *r,
>>           argv_array_push(&cmd.args, git_path_merge_msg(r));
>>           if (opts->gpg_sign)
>>               argv_array_push(&cmd.args, opts->gpg_sign);
>> +        if (opts->ignore_date)
>> +            argv_array_pushf(&cmd.args,
>> +                     "GIT_AUTHOR_DATE=%ld", time(NULL));
>>           /* Add the tips to be merged */
>>           for (j = to_merge; j; j = j->next)
>> @@ -3756,7 +3793,8 @@ static int pick_commits(struct repository *r,
>>       if (opts->allow_ff)
>>           assert(!(opts->signoff || opts->no_commit ||
>>                   opts->record_origin || opts->edit ||
>> -                opts->committer_date_is_author_date));
>> +                opts->committer_date_is_author_date ||
>> +                opts->ignore_date));
>>       if (read_and_refresh_cache(r, opts))
>>           return -1;
>> diff --git a/sequencer.h b/sequencer.h
>> index e6cba468db..73d0515a3e 100644
>> --- a/sequencer.h
>> +++ b/sequencer.h
>> @@ -44,6 +44,7 @@ struct replay_opts {
>>       int quiet;
>>       int reschedule_failed_exec;
>>       int committer_date_is_author_date;
>> +    int ignore_date;
>>       int mainline;
>> diff --git a/t/t3433-rebase-options-compatibility.sh 
>> b/t/t3433-rebase-options-compatibility.sh
>> index ceab48a831..95d99c4b7b 100755
>> --- a/t/t3433-rebase-options-compatibility.sh
>> +++ b/t/t3433-rebase-options-compatibility.sh
>> @@ -81,4 +81,20 @@ test_expect_success 
>> '--committer-date-is-author-date works with interactive back
>>       test_cmp authortime committertime
>>   '
>> +# Checking for +0000 in author time is enough since default
>> +# timezone is UTC, but the timezone used while committing
>> +# sets to +0530.
> 
> That sounds potentially fragile but I guess the timezone is unlikely to 
> change in the future
> 
> Best Wishes
> 
> Phillip
> 
>> +test_expect_success '--ignore-date works with am backend' '
>> +    git commit --amend --date="$GIT_AUTHOR_DATE" &&
>> +    git rebase --ignore-date HEAD^ &&
>> +    git show HEAD --pretty="format:%ai" >authortime &&
>> +    grep "+0000" authortime
>> +'
>> +
>> +test_expect_success '--ignore-date works with interactive backend' '
>> +    git commit --amend --date="$GIT_AUTHOR_DATE" &&
>> +    git rebase --ignore-date -i HEAD^ &&
>> +    git show HEAD --pretty="format:%ai" >authortime &&
>> +    grep "+0000" authortime
>> +'
>>   test_done
>>

> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt | 1 +
>   builtin/rebase.c             | 2 ++
>   2 files changed, 3 insertions(+)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index a5cdf8518b..bb60426911 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -388,6 +388,7 @@ See also INCOMPATIBLE OPTIONS below.
>   	as the committer date. This implies --force-rebase.
>   
>   --ignore-date::
> +--author-date-is-committer-date::
>   	Lie about the author date by re-setting it to the value
>   	same as committer (current) date. This implies --force-rebase.
>   +
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 7f464fc9ba..a9a42f9ee4 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1433,6 +1433,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		OPT_BOOL(0, "committer-date-is-author-date",
>   			 &options.committer_date_is_author_date,
>   			 N_("make committer date match author date")),
> +		OPT_BOOL(0, "author-date-is-committer-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>   		OPT_BOOL(0, "ignore-date", &options.ignore_date,
>   			 "ignore author date and use current date"),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
> 

> There are two backends available for rebasing, viz, the am and the
> interactive. Naturally, there shall be some features that are
> implemented in one but not in the other. One such flag is
> --ignore-whitespace which indicates merge mechanism to treat lines
> with only whitespace changes as unchanged. Wire the interactive
> rebase to also understand the --ignore-whitespace flag by
> translating it to -Xignore-space-change.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 10 +++-
>   builtin/rebase.c                        | 29 +++++++++--
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 65 +++++++++++++++++++++++++
>   4 files changed, 97 insertions(+), 8 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 6156609cf7..28e5e08a83 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -371,8 +371,13 @@ If either <upstream> or --root is given on the command line, then the
>   default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   
>   --ignore-whitespace::
> +	This flag is either passed to the 'git apply' program
> +	(see linkgit:git-apply[1]), or to 'git merge' program
> +	(see linkgit:git-merge[1]) as `-Xignore-space-change`,
> +	depending on which backend is selected by other options.

> +
>   --whitespace=<option>::
> -	These flag are passed to the 'git apply' program
> +	This flag is passed to the 'git apply' program
>   	(see linkgit:git-apply[1]) that applies the patch.
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -520,7 +525,6 @@ The following options:
>    * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
> - * --ignore-whitespace
>    * -C
>   
>   are incompatible with the following options:
> @@ -543,6 +547,8 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --interactive
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
> + * --preserve-merges and --ignore-whitespace
> + * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
>   
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 670096c065..ab1bbb78ee 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -79,6 +79,7 @@ struct rebase_options {
>   	int allow_rerere_autoupdate;
>   	int keep_empty;
>   	int autosquash;
> +	int ignore_whitespace;
>   	char *gpg_sign_opt;
>   	int autostash;
>   	char *cmd;
> @@ -99,6 +100,7 @@ struct rebase_options {
>   
>   static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   {
> +	char *strategy_opts = opts->strategy_opts;

>   	struct replay_opts replay = REPLAY_OPTS_INIT;
>   
>   	replay.action = REPLAY_INTERACTIVE_REBASE;
> @@ -114,8 +116,19 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
> -	if (opts->strategy_opts)
> -		parse_strategy_opts(&replay, opts->strategy_opts);
> +
> +	if (opts->ignore_whitespace) {
> +		struct strbuf buf = STRBUF_INIT;
> +
> +		if (strategy_opts)
> +			strbuf_addstr(&buf, strategy_opts);

>   
>   	return replay;
>   }
> @@ -511,6 +524,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   	argc = parse_options(argc, argv, prefix, options,
>   			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
>   
> +	opts.strategy_opts = xstrdup_or_null(opts.strategy_opts);
> +
>   	if (!is_null_oid(&squash_onto))
>   		opts.squash_onto = &squash_onto;
>   
> @@ -964,6 +979,8 @@ static int run_am(struct rebase_options *opts)
>   	am.git_cmd = 1;
>   	argv_array_push(&am.args, "am");
>   
> +	if (opts->ignore_whitespace)
> +		argv_array_push(&am.args, "--ignore-whitespace");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1407,9 +1424,6 @@ 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, "ignore-whitespace", &options.git_am_opts,
> -				  NULL, N_("passed to 'git am'"),
> -				  PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
>   				  &options.git_am_opts, NULL,
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
> @@ -1417,6 +1431,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
> +		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> +			 N_("ignore changes in whitespace")),
>   		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
>   				  N_("action"), N_("passed to 'git apply'"), 0),
>   		OPT_BIT('f', "force-rebase", &options.flags,
> @@ -1834,6 +1850,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   	}
>   
>   	if (options.rebase_merges) {
> +		if (options.ignore_whitespace)
> +			die(_("cannot combine '--rebase-merges' with "
> +			      "'--ignore-whitespace'"));
>   		if (strategy_options.nr)
>   			die(_("cannot combine '--rebase-merges' with "
>   			      "'--strategy-option'"));
> diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> index a5868ea152..4342f79eea 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 --ignore-whitespace
>   test_rebase_am_only --committer-date-is-author-date
>   test_rebase_am_only -C4
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> new file mode 100755
> index 0000000000..2e16e00a9d
> --- /dev/null
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -0,0 +1,65 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2019 Rohit Ashiwal
> +#
> +
> +test_description='tests to ensure compatibility between am and interactive backends'
> +
> +. ./test-lib.sh
> +
> +# 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.
> +test_expect_success 'setup' '
> +	git checkout -b topic &&
> +	q_to_tab >file <<-\EOF &&
> +	line 1
> +	Qline 2
> +	line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	cat >file <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	git commit -am "update file" &&
> +	git tag side &&
> +
> +	git checkout --orphan master &&
> +	sed -e "s/^|//" >file <<-\EOF &&
> +	|line 1
> +	|        line 2
> +	|line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	git tag main
> +'
> +
> +test_expect_success '--ignore-whitespace works with am backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase main side &&
> +	git rebase --abort &&
> +	git rebase --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_expect_success '--ignore-whitespace works with interactive backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase --merge main side &&
> +	git rebase --abort &&
> +	git rebase --merge --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_done
> 

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  8 +++-
>   builtin/rebase.c                        | 20 ++++++---
>   sequencer.c                             | 57 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 96 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 28e5e08a83..697ce8e6ff 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -383,8 +383,12 @@ default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This implies --force-rebase.
> +
>   --ignore-date::
> -	These flags are passed to 'git am' to easily change the dates
> +	This flag is passed to 'git am' to change the author date
>   	of the rebased commits (see linkgit:git-am[1]).
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -522,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -548,6 +551,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index ab1bbb78ee..b1039f8db0 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ 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;
> @@ -114,6 +115,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	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;
>   
> @@ -533,6 +536,9 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> +	if (opts.committer_date_is_author_date)
> +		opts.flags |= REBASE_FORCE;
> +
>   	return !!run_rebase_interactive(&opts, command);
>   }
>   
> @@ -981,6 +987,8 @@ 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);
> @@ -1424,9 +1432,9 @@ 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"),
> @@ -1697,10 +1705,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	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"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index 30d77c2682..fbc0ed0cad 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -879,6 +880,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}
> +
>   /* Read author-script and return an ident line (author <email> timestamp) */
>   static const char *read_author_ident(struct strbuf *buf)
>   {
> @@ -964,6 +976,25 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> +	if (opts->committer_date_is_author_date) {
> +		size_t len;
> +		int res = -1;
> +		struct strbuf datebuf = STRBUF_INIT;
> +		char *date = read_author_date_or_null();

> +		free(date);
> +
> +		date = strbuf_detach(&datebuf, &len);
> +
> +		if (len > 1)
> +			res = setenv("GIT_COMMITTER_DATE", date, 1);
> +
> +		free(date);
> +
> +		if (res)
> +			return -1;
> +	}
>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>   		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>   		const char *author = NULL;
> @@ -1400,7 +1431,6 @@ 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", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1427,6 +1457,21 @@ 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;
> +
> +		split_ident_line(&ident, author, len);
> +
> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));

> +		setenv("GIT_COMMITTER_DATE", date.buf, 1);
> +		strbuf_release(&date);
> +	}
> +
>   	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;
> @@ -2542,6 +2587,11 @@ 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;
>   
> @@ -2624,6 +2674,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3821,7 +3873,8 @@ 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 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..b2419a2b75 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
>   test_done
> 

> Hi Rohit
> 
> [...]
>> @@ -964,6 +976,25 @@ static int run_git_commit(struct repository *r,
>>   {
>>       struct child_process cmd = CHILD_PROCESS_INIT;
>> +    if (opts->committer_date_is_author_date) {
>> +        size_t len;
>> +        int res = -1;
>> +        struct strbuf datebuf = STRBUF_INIT;
>> +        char *date = read_author_date_or_null();
> 
> You must always check the return value of functions that might return 
> NULL. In this case we should return an error as you do in try_to 
> _commit() later
> 
>> +
>> +        strbuf_addf(&datebuf, "@%s", date);
> 
> GNU printf() will add something like '(null)' to the buffer if you pass 
> a NULL pointer so I don't think we can be sure that this will not 
> increase the length of the buffer if date is NULL.

