Subject: Re: [GSoC][PATCHl 5/6] rebase -i: support --ignore-date

From: Phillip Wood <[email-masked]>
Date: Thu, 8 Aug 2019 12:42:19 +0100

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 <[email-masked]>
> ---
>   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.

I'm not keen on talking about lying with the implication of deceit. Just 
say that this resets the author date, there are perfectly legitimate 
reasons to do this.

>   +
>   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));

strchr? I'd be happy to see this using the functions in ident.c which 
check the author is formatted correctly, as it stands this code will 
happily continue if idx == NULL.

> +
> +	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;

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
>