submodule summary: ignore --for-status option

The --for-status option was an undocumented option used only by
wt-status.c, which inserted a header and commented out the output. We can
achieve the same result within wt-status.c, without polluting the
submodule command-line options.

This will make it easier to disable the comments from wt-status.c later.

The --for-status is kept so that another topic in flight
(bc/submodule-status-ignored) can continue relying on it, although it is
currently a no-op.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-submodule.sh

@@ -1149,18 +1149,7 @@ cmd_summary() {
 			echo
 		fi
 		echo
-	done |
-	if test -n "$for_status"; then
-		if [ -n "$files" ]; then
-			gettextln "Submodules changed but not updated:" | git stripspace -c
-		else
-			gettextln "Submodule changes to be committed:" | git stripspace -c
-		fi
-		printf "\n" | git stripspace -c
-		git stripspace -c
-	else
-		cat
-	fi
+	done
 }
 #
 # List all submodules, prefixed with:

t/t7401-submodule-summary.sh

@@ -265,13 +265,11 @@ EOF
 test_expect_success '--for-status' "
 	git submodule summary --for-status HEAD^ >actual &&
 	test_i18ncmp actual - <<EOF
-# Submodule changes to be committed:
-#
-# * sm1 $head6...0000000:
-#
-# * sm2 0000000...$head7 (2):
-#   > Add foo9
-#
+* sm1 $head6...0000000:
+
+* sm2 0000000...$head7 (2):
+  > Add foo9
+
 EOF
 "
 

wt-status.c

@@ -665,6 +665,10 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 	char index[PATH_MAX];
 	const char *env[] = { NULL, NULL };
 	struct argv_array argv = ARGV_ARRAY_INIT;
+	struct strbuf cmd_stdout = STRBUF_INIT;
+	struct strbuf summary = STRBUF_INIT;
+	char *summary_content;
+	size_t len;
 
 	sprintf(summary_limit, "%d", s->submodule_summary);
 	snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", s->index_file);
@@ -685,9 +689,30 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 	sm_summary.git_cmd = 1;
 	sm_summary.no_stdin = 1;
 	fflush(s->fp);
-	sm_summary.out = dup(fileno(s->fp));    /* run_command closes it */
+	sm_summary.out = -1;
+
 	run_command(&sm_summary);
 	argv_array_clear(&argv);
+
+	len = strbuf_read(&cmd_stdout, sm_summary.out, 1024);
+
+	/* prepend header, only if there's an actual output */
+	if (len) {
+		if (uncommitted)
+			strbuf_addstr(&summary, _("Submodules changed but not updated:"));
+		else
+			strbuf_addstr(&summary, _("Submodule changes to be committed:"));
+		strbuf_addstr(&summary, "\n\n");
+	}
+	strbuf_addbuf(&summary, &cmd_stdout);
+	strbuf_release(&cmd_stdout);
+
+	summary_content = strbuf_detach(&summary, &len);
+	strbuf_add_commented_lines(&summary, summary_content, len);
+	free(summary_content);
+
+	fputs(summary.buf, s->fp);
+	strbuf_release(&summary);
 }
 
 static void wt_status_print_other(struct wt_status *s,