> above would be much clearer as well rather than checking len later. What 
> happens if you don't add the '@' at the beginning? (I'm don't know much 
> about git's date handling)
> 
>> +        free(date);
>> +
>> +        date = strbuf_detach(&datebuf, &len);
>> +
>> +        if (len > 1)
>> +            res = setenv("GIT_COMMITTER_DATE", date, 1);
>> +
>> +        free(date);
>> +
>> +        if (res)
>> +            return -1;
>> +    }
>>       if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>>           struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>>           const char *author = NULL;
>> @@ -1400,7 +1431,6 @@ 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", NULL };
>>           const char *out_enc = get_commit_output_encoding();
>> @@ -1427,6 +1457,21 @@ 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;
>> +
>> +        split_ident_line(&ident, author, len);
>> +
>> +        if (!ident.date_begin)
>> +            return error(_("corrupted author without date 
>> information"));
> 
> We return an error if we cannot get the date - this is exactly what we 
> should be doing above. It is also great to see a single version of this 
> being used whether or not we are amending.
> 
>> +
>> +        strbuf_addf(&date, "@%s",ident.date_begin);
> 
> I think we should use %s.* and ident.date_end to be sure we getting what 
> we want. Your version is OK if the author is formatted correctly but I'm 
> uneasy about relying on that when we can get the verified end from ident.
> 
> Best Wishes
> 
> Phillip
> 
>> +        setenv("GIT_COMMITTER_DATE", date.buf, 1);
>> +        strbuf_release(&date);
>> +    }
>> +
>>       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;
>> @@ -2542,6 +2587,11 @@ 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;
>> @@ -2624,6 +2674,8 @@ int write_basic_state(struct replay_opts *opts, 
>> const char *head_name,
>>           write_file(rebase_path_gpg_sign_opt(), "-S%s\n", 
>> opts->gpg_sign);
>>       if (opts->signoff)
>>           write_file(rebase_path_signoff(), "--signoff\n");
>> +    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", "");
>> @@ -3821,7 +3873,8 @@ 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 6704acbb9c..e3881e9275 100644
>> --- a/sequencer.h
>> +++ b/sequencer.h
>> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh 
>> b/t/t3433-rebase-options-compatibility.sh
>> index 2e16e00a9d..b2419a2b75 100755
>> --- a/t/t3433-rebase-options-compatibility.sh
>> +++ b/t/t3433-rebase-options-compatibility.sh
>> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility 
>> between am and interactive backe
>>   . ./test-lib.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.
>> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with 
>> interactive backend' '
>>       test_cmp expect file
>>   '
>> +test_expect_success '--committer-date-is-author-date works with am 
>> backend' '
>> +    git commit --amend &&
>> +    git rebase --committer-date-is-author-date HEAD^ &&
>> +    git show HEAD --pretty="format:%ai" >authortime &&
>> +    git show HEAD --pretty="format:%ci" >committertime &&
>> +    test_cmp authortime committertime
>> +'
>> +
>> +test_expect_success '--committer-date-is-author-date works with 
>> interactive backend' '
>> +    git commit --amend &&
>> +    git rebase -i --committer-date-is-author-date HEAD^ &&
>> +    git show HEAD --pretty="format:%ai" >authortime &&
>> +    git show HEAD --pretty="format:%ci" >committertime &&
>> +    test_cmp authortime committertime
>> +'
>> +
>>   test_done
>>

>>   +	if (opts->committer_date_is_author_date) {
>> +		size_t len;
>> +		int res = -1;
>> +		struct strbuf datebuf = STRBUF_INIT;
>> +		char *date = read_author_date_or_null();
>
> You must always check the return value of functions that might return
> NULL. In this case we should return an error as you do in try_to
> _commit() later
>
>> +
>> +		strbuf_addf(&datebuf, "@%s", date);
>
> GNU printf() will add something like '(null)' to the buffer if you
> pass a NULL pointer so I don't think we can be sure that this will not
> increase the length of the buffer if date is NULL.

>>   +	if (opts->committer_date_is_author_date) {
>> +		int len = strlen(author);
>> +		struct ident_split ident;
>> +		struct strbuf date = STRBUF_INIT;
>> +
>> +		split_ident_line(&ident, author, len);
>> +
>> +		if (!ident.date_begin)
>> +			return error(_("corrupted author without date information"));
>
> We return an error if we cannot get the date - this is exactly what we
> should be doing above. It is also great to see a single version of
> this being used whether or not we are amending.
>
>> +
>> +		strbuf_addf(&date, "@%s",ident.date_begin);
>
> I think we should use %s.* and ident.date_end to be sure we getting
> what we want. Your version is OK if the author is formatted correctly
> but I'm uneasy about relying on that when we can get the verified end
> from ident.

> Phillip Wood <phillip.wood123@gmail.com> writes:
>  [...]
>>> +
>>> +		strbuf_addf(&date, "@%s",ident.date_begin);
>>
>> I think we should use %s.* and ident.date_end to be sure we getting
>> what we want. Your version is OK if the author is formatted correctly
>> but I'm uneasy about relying on that when we can get the verified end
>> from ident.
> 
> If the author line is not formatted correctly, split_ident_line()
> would notice and return NULL in these fields, I think (in other
> words, my take on the call to split_ident_line() above is not
> necessarily done in order to "split", but primarily to validate that
> the line is formatted correctly---and find the beginning of the
> timestamp field).

> But your "pay attention to date_end" raises an interesting point.
> 
> The string that follows ident.date_begin would be a large integer
> (i.e. number of seconds since epoch), a SP, a positive or negative
> sign (i.e. east or west of GMT), 4 digits (i.e. timezone offset), so
> if you want to leave something like "@1544328981" in the buffer, you
> need to stop at .date_end to omit the timezone information.
> 
> On the other hand, if you do want the timezone information as well
> (which I think is the case for this codepath), you should not stop
> at there and have something like "@1544328981 +0900", the code as
> written would give better result.

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  8 +++-
>   builtin/rebase.c                        | 20 ++++++---
>   sequencer.c                             | 57 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 96 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 28e5e08a83..697ce8e6ff 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -383,8 +383,12 @@ default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This implies --force-rebase.
> +
>   --ignore-date::
> -	These flags are passed to 'git am' to easily change the dates
> +	This flag is passed to 'git am' to change the author date

>   	of the rebased commits (see linkgit:git-am[1]).
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -522,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -548,6 +551,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index ab1bbb78ee..b1039f8db0 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ 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;
> @@ -114,6 +115,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	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;
>   
> @@ -533,6 +536,9 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> +	if (opts.committer_date_is_author_date)
> +		opts.flags |= REBASE_FORCE;
> +
>   	return !!run_rebase_interactive(&opts, command);
>   }
>   
> @@ -981,6 +987,8 @@ 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);
> @@ -1424,9 +1432,9 @@ 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"),
> @@ -1697,10 +1705,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	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"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index 30d77c2682..fbc0ed0cad 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -879,6 +880,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}
> +
>   /* Read author-script and return an ident line (author <email> timestamp) */
>   static const char *read_author_ident(struct strbuf *buf)
>   {
> @@ -964,6 +976,25 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> +	if (opts->committer_date_is_author_date) {
> +		size_t len;
> +		int res = -1;
> +		struct strbuf datebuf = STRBUF_INIT;
> +		char *date = read_author_date_or_null();
> +
> +		strbuf_addf(&datebuf, "@%s", date);
> +		free(date);
> +
> +		date = strbuf_detach(&datebuf, &len);
> +
> +		if (len > 1)
> +			res = setenv("GIT_COMMITTER_DATE", date, 1);
> +
> +		free(date);
> +
> +		if (res)
> +			return -1;
> +	}
>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>   		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>   		const char *author = NULL;
> @@ -1400,7 +1431,6 @@ 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", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1427,6 +1457,21 @@ 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;
> +
> +		split_ident_line(&ident, author, len);
> +
> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));
> +
> +		strbuf_addf(&date, "@%s",ident.date_begin);
> +		setenv("GIT_COMMITTER_DATE", date.buf, 1);
> +		strbuf_release(&date);
> +	}
> +
>   	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;
> @@ -2542,6 +2587,11 @@ 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;
>   
> @@ -2624,6 +2674,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3821,7 +3873,8 @@ 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 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..b2419a2b75 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
>   test_done
> 

> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   sequencer.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index fbc0ed0cad..e186136ccc 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -1424,7 +1424,7 @@ static int try_to_commit(struct repository *r,
>   	struct commit_extra_header *extra = NULL;
>   	struct strbuf err = STRBUF_INIT;
>   	struct strbuf commit_msg = STRBUF_INIT;
> -	char *amend_author = NULL;
> +	char *author_to_free = NULL;
>   	const char *hook_commit = NULL;
>   	enum commit_msg_cleanup_mode cleanup;
>   	int res = 0;
> @@ -1445,7 +1445,7 @@ static int try_to_commit(struct repository *r,
>   			strbuf_addstr(msg, orig_message);
>   			hook_commit = "HEAD";
>   		}
> -		author = amend_author = get_author(message);
> +		author = author_to_free = get_author(message);
>   		unuse_commit_buffer(current_head, message);
>   		if (!author) {
>   			res = error(_("unable to parse commit author"));
> @@ -1534,7 +1534,7 @@ static int try_to_commit(struct repository *r,
>   	free_commit_extra_headers(extra);
>   	strbuf_release(&err);
>   	strbuf_release(&commit_msg);
> -	free(amend_author);
> +	free(author_to_free);
>   
>   	return res;
>   }
> 

> rebase am already has this flag to "lie" about the author date
> by changing it to the committer (current) date. Let's add the same
> for interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  6 +--
>   builtin/rebase.c                        | 21 +++++++---
>   sequencer.c                             | 55 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3433-rebase-options-compatibility.sh | 16 +++++++
>   5 files changed, 88 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 697ce8e6ff..24ad2dda0b 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -388,8 +388,8 @@ See also INCOMPATIBLE OPTIONS below.
>   	as the committer date. This implies --force-rebase.
>   
>   --ignore-date::
> -	This flag is passed to 'git am' to change the author date
> -	of the rebased commits (see linkgit:git-am[1]).
> +	Instead of using the given author date, re-set

>   +
>   See also INCOMPATIBLE OPTIONS below.
>   
> @@ -526,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --ignore-date
>    * --whitespace
>    * -C
>   
> @@ -552,6 +551,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
>    * --preserve-merges and --committer-date-is-author-date
> + * --preserve-merges and --ignore-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index b1039f8db0..ed58ca8e5a 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -83,6 +83,7 @@ struct rebase_options {
>   	char *gpg_sign_opt;
>   	int autostash;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   	char *cmd;
>   	int allow_empty_message;
>   	int rebase_merges, rebase_cousins;
> @@ -117,6 +118,7 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.committer_date_is_author_date =
>   					opts->committer_date_is_author_date;
> +	replay.ignore_date = opts->ignore_date;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
>   
> @@ -536,7 +538,10 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> -	if (opts.committer_date_is_author_date)
> +	if (opts.ignore_date)
> +		opts.committer_date_is_author_date = 0;
> +	if (opts.committer_date_is_author_date ||
> +	    opts.ignore_date)
>   		opts.flags |= REBASE_FORCE;

>   	return !!run_rebase_interactive(&opts, command);
> @@ -989,6 +994,8 @@ static int run_am(struct rebase_options *opts)
>   		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->ignore_date)
> +		argv_array_push(&opts->git_am_opts, "--ignore-date");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1435,8 +1442,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		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_BOOL(0, "ignore-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
>   		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> @@ -1705,13 +1712,15 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> -	if (options.committer_date_is_author_date)
> +	if (options.ignore_date)
> +		options.committer_date_is_author_date = 0;

> +	if (options.committer_date_is_author_date ||
> +	    options.ignore_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, "--ignore-date") ||
> -		    !strcmp(option, "--whitespace=fix") ||
> +		if (!strcmp(option, "--whitespace=fix") ||
>   		    !strcmp(option, "--whitespace=strip"))
>   			options.flags |= REBASE_FORCE;
>   		else if (skip_prefix(option, "-C", &p)) {
> diff --git a/sequencer.c b/sequencer.c
> index e186136ccc..aecd9b4ad8 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -148,6 +148,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
>    */
>   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_ignore_date, "rebase-merge/ignore_date")
>   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")
> @@ -919,6 +920,31 @@ static const char *read_author_ident(struct strbuf *buf)
>   	return buf->buf;
>   }
>   
> +static void ignore_author_date(const char **author)
> +{
> +	int len = strlen(*author);
> +	struct ident_split ident;
> +	struct strbuf new_author = STRBUF_INIT;
> +
> +	split_ident_line(&ident, *author, len);
> +	len = ident.mail_end - ident.name_begin + 1;
> +
> +	strbuf_addf(&new_author, "%.*s", len, *author);
> +	datestamp(&new_author);
> +	*author = strbuf_detach(&new_author, NULL);
> +}

> +
> +static void push_dates(struct child_process *child)
> +{
> +	time_t now = time(NULL);
> +	struct strbuf date = STRBUF_INIT;
> +
> +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
> +	argv_array_pushf(&child->args, "--date=%s", date.buf);

> +	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);
> +	strbuf_release(&date);
> +}
> +
>   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"
> @@ -1020,10 +1046,18 @@ static int run_git_commit(struct repository *r,
>   
>   		if (res <= 0)
>   			res = error_errno(_("could not read '%s'"), defmsg);
> -		else
> +		else {
> +			if (opts->ignore_date) {
> +				if (!author)
> +					BUG("ignore-date can only be used with "
> +					    "rebase, which must set the author "
> +					    "before committing the tree");
> +				ignore_author_date(&author);

> +			}
>   			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>   					  NULL, &root_commit, author,
>   					  opts->gpg_sign);
> +		}
>   
>   		strbuf_release(&msg);
>   		strbuf_release(&script);
> @@ -1053,6 +1087,8 @@ static int run_git_commit(struct repository *r,
>   		argv_array_push(&cmd.args, "--amend");
>   	if (opts->gpg_sign)
>   		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		push_dates(&cmd);
>   	if (defmsg)
>   		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>   	else if (!(flags & EDIT_MSG))
> @@ -1515,6 +1551,11 @@ static int try_to_commit(struct repository *r,
>   
>   	reset_ident_date();
>   
> +	if (opts->ignore_date) {
> +		ignore_author_date(&author);
> +		free(author_to_free);

