hiding under a cockatrice corpse

Reported a while back, a (stonable) hiding monster will hide at a location
containing only a cockatrice corpse.  While it would be interesting to
allow monsters to try, and stone themselves as a result, I chose the
simpler fix which is to not have monsters hide in such situations.  I found
the hiding code was duplicated in several places, so I moved it into a new
hideunder() function that works for both the hero and monsters.

doc/fixes35.0

@@ -34,6 +34,7 @@ grammar, spelling and other typos
 oracle and rumor regarding priestly donations
 keep various delayed killers separate to avoid mixed up messages
 don't place randomly-placed aquatic monsters in lava on special levels
+hiding monsters don't hide under cockatrice/chickatrice corpses
 
 
 Platform- and/or Interface-Specific Fixes

include/extern.h

@@ -1148,6 +1148,7 @@ E void FDECL(seemimic, (struct monst *));
 E void NDECL(rescham);
 E void NDECL(restartcham);
 E void FDECL(restore_cham, (struct monst *));
+E boolean FDECL(hideunder, (struct monst*));
 E void FDECL(mon_animal_list, (BOOLEAN_P));
 E int FDECL(newcham, (struct monst *,struct permonst *,BOOLEAN_P,BOOLEAN_P));
 E int FDECL(can_be_hatched, (int));

src/hack.c

@@ -1339,12 +1339,9 @@ domove()
 		    nomul(0);
 	}
 
-	if (hides_under(youmonst.data))
-	    u.uundetected = OBJ_AT(u.ux, u.uy);
-	else if (youmonst.data->mlet == S_EEL)
-	    u.uundetected = is_pool(u.ux, u.uy) && !Is_waterlevel(&u.uz);
-	else if (u.dx || u.dy)
-	    u.uundetected = 0;
+	if (hides_under(youmonst.data) || (youmonst.data->mlet == S_EEL) ||
+	    u.dx || u.dy)
+	    (void) hideunder(&youmonst);
 
 	/*
 	 * Mimics (or whatever) become noticeable if they move and are

src/invent.c

@@ -2506,7 +2506,7 @@ long numused;
 	}
 	delobj(otmp);
 	if (at_u && u.uundetected && hides_under(youmonst.data))
-	    u.uundetected = OBJ_AT(u.ux, u.uy);
+	    (void) hideunder(&youmonst);
 }
 
 /*

src/makemon.c

@@ -924,8 +924,7 @@ register int	mmflags;
 			if(in_mklev)
 			    if(x && y)
 				(void) mkobj_at(0, x, y, TRUE);
-			if(hides_under(ptr) && OBJ_AT(x, y))
-			    mtmp->mundetected = TRUE;
+			(void) hideunder(mtmp);
 			break;
 		case S_LIGHT:
 		case S_ELEMENTAL:
@@ -935,8 +934,7 @@ register int	mmflags;
 			}
 			break;
 		case S_EEL:
-			if (is_pool(x, y))
-			    mtmp->mundetected = TRUE;
+			(void) hideunder(mtmp);
 			break;
 		case S_LEPRECHAUN:
 			mtmp->msleeping = 1;

src/mon.c

@@ -2248,6 +2248,32 @@ register struct monst *mtmp;
 	return(FALSE);
 }
 
+/* monster/hero tries to hide under something at the current location */
+boolean
+hideunder(mtmp)
+struct monst *mtmp;
+{
+	boolean undetected = FALSE;
+	xchar x = (mtmp == &youmonst) ? u.ux : mtmp->mx;
+	xchar y = (mtmp == &youmonst) ? u.uy : mtmp->my;
+
+	if (mtmp->data->mlet == S_EEL) {
+	    undetected = (is_pool(x, y) && !Is_waterlevel(&u.uz));
+	} else if (hides_under(mtmp->data) && OBJ_AT(x, y)) {
+	    struct obj *otmp = level.objects[x][y];
+
+	    /* most monsters won't hide under cockatrice corpse */
+	    if (otmp->nexthere || otmp->otyp != CORPSE ||
+		(mtmp == &youmonst ? Stone_resistance : resists_ston(mtmp)) ||
+		!touch_petrifies(&mons[otmp->corpsenm]))
+		undetected = TRUE;
+	}
+
+	if (mtmp == &youmonst) u.uundetected = undetected;
+	else mtmp->mundetected = undetected;
+	return undetected;
+}
+
 short *animal_list = 0;		/* list of PM values for animal monsters */
 int animal_list_count;
 
