Re: [RFC PATCH v2] shortlog: add group-by options for year and month

[Jeff King <peff@peff.net>]

On Fri, Sep 23, 2022 at 09:38:29PM -0700, Jacob Stopak wrote:

> Hmm I tried passing in --date=format:... to my patched shortlog command
> along with setting some date placeholder like "... %cd ..." in the code,
> but it's not picking up on the format. Do you know how the date format
> can be wedged into the format_commit_message(...) "format" argument?

It comes to the format code via the pretty_print_context. And we pick up
the --date command via setup_revisions(), where it ends up in
rev_info.date_mode.

In a normal git-log, I think that data gets shuffled across by
show_log(). But shortlog has its own traversal.

I think something like this:

diff --git a/builtin/shortlog.c b/builtin/shortlog.c
index 7a1e1fe7c0..53c379a51d 100644
--- a/builtin/shortlog.c
+++ b/builtin/shortlog.c
@@ -211,7 +211,7 @@ void shortlog_add_commit(struct shortlog *log, struct commit *commit)
 	ctx.fmt = CMIT_FMT_USERFORMAT;
 	ctx.abbrev = log->abbrev;
 	ctx.print_email_subject = 1;
-	ctx.date_mode.type = DATE_NORMAL;
+	ctx.date_mode = log->date_mode;
 	ctx.output_encoding = get_log_output_encoding();
 
 	if (!log->summary) {
@@ -407,6 +407,7 @@ int cmd_shortlog(int argc, const char **argv, const char *prefix)
 	log.user_format = rev.commit_format == CMIT_FMT_USERFORMAT;
 	log.abbrev = rev.abbrev;
 	log.file = rev.diffopt.file;
+	log.date_mode = rev.date_mode;
 
 	if (!log.groups)
 		log.groups = SHORTLOG_GROUP_AUTHOR;
diff --git a/shortlog.h b/shortlog.h
index 3f7e9aabca..ef3a3dbc65 100644
--- a/shortlog.h
+++ b/shortlog.h
@@ -15,6 +15,7 @@ struct shortlog {
 	int in2;
 	int user_format;
 	int abbrev;
+	struct date_mode date_mode;
 
 	enum {
 		SHORTLOG_GROUP_AUTHOR = (1 << 0),

is enough. At least it allows:

  git shortlog --format='%ad %s' --date=format:%Y-%m

to work as you'd expect (but of course that's just the output for each
commit that we show, not the actual grouping).

> > Unfortunately there's no way to specify the format as part of the
> > placeholder. The for-each-ref formatter understands this, like:
> > 
> >   %(authordate:format:%Y-%m)
> >
> > I wouldn't be opposed to teaching the git-log formatter something
> > similar.
> 
> Oh that would solve my problem... Would it be a hefty effort to teach
> this to the git-log formatter?

Probably not a huge amount of work. But it puts us in a weird in-between
situation where we support _one_ of the more advanced ref-filter
placeholders, but not the others. And of course no code is shared.

That might be OK, as long as the syntax and semantics are identical to
what ref-filter can do. Then in the long run, if we eventually merge the
two implementations, there's no compatibility problem.

That said, I think it may just be easier to respect --date, as above.
It's not quite as flexible, but it's probably flexible enough.

-Peff