> +	}
>   	if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
>   				 oid, author, opts->gpg_sign, extra)) {
>   		res = error(_("failed to write commit object"));
> @@ -2592,6 +2633,11 @@ static int read_populate_opts(struct replay_opts *opts)
>   			opts->committer_date_is_author_date = 1;
>   		}
>   
> +		if (file_exists(rebase_path_ignore_date())) {
> +			opts->allow_ff = 0;
> +			opts->ignore_date = 1;
> +		}
> +
>   		if (file_exists(rebase_path_reschedule_failed_exec()))
>   			opts->reschedule_failed_exec = 1;
>   
> @@ -2676,6 +2722,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_signoff(), "--signoff\n");
>   	if (opts->committer_date_is_author_date)
>   		write_file(rebase_path_cdate_is_adate(), "%s", "");
> +	if (opts->ignore_date)
> +		write_file(rebase_path_ignore_date(), "%s", "");
>   	if (opts->reschedule_failed_exec)
>   		write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>   
> @@ -3601,6 +3649,8 @@ static int do_merge(struct repository *r,
>   		argv_array_push(&cmd.args, git_path_merge_msg(r));
>   		if (opts->gpg_sign)
>   			argv_array_push(&cmd.args, opts->gpg_sign);
> +		if (opts->ignore_date)
> +			push_dates(&cmd);
>   
>   		/* Add the tips to be merged */
>   		for (j = to_merge; j; j = j->next)
> @@ -3874,7 +3924,8 @@ static int pick_commits(struct repository *r,
>   	if (opts->allow_ff)
>   		assert(!(opts->signoff || opts->no_commit ||
>   				opts->record_origin || opts->edit ||
> -				opts->committer_date_is_author_date));
> +				opts->committer_date_is_author_date ||
> +				opts->ignore_date));
>   	if (read_and_refresh_cache(r, opts))
>   		return -1;
>   
> diff --git a/sequencer.h b/sequencer.h
> index e3881e9275..bf5a79afdb 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -44,6 +44,7 @@ struct replay_opts {
>   	int quiet;
>   	int reschedule_failed_exec;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   
>   	int mainline;
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index b2419a2b75..c060fcd10b 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -81,4 +81,20 @@ test_expect_success '--committer-date-is-author-date works with interactive back
>   	test_cmp authortime committertime
>   '
>   
> +# Checking for +0000 in author time is enough since default
> +# timezone is UTC, but the timezone used while committing
> +# sets to +0530.
> +test_expect_success '--ignore-date works with am backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
> +
> +test_expect_success '--ignore-date works with interactive backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date -i HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
>   test_done
> 

>> +static void push_dates(struct child_process *child)
>> +{
>> +	time_t now = time(NULL);
>> +	struct strbuf date = STRBUF_INIT;
>> +
>> +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
>> +	argv_array_pushf(&child->args, "--date=%s", date.buf);
>
> it doesn't matter but it might have been nicer to set both dates the
> same way in the environment.
> +	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);

>> +			if (opts->ignore_date) {
>> +				if (!author)
>> +					BUG("ignore-date can only be used with "
>> +					    "rebase, which must set the author "
>> +					    "before committing the tree");
>> +				ignore_author_date(&author);
>
> Is this leaking the old author? I'd rather see
>
> 	tmp_author = ignore_author_date(author);
> 	free(author);
> 	author = tmp_author;

>> +			}
>>   			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>>   					  NULL, &root_commit, author,
>>   					  opts->gpg_sign);
>> +		}
>>     		strbuf_release(&msg);
>>   		strbuf_release(&script);
>> @@ -1053,6 +1087,8 @@ static int run_git_commit(struct repository *r,
>>   		argv_array_push(&cmd.args, "--amend");
>>   	if (opts->gpg_sign)
>>   		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>> +	if (opts->ignore_date)
>> +		push_dates(&cmd);
>>   	if (defmsg)
>>   		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>>   	else if (!(flags & EDIT_MSG))
>> @@ -1515,6 +1551,11 @@ static int try_to_commit(struct repository *r,
>>     	reset_ident_date();
>>   +	if (opts->ignore_date) {
>> +		ignore_author_date(&author);
>> +		free(author_to_free);
>
> Where is author_to_free set? We should always free the old author, see
> above.

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>>> +static void push_dates(struct child_process *child)
>>> +{
>>> +	time_t now = time(NULL);
>>> +	struct strbuf date = STRBUF_INIT;
>>> +
>>> +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
>>> +	argv_array_pushf(&child->args, "--date=%s", date.buf);
>>
>> it doesn't matter but it might have been nicer to set both dates the
>> same way in the environment.
>> +	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);
> 
> We can see that this date string lacks timezone information, which
> would likely fall back to whatever timezone the user is in.  Is that
> what we want?  I am guessing it is, as we are dealing with "now"
> timestamp, but wanted to double check.

>>> +			if (opts->ignore_date) {
>>> +				if (!author)
>>> +					BUG("ignore-date can only be used with "
>>> +					    "rebase, which must set the author "
>>> +					    "before committing the tree");
>>> +				ignore_author_date(&author);
>>
>> Is this leaking the old author? I'd rather see
>>
>> 	tmp_author = ignore_author_date(author);
>> 	free(author);
>> 	author = tmp_author;
> 
> Or make sure ignore_author_date() does not leak the original, when
> it rewrites its parameter.
> 
> But I have a larger question at the higher design level.  Why are we
> passing a single string "author" around, instead of parsed and split
> fields, like <name, email, timestamp, tz> tuple?  That would allow us
> to replace only the time part a lot more easily.  Would it make the
> other parts of the code more cumbersome (I didn't check---and if
> that is the case, then that is a valid reason why we want to stick
> to the current "a single string 'author' keeps the necessary info
> for the 4-tuple" design).

>>> +			}
>>>    			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>>>    					  NULL, &root_commit, author,
>>>    					  opts->gpg_sign);
>>> +		}
>>>      		strbuf_release(&msg);
>>>    		strbuf_release(&script);
>>> @@ -1053,6 +1087,8 @@ static int run_git_commit(struct repository *r,
>>>    		argv_array_push(&cmd.args, "--amend");
>>>    	if (opts->gpg_sign)
>>>    		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>>> +	if (opts->ignore_date)
>>> +		push_dates(&cmd);
>>>    	if (defmsg)
>>>    		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>>>    	else if (!(flags & EDIT_MSG))
>>> @@ -1515,6 +1551,11 @@ static int try_to_commit(struct repository *r,
>>>      	reset_ident_date();
>>>    +	if (opts->ignore_date) {
>>> +		ignore_author_date(&author);
>>> +		free(author_to_free);
>>
>> Where is author_to_free set? We should always free the old author, see
>> above.
> 
> Or require callers to pass a free()able memory to ignore_author_date()
> and have the callee free the original?
> 

>  --ignore-date::
> -	This flag is passed to 'git am' to change the author date
> -	of the rebased commits (see linkgit:git-am[1]).
> +	Instead of using the given author date, re-set it to the value
> +	same as committer (current) date. This implies --force-rebase.

> Rohit Ashiwal <rohit.ashiwal265@gmail.com> writes:
> 
>>   --ignore-date::
>> -	This flag is passed to 'git am' to change the author date
>> -	of the rebased commits (see linkgit:git-am[1]).
>> +	Instead of using the given author date, re-set it to the value
>> +	same as committer (current) date. This implies --force-rebase.
> 
> s/to the value same as .* date\./the current time./;
> 
> The more important thing is that we record the current timestamp as
> the author date; that timestamp being very close to the committer
> date of the resulting commit is a mere consequence of the fact that
> we use the current time for committer date and much less important.

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>> That's an important distinction, particularly if GIT_COMMITTER_DATE is
>> set in the environment - are we aiming to have the author and
>> committer dates match or are we just resetting the author date to now?
>> Rohit - do you know which --ignore-date does in the am based rebase?
> 
> The purpose "am --ignore-date" was to ignore "Date:" that came from
> the patch message, overriding it with the current date.  It might
> have become harder to read in the C version, but "git show v2.0.0:git-am.sh"
> would be an easier way to read how "--ignore-date" wanted to behave.

> There are two backends available for rebasing, viz, the am and the
> interactive. Naturally, there shall be some features that are
> implemented in one but not in the other. One such flag is
> --ignore-whitespace which indicates merge mechanism to treat lines
> with only whitespace changes as unchanged. Wire the interactive
> rebase to also understand the --ignore-whitespace flag by
> translating it to -Xignore-space-change.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 13 ++++-
>   builtin/rebase.c                        | 22 +++++++--
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 65 +++++++++++++++++++++++++
>   4 files changed, 94 insertions(+), 7 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 6156609cf7..873eb5768c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -371,8 +371,16 @@ If either <upstream> or --root is given on the command line, then the
>   default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   
>   --ignore-whitespace::
> +	Behaves differently depending on which backend is selected.
> ++
> +'am' backend: When applying a patch, ignore changes in whitespace in
> +context lines if necessary.
> ++
> +'interactive' backend: Treat lines with only whitespace changes as
> +unchanged for the sake of a three-way merge.
> +

>   --whitespace=<option>::
> -	These flag are passed to the 'git apply' program
> +	This flag is passed to the 'git apply' program
>   	(see linkgit:git-apply[1]) that applies the patch.
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -520,7 +528,6 @@ The following options:
>    * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
> - * --ignore-whitespace
>    * -C
>   
>   are incompatible with the following options:
> @@ -543,6 +550,8 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --interactive
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
> + * --preserve-merges and --ignore-whitespace
> + * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
>   
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 670096c065..f8a618d54c 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -79,6 +79,7 @@ struct rebase_options {
>   	int allow_rerere_autoupdate;
>   	int keep_empty;
>   	int autosquash;
> +	int ignore_whitespace;
>   	char *gpg_sign_opt;
>   	int autostash;
>   	char *cmd;
> @@ -99,6 +100,7 @@ struct rebase_options {
>   
>   static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   {
> +	struct strbuf strategy_buf = STRBUF_INIT;
>   	struct replay_opts replay = REPLAY_OPTS_INIT;
>   
>   	replay.action = REPLAY_INTERACTIVE_REBASE;
> @@ -114,9 +116,15 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
> +
>   	if (opts->strategy_opts)
> -		parse_strategy_opts(&replay, opts->strategy_opts);
> +		strbuf_addstr(&strategy_buf, opts->strategy_opts);
> +	if (opts->ignore_whitespace)
> +		strbuf_addstr(&strategy_buf, " --ignore-space-change");
> +	if (strategy_buf.len)
> +		parse_strategy_opts(&replay, strategy_buf.buf);
>   
> +	strbuf_release(&strategy_buf);
>   	return replay;
>   }
>   
> @@ -511,6 +519,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   	argc = parse_options(argc, argv, prefix, options,
>   			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
>   
> +	opts.strategy_opts = xstrdup_or_null(opts.strategy_opts);
> +
>   	if (!is_null_oid(&squash_onto))
>   		opts.squash_onto = &squash_onto;
>   
> @@ -964,6 +974,8 @@ static int run_am(struct rebase_options *opts)
>   	am.git_cmd = 1;
>   	argv_array_push(&am.args, "am");
>   
> +	if (opts->ignore_whitespace)
> +		argv_array_push(&am.args, "--ignore-whitespace");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1407,9 +1419,6 @@ 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, "ignore-whitespace", &options.git_am_opts,
> -				  NULL, N_("passed to 'git am'"),
> -				  PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
>   				  &options.git_am_opts, NULL,
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
> @@ -1417,6 +1426,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
> +		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> +			 N_("ignore changes in whitespace")),
>   		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
>   				  N_("action"), N_("passed to 'git apply'"), 0),
>   		OPT_BIT('f', "force-rebase", &options.flags,
> @@ -1834,6 +1845,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   	}
>   
>   	if (options.rebase_merges) {
> +		if (options.ignore_whitespace)
> +			die(_("cannot combine '--rebase-merges' with "
> +			      "'--ignore-whitespace'"));
>   		if (strategy_options.nr)
>   			die(_("cannot combine '--rebase-merges' with "
>   			      "'--strategy-option'"));
> diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> index a5868ea152..4342f79eea 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 --ignore-whitespace
>   test_rebase_am_only --committer-date-is-author-date
>   test_rebase_am_only -C4
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> new file mode 100755
> index 0000000000..2e16e00a9d
> --- /dev/null
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -0,0 +1,65 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2019 Rohit Ashiwal
> +#
> +
> +test_description='tests to ensure compatibility between am and interactive backends'
> +
> +. ./test-lib.sh
> +
> +# 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.
> +test_expect_success 'setup' '
> +	git checkout -b topic &&
> +	q_to_tab >file <<-\EOF &&
> +	line 1
> +	Qline 2
> +	line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	cat >file <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	git commit -am "update file" &&
> +	git tag side &&
> +
> +	git checkout --orphan master &&
> +	sed -e "s/^|//" >file <<-\EOF &&
> +	|line 1
> +	|        line 2
> +	|line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	git tag main
> +'
> +
> +test_expect_success '--ignore-whitespace works with am backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase main side &&
> +	git rebase --abort &&
> +	git rebase --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_expect_success '--ignore-whitespace works with interactive backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase --merge main side &&
> +	git rebase --abort &&
> +	git rebase --merge --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_done
> 

>
> Thanks for spelling out exactly what this does. I had not appreciated
> the difference before. Does this mean that if I have a branch with some
> whitespace cleanups I'll get different results if I rebase it with the
> sequencer compared to am? (I suspect from the description that the
> sequencer will simply ignore all my whitespace changes)

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 10 +++--
>   builtin/rebase.c                        | 17 +++++---
>   sequencer.c                             | 57 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 94 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 873eb5768c..e7c0eac18c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -386,9 +386,13 @@ unchanged for the sake of a three-way merge.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This 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.
>   
> @@ -525,7 +529,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -551,6 +554,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index f8a618d54c..656bc7d7e9 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ 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;
> @@ -114,6 +115,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	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;
>   
> @@ -976,6 +979,8 @@ 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);
> @@ -1419,9 +1424,9 @@ 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"),
> @@ -1692,10 +1697,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	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"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index 30d77c2682..29b67bc1ae 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -879,6 +880,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}
> +
>   /* Read author-script and return an ident line (author <email> timestamp) */
>   static const char *read_author_ident(struct strbuf *buf)
>   {
> @@ -964,6 +976,25 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> +	if (opts->committer_date_is_author_date) {
> +		size_t len;
> +		int res = -1;
> +		struct strbuf datebuf = STRBUF_INIT;
> +		char *date = read_author_date_or_null();
> +
> +		if (!date)
> +			return -1;

