combine-diff: do not lose hunks with only deletion at end.

We used to lose hunks that appear at the end and have only
deletion.  This makes sure that the record beyond the end of
file (which holds such deletions) is examined.

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

combine-diff.c

@@ -243,7 +243,7 @@ static void combine_diff(const unsigned char *parent, mmfile_t *result_file,
 	 * started by showing sline[lno] (possibly showing the lost
 	 * lines attached to it first).
 	 */
-	for (lno = 0,  p_lno = 1; lno < cnt; lno++) {
+	for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
 		struct lline *ll;
 		sline[lno].p_lno[n] = p_lno;
 
@@ -254,7 +254,7 @@ static void combine_diff(const unsigned char *parent, mmfile_t *result_file,
 				p_lno++; /* '-' means parent had it */
 			ll = ll->next;
 		}
-		if (!(sline[lno].flag & nmask))
+		if (lno < cnt && !(sline[lno].flag & nmask))
 			p_lno++; /* no '+' means parent had it */
 	}
 	sline[lno].p_lno[n] = p_lno; /* trailer */
@@ -509,15 +509,28 @@ static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 		int hunk_end;
 		while (lno < cnt && !(sline[lno].flag & mark))
 			lno++;
-		if (cnt <= lno)
+		if (cnt < lno)
 			break;
+		else if (cnt == lno) {
+			/* See if there is anything interesting */
+			struct lline *ll;
+			for (ll = sline[lno].lost_head; ll; ll = ll->next)
+				if (ll->parent_map)
+					break;
+			if (!ll)
+				break;
+			hunk_end = cnt + 1;
+		}
+		else {
 			for (hunk_end = lno + 1; hunk_end < cnt; hunk_end++)
 				if (!(sline[hunk_end].flag & mark))
 					break;
+		}
 		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 		for (i = 0; i < num_parent; i++)
 			show_parent_lno(sline, lno, hunk_end, cnt, i);
-		printf(" +%lu,%lu ", lno+1, hunk_end-lno);
+		printf(" +%lu,%lu ", lno+1,
+		       (cnt == lno) ? 0 : hunk_end - lno);
 		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 		putchar('\n');
 		while (lno < hunk_end) {
@@ -536,6 +549,8 @@ static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 				puts(ll->line);
 				ll = ll->next;
 			}
+			if (cnt <= lno)
+				break;
 			p_mask = 1;
 			for (j = 0; j < num_parent; j++) {
 				if (p_mask & sl->flag)
@@ -560,7 +575,7 @@ static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 	imask = (1UL<<i);
 	jmask = (1UL<<j);
 
-	for (lno = 0; lno < cnt; lno++) {
+	for (lno = 0; lno <= cnt; lno++) {
 		struct lline *ll = sline->lost_head;
 		sline->p_lno[i] = sline->p_lno[j];
 		while (ll) {
@@ -632,10 +647,10 @@ static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
 	if (result_size && result[result_size-1] != '\n')
 		cnt++; /* incomplete line */
 
-	sline = xcalloc(cnt+1, sizeof(*sline));
+	sline = xcalloc(cnt+2, sizeof(*sline));
 	ep = result;
 	sline[0].bol = result;
-	for (lno = 0; lno <= cnt; lno++) {
+	for (lno = 0; lno <= cnt + 1; lno++) {
 		sline[lno].lost_tail = &sline[lno].lost_head;
 		sline[lno].flag = 0;
 	}
@@ -653,8 +668,11 @@ static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
 	result_file.ptr = result;
 	result_file.size = result_size;
 
-	sline[0].p_lno = xcalloc((cnt+1) * num_parent, sizeof(unsigned long));
-	for (lno = 0; lno < cnt; lno++)
+	/* Even p_lno[cnt+1] is valid -- that is for the end line number
+	 * for deletion hunk at the end.
+	 */
+	sline[0].p_lno = xcalloc((cnt+2) * num_parent, sizeof(unsigned long));
+	for (lno = 0; lno <= cnt; lno++)
 		sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 
 	for (i = 0; i < num_parent; i++) {