shortlog: accept `--date`-related options

Prepare for a future patch which will introduce arbitrary pretty formats
via the `--group` argument.

To allow additional customizability (for example, to support something
like `git shortlog -s --group='%aD' --date='format:%Y-%m' ...` (which
groups commits by the datestring 'YYYY-mm' according to author date), we
must store off the `--date` parsed from calling `parse_revision_opt()`.

Note that this also affects custom output `--format` strings in `git
shortlog`. Though this is a behavior change, this is arguably fixing a
long-standing bug (ie., that `--format` strings are not affected by
`--date` specifiers as they should be).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-shortlog.txt

@@ -47,6 +47,11 @@ OPTIONS
 
 	Each pretty-printed commit will be rewrapped before it is shown.
 
+--date=<format>::
+	Show dates formatted according to the given date string. (See
+	the `--date` option in the "Commit Formatting" section of
+	linkgit:git-log[1]).
+
 --group=<type>::
 	Group commits based on `<type>`. If no `--group` option is
 	specified, the default is `author`. `<type>` is one of:

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 @@ parse_done:
 	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;

shortlog.h

@@ -2,6 +2,7 @@
 #define SHORTLOG_H
 
 #include "string-list.h"
+#include "date.h"
 
 struct commit;
 
@@ -15,6 +16,7 @@ struct shortlog {
 	int in2;
 	int user_format;
 	int abbrev;
+	struct date_mode date_mode;
 
 	enum {
 		SHORTLOG_GROUP_AUTHOR = (1 << 0),

t/t4201-shortlog.sh

@@ -83,6 +83,13 @@ test_expect_success 'pretty format' '
 	test_cmp expect log.predictable
 '
 
+test_expect_success 'pretty format (with --date)' '
+	sed "s/SUBJECT/2005-04-07 OBJECT_NAME/" expect.template >expect &&
+	git shortlog --format="%ad %H" --date=short HEAD >log &&
+	fuzz log >log.predictable &&
+	test_cmp expect log.predictable
+'
+
 test_expect_success '--abbrev' '
 	sed s/SUBJECT/OBJID/ expect.template >expect &&
 	git shortlog --format="%h" --abbrev=35 HEAD >log &&