Corpse-eating monsters will home in on corpses

Also allow non-tame ghouls to eat corpses.

doc/fixes3-7-0.txt

@@ -1148,6 +1148,7 @@ prevent hug attacks and touch or engulf attacks for wrap, stick-to, and
 	vortices, a few others)
 wand of speed gives temporary speed, potion gives intrinsic
 some monsters (riders, shopkeepers, priests, quest leader) can break boulders
+corpse-eating monsters will go out of their way to eat corpses on the floor
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

include/extern.h

@@ -1699,6 +1699,7 @@ extern int mstrength(struct permonst *);
 /* ### monmove.c ### */
 
 extern boolean mon_would_take_item(struct monst *, struct obj *);
+extern boolean mon_would_consume_item(struct monst *, struct obj *);
 extern boolean itsstuck(struct monst *);
 extern boolean mb_trapped(struct monst *, boolean);
 extern void mon_track_add(struct monst *, coordxy, coordxy);

include/mondata.h

@@ -254,6 +254,12 @@
     (vegan(ptr)         \
      || ((ptr)->mlet == S_PUDDING && (ptr) != &mons[PM_BLACK_PUDDING]))
 
+#define corpse_eater(ptr)                    \
+    (ptr == &mons[PM_PURPLE_WORM]            \
+     || ptr == &mons[PM_BABY_PURPLE_WORM]    \
+     || ptr == &mons[PM_GHOUL]               \
+     || ptr == &mons[PM_PIRANHA])
+
 /* monkeys are tamable via bananas but not pacifiable via food,
    otherwise their theft attack could be nullified too easily;
    dogs and cats can be tamed by anything they like to eat and are

src/monmove.c

@@ -910,6 +910,17 @@ mon_would_take_item(struct monst *mtmp, struct obj *otmp)
     return FALSE;
 }
 
+/* monster mtmp would love to consume object otmp, without picking it up */
+boolean
+mon_would_consume_item(struct monst *mtmp, struct obj *otmp)
+{
+    if (otmp->otyp == CORPSE && !touch_petrifies(&mons[otmp->corpsenm])
+        && corpse_eater(mtmp->data))
+        return TRUE;
+
+    return FALSE;
+}
+
 boolean
 itsstuck(register struct monst* mtmp)
 {
@@ -1224,8 +1235,9 @@ m_search_items(struct monst *mtmp, coordxy *ggx, coordxy *ggy, schar *mmoved, in
                 if (costly && !otmp->no_charge)
                     continue;
 
-                if (mon_would_take_item(mtmp, otmp)
+                if (((mon_would_take_item(mtmp, otmp)
-                    && (can_carry(mtmp, otmp) > 0)
+                      && (can_carry(mtmp, otmp) > 0))
+                     || mon_would_consume_item(mtmp, otmp))
                     && can_touch_safely(mtmp, otmp)) {
                     minr = distmin(omx, omy, xx, yy);
                     *ggx = otmp->ox;
@@ -1794,9 +1806,7 @@ m_move(register struct monst* mtmp, register int after)
                     return etmp; /* it died or got forced off the level */
             }
             /* Maybe a purple worm ate a corpse */
-            if (ptr == &mons[PM_PURPLE_WORM]
+            if (corpse_eater(ptr)) {
-                || ptr == &mons[PM_BABY_PURPLE_WORM]
-                || ptr == &mons[PM_PIRANHA]) {
                 if ((etmp = meatcorpse(mtmp)) >= 2)
                     return etmp; /* it died or got forced off the level */
             }