@@ -2444,9 +2470,7 @@ boolean msg;		/* "The oldmon turns into a newmon!" */
 	if (!mtmp->perminvis || pm_invisible(olddata))
 	    mtmp->perminvis = pm_invisible(mdat);
 	mtmp->minvis = mtmp->invis_blkd ? 0 : mtmp->perminvis;
-	if (!(hides_under(mdat) && OBJ_AT(mtmp->mx, mtmp->my)) &&
-			!(mdat->mlet == S_EEL && is_pool(mtmp->mx, mtmp->my)))
-		mtmp->mundetected = 0;
+	if (mtmp->mundetected) (void) hideunder(mtmp);
 	if (u.ustuck == mtmp) {
 		if(u.uswallow) {
 			if(!attacktype(mdat,AT_ENGL)) {

src/monmove.c

@@ -1181,9 +1181,7 @@ postmov:
 		   usually set mundetected unless monster can't move.  */
 		if (mtmp->mundetected ||
 			(mtmp->mcanmove && !mtmp->msleeping && rn2(5)))
-		    mtmp->mundetected = (ptr->mlet != S_EEL) ?
-			OBJ_AT(mtmp->mx, mtmp->my) :
-			(is_pool(mtmp->mx, mtmp->my) && !Is_waterlevel(&u.uz));
+		    (void) hideunder(mtmp);
 		newsym(mtmp->mx, mtmp->my);
 	    }
 	    if (mtmp->isshk) {

src/pickup.c

@@ -585,13 +585,13 @@ end_query:
 	}
 
 	if (!u.uswallow) {
-		if (!OBJ_AT(u.ux,u.uy)) u.uundetected = 0;
+	    if (hides_under(youmonst.data)) (void) hideunder(&youmonst);
 
-		/* position may need updating (invisible hero) */
-		if (n_picked) newsym(u.ux,u.uy);
+	    /* position may need updating (invisible hero) */
+	    if (n_picked) newsym(u.ux,u.uy);
 
-		/* see whether there's anything else here, after auto-pickup is done */
-		if (autopickup) check_here(n_picked > 0);
+	    /* check if there's anything else here after auto-pickup is done */
+	    if (autopickup) check_here(n_picked > 0);
 	}
 	return (n_tried > 0);
 }

src/polyself.c

@@ -458,12 +458,7 @@ int	mntmp;
 		skinback(FALSE);
 	break_armor();
 	drop_weapon(1);
-	if (hides_under(youmonst.data))
-		u.uundetected = OBJ_AT(u.ux, u.uy);
-	else if (youmonst.data->mlet == S_EEL)
-		u.uundetected = is_pool(u.ux, u.uy);
-	else
-		u.uundetected = 0;
+	(void) hideunder(&youmonst);
 
 	if (u.utraptype == TT_PIT) {
 	    if (could_pass_walls && !Passes_walls) {

src/teleport.c

@@ -274,15 +274,9 @@ boolean allow_drag;
 	u.ux0 = u.ux;
 	u.uy0 = u.uy;
 
-	if (hides_under(youmonst.data))
-		u.uundetected = OBJ_AT(nux, nuy);
-	else if (youmonst.data->mlet == S_EEL)
-		u.uundetected = is_pool(nux, nuy);
-	else {
-		u.uundetected = 0;
-		/* mimics stop being unnoticed */
-		if (youmonst.data->mlet == S_MIMIC)
-		    youmonst.m_ap_type = M_AP_NOTHING;
+	if (!hideunder(&youmonst) && youmonst.data->mlet == S_MIMIC) {
+	    /* mimics stop being unnoticed */
+	    youmonst.m_ap_type = M_AP_NOTHING;
 	}
 
 	if (u.uswallow) {