> +
> +		strbuf_addf(&datebuf, "@%s", date);
> +		free(date);
> +
> +		date = strbuf_detach(&datebuf, &len);
> +		res = setenv("GIT_COMMITTER_DATE", date, 1);
> +		free(date);

> +
> +		if (res)
> +			return -1;
> +	}
>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>   		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>   		const char *author = NULL;
> @@ -1400,7 +1431,6 @@ 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", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1427,6 +1457,21 @@ 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;
> +
> +		split_ident_line(&ident, author, len);
> +
> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));

> +		strbuf_release(&date);
> +	}
> +
>   	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;
> @@ -2542,6 +2587,11 @@ 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;
>   
> @@ -2624,6 +2674,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3821,7 +3873,8 @@ 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 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..b2419a2b75 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
>   test_done
> 

> rebase am already has this flag to "lie" about the author date
> by changing it to the committer (current) date. Let's add the same
> for interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            |  6 +--
>   builtin/rebase.c                        | 16 ++++---
>   sequencer.c                             | 58 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3433-rebase-options-compatibility.sh | 16 +++++++
>   5 files changed, 87 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index e7c0eac18c..e7ac9fae0b 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -391,8 +391,8 @@ See also INCOMPATIBLE OPTIONS below.
>   	as the committer date. This implies --force-rebase.
>   
>   --ignore-date::
> -	This flag is passed to 'git am' to change the author date
> -	of each rebased commit (see linkgit:git-am[1]).
> +	Instead of using the given author date, reset it to the value
> +	same as the current time. This implies --force-rebase.
>   +
>   See also INCOMPATIBLE OPTIONS below.
>   
> @@ -529,7 +529,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --ignore-date
>    * --whitespace
>    * -C
>   
> @@ -555,6 +554,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
>    * --preserve-merges and --committer-date-is-author-date
> + * --preserve-merges and --ignore-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 656bc7d7e9..a63531ee90 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -83,6 +83,7 @@ struct rebase_options {
>   	char *gpg_sign_opt;
>   	int autostash;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   	char *cmd;
>   	int allow_empty_message;
>   	int rebase_merges, rebase_cousins;
> @@ -117,6 +118,7 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.committer_date_is_author_date =
>   					opts->committer_date_is_author_date;
> +	replay.ignore_date = opts->ignore_date;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
>   
> @@ -981,6 +983,8 @@ static int run_am(struct rebase_options *opts)
>   		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->ignore_date)
> +		argv_array_push(&opts->git_am_opts, "--ignore-date");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1427,8 +1431,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		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_BOOL(0, "ignore-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
>   		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> @@ -1697,13 +1701,15 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> -	if (options.committer_date_is_author_date)
> +	if (options.ignore_date)
> +		options.committer_date_is_author_date = 0;
> +	if (options.committer_date_is_author_date ||
> +	    options.ignore_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, "--ignore-date") ||
> -		    !strcmp(option, "--whitespace=fix") ||
> +		if (!strcmp(option, "--whitespace=fix") ||
>   		    !strcmp(option, "--whitespace=strip"))
>   			options.flags |= REBASE_FORCE;
>   		else if (skip_prefix(option, "-C", &p)) {
> diff --git a/sequencer.c b/sequencer.c
> index 8f7b984333..f5a9590844 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -148,6 +148,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
>    */
>   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_ignore_date, "rebase-merge/ignore_date")
>   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")
> @@ -919,6 +920,32 @@ static const char *read_author_ident(struct strbuf *buf)
>   	return buf->buf;
>   }
>   
> +/* Construct a free()able author string with current time as the author date */
> +static char *ignore_author_date(const char *author)
> +{
> +	int len = strlen(author);
> +	struct ident_split ident;
> +	struct strbuf new_author = STRBUF_INIT;
> +
> +	split_ident_line(&ident, author, len);

> +	len = ident.mail_end - ident.name_begin + 1;
> +
> +	strbuf_addf(&new_author, "%.*s ", len, author);
> +	datestamp(&new_author);
> +	return strbuf_detach(&new_author, NULL);
> +}

> +
> +static void push_dates(struct child_process *child)
> +{
> +	time_t now = time(NULL);
> +	struct strbuf date = STRBUF_INIT;
> +
> +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
> +	argv_array_pushf(&child->args, "--date=%s", date.buf);
> +	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);

> +	strbuf_release(&date);
> +}
> +
>   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"
> @@ -1020,10 +1047,20 @@ static int run_git_commit(struct repository *r,
>   
>   		if (res <= 0)
>   			res = error_errno(_("could not read '%s'"), defmsg);
> -		else
> +		else {
> +			if (opts->ignore_date) {
> +				char *new_author = ignore_author_date(author);
> +				if (!author)
> +					BUG("ignore-date can only be used with "
> +					    "rebase, which must set the author "
> +					    "before committing the tree");
> +				free((void *)author);
> +				author = new_author;
> +			}
>   			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>   					  NULL, &root_commit, author,
>   					  opts->gpg_sign);
> +		}
>   
>   		strbuf_release(&msg);
>   		strbuf_release(&script);
> @@ -1053,6 +1090,8 @@ static int run_git_commit(struct repository *r,
>   		argv_array_push(&cmd.args, "--amend");
>   	if (opts->gpg_sign)
>   		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		push_dates(&cmd);
>   	if (defmsg)
>   		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>   	else if (!(flags & EDIT_MSG))
> @@ -1515,6 +1554,11 @@ static int try_to_commit(struct repository *r,
>   
>   	reset_ident_date();
>   
> +	if (opts->ignore_date) {
> +		author = ignore_author_date(author);
> +		free(author_to_free);
> +		author_to_free = (char *)author;
> +	}

>   	if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
>   				 oid, author, opts->gpg_sign, extra)) {
>   		res = error(_("failed to write commit object"));
> @@ -2592,6 +2636,11 @@ static int read_populate_opts(struct replay_opts *opts)
>   			opts->committer_date_is_author_date = 1;
>   		}
>   
> +		if (file_exists(rebase_path_ignore_date())) {
> +			opts->allow_ff = 0;
> +			opts->ignore_date = 1;
> +		}
> +
>   		if (file_exists(rebase_path_reschedule_failed_exec()))
>   			opts->reschedule_failed_exec = 1;
>   
> @@ -2676,6 +2725,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_signoff(), "--signoff\n");
>   	if (opts->committer_date_is_author_date)
>   		write_file(rebase_path_cdate_is_adate(), "%s", "");
> +	if (opts->ignore_date)
> +		write_file(rebase_path_ignore_date(), "%s", "");
>   	if (opts->reschedule_failed_exec)
>   		write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>   
> @@ -3601,6 +3652,8 @@ static int do_merge(struct repository *r,
>   		argv_array_push(&cmd.args, git_path_merge_msg(r));
>   		if (opts->gpg_sign)
>   			argv_array_push(&cmd.args, opts->gpg_sign);
> +		if (opts->ignore_date)
> +			push_dates(&cmd);
>   
>   		/* Add the tips to be merged */
>   		for (j = to_merge; j; j = j->next)
> @@ -3874,7 +3927,8 @@ static int pick_commits(struct repository *r,
>   	if (opts->allow_ff)
>   		assert(!(opts->signoff || opts->no_commit ||
>   				opts->record_origin || opts->edit ||
> -				opts->committer_date_is_author_date));
> +				opts->committer_date_is_author_date ||
> +				opts->ignore_date));
>   	if (read_and_refresh_cache(r, opts))
>   		return -1;
>   
> diff --git a/sequencer.h b/sequencer.h
> index e3881e9275..bf5a79afdb 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -44,6 +44,7 @@ struct replay_opts {
>   	int quiet;
>   	int reschedule_failed_exec;
>   	int committer_date_is_author_date;
> +	int ignore_date;
>   
>   	int mainline;
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index b2419a2b75..c060fcd10b 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -81,4 +81,20 @@ test_expect_success '--committer-date-is-author-date works with interactive back
>   	test_cmp authortime committertime
>   '
>   
> +# Checking for +0000 in author time is enough since default
> +# timezone is UTC, but the timezone used while committing
> +# sets to +0530.

> +test_expect_success '--ignore-date works with am backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
> +
> +test_expect_success '--ignore-date works with interactive backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date -i HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	grep "+0000" authortime
> +'
>   test_done
> 

> @@ -1020,10 +1047,20 @@ static int run_git_commit(struct repository *r,
>  
>  		if (res <= 0)
>  			res = error_errno(_("could not read '%s'"), defmsg);
> -		else
> +		else {
> +			if (opts->ignore_date) {
> +				char *new_author = ignore_author_date(author);
> +				if (!author)
> +					BUG("ignore-date can only be used with "
> +					    "rebase, which must set the author "
> +					    "before committing the tree");

> Rohit Ashiwal <rohit.ashiwal265@gmail.com> writes:
> 
>> +/* Construct a free()able author string with current time as the author date */
>> +static char *ignore_author_date(const char *author)
>> +{
>> +	int len = strlen(author);
> 
> Mental note: ignore_author_date() would not allow author==NULL as its input.
> 
>> @@ -1020,10 +1047,20 @@ static int run_git_commit(struct repository *r,
>>   
>>   		if (res <= 0)
>>   			res = error_errno(_("could not read '%s'"), defmsg);
>> -		else
>> +		else {
>> +			if (opts->ignore_date) {
>> +				char *new_author = ignore_author_date(author);
>> +				if (!author)
>> +					BUG("ignore-date can only be used with "
>> +					    "rebase, which must set the author "
>> +					    "before committing the tree");
> 
> Yet, author is used and then checked for NULL-ness, which is
> backwards.  Before we have a chance to issue this BUG(), we would
> already have segfaulted inside ignore_author_date().
> 

> 
> Some points:
>    - According to v2.0.0's git-am.sh, ignore-date should override
>      committer-date-is-author-date. Ergo, we are not barfing out
>      when both flags are provided.
>    - Should the 'const' qualifier be removed[2]? Since it is leaving
>      a false impression that author should not be free()'d.

