followup to fix for M63 - magic lamp wishes

This uses Michael's suggestion for keeping the display up to date when
removing a djinni or water demon in advance of granting a wish (so that it
won't be present in a bones file if the wish is fatal--problem with earlier
fix was that player could notice monster was already gone while responding
to the wish prompt).  It's not quite as straightforward as I was hoping for
and would get a lot messier if it needed to cope with Warning & Warn_of_mon.

doc/fixes34.4

@@ -119,6 +119,7 @@ reanimating a statue containing gold produced double gold
 probing the resulting double-gold monster caused "static object freed" panic
 cursed wand might explode if used to engrave
 fatal wish from magic lamp left functional magic lamp in bones data
+fatal wish granted by monster left that monster in bones data
 
 
 Platform- and/or Interface-Specific Fixes

include/extern.h

@@ -1625,6 +1625,7 @@ E void FDECL(potionhit, (struct monst *,struct obj *,BOOLEAN_P));
 E void FDECL(potionbreathe, (struct obj *));
 E boolean FDECL(get_wet, (struct obj *));
 E int NDECL(dodip);
+E void FDECL(mongrantswish, (struct monst **));
 E void FDECL(djinni_from_bottle, (struct obj *));
 E struct monst *FDECL(split_mon, (struct monst *,struct monst *));
 E const char *NDECL(bottlename);

src/fountain.c

@@ -56,10 +56,8 @@ dowaterdemon() /* Water demon */
 	    if (rnd(100) > (80 + level_difficulty())) {
 		pline("Grateful for %s release, %s grants you a wish!",
 		      mhis(mtmp), mhe(mtmp));
-		/* bones prep:  remove demon first in case the wish
-		   turns out to be fatal (artifact blast) */
-		mongone(mtmp);
-		makewish();
+		/* give a wish and discard the monster (mtmp set to null) */
+		mongrantswish(&mtmp);
 	    } else if (t_at(mtmp->mx, mtmp->my))
 		(void) mintrap(mtmp);
 	}

src/potion.c

@@ -2042,6 +2042,34 @@ dodip()
 	return(1);
 }
 
+/* *monp grants a wish and then leaves the game */
+void
+mongrantswish(monp)
+struct monst **monp;
+{
+    /* note: `mon' is still valid after mongone() (til next dmonsfree())
+       but it's no longer on the map--affects coordinates and visibility */
+    struct monst *mon = *monp;
+    int mx = mon->mx, my = mon->my;
+    boolean monspotted = canspotmon(mon),
+	    /* no need to handle Warning since monster is peaceful */
+	    disp_hackery = monspotted || Detect_monsters;
+    
+    /* remove the monster first in case wish proves to be fatal
+       (blasted by artifact), to keep it out of resulting bones file */
+    mongone(mon); 
+    *monp = 0;		/* inform caller than monster is gone */
+    /* hide that removal from the player--map is visible during wish prompt */
+    if (disp_hackery) {
+	tmp_at(DISP_ALWAYS,
+	       monspotted ? mon_to_glyph(mon) : detected_mon_to_glyph(mon));
+	tmp_at(mx, my);
+    }
+    /* grant the wish */
+    makewish();
+    /* clean up */
+    if (disp_hackery) tmp_at(DISP_END, 0);
+}
 
 void
 djinni_from_bottle(obj)
@@ -2070,10 +2098,8 @@ register struct obj *obj;
 
 	switch (chance) {
 	case 0 : verbalize("I am in your debt.  I will grant one wish!");
-		/* bones prep:  remove djinni first in case the wish
-		   turns out to be fatal (artifact blast) */
-		mongone(mtmp);
-		makewish();
+		/* give a wish and discard the monster (mtmp set to null) */
+		mongrantswish(&mtmp);
 		break;
 	case 1 : verbalize("Thank you for freeing me!");
 		(void) tamedog(mtmp, (struct obj *)0);