Re: [PATCH v5 4/5] rebase -i: support --ignore-date

> From: Phillip Wood <phillip.wood@dunelm.org.uk>
> 
> Rebase is implemented with two different backends - 'apply' and
> 'merge' each of which support a different set of options. In
> particular the apply backend supports a number of options implemented
> by 'git am' that are not implemented in the merge backend. This means
> that the available options are different depending on which backend is
> used which is confusing. This patch adds support for the --ignore-date
> option to the merge backend. This option uses the current time as the
> author date rather than reusing the original author date when
> rewriting commits. We take care to handle the combination of
> --ignore-date and --committer-date-is-author-date in the same way as
> the apply backend.
> 
> Original-patch-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
> ---
>  Documentation/git-rebase.txt   |  7 +++--
>  builtin/rebase.c               | 13 +++++---
>  sequencer.c                    | 50 ++++++++++++++++++++++++++++--
>  sequencer.h                    |  1 +
>  t/t3436-rebase-more-options.sh | 56 ++++++++++++++++++++++++++++++++++
>  5 files changed, 117 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index dfa70263e6..e2717e20e6 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -450,8 +450,9 @@ See also INCOMPATIBLE OPTIONS below.
>  	date. This option 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 author date of the original commit, use
> +	the current time as the	author date of the rebased commit.  This
> +	option implies `--force-rebase`.
>  +
>  See also INCOMPATIBLE OPTIONS below.
>  
> @@ -589,7 +590,6 @@ INCOMPATIBLE OPTIONS
>  The following options:
>  
>   * --apply
> - * --ignore-date
>   * --whitespace
>   * -C
>  
> @@ -617,6 +617,7 @@ In addition, the following pairs of options are incompatible:
>   * --preserve-merges and --empty=
>   * --preserve-merges and --ignore-whitespace
>   * --preserve-merges and --committer-date-is-author-date
> + * --preserve-merges and --ignore-date
>   * --keep-base and --onto
>   * --keep-base and --root
>  
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index a7c3d5c92b..890dd4c588 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -89,6 +89,7 @@ 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;
> @@ -127,6 +128,7 @@ 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;
>  
> @@ -1503,8 +1505,8 @@ 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", &ignore_whitespace,
> @@ -1797,13 +1799,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  	    options.autosquash) {
>  		allow_preemptive_ff = 0;
>  	}
> -	if (options.committer_date_is_author_date)
> +	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"))
>  			allow_preemptive_ff = 0;
>  		else if (skip_prefix(option, "-C", &p)) {
> @@ -1862,6 +1863,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>  		if (options.committer_date_is_author_date)
>  			argv_array_push(&options.git_am_opts,
>  					"--committer-date-is-author-date");
> +		if (options.ignore_date)
> +			argv_array_push(&options.git_am_opts, "--ignore-date");
>  	} else if (ignore_whitespace) {
>  			string_list_append (&strategy_options,
>  					    "ignore-space-change");
> diff --git a/sequencer.c b/sequencer.c
> index 29f6d1bc39..f8e1e38623 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -150,6 +150,7 @@ 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")
> @@ -889,6 +890,24 @@ static const char *author_date_from_env_array(const struct argv_array *env)
>  	BUG("GIT_AUTHOR_DATE missing from author script");
>  }
>  
> +/* 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 '%s'"), author);
> +		return NULL;
> +	}
> +
> +	len = ident.mail_end - ident.name_begin + 1;
> +	strbuf_addf(&new_author, "%.*s ", len, ident.name_begin);