> 
> [1]: git show v2.0.0:git-am.sh
> [2]: https://github.com/git/git/blob/v2.23.0/sequencer.c#L959
> 
> Rohit Ashiwal (6):
>    rebase -i: add --ignore-whitespace flag
>    sequencer: add NULL checks under read_author_script
>    rebase -i: support --committer-date-is-author-date
>    sequencer: rename amend_author to author_to_rename
>    rebase -i: support --ignore-date
>    rebase: add --reset-author-date
> 
>   Documentation/git-rebase.txt            |  26 +++--
>   builtin/rebase.c                        |  53 +++++++---
>   sequencer.c                             | 135 ++++++++++++++++++++++--
>   sequencer.h                             |   2 +
>   t/t3422-rebase-incompatible-options.sh  |   2 -
>   t/t3433-rebase-options-compatibility.sh | 100 ++++++++++++++++++
>   6 files changed, 289 insertions(+), 29 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> Range-diff:
> 1:  4cd0aa3084 ! 1:  e82ed8cad5 rebase -i: add --ignore-whitespace flag
>      @@ -19,10 +19,13 @@
>        default is `--no-fork-point`, otherwise the default is `--fork-point`.
>        
>        --ignore-whitespace::
>      -+	This flag is either passed to the 'git apply' program
>      -+	(see linkgit:git-apply[1]), or to 'git merge' program
>      -+	(see linkgit:git-merge[1]) as `-Xignore-space-change`,
>      -+	depending on which backend is selected by other options.
>      ++	Behaves differently depending on which backend is selected.
>      +++
>      ++'am' backend: When applying a patch, ignore changes in whitespace in
>      ++context lines if necessary.
>      +++
>      ++'interactive' backend: Treat lines with only whitespace changes as
>      ++unchanged for the sake of a three-way merge.
>       +
>        --whitespace=<option>::
>       -	These flag are passed to the 'git apply' program
>      @@ -63,7 +66,7 @@
>        
>        static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>        {
>      -+	char *strategy_opts = opts->strategy_opts;
>      ++	struct strbuf strategy_buf = STRBUF_INIT;
>        	struct replay_opts replay = REPLAY_OPTS_INIT;
>        
>        	replay.action = REPLAY_INTERACTIVE_REBASE;
>      @@ -71,24 +74,19 @@
>        	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>        	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>        	replay.strategy = opts->strategy;
>      --	if (opts->strategy_opts)
>      --		parse_strategy_opts(&replay, opts->strategy_opts);
>      -+
>      -+	if (opts->ignore_whitespace) {
>      -+		struct strbuf buf = STRBUF_INIT;
>      -+
>      -+		if (strategy_opts)
>      -+			strbuf_addstr(&buf, strategy_opts);
>       +
>      -+		strbuf_addstr(&buf, " --ignore-space-change");
>      -+		free(strategy_opts);
>      -+		strategy_opts = strbuf_detach(&buf, NULL);
>      -+	}
>      -+	if (strategy_opts)
>      -+		parse_strategy_opts(&replay, strategy_opts);
>      + 	if (opts->strategy_opts)
>      +-		parse_strategy_opts(&replay, opts->strategy_opts);
>      ++		strbuf_addstr(&strategy_buf, opts->strategy_opts);
>      ++	if (opts->ignore_whitespace)
>      ++		strbuf_addstr(&strategy_buf, " --ignore-space-change");
>      ++	if (strategy_buf.len)
>      ++		parse_strategy_opts(&replay, strategy_buf.buf);
>        
>      ++	strbuf_release(&strategy_buf);
>        	return replay;
>        }
>      +
>       @@
>        	argc = parse_options(argc, argv, prefix, options,
>        			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
> 2:  e2c0304587 = 2:  209057b361 sequencer: add NULL checks under read_author_script
> 3:  6aed57ae2e ! 3:  a4e6644ef8 rebase -i: support --committer-date-is-author-date
>      @@ -21,10 +21,12 @@
>       +
>        --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 the rebased commits (see linkgit:git-am[1]).
>      ++	of each rebased commit (see linkgit:git-am[1]).
>        +
>        See also INCOMPATIBLE OPTIONS below.
>      +
>       @@
>        
>        The following options:
>      @@ -62,16 +64,6 @@
>        	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>        	replay.strategy = opts->strategy;
>        
>      -@@
>      - 		warning(_("--[no-]rebase-cousins has no effect without "
>      - 			  "--rebase-merges"));
>      -
>      -+	if (opts.committer_date_is_author_date)
>      -+		opts.flags |= REBASE_FORCE;
>      -+
>      - 	return !!run_rebase_interactive(&opts, command);
>      - }
>      -
>       @@
>        
>        	if (opts->ignore_whitespace)
>      @@ -149,14 +141,14 @@
>       +		struct strbuf datebuf = STRBUF_INIT;
>       +		char *date = read_author_date_or_null();
>       +
>      ++		if (!date)
>      ++			return -1;
>      ++
>       +		strbuf_addf(&datebuf, "@%s", date);
>       +		free(date);
>       +
>       +		date = strbuf_detach(&datebuf, &len);
>      -+
>      -+		if (len > 1)
>      -+			res = setenv("GIT_COMMITTER_DATE", date, 1);
>      -+
>      ++		res = setenv("GIT_COMMITTER_DATE", date, 1);
>       +		free(date);
>       +
>       +		if (res)
>      @@ -187,7 +179,7 @@
>       +		if (!ident.date_begin)
>       +			return error(_("corrupted author without date information"));
>       +
>      -+		strbuf_addf(&date, "@%s",ident.date_begin);
>      ++		strbuf_addf(&date, "@%s", ident.date_begin);
>       +		setenv("GIT_COMMITTER_DATE", date.buf, 1);
>       +		strbuf_release(&date);
>       +	}
> 4:  36a0c017c2 = 4:  6ac1885c54 sequencer: rename amend_author to author_to_rename
> 5:  3a4ffeb995 ! 5:  a69749dd67 rebase -i: support --ignore-date
>      @@ -16,9 +16,9 @@
>        
>        --ignore-date::
>       -	This flag is passed to 'git am' to change the author date
>      --	of the rebased commits (see linkgit:git-am[1]).
>      -+	Instead of using the given author date, re-set it to the value
>      -+	same as committer (current) date. This implies --force-rebase.
>      +-	of each rebased commit (see linkgit:git-am[1]).
>      ++	Instead of using the given author date, reset it to the value
>      ++	same as the current time. This implies --force-rebase.
>        +
>        See also INCOMPATIBLE OPTIONS below.
>        
>      @@ -58,18 +58,6 @@
>        	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>        	replay.strategy = opts->strategy;
>        
>      -@@
>      - 		warning(_("--[no-]rebase-cousins has no effect without "
>      - 			  "--rebase-merges"));
>      -
>      --	if (opts.committer_date_is_author_date)
>      -+	if (opts.ignore_date)
>      -+		opts.committer_date_is_author_date = 0;
>      -+	if (opts.committer_date_is_author_date ||
>      -+	    opts.ignore_date)
>      - 		opts.flags |= REBASE_FORCE;
>      -
>      - 	return !!run_rebase_interactive(&opts, command);
>       @@
>        		argv_array_push(&am.args, "--ignore-whitespace");
>        	if (opts->committer_date_is_author_date)
>      @@ -125,18 +113,19 @@
>        	return buf->buf;
>        }
>        
>      -+static void ignore_author_date(const char **author)
>      ++/* Construct a free()able author string with current time as the author date */
>      ++static char *ignore_author_date(const char *author)
>       +{
>      -+	int len = strlen(*author);
>      ++	int len = strlen(author);
>       +	struct ident_split ident;
>       +	struct strbuf new_author = STRBUF_INIT;
>       +
>      -+	split_ident_line(&ident, *author, len);
>      ++	split_ident_line(&ident, author, len);
>       +	len = ident.mail_end - ident.name_begin + 1;
>       +
>      -+	strbuf_addf(&new_author, "%.*s", len, *author);
>      ++	strbuf_addf(&new_author, "%.*s ", len, author);
>       +	datestamp(&new_author);
>      -+	*author = strbuf_detach(&new_author, NULL);
>      ++	return strbuf_detach(&new_author, NULL);
>       +}
>       +
>       +static void push_dates(struct child_process *child)
>      @@ -160,11 +149,13 @@
>       -		else
>       +		else {
>       +			if (opts->ignore_date) {
>      ++				char *new_author = ignore_author_date(author);
>       +				if (!author)
>       +					BUG("ignore-date can only be used with "
>       +					    "rebase, which must set the author "
>       +					    "before committing the tree");
>      -+				ignore_author_date(&author);
>      ++				free((void *)author);
>      ++				author = new_author;
>       +			}
>        			res = commit_tree(msg.buf, msg.len, cache_tree_oid,
>        					  NULL, &root_commit, author,
>      @@ -187,7 +178,7 @@
>        	reset_ident_date();
>        
>       +	if (opts->ignore_date) {
>      -+		ignore_author_date(&author);
>      ++		author = ignore_author_date(author);
>       +		free(author_to_free);
>       +		author_to_free = (char *)author;
>       +	}
> 6:  cb81e6c4e5 ! 6:  210d15cca0 rebase: add --author-date-is-committer-date
>      @@ -1,6 +1,6 @@
>       Author: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
>       
>      -    rebase: add --author-date-is-committer-date
>      +    rebase: add --reset-author-date
>       
>           The previous commit introduced --ignore-date flag to interactive
>           rebase, but the name is actually very vague in context of rebase -i
>      @@ -16,9 +16,9 @@
>        	as the committer date. This implies --force-rebase.
>        
>        --ignore-date::
>      -+--author-date-is-committer-date::
>      - 	Instead of using the given author date, re-set it to the value
>      - 	same as committer (current) date. This implies --force-rebase.
>      ++--reset-author-date::
>      + 	Instead of using the given author date, reset it to the value
>      + 	same as the current time. This implies --force-rebase.
>        +
>       
>        diff --git a/builtin/rebase.c b/builtin/rebase.c
>      @@ -28,7 +28,7 @@
>        		OPT_BOOL(0, "committer-date-is-author-date",
>        			 &options.committer_date_is_author_date,
>        			 N_("make committer date match author date")),
>      -+		OPT_BOOL(0, "author-date-is-committer-date", &options.ignore_date,
>      ++		OPT_BOOL(0, "reset-author-date", &options.ignore_date,
>       +			 "ignore author date and use current date"),
>        		OPT_BOOL(0, "ignore-date", &options.ignore_date,
>        			 "ignore author date and use current date"),
> 

> Hi Rohit
>
> On 20/08/2019 04:45, Rohit Ashiwal wrote:
>> I've tries to incorporated all the suggestions.
>
> It is helpful if you can list the changes to remind us all what we
> said. (as a patch author I find composing that is helpful to remind me
> if there's anything I've forgotten to address)
>
> Also there are a couple of things that were discussed such as
> splitting up the author and passing it round as a <name, email, date,
> tz> tuple and testing a non-default timezone which aren't included -
> that's fine but it helps if you take a moment to explain why in the
> cover letter.
>
>>
>> Some points:
>>    - According to v2.0.0's git-am.sh, ignore-date should override
>>      committer-date-is-author-date. Ergo, we are not barfing out
>>      when both flags are provided.
>>    - Should the 'const' qualifier be removed[2]? Since it is leaving
>>      a false impression that author should not be free()'d.
>
> The author returned by read_author_ident() is owned by the strbuf that
> you pass to read_author_ident() which is confusing.
>
> Best Wishes
>
> Phillip

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>> Hi Rohit
>>
>> On 20/08/2019 04:45, Rohit Ashiwal wrote:
>>> I've tries to incorporated all the suggestions.
>>
>> It is helpful if you can list the changes to remind us all what we
>> said. (as a patch author I find composing that is helpful to remind me
>> if there's anything I've forgotten to address)
>>
>> Also there are a couple of things that were discussed such as
>> splitting up the author and passing it round as a <name, email, date,
>> tz> tuple and testing a non-default timezone which aren't included -
>> that's fine but it helps if you take a moment to explain why in the
>> cover letter.
>>
>>>
>>> Some points:
>>>     - According to v2.0.0's git-am.sh, ignore-date should override
>>>       committer-date-is-author-date. Ergo, we are not barfing out
>>>       when both flags are provided.
>>>     - Should the 'const' qualifier be removed[2]? Since it is leaving
>>>       a false impression that author should not be free()'d.
>>
>> The author returned by read_author_ident() is owned by the strbuf that
>> you pass to read_author_ident() which is confusing.
>>
>> Best Wishes
>>
>> Phillip
> 
> I've looked at this round, but will push out v2 for today's
> integration cycle, mostly due to lack of time, but there do not seem
> to be great difference between the iterations.
> 
> The "ignore-date" step conflicts semantically with b0a31861
> ("sequencer: simplify root commit creation", 2019-08-19) but in a
> good way.  Without the clean-up b0a31861 makes, we need to munge the
> timestamp in two places, but with it, there is only one place that
> needs to modify the timestamp for the feature (in try_to_commit()).

> You may want to see if these "more options" topic can take advantage
> of the "simplify root commit creation" by building on top of some
> form of it (I do not know offhand if b0a31861 ("sequencer: simplify
> root commit creation", 2019-08-19) must build on other two patches
> to fix "rebase -i" or it can be split out as an independent
> clean-up), and if it is feasible, work with your student to make it
> happen, perhaps?

> There are two backends available for rebasing, viz, the am and the
> interactive. Naturally, there shall be some features that are
> implemented in one but not in the other. One such flag is
> --ignore-whitespace which indicates merge mechanism to treat lines
> with only whitespace changes as unchanged. Wire the interactive
> rebase to also understand the --ignore-whitespace flag by
> translating it to -Xignore-space-change.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 13 ++++-
>   builtin/rebase.c                        | 22 +++++++--
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 65 +++++++++++++++++++++++++
>   4 files changed, 94 insertions(+), 7 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 6156609cf7..873eb5768c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -371,8 +371,16 @@ If either <upstream> or --root is given on the command line, then the
>   default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   
>   --ignore-whitespace::
> +	Behaves differently depending on which backend is selected.
> ++
> +'am' backend: When applying a patch, ignore changes in whitespace in
> +context lines if necessary.
> ++
> +'interactive' backend: Treat lines with only whitespace changes as
> +unchanged for the sake of a three-way merge.
> +
>   --whitespace=<option>::
> -	These flag are passed to the 'git apply' program
> +	This flag is passed to the 'git apply' program
>   	(see linkgit:git-apply[1]) that applies the patch.
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -520,7 +528,6 @@ The following options:
>    * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
> - * --ignore-whitespace
>    * -C
>   
>   are incompatible with the following options:
> @@ -543,6 +550,8 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --interactive
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
> + * --preserve-merges and --ignore-whitespace
> + * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
>   
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 670096c065..f8a618d54c 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -79,6 +79,7 @@ struct rebase_options {
>   	int allow_rerere_autoupdate;
>   	int keep_empty;
>   	int autosquash;
> +	int ignore_whitespace;
>   	char *gpg_sign_opt;
>   	int autostash;
>   	char *cmd;
> @@ -99,6 +100,7 @@ struct rebase_options {
>   
>   static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   {
> +	struct strbuf strategy_buf = STRBUF_INIT;
>   	struct replay_opts replay = REPLAY_OPTS_INIT;
>   
>   	replay.action = REPLAY_INTERACTIVE_REBASE;
> @@ -114,9 +116,15 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
> +
>   	if (opts->strategy_opts)
> -		parse_strategy_opts(&replay, opts->strategy_opts);
> +		strbuf_addstr(&strategy_buf, opts->strategy_opts);
> +	if (opts->ignore_whitespace)
> +		strbuf_addstr(&strategy_buf, " --ignore-space-change");
> +	if (strategy_buf.len)
> +		parse_strategy_opts(&replay, strategy_buf.buf);
>   
> +	strbuf_release(&strategy_buf);
>   	return replay;
>   }
>   
> @@ -511,6 +519,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   	argc = parse_options(argc, argv, prefix, options,
>   			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
>   
> +	opts.strategy_opts = xstrdup_or_null(opts.strategy_opts);
> +
>   	if (!is_null_oid(&squash_onto))
>   		opts.squash_onto = &squash_onto;
>   
> @@ -964,6 +974,8 @@ static int run_am(struct rebase_options *opts)
>   	am.git_cmd = 1;
>   	argv_array_push(&am.args, "am");
>   
> +	if (opts->ignore_whitespace)
> +		argv_array_push(&am.args, "--ignore-whitespace");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1407,9 +1419,6 @@ 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, "ignore-whitespace", &options.git_am_opts,
> -				  NULL, N_("passed to 'git am'"),
> -				  PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
>   				  &options.git_am_opts, NULL,
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
> @@ -1417,6 +1426,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>   				  N_("passed to 'git apply'"), 0),
> +		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> +			 N_("ignore changes in whitespace")),
>   		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
>   				  N_("action"), N_("passed to 'git apply'"), 0),
>   		OPT_BIT('f', "force-rebase", &options.flags,
> @@ -1834,6 +1845,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   	}
>   
>   	if (options.rebase_merges) {
> +		if (options.ignore_whitespace)
> +			die(_("cannot combine '--rebase-merges' with "
> +			      "'--ignore-whitespace'"));

>   		if (strategy_options.nr)
>   			die(_("cannot combine '--rebase-merges' with "
>   			      "'--strategy-option'"));
> diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> index a5868ea152..4342f79eea 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 --ignore-whitespace
>   test_rebase_am_only --committer-date-is-author-date
>   test_rebase_am_only -C4
>   
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> new file mode 100755
> index 0000000000..2e16e00a9d
> --- /dev/null
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -0,0 +1,65 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2019 Rohit Ashiwal
> +#
> +
> +test_description='tests to ensure compatibility between am and interactive backends'
> +
> +. ./test-lib.sh
> +
> +# This is a special case in which both am and interactive backends
> +# provide the same output. 

