From d5d88e7104eb008581ae5507bcb6ad8270d769e5 Mon Sep 17 00:00:00 2001
From: backwardsEric
Date: Fri, 13 Sep 2019 21:07:53 -0700
Subject: [PATCH] Observed levels in Yeek's den (most frequently level 12) with
 patches of unrecognied terrain and had crashes on such levels where the
 common symptom was an out-of-bounds feature index.  Changed floor-generate.c
 so that nothing is done when adding a river to a dungeon, like Yeek's den,
 that does not accept any of the river types.  Have not seen levels with
 patches of unrecognized terrain since the change.

---
 src/floor-generate.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/floor-generate.c b/src/floor-generate.c
index 909c0eb7..a02de14b 100644
--- a/src/floor-generate.c
+++ b/src/floor-generate.c
@@ -698,7 +698,7 @@ static bool cave_gen(void)
 			{
 				FEAT_IDX select_deep_feat[10];
 				FEAT_IDX select_shallow_feat[10];
-				int select_id_max = 0, selected;
+				int select_id_max = 0;
 
 				if (d_info[p_ptr->dungeon_idx].flags1 & DF1_LAVA_RIVER)
 				{
@@ -719,9 +719,13 @@ static bool cave_gen(void)
 					select_id_max++;
 				}
 
-				selected = randint0(select_id_max);
-				feat1 = select_deep_feat[selected];
-				feat2 = select_shallow_feat[selected];
+				if (select_id_max > 0)
+				{
+					int selected = randint0(select_id_max);
+
+					feat1 = select_deep_feat[selected];
+					feat2 = select_shallow_feat[selected];
+				}
 			}
 
 			if (feat1)
-- 
2.20.1 (Apple Git-117)