Fix: bill_dummy_obj billed excessively for stacks

Add a way to request that unpaid_cost() produce the cost for a single
item, which is necessary for the price adjustment made in
bill_dummy_object.  Another option would be to simply divide by quan in
bill_dummy_object, but this might be more future-proof in case
unpaid_cost ever involves more than simple multiplication by quan
(e.g. the use of alternate units vs the base price, as are used for
globs).

Fixes #1236

include/extern.h

@@ -2809,7 +2809,7 @@ extern long contained_gold(struct obj *, boolean) NONNULLARG1;
 extern void picked_container(struct obj *) NONNULLARG1;
 extern void gem_learned(int);
 extern void alter_cost(struct obj *, long) NONNULLARG1;
-extern long unpaid_cost(struct obj *, boolean) NONNULLARG1;
+extern long unpaid_cost(struct obj *, uchar) NONNULLARG1;
 extern boolean billable(struct monst **, struct obj *, char,
                         boolean) NONNULLARG12;
 extern void addtobill(struct obj *, boolean, boolean, boolean) NONNULLARG1;

include/hack.h

@@ -308,6 +308,13 @@ enum cost_alteration_types {
     COST_CRACK   = 19, /* damage to crystal armor */
 };
 
+/* used by unpaid_cost(shk.h) */
+enum unpaid_cost_flags {
+    COST_NOCONTENTS = 0,
+    COST_CONTENTS   = 1,
+    COST_SINGLEOBJ  = 2,
+};
+
 /* read.c, create_particular() & create_particular_parse() */
 struct _create_particular_data {
     int quan;

src/dogmove.c

@@ -314,7 +314,7 @@ dog_eat(struct monst *mtmp,
         if (obj->unpaid) {
             /* edible item owned by shop has been thrown or kicked
                by hero and caught by tame or food-tameable monst */
-            oprice = unpaid_cost(obj, TRUE);
+            oprice = unpaid_cost(obj, COST_CONTENTS);
             pline("That %s will cost you %ld %s.", objnambuf, oprice,
                   currency(oprice));
             /* m_consume_obj->delobj->obfree will handle actual shop billing update */

src/invent.c

@@ -4110,7 +4110,7 @@ dounpaid(
     }
     if  (otmp && !contnr) {
         /* 1 item; use pline instead of popup menu */
-        cost = unpaid_cost(otmp, FALSE);
+        cost = unpaid_cost(otmp, COST_NOCONTENTS);
         iflags.suppress_price++; /* suppress "(unpaid)" suffix */
         pline1(xprname(otmp, distant_name(otmp, doname),
                        carried(otmp) ? otmp->invlet : CONTAINED_SYM,
@@ -4136,7 +4136,7 @@ dounpaid(
                         classcount++;
                     }
 
-                    totcost += cost = unpaid_cost(otmp, FALSE);
+                    totcost += cost = unpaid_cost(otmp, COST_NOCONTENTS);
                     iflags.suppress_price++; /* suppress "(unpaid)" suffix */
                     putstr(win, 0, xprname(otmp, distant_name(otmp, doname),
                                            ilet, TRUE, cost, 0L));
@@ -4162,7 +4162,7 @@ dounpaid(
 
                 marker = (struct obj *) 0; /* haven't found any */
                 while (find_unpaid(otmp->cobj, &marker)) {
-                    totcost += cost = unpaid_cost(marker, FALSE);
+                    totcost += cost = unpaid_cost(marker, COST_NOCONTENTS);
                     contcost += cost;
                     if (otmp->cknown) {
                         iflags.suppress_price++; /* suppress "(unpaid)" sfx */

src/mkobj.c

@@ -710,7 +710,7 @@ bill_dummy_object(struct obj *otmp)
     long cost = 0L;
 
     if (otmp->unpaid) {
-        cost = unpaid_cost(otmp, FALSE);
+        cost = unpaid_cost(otmp, COST_SINGLEOBJ);
         subfrombill(otmp, shop_keeper(*u.ushops));
     }
     dummy = newobj();

src/objnam.c

@@ -1624,7 +1624,7 @@ doname_base(
         ; /* don't attempt to obtain any shop pricing, even if 'with_price' */
     } else if (is_unpaid(obj)) { /* in inventory or in container in invent */
         char pricebuf[40];
-        long quotedprice = unpaid_cost(obj, TRUE);
+        long quotedprice = unpaid_cost(obj, COST_CONTENTS);
 
         /* separately formatted suffix avoids need for ConcatF3() */
         Sprintf(pricebuf, "%ld %s", quotedprice, currency(quotedprice));

src/shk.c

@@ -2705,7 +2705,7 @@ alter_cost(
 long
 unpaid_cost(
     struct obj *unp_obj, /* known to be unpaid or contain unpaid */
-    boolean include_contents)
+    uchar cost_type) /* COST_NOCONTENTS, COST_CONTENTS, or COST_SINGLEOBJ */
 {
     struct bill_x *bp = (struct bill_x *) 0;
     struct monst *shkp = 0;
@@ -2729,9 +2729,15 @@ unpaid_cost(
 #endif
     for (shop = u.ushops; *shop; shop++) {
         if ((shkp = shop_keeper(*shop)) != 0) {
-            if ((bp = onbill(unp_obj, shkp, TRUE)))
+            if ((bp = onbill(unp_obj, shkp, TRUE))) {
-                amt = unp_obj->quan * bp->price;
+                amt = bp->price;
-            if (include_contents && Has_contents(unp_obj))
+                if (cost_type != COST_SINGLEOBJ) {
+                    /* use quan rather than get_pricing_units -- glob weight
+                       should already be factored into bp->price */
+                    amt *= unp_obj->quan;
+                }
+            }
+            if (cost_type == COST_CONTENTS && Has_contents(unp_obj))
                 amt = contained_cost(unp_obj, shkp, amt, FALSE, TRUE);
             if (bp || (!unp_obj->unpaid && amt))
                 break;