> +# both the backends fall short of optimal behaviour.
> +test_expect_success 'setup' '
> +	git checkout -b topic &&
> +	q_to_tab >file <<-\EOF &&
> +	line 1
> +	Qline 2
> +	line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	cat >file <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	git commit -am "update file" &&
> +	git tag side &&
> +
> +	git checkout --orphan master &&
> +	sed -e "s/^|//" >file <<-\EOF &&
> +	|line 1
> +	|        line 2
> +	|line 3
> +	EOF
> +	git add file &&
> +	git commit -m "add file" &&
> +	git tag main
> +'
> +
> +test_expect_success '--ignore-whitespace works with am backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase main side &&
> +	git rebase --abort &&
> +	git rebase --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_expect_success '--ignore-whitespace works with interactive backend' '
> +	cat >expect <<-\EOF &&
> +	line 1
> +	new line 2
> +	line 3
> +	EOF
> +	test_must_fail git rebase --merge main side &&
> +	git rebase --abort &&
> +	git rebase --merge --ignore-whitespace main side &&
> +	test_cmp expect file
> +'
> +
> +test_done
> 

>
> Hi Rohit
>
> On 07/09/2019 12:50, Rohit Ashiwal wrote:
> > There are two backends available for rebasing, viz, the am and the
> > interactive. Naturally, there shall be some features that are
> > implemented in one but not in the other. One such flag is
> > --ignore-whitespace which indicates merge mechanism to treat lines
> > with only whitespace changes as unchanged. Wire the interactive
> > rebase to also understand the --ignore-whitespace flag by
> > translating it to -Xignore-space-change.
> >
> > Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> > ---
> >   Documentation/git-rebase.txt            | 13 ++++-
> >   builtin/rebase.c                        | 22 +++++++--
> >   t/t3422-rebase-incompatible-options.sh  |  1 -
> >   t/t3433-rebase-options-compatibility.sh | 65 +++++++++++++++++++++++++
> >   4 files changed, 94 insertions(+), 7 deletions(-)
> >   create mode 100755 t/t3433-rebase-options-compatibility.sh
> >
> > diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> > index 6156609cf7..873eb5768c 100644
> > --- a/Documentation/git-rebase.txt
> > +++ b/Documentation/git-rebase.txt
> > @@ -371,8 +371,16 @@ If either <upstream> or --root is given on the command line, then the
> >   default is `--no-fork-point`, otherwise the default is `--fork-point`.
> >
> >   --ignore-whitespace::
> > +     Behaves differently depending on which backend is selected.
> > ++
> > +'am' backend: When applying a patch, ignore changes in whitespace in
> > +context lines if necessary.
> > ++
> > +'interactive' backend: Treat lines with only whitespace changes as
> > +unchanged for the sake of a three-way merge.
> > +
> >   --whitespace=<option>::
> > -     These flag are passed to the 'git apply' program
> > +     This flag is passed to the 'git apply' program
> >       (see linkgit:git-apply[1]) that applies the patch.
> >   +
> >   See also INCOMPATIBLE OPTIONS below.
> > @@ -520,7 +528,6 @@ The following options:
> >    * --committer-date-is-author-date
> >    * --ignore-date
> >    * --whitespace
> > - * --ignore-whitespace
> >    * -C
> >
> >   are incompatible with the following options:
> > @@ -543,6 +550,8 @@ In addition, the following pairs of options are incompatible:
> >    * --preserve-merges and --interactive
> >    * --preserve-merges and --signoff
> >    * --preserve-merges and --rebase-merges
> > + * --preserve-merges and --ignore-whitespace
> > + * --rebase-merges and --ignore-whitespace
> >    * --rebase-merges and --strategy
> >    * --rebase-merges and --strategy-option
> >
> > diff --git a/builtin/rebase.c b/builtin/rebase.c
> > index 670096c065..f8a618d54c 100644
> > --- a/builtin/rebase.c
> > +++ b/builtin/rebase.c
> > @@ -79,6 +79,7 @@ struct rebase_options {
> >       int allow_rerere_autoupdate;
> >       int keep_empty;
> >       int autosquash;
> > +     int ignore_whitespace;
> >       char *gpg_sign_opt;
> >       int autostash;
> >       char *cmd;
> > @@ -99,6 +100,7 @@ struct rebase_options {
> >
> >   static struct replay_opts get_replay_opts(const struct rebase_options *opts)
> >   {
> > +     struct strbuf strategy_buf = STRBUF_INIT;
> >       struct replay_opts replay = REPLAY_OPTS_INIT;
> >
> >       replay.action = REPLAY_INTERACTIVE_REBASE;
> > @@ -114,9 +116,15 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
> >       replay.reschedule_failed_exec = opts->reschedule_failed_exec;
> >       replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
> >       replay.strategy = opts->strategy;
> > +
> >       if (opts->strategy_opts)
> > -             parse_strategy_opts(&replay, opts->strategy_opts);
> > +             strbuf_addstr(&strategy_buf, opts->strategy_opts);
> > +     if (opts->ignore_whitespace)
> > +             strbuf_addstr(&strategy_buf, " --ignore-space-change");
> > +     if (strategy_buf.len)
> > +             parse_strategy_opts(&replay, strategy_buf.buf);
> >
> > +     strbuf_release(&strategy_buf);
> >       return replay;
> >   }
> >
> > @@ -511,6 +519,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
> >       argc = parse_options(argc, argv, prefix, options,
> >                       builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
> >
> > +     opts.strategy_opts = xstrdup_or_null(opts.strategy_opts);
> > +
> >       if (!is_null_oid(&squash_onto))
> >               opts.squash_onto = &squash_onto;
> >
> > @@ -964,6 +974,8 @@ static int run_am(struct rebase_options *opts)
> >       am.git_cmd = 1;
> >       argv_array_push(&am.args, "am");
> >
> > +     if (opts->ignore_whitespace)
> > +             argv_array_push(&am.args, "--ignore-whitespace");
> >       if (opts->action && !strcmp("continue", opts->action)) {
> >               argv_array_push(&am.args, "--resolved");
> >               argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> > @@ -1407,9 +1419,6 @@ 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, "ignore-whitespace", &options.git_am_opts,
> > -                               NULL, N_("passed to 'git am'"),
> > -                               PARSE_OPT_NOARG),
> >               OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
> >                                 &options.git_am_opts, NULL,
> >                                 N_("passed to 'git am'"), PARSE_OPT_NOARG),
> > @@ -1417,6 +1426,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> >                                 N_("passed to 'git am'"), PARSE_OPT_NOARG),
> >               OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
> >                                 N_("passed to 'git apply'"), 0),
> > +             OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> > +                      N_("ignore changes in whitespace")),
> >               OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
> >                                 N_("action"), N_("passed to 'git apply'"), 0),
> >               OPT_BIT('f', "force-rebase", &options.flags,
> > @@ -1834,6 +1845,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> >       }
> >
> >       if (options.rebase_merges) {
> > +             if (options.ignore_whitespace)
> > +                     die(_("cannot combine '--rebase-merges' with "
> > +                           "'--ignore-whitespace'"));
>
> --rebase-merges now supports --strategy_option so we should fix this.
>
> >               if (strategy_options.nr)
> >                       die(_("cannot combine '--rebase-merges' with "
> >                             "'--strategy-option'"));
> > diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> > index a5868ea152..4342f79eea 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 --ignore-whitespace
> >   test_rebase_am_only --committer-date-is-author-date
> >   test_rebase_am_only -C4
> >
> > diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> > new file mode 100755
> > index 0000000000..2e16e00a9d
> > --- /dev/null
> > +++ b/t/t3433-rebase-options-compatibility.sh
> > @@ -0,0 +1,65 @@
> > +#!/bin/sh
> > +#
> > +# Copyright (c) 2019 Rohit Ashiwal
> > +#
> > +
> > +test_description='tests to ensure compatibility between am and interactive backends'
> > +
> > +. ./test-lib.sh
> > +
> > +# This is a special case in which both am and interactive backends
> > +# provide the same output.
>
> I'm still concerned that we have to construct a special test case to get
> both backends to generate the same output. If this series is about
> supporting the behavior of the am backend in the sequencer then I'm
> worried that having the same option name have two different behaviors
> will create more problems than it solves. Do you have a feeling for how
> often the two backends give different results?

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 10 ++--
>   builtin/rebase.c                        | 17 +++++--
>   sequencer.c                             | 61 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 37 +++++++++++++++
>   6 files changed, 116 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 873eb5768c..e7c0eac18c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -386,9 +386,13 @@ unchanged for the sake of a three-way merge.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This 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.
>   
> @@ -525,7 +529,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -551,6 +554,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index f8a618d54c..656bc7d7e9 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ 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;
> @@ -114,6 +115,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	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;
>   
> @@ -976,6 +979,8 @@ 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);
> @@ -1419,9 +1424,9 @@ 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"),
> @@ -1692,10 +1697,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	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"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index adeff2561e..fd925f2d72 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -879,6 +880,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}
> +
>   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 +950,24 @@ static int run_git_commit(struct repository *r,
>   
>   	cmd.git_cmd = 1;
>   
> +        if (opts->committer_date_is_author_date) {
> +	        int res = -1;
> +	        struct strbuf datebuf = STRBUF_INIT;
> +	        char *date = read_author_date_or_null();
> +
> +	        if (!date)
> +	                return -1;
> +
> +	        strbuf_addf(&datebuf, "@%s", date);
> +	        res = setenv("GIT_COMMITTER_DATE", datebuf.buf, 1);
> +
> +		strbuf_release(&datebuf);
> +	        free(date);
> +
> +	        if (res)
> +	                return -1;
> +        }
> +
>   	if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
>   		const char *gpg_opt = gpg_sign_opt_quoted(opts);
>   
> @@ -1331,7 +1361,6 @@ 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", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1359,6 +1388,26 @@ 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)
> +			return error(_("malformed ident line"));

> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));
> +
> +		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;
> @@ -2473,6 +2522,11 @@ 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;
>   
> @@ -2555,6 +2609,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3752,7 +3808,8 @@ 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 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..6c1fbab4d8 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -26,8 +29,13 @@ 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
> @@ -62,4 +70,33 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with rebase -r' '
> +	git checkout side &&
> +	git merge commit3 &&
> +	git rebase -r --root --committer-date-is-author-date &&
> +	git rev-list HEAD >rev_list &&
> +	while read HASH
> +	do
> +		git show $HASH --pretty="format:%ai" >authortime
> +		git show $HASH --pretty="format:%ci" >committertime
> +		test_cmp authortime committertime
> +	done <rev_list
> +'
> +
>   test_done
> 

>
> > +	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)
> > +			return error(_("malformed ident line"));
>
> Here (and just below) we return if there is an error but later on we 
> `goto out` should we be doing that here to clean something up?

> Best Wishes
>
> Phillip
>
> > +		if (!ident.date_begin)
> > +			return error(_("corrupted author without date information"));
> > +
> > +		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;
> > +	}
> > +

> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> [...]> diff --git a/sequencer.c b/sequencer.c
> index adeff2561e..fd925f2d72 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ 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")
> @@ -879,6 +880,17 @@ static char *get_author(const char *message)
>   	return NULL;
>   }
>   
> +/* Returns a "date" string that needs to be free()'d by the caller */
> +static char *read_author_date_or_null(void)
> +{
> +	char *date;
> +
> +	if (read_author_script(rebase_path_author_script(),
> +			       NULL, NULL, &date, 0))
> +		return NULL;
> +	return date;
> +}

>   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 +950,24 @@ static int run_git_commit(struct repository *r,
>   
>   	cmd.git_cmd = 1;
>   
> +        if (opts->committer_date_is_author_date) {
> +	        int res = -1;
> +	        struct strbuf datebuf = STRBUF_INIT;
> +	        char *date = read_author_date_or_null();
> +
> +	        if (!date)
> +	                return -1;
> +
> +	        strbuf_addf(&datebuf, "@%s", date);
> +	        res = setenv("GIT_COMMITTER_DATE", datebuf.buf, 1);
> +
> +		strbuf_release(&datebuf);
> +	        free(date);
> +
> +	        if (res)
> +	                return -1;
> +        }
> +
>   	if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
>   		const char *gpg_opt = gpg_sign_opt_quoted(opts);
>   
> @@ -1331,7 +1361,6 @@ 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", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1359,6 +1388,26 @@ 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)
> +			return error(_("malformed ident line"));
> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));
> +
> +		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;
> @@ -2473,6 +2522,11 @@ 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;
>   
> @@ -2555,6 +2609,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	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", "");
>   
> @@ -3752,7 +3808,8 @@ 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 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ 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 4342f79eea..7402f7e3da 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/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..6c1fbab4d8 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.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.
> @@ -26,8 +29,13 @@ 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
> @@ -62,4 +70,33 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with rebase -r' '
> +	git checkout side &&
> +	git merge commit3 &&
> +	git rebase -r --root --committer-date-is-author-date &&
> +	git rev-list HEAD >rev_list &&
> +	while read HASH
> +	do
> +		git show $HASH --pretty="format:%ai" >authortime
> +		git show $HASH --pretty="format:%ci" >committertime
> +		test_cmp authortime committertime
> +	done <rev_list
> +'
> +
>   test_done
> 

> +	git rebase -r --root --ignore-date &&
> +	git rev-list HEAD >rev_list &&
> +	while read HASH
> +	do
> +		git show $HASH --pretty="format:%ai" >authortime
> +		git show $HASH --pretty="format:%ci" >committertime
> +		grep "+0000" authortime
> +		grep "+0000" committertime
> +	done <rev_list
> +'
> [...]

