diff-files --stat: do not dump core with unmerged index.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff.c

@@ -202,6 +202,8 @@ struct diffstat_t {
 	int alloc;
 	struct diffstat_file {
 		char *name;
+		unsigned is_unmerged:1;
+		unsigned is_binary:1;
 		unsigned int added, deleted;
 	} **files;
 };
@@ -248,6 +250,8 @@ static void show_stats(struct diffstat_t* data)
 	for (i = 0; i < data->nr; i++) {
 		struct diffstat_file *file = data->files[i];
 
+		if (file->is_binary || file->is_unmerged)
+			continue;
 		if (max_change < file->added + file->deleted)
 			max_change = file->added + file->deleted;
 		len = strlen(file->name);
@@ -292,11 +296,15 @@ static void show_stats(struct diffstat_t* data)
 		if (max + len > 70)
 			max = 70 - len;
 
-		if (added < 0) {
-			/* binary file */
+		if (data->files[i]->is_binary) {
 			printf(" %s%-*s |  Bin\n", prefix, len, name);
 			goto free_diffstat_file;
-		} else if (added + deleted == 0) {
+		}
+		else if (data->files[i]->is_unmerged) {
+			printf(" %s%-*s |  Unmerged\n", prefix, len, name);
+			goto free_diffstat_file;
+		}
+		else if (added + deleted == 0) {
 			total_files--;
 			goto free_diffstat_file;
 		}
@@ -424,11 +432,16 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 
 	data = diffstat_add(diffstat, name_a ? name_a : name_b);
 
+	if (!one || !two) {
+		data->is_unmerged = 1;
+		return;
+	}
+
 	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 		die("unable to read files to diff");
 
 	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
-		data->added = -1;
+		data->is_binary = 1;
 	else {
 		/* Crazy xdl interfaces.. */
 		xpparam_t xpp;