Merge branch 'jk/reflog-date' into maint

The reflog output format is documented better, and a new format
--date=unix to report the seconds-since-epoch (without timezone)
has been added.

* jk/reflog-date:
  date: clarify --date=raw description
  date: add "unix" format
  date: document and test "raw-local" mode
  doc/pretty-formats: explain shortening of %gd
  doc/pretty-formats: describe index/time formats for %gd
  doc/rev-list-options: explain "-g" output formats
  doc/rev-list-options: clarify "commit@{Nth}" for "-g" option

Documentation/pretty-formats.txt

@@ -147,8 +147,14 @@ endif::git-rev-list[]
   "U" for a good signature with unknown validity and "N" for no signature
 - '%GS': show the name of the signer for a signed commit
 - '%GK': show the key used to sign a signed commit
-- '%gD': reflog selector, e.g., `refs/stash@{1}`
+- '%gD': reflog selector, e.g., `refs/stash@{1}` or
-- '%gd': shortened reflog selector, e.g., `stash@{1}`
+  `refs/stash@{2 minutes ago`}; the format follows the rules described
+  for the `-g` option. The portion before the `@` is the refname as
+  given on the command line (so `git log -g refs/heads/master` would
+  yield `refs/heads/master@{0}`).
+- '%gd': shortened reflog selector; same as `%gD`, but the refname
+  portion is shortened for human readability (so `refs/heads/master`
+  becomes just `master`).
 - '%gn': reflog identity name
 - '%gN': reflog identity name (respecting .mailmap, see
   linkgit:git-shortlog[1] or linkgit:git-blame[1])

Documentation/rev-list-options.txt

@@ -252,10 +252,25 @@ list.
 +
 With `--pretty` format other than `oneline` (for obvious reasons),
 this causes the output to have two extra lines of information
-taken from the reflog.  By default, 'commit@\{Nth}' notation is
+taken from the reflog.  The reflog designator in the output may be shown
-used in the output.  When the starting commit is specified as
+as `ref@{Nth}` (where `Nth` is the reverse-chronological index in the
-'commit@\{now}', output also uses 'commit@\{timestamp}' notation
+reflog) or as `ref@{timestamp}` (with the timestamp for that entry),
-instead.  Under `--pretty=oneline`, the commit message is
+depending on a few rules:
++
+--
+1. If the starting point is specified as `ref@{Nth}`, show the index
+format.
++
+2. If the starting point was specified as `ref@{now}`, show the
+timestamp format.
++
+3. If neither was used, but `--date` was given on the command line, show
+the timestamp in the format requested by `--date`.
++
+4. Otherwise, show the index format.
+--
++
+Under `--pretty=oneline`, the commit message is
 prefixed with this information on the same line.
 This option cannot be combined with `--reverse`.
 See also linkgit:git-reflog[1].
@@ -710,8 +725,8 @@ include::pretty-options.txt[]
 	`iso-local`), the user's local time zone is used instead.
 +
 `--date=relative` shows dates relative to the current time,
-e.g. ``2 hours ago''. The `-local` option cannot be used with
+e.g. ``2 hours ago''. The `-local` option has no effect for
-`--raw` or `--relative`.
+`--date=relative`.
 +
 `--date=local` is an alias for `--date=default-local`.
 +
@@ -731,7 +746,18 @@ format, often found in email messages.
 +
 `--date=short` shows only the date, but not the time, in `YYYY-MM-DD` format.
 +
-`--date=raw` shows the date in the internal raw Git format `%s %z` format.
+`--date=raw` shows the date as seconds since the epoch (1970-01-01
+00:00:00 UTC), followed by a space, and then the timezone as an offset
+from UTC (a `+` or `-` with four digits; the first two are hours, and
+the second two are minutes). I.e., as if the timestamp were formatted
+with `strftime("%s %z")`).
+Note that the `-local` option does not affect the seconds-since-epoch
+value (which is always measured in UTC), but does switch the accompanying
+timezone value.
++
+`--date=unix` shows the date as a Unix epoch timestamp (seconds since
+1970).  As with `--raw`, this is always in UTC and therefore `-local`
+has no effect.
 +
 `--date=format:...` feeds the format `...` to your system `strftime`.
 Use `--date=format:%c` to show the date in your system locale's

builtin/blame.c

@@ -2633,6 +2633,9 @@ parse_done:
 	case DATE_RAW:
 		blame_date_width = sizeof("1161298804 -0700");
 		break;
+	case DATE_UNIX:
+		blame_date_width = sizeof("1161298804");
+		break;
 	case DATE_SHORT:
 		blame_date_width = sizeof("2006-10-19");
 		break;

cache.h

@@ -1224,7 +1224,8 @@ struct date_mode {
 		DATE_ISO8601_STRICT,
 		DATE_RFC2822,
 		DATE_STRFTIME,
-		DATE_RAW
+		DATE_RAW,
+		DATE_UNIX
 	} type;
 	const char *strftime_fmt;
 	int local;

date.c

@@ -177,6 +177,12 @@ const char *show_date(unsigned long time, int tz, const struct date_mode *mode)
 	struct tm *tm;
 	static struct strbuf timebuf = STRBUF_INIT;
 
+	if (mode->type == DATE_UNIX) {
+		strbuf_reset(&timebuf);
+		strbuf_addf(&timebuf, "%lu", time);
+		return timebuf.buf;
+	}
+
 	if (mode->local)
 		tz = local_tzoffset(time);
 
@@ -792,6 +798,8 @@ static enum date_mode_type parse_date_type(const char *format, const char **end)
 		return DATE_NORMAL;
 	if (skip_prefix(format, "raw", end))
 		return DATE_RAW;
+	if (skip_prefix(format, "unix", end))
+		return DATE_UNIX;
 	if (skip_prefix(format, "format", end))
 		return DATE_STRFTIME;
 

t/t0006-date.sh

@@ -46,7 +46,10 @@ check_show rfc2822 "$TIME" 'Wed, 15 Jun 2016 16:13:20 +0200'
 check_show short "$TIME" '2016-06-15'
 check_show default "$TIME" 'Wed Jun 15 16:13:20 2016 +0200'
 check_show raw "$TIME" '1466000000 +0200'
+check_show unix "$TIME" '1466000000'
 check_show iso-local "$TIME" '2016-06-15 14:13:20 +0000'
+check_show raw-local "$TIME" '1466000000 +0000'
+check_show unix-local "$TIME" '1466000000'
 
 # arbitrary time absurdly far in the future
 FUTURE="5758122296 -0400"