> rebase am already has this flag to "lie" about the author date
> by changing it to the committer (current) date. Let's add the same
> for interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>  Documentation/git-rebase.txt            |  6 +--
>  builtin/rebase.c                        | 18 ++++++---
>  sequencer.c                             | 53 ++++++++++++++++++++++++-
>  sequencer.h                             |  1 +
>  t/t3433-rebase-options-compatibility.sh | 35 ++++++++++++++++
>  5 files changed, 104 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index e7c0eac18c..e7ac9fae0b 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -391,8 +391,8 @@ See also INCOMPATIBLE OPTIONS below.
>  	as the committer date. This implies --force-rebase.
>  
>  --ignore-date::
> -	This flag is passed to 'git am' to change the author date
> -	of each rebased commit (see linkgit:git-am[1]).
> +	Instead of using the given author date, reset it to the value
> +	same as the current time. This implies --force-rebase.

>  +
>  See also INCOMPATIBLE OPTIONS below.
>  
> @@ -529,7 +529,6 @@ INCOMPATIBLE OPTIONS
>  
>  The following options:
>  
> - * --ignore-date
>   * --whitespace
>   * -C
>  
> @@ -555,6 +554,7 @@ In addition, the following pairs of options are incompatible:
>   * --preserve-merges and --rebase-merges
>   * --preserve-merges and --ignore-whitespace
>   * --preserve-merges and --committer-date-is-author-date
> + * --preserve-merges and --ignore-date
>   * --rebase-merges and --ignore-whitespace
>   * --rebase-merges and --strategy
>   * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 656bc7d7e9..e6f90f61dd 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -83,6 +83,7 @@ struct rebase_options {
>  	char *gpg_sign_opt;
>  	int autostash;
>  	int committer_date_is_author_date;
> +	int ignore_date;
>  	char *cmd;
>  	int allow_empty_message;
>  	int rebase_merges, rebase_cousins;
> @@ -117,6 +118,7 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>  	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
>  	replay.committer_date_is_author_date =
>  					opts->committer_date_is_author_date;
> +	replay.ignore_date = opts->ignore_date;
>  	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>  	replay.strategy = opts->strategy;
>  
> @@ -981,6 +983,8 @@ static int run_am(struct rebase_options *opts)
>  		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->ignore_date)
> +		argv_array_push(&opts->git_am_opts, "--ignore-date");
>  	if (opts->action && !strcmp("continue", opts->action)) {
>  		argv_array_push(&am.args, "--resolved");
>  		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1427,8 +1431,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  		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_BOOL(0, "ignore-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>  		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>  				  N_("passed to 'git apply'"), 0),
>  		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> @@ -1697,13 +1701,17 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  		    state_dir_base, cmd_live_rebase, buf.buf);
>  	}
>  
> -	if (options.committer_date_is_author_date)
> +	if (options.ignore_date) {
> +		options.committer_date_is_author_date = 0;
> +		setenv("GIT_COMMITTER_DATE", "", 1);
> +	}

> +	if (options.committer_date_is_author_date ||
> +	    options.ignore_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, "--ignore-date") ||
> -		    !strcmp(option, "--whitespace=fix") ||
> +		if (!strcmp(option, "--whitespace=fix") ||
>  		    !strcmp(option, "--whitespace=strip"))
>  			options.flags |= REBASE_FORCE;
>  		else if (skip_prefix(option, "-C", &p)) {
> diff --git a/sequencer.c b/sequencer.c
> index 0d78abeec8..188499190f 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -148,6 +148,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
>   */
>  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_ignore_date, "rebase-merge/ignore_date")
>  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")
> @@ -891,6 +892,35 @@ static char *read_author_date_or_null(void)
>  	return date;
>  }
>  
> +/* Construct a free()able author string with current time as the author date */
> +static char *ignore_author_date(const char *author)
> +{
> +	int len = strlen(author);
> +	struct ident_split ident;
> +	struct strbuf new_author = STRBUF_INIT;
> +
> +	if (split_ident_line(&ident, author, len) < 0) {
> +		error(_("malformed ident line"));
> +		return NULL;
> +	}

> +	datestamp(&new_author);
> +	return strbuf_detach(&new_author, NULL);
> +}
> +
> +static void push_dates(struct child_process *child)
> +{
> +	time_t now = time(NULL);
> +	struct strbuf date = STRBUF_INIT;
> +
> +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
> +	argv_array_pushf(&child->env_array, "GIT_AUTHOR_DATE=%s", date.buf);
> +	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);

> +	strbuf_release(&date);
> +}
> +
>  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"
> @@ -983,6 +1013,8 @@ static int run_git_commit(struct repository *r,
>  		argv_array_push(&cmd.args, "--amend");
>  	if (opts->gpg_sign)
>  		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		push_dates(&cmd);
>  	if (defmsg)
>  		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>  	else if (!(flags & EDIT_MSG))
> @@ -1451,6 +1483,15 @@ static int try_to_commit(struct repository *r,
>  
>  	reset_ident_date();
>  
> +	if (opts->ignore_date) {
> +		author = ignore_author_date(author);
> +		if (!author) {
> +			res = -1;
> +			goto out;
> +		}

> +		free(author_to_free);
> +		author_to_free = (char *)author;
> +	}
>  	if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
>  				 oid, author, opts->gpg_sign, extra)) {
>  		res = error(_("failed to write commit object"));
> @@ -2527,6 +2568,11 @@ static int read_populate_opts(struct replay_opts *opts)
>  			opts->committer_date_is_author_date = 1;
>  		}
>  
> +		if (file_exists(rebase_path_ignore_date())) {
> +			opts->allow_ff = 0;
> +			opts->ignore_date = 1;
> +		}
> +
>  		if (file_exists(rebase_path_reschedule_failed_exec()))
>  			opts->reschedule_failed_exec = 1;
>  
> @@ -2611,6 +2657,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>  		write_file(rebase_path_signoff(), "--signoff\n");
>  	if (opts->committer_date_is_author_date)
>  		write_file(rebase_path_cdate_is_adate(), "%s", "");
> +	if (opts->ignore_date)
> +		write_file(rebase_path_ignore_date(), "%s", "");
>  	if (opts->reschedule_failed_exec)
>  		write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>  
> @@ -3536,6 +3584,8 @@ static int do_merge(struct repository *r,
>  		argv_array_push(&cmd.args, git_path_merge_msg(r));
>  		if (opts->gpg_sign)
>  			argv_array_push(&cmd.args, opts->gpg_sign);
> +		if (opts->ignore_date)
> +			push_dates(&cmd);
>  
>  		/* Add the tips to be merged */
>  		for (j = to_merge; j; j = j->next)
> @@ -3809,7 +3859,8 @@ static int pick_commits(struct repository *r,
>  	if (opts->allow_ff)
>  		assert(!(opts->signoff || opts->no_commit ||
>  				opts->record_origin || opts->edit ||
> -				opts->committer_date_is_author_date));
> +				opts->committer_date_is_author_date ||
> +				opts->ignore_date));
>  	if (read_and_refresh_cache(r, opts))
>  		return -1;
>  
> diff --git a/sequencer.h b/sequencer.h
> index e3881e9275..bf5a79afdb 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -44,6 +44,7 @@ struct replay_opts {
>  	int quiet;
>  	int reschedule_failed_exec;
>  	int committer_date_is_author_date;
> +	int ignore_date;
>  
>  	int mainline;
>  
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 6c1fbab4d8..0ad7bfc6a0 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -99,4 +99,39 @@ test_expect_success '--committer-date-is-author-date works with rebase -r' '
>  	done <rev_list
>  '
>  
> +# Checking for +0000 in author time is enough since default
> +# timezone is UTC, but the timezone used while committing
> +# sets to +0530.
> +test_expect_success '--ignore-date works with am backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	grep "+0000" authortime &&
> +	grep "+0000" committertime
> +'
> +
> +test_expect_success '--ignore-date works with interactive backend' '
> +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
> +	git rebase --ignore-date -i HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	grep "+0000" authortime &&
> +	grep "+0000" committertime
> +'
> +
> +test_expect_success '--ignore-date works with rebase -r' '
> +	git checkout side &&
> +	git merge commit3 &&
> +	git rebase -r --root --ignore-date &&
> +	git rev-list HEAD >rev_list &&
> +	while read HASH
> +	do
> +		git show $HASH --pretty="format:%ai" >authortime
> +		git show $HASH --pretty="format:%ci" >committertime
> +		grep "+0000" authortime
> +		grep "+0000" committertime
> +	done <rev_list
> +'

> [...]
> It's good to see the new test. Did you see Stolee's email [4] about the
> test coverage of the previous version of this series? You should check
> that this series tests all the untested non-error handling lines.
>
> [4]
> https://public-inbox.org/git/1ed86989-9ba2-0cd7-b6f7-654d1943b1d7@gmail.com/

> On Fri, 27 Sep 2019 11:00:58 +0100 Phillip Wood <phillip.wood123@gmail.com> wrote:
>>
>> [...]
> 
> Thanks for all the advice and improvements.
> 
>> [...]
>> It's good to see the new test. Did you see Stolee's email [4] about the
>> test coverage of the previous version of this series? You should check
>> that this series tests all the untested non-error handling lines.
>>
>> [4]
>> https://public-inbox.org/git/1ed86989-9ba2-0cd7-b6f7-654d1943b1d7@gmail.com/
> 
> Yes, I've seen it and have improved the test since.

> Rohit Ashiwal <rohit.ashiwal265@gmail.com> writes:
> 
>> Following the suggestion of Phillip I've rebased my patch on master (745f681289)
>> and cherry-picking b0a3186140.
> 
> Sorry, but that's horrible.  The latter does not even cleanly apply
> on the former.

> @@ -958,7 +989,8 @@ static int run_git_commit(struct repository *r,
>  	                return -1;
>  
>  	        strbuf_addf(&datebuf, "@%s", date);
> -	        res = setenv("GIT_COMMITTER_DATE", datebuf.buf, 1);
> +		res = setenv("GIT_COMMITTER_DATE",
> +			     opts->ignore_date ? "" : datebuf.buf, 1);

> @@ -982,6 +1014,8 @@ static int run_git_commit(struct repository *r,
>  		argv_array_push(&cmd.args, "--amend");
>  	if (opts->gpg_sign)
>  		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
> +	if (opts->ignore_date)
> +		push_dates(&cmd, opts->committer_date_is_author_date);
>  	if (defmsg)
>  		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>  	else if (!(flags & EDIT_MSG))
> @@ -1404,7 +1438,8 @@ static int try_to_commit(struct repository *r,
>  		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);
> +		res = setenv("GIT_COMMITTER_DATE",
> +			     opts->ignore_date ? "" : date.buf, 1);

> @@ -1454,6 +1489,15 @@ static int try_to_commit(struct repository *r,
>  
>  	reset_ident_date();
>  
> +	if (opts->ignore_date) {
> +		author = ignore_author_date(author);

> +		if (!author) {
> +			res = -1;
> +			goto out;
> +		}
> +		free(author_to_free);
> +		author_to_free = (char *)author;
> +	}

> @@ -2538,6 +2582,11 @@ static int read_populate_opts(struct replay_opts *opts)
>  			opts->committer_date_is_author_date = 1;
>  		}
>  
> +		if (file_exists(rebase_path_ignore_date())) {
> +			opts->allow_ff = 0;
> +			opts->ignore_date = 1;
> +		}

> @@ -3557,6 +3608,8 @@ static int do_merge(struct repository *r,
>  		argv_array_push(&cmd.args, git_path_merge_msg(r));
>  		if (opts->gpg_sign)
>  			argv_array_push(&cmd.args, opts->gpg_sign);
> +		if (opts->ignore_date)
> +			push_dates(&cmd, opts->committer_date_is_author_date);

> @@ -3830,7 +3883,8 @@ static int pick_commits(struct repository *r,
>  	if (opts->allow_ff)
>  		assert(!(opts->signoff || opts->no_commit ||
>  				opts->record_origin || opts->edit ||
> -				opts->committer_date_is_author_date));
> +				opts->committer_date_is_author_date ||
> +				opts->ignore_date));

> Rohit Ashiwal <rohit.ashiwal265@gmail.com> writes:
>
>>  --ignore-date::
>> +	Instead of using the given author date, reset it to the
>> +	current time. This implies --force-rebase.
>
> The first sentence is unclear and puzzles me with "for what?".  IOW,
> you are saying that by default the command uses the given (I presume
> that you meant what is recorded in the original commits being
> rebased---but we should find a way to explain it more clearly)
> author date, but with this option what is used is reset to the
> current time.  It is left unspecified what the command is using that
> time for.
>
> Perhaps (I am writing this paragraph after writing the rest of the
> message, i.e. after reading the patch through):

> 	By default, the author date recorded in the commit being
> 	rebased as the author date is used as the author date of the
> 	rebased commits.  The option tells Git to use the current
> 	timestamp as the author date of the rebased commits instead.
> 	This implies `--force-rebase`.

