diff-options: add --patch-with-stat

With this option, git prepends a diffstat in front of the patch.

Since I really, really do not know what a diffstat of a combined diff
("merge diff") should look like, the diffstat is not generated for these.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/diff-options.txt

@@ -10,6 +10,9 @@
 --stat::
 	Generate a diffstat instead of a patch.
 
+--patch-with-stat::
+	Generate patch and prepend its diffstat.
+
 -z::
 	\0 line termination on output
 

diff.c

@@ -1060,6 +1060,10 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	}
 	else if (!strcmp(arg, "--stat"))
 		options->output_format = DIFF_FORMAT_DIFFSTAT;
+	else if (!strcmp(arg, "--patch-with-stat")) {
+		options->output_format = DIFF_FORMAT_PATCH;
+		options->with_stat = 1;
+	}
 	else if (!strcmp(arg, "-z"))
 		options->line_termination = 0;
 	else if (!strncmp(arg, "-l", 2))
@@ -1529,7 +1533,7 @@ void diff_flush(struct diff_options *options)
 	int diff_output_format = options->output_format;
 	struct diffstat_t *diffstat = NULL;
 
-	if (diff_output_format == DIFF_FORMAT_DIFFSTAT) {
+	if (diff_output_format == DIFF_FORMAT_DIFFSTAT || options->with_stat) {
 		diffstat = xcalloc(sizeof (struct diffstat_t), 1);
 		diffstat->xm.consume = diffstat_consume;
 	}
@@ -1541,6 +1545,17 @@ void diff_flush(struct diff_options *options)
 		}
 		putchar(options->line_termination);
 	}
+	if (options->with_stat) {
+		for (i = 0; i < q->nr; i++) {
+			struct diff_filepair *p = q->queue[i];
+			flush_one_pair(p, DIFF_FORMAT_DIFFSTAT, options,
+					diffstat);
+		}
+		show_stats(diffstat);
+		free(diffstat);
+		diffstat = NULL;
+		putchar(options->line_termination);
+	}
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
 		flush_one_pair(p, diff_output_format, options, diffstat);

diff.h

@@ -25,6 +25,7 @@ struct diff_options {
 	const char *pickaxe;
 	unsigned recursive:1,
 		 with_raw:1,
+		 with_stat:1,
 		 tree_in_recursive:1,
 		 full_index:1;
 	int break_opt;
@@ -120,6 +121,8 @@ extern void diffcore_std_no_resolve(struct diff_options *);
 "  --patch-with-raw\n" \
 "                output both a patch and the diff-raw format.\n" \
 "  --stat        show diffstat instead of patch.\n" \
+"  --patch-with-stat\n" \
+"                output a patch and prepend its diffstat.\n" \
 "  --name-only   show only names of changed files.\n" \
 "  --name-status show names and status of changed files.\n" \
 "  --full-index  show full object name on index lines.\n" \