>  --ignore-date::
> +--reset-author-date::
>  	Instead of using the given author date, reset it to the
>  	current time. This implies --force-rebase.
>  +
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 7edae668f8..edefdd016b 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1455,6 +1455,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  		OPT_BOOL(0, "committer-date-is-author-date",
>  			 &options.committer_date_is_author_date,
>  			 N_("make committer date match author date")),
> +		OPT_BOOL(0, "reset-author-date", &options.ignore_date,
> +			 "ignore author date and use current date"),
>  		OPT_BOOL(0, "ignore-date", &options.ignore_date,
>  			 "ignore author date and use current date"),

> As I hate to leave a mostly done topic hanging around forever, I am
> tempted to queue these fixups on top (instead of squash them in) to
> tie the loose ends after a few weeks' inactivity.
> 
> Thanks.
> 
> -- >8 --
> Subject: rebase -i: finishes touches to --reset-author-date
> 
> Clarify the way the `--reset-author-date` option is described,
> and mark its usage string translatable.
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  Documentation/git-rebase.txt | 6 ++++--
>  builtin/rebase.c             | 6 +++---
>  2 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index c8d54d221d..03809da835 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -392,8 +392,10 @@ See also INCOMPATIBLE OPTIONS below.
>  
>  --ignore-date::
>  --reset-author-date::
> -	Instead of using the given author date, reset it to the
> -	current time. This implies --force-rebase.
> +	By default, the author date of the original commit is used
> +	as the author date for the resulting commit.  This option
> +	tells Git to use the current timestamp instead and implies
> +	`--force-rebase`.
>  +
>  See also INCOMPATIBLE OPTIONS below.
>  
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 44768082b8..d5c09f159c 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1437,9 +1437,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  			 &options.committer_date_is_author_date,
>  			 N_("make committer date match author date")),
>  		OPT_BOOL(0, "reset-author-date", &options.ignore_date,
> -			 "ignore author date and use current date"),
> -		OPT_BOOL(0, "ignore-date", &options.ignore_date,
> -			 "ignore author date and use current date"),
> +			 N_("ignore author date and use current date")),
> +		OPT_HIDDEN_BOOL(0, "ignore-date", &options.ignore_date,
> +				N_("synonym of --reset-autohr-date")),

>  		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
>  				  N_("passed to 'git apply'"), 0),
>  		OPT_BOOL(0, "ignore-whitespace", &options.ignore_whitespace,
> 
> 

> Hey Everyone
> 
> I got really busy lately, posting the patch now.
>   - Now handles the combination of --ignore-date and
>     --committer-date-is-author-date properly.
>   - Improved code coverage

>   - addressed the compatibility of --rebase-merges with --strategy
> 
> Thanks
> Rohit
> 
> Rohit Ashiwal (6):
>    rebase -i: add --ignore-whitespace flag
>    sequencer: allow callers of read_author_script() to ignore fields
>    rebase -i: support --committer-date-is-author-date
>    sequencer: rename amend_author to author_to_rename
>    rebase -i: support --ignore-date
>    rebase: add --reset-author-date
> 
>   Documentation/git-rebase.txt            |  25 ++++-
>   builtin/rebase.c                        |  48 ++++++--
>   sequencer.c                             | 141 ++++++++++++++++++++++--
>   sequencer.h                             |   2 +
>   t/t3422-rebase-incompatible-options.sh  |   2 -
>   t/t3433-rebase-options-compatibility.sh | 131 ++++++++++++++++++++++
>   6 files changed, 321 insertions(+), 28 deletions(-)
>   create mode 100755 t/t3433-rebase-options-compatibility.sh
> 
> Range-diff:
>    2:  77af1d66db ! 491:  e155af5a39 rebase -i: add --ignore-whitespace flag
>      @@ -16,7 +16,7 @@
>        --- a/Documentation/git-rebase.txt
>        +++ b/Documentation/git-rebase.txt
>       @@
>      - default is `--no-fork-point`, otherwise the default is `--fork-point`.
>      + with `--keep-base` in order to drop those commits from your branch.
>        
>        --ignore-whitespace::
>       +	Behaves differently depending on which backend is selected.
>      @@ -46,9 +46,8 @@
>         * --preserve-merges and --signoff
>         * --preserve-merges and --rebase-merges
>       + * --preserve-merges and --ignore-whitespace
>      -+ * --rebase-merges and --ignore-whitespace
>      -  * --rebase-merges and --strategy
>      -  * --rebase-merges and --strategy-option
>      +  * --keep-base and --onto
>      +  * --keep-base and --root
>        
>       
>        diff --git a/builtin/rebase.c b/builtin/rebase.c
>      @@ -124,16 +123,6 @@
>        		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
>        				  N_("action"), N_("passed to 'git apply'"), 0),
>        		OPT_BIT('f', "force-rebase", &options.flags,
>      -@@
>      - 	}
>      -
>      - 	if (options.rebase_merges) {
>      -+		if (options.ignore_whitespace)
>      -+			die(_("cannot combine '--rebase-merges' with "
>      -+			      "'--ignore-whitespace'"));
>      - 		if (strategy_options.nr)
>      - 			die(_("cannot combine '--rebase-merges' with "
>      - 			      "'--strategy-option'"));
>       
>        diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
>        --- a/t/t3422-rebase-incompatible-options.sh
>    3:  1f7f1407b2 = 492:  7ec673ebcb sequencer: allow callers of read_author_script() to ignore fields
>    4:  cc1614154e ! 493:  5af0d628de rebase -i: support --committer-date-is-author-date
>      @@ -40,9 +40,9 @@
>         * --preserve-merges and --rebase-merges
>         * --preserve-merges and --ignore-whitespace
>       + * --preserve-merges and --committer-date-is-author-date
>      -  * --rebase-merges and --ignore-whitespace
>      -  * --rebase-merges and --strategy
>      -  * --rebase-merges and --strategy-option
>      +  * --keep-base and --onto
>      +  * --keep-base and --root
>      +
>       
>        diff --git a/builtin/rebase.c b/builtin/rebase.c
>        --- a/builtin/rebase.c
>      @@ -173,10 +173,14 @@
>       +		struct ident_split ident;
>       +		struct strbuf date = STRBUF_INIT;
>       +
>      -+		if (split_ident_line(&ident, author, len) < 0)
>      -+			return error(_("malformed ident line"));
>      -+		if (!ident.date_begin)
>      -+			return error(_("corrupted author without date information"));
>      ++		if (split_ident_line(&ident, author, len) < 0) {
>      ++			res = error(_("malformed ident line"));
>      ++			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,
>      @@ -296,7 +300,7 @@
>       +
>       +test_expect_success '--committer-date-is-author-date works with rebase -r' '
>       +	git checkout side &&
>      -+	git merge commit3 &&
>      ++	git merge --no-ff commit3 &&
>       +	git rebase -r --root --committer-date-is-author-date &&
>       +	git rev-list HEAD >rev_list &&
>       +	while read HASH
>    5:  9e92c79bda = 494:  c7846945dd sequencer: rename amend_author to author_to_rename
>    6:  fc68e55e78 ! 495:  02f797b84d rebase -i: support --ignore-date
>      @@ -17,8 +17,8 @@
>        --ignore-date::
>       -	This flag is passed to 'git am' to change the author date
>       -	of each rebased commit (see linkgit:git-am[1]).
>      -+	Instead of using the given author date, reset it to the value
>      -+	same as the current time. This implies --force-rebase.
>      ++	Instead of using the given author date, reset it to the
>      ++	current time. This implies --force-rebase.
>        +
>        See also INCOMPATIBLE OPTIONS below.
>        
>      @@ -35,9 +35,9 @@
>         * --preserve-merges and --ignore-whitespace
>         * --preserve-merges and --committer-date-is-author-date
>       + * --preserve-merges and --ignore-date
>      -  * --rebase-merges and --ignore-whitespace
>      -  * --rebase-merges and --strategy
>      -  * --rebase-merges and --strategy-option
>      +  * --keep-base and --onto
>      +  * --keep-base and --root
>      +
>       
>        diff --git a/builtin/rebase.c b/builtin/rebase.c
>        --- a/builtin/rebase.c
>      @@ -83,10 +83,6 @@
>        	}
>        
>       -	if (options.committer_date_is_author_date)
>      -+	if (options.ignore_date) {
>      -+		options.committer_date_is_author_date = 0;
>      -+		setenv("GIT_COMMITTER_DATE", "", 1);
>      -+	}
>       +	if (options.committer_date_is_author_date ||
>       +	    options.ignore_date)
>        		options.flags |= REBASE_FORCE;
>      @@ -128,35 +124,56 @@
>       +	}
>       +	len = ident.mail_end - ident.name_begin + 1;
>       +
>      -+	strbuf_addf(&new_author, "%.*s ", len, author);
>      ++	strbuf_addf(&new_author, "%.*s ", len, ident.name_begin);
>       +	datestamp(&new_author);
>       +	return strbuf_detach(&new_author, NULL);
>       +}
>       +
>      -+static void push_dates(struct child_process *child)
>      ++static void push_dates(struct child_process *child, int change_committer_date)
>       +{
>       +	time_t now = time(NULL);
>       +	struct strbuf date = STRBUF_INIT;
>       +
>       +	strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
>       +	argv_array_pushf(&child->env_array, "GIT_AUTHOR_DATE=%s", date.buf);
>      -+	argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);
>      ++	if (change_committer_date)
>      ++		argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);
>       +	strbuf_release(&date);
>       +}
>       +
>        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"
>      +@@
>      + 	                return -1;
>      +
>      + 	        strbuf_addf(&datebuf, "@%s", date);
>      +-	        res = setenv("GIT_COMMITTER_DATE", datebuf.buf, 1);
>      ++		res = setenv("GIT_COMMITTER_DATE",
>      ++			     opts->ignore_date ? "" : datebuf.buf, 1);
>      +
>      + 		strbuf_release(&datebuf);
>      + 	        free(date);
>       @@
>        		argv_array_push(&cmd.args, "--amend");
>        	if (opts->gpg_sign)
>        		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>       +	if (opts->ignore_date)
>      -+		push_dates(&cmd);
>      ++		push_dates(&cmd, opts->committer_date_is_author_date);
>        	if (defmsg)
>        		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>        	else if (!(flags & EDIT_MSG))
>       @@
>      + 		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);
>      ++		res = setenv("GIT_COMMITTER_DATE",
>      ++			     opts->ignore_date ? "" : date.buf, 1);
>      + 		strbuf_release(&date);
>      +
>      + 		if (res)
>      +@@
>        
>        	reset_ident_date();
>        
>      @@ -198,7 +215,7 @@
>        		if (opts->gpg_sign)
>        			argv_array_push(&cmd.args, opts->gpg_sign);
>       +		if (opts->ignore_date)
>      -+			push_dates(&cmd);
>      ++			push_dates(&cmd, opts->committer_date_is_author_date);
>        
>        		/* Add the tips to be merged */
>        		for (j = to_merge; j; j = j->next)
>      @@ -239,31 +256,25 @@
>       +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
>       +	git rebase --ignore-date HEAD^ &&
>       +	git show HEAD --pretty="format:%ai" >authortime &&
>      -+	git show HEAD --pretty="format:%ci" >committertime &&
>      -+	grep "+0000" authortime &&
>      -+	grep "+0000" committertime
>      ++	grep "+0000" authortime
>       +'
>       +
>       +test_expect_success '--ignore-date works with interactive backend' '
>       +	git commit --amend --date="$GIT_AUTHOR_DATE" &&
>       +	git rebase --ignore-date -i HEAD^ &&
>       +	git show HEAD --pretty="format:%ai" >authortime &&
>      -+	git show HEAD --pretty="format:%ci" >committertime &&
>      -+	grep "+0000" authortime &&
>      -+	grep "+0000" committertime
>      ++	grep "+0000" authortime
>       +'
>       +
>       +test_expect_success '--ignore-date works with rebase -r' '
>       +	git checkout side &&
>      -+	git merge commit3 &&
>      ++	git merge --no-ff commit3 &&
>       +	git rebase -r --root --ignore-date &&
>       +	git rev-list HEAD >rev_list &&
>       +	while read HASH
>       +	do
>       +		git show $HASH --pretty="format:%ai" >authortime
>      -+		git show $HASH --pretty="format:%ci" >committertime
>       +		grep "+0000" authortime
>      -+		grep "+0000" committertime
>       +	done <rev_list
>       +'
>       +
>    7:  396d5f16eb ! 496:  7a9fe1e612 rebase: add --reset-author-date
>      @@ -17,8 +17,8 @@
>        
>        --ignore-date::
>       +--reset-author-date::
>      - 	Instead of using the given author date, reset it to the value
>      - 	same as the current time. This implies --force-rebase.
>      + 	Instead of using the given author date, reset it to the
>      + 	current time. This implies --force-rebase.
>        +
>       
>        diff --git a/builtin/rebase.c b/builtin/rebase.c
>