reset travel cache when changing levels

When travel fails to reach its destination, it remembers the target
spot to use as default next time.  But that spot is only meaningful
on the current level.  Discard last travel destination when moving
to a different level.

Also, discard unlocking context when changing level unless the
context is for a container being brought along (after having been
picked up since you can't unlock a carried box).  Previously, a
door pointer on the new level could happen to match the last one
being unlocked on the old level.

Discard trap setting context when changing level even if the trap
object is brought along.

Somehow the code for applying a touchstone got inserted in between
two sections of code for applying a trap (ages ago; probably since
touchstone was first introduced however many versions back), so
clean that up.

doc/fixes36.1

@@ -53,6 +53,7 @@ dipping fruit juice into enlightenment gave different result than the inverse
 make travel walk up to a trap and stop when the trap blocks the only
 	way forward, instead of trying to go straight line
 travel will displace pets rather than stop
+discard travel cache when moving to a different dungeon level
 do not autopickup unpaid items in shops
 death due an unseen gas spore's explosion resulted in "killed by a died"
 allow optional parameter "true", "yes", "false", or "no" for boolean options

include/extern.h

@@ -1013,6 +1013,7 @@ E boolean FDECL(picking_lock, (int *, int *));
 E boolean FDECL(picking_at, (int, int));
 E void FDECL(breakchestlock, (struct obj *, BOOLEAN_P));
 E void NDECL(reset_pick);
+E void NDECL(maybe_reset_pick);
 E int FDECL(pick_lock, (struct obj *));
 E int NDECL(doforce);
 E boolean FDECL(boxlock, (struct obj *, struct obj *));

src/apply.c

@@ -2179,20 +2179,6 @@ struct obj *obj;
     update_inventory();
 }
 
-static struct trapinfo {
-    struct obj *tobj;
-    xchar tx, ty;
-    int time_needed;
-    boolean force_bungle;
-} trapinfo;
-
-void
-reset_trapset()
-{
-    trapinfo.tobj = 0;
-    trapinfo.force_bungle = 0;
-}
-
 /* touchstones - by Ken Arnold */
 STATIC_OVL void
 use_stone(tstone)
@@ -2322,6 +2308,20 @@ struct obj *tstone;
     return;
 }
 
+static struct trapinfo {
+    struct obj *tobj;
+    xchar tx, ty;
+    int time_needed;
+    boolean force_bungle;
+} trapinfo;
+
+void
+reset_trapset()
+{
+    trapinfo.tobj = 0;
+    trapinfo.force_bungle = 0;
+}
+
 /* Place a landmine/bear trap.  Helge Hafting */
 STATIC_OVL void
 use_trap(otmp)

src/do.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	do.c	$NHDT-Date: 1454033599 2016/01/29 02:13:19 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.153 $ */
+/* NetHack 3.6	do.c	$NHDT-Date: 1464487100 2016/05/29 01:58:20 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.156 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -1523,13 +1523,20 @@ boolean at_stairs, falling, portal;
     save_currentstate();
 #endif
 
-    if ((annotation = get_annotation(&u.uz)))
+    if ((annotation = get_annotation(&u.uz)) != 0)
         You("remember this level as %s.", annotation);
 
     /* assume this will always return TRUE when changing level */
     (void) in_out_region(u.ux, u.uy);
     (void) pickup(1);
-    context.polearm.hitmon = NULL;
+
+    /* discard context which applied to previous level */
+    maybe_reset_pick(); /* for door or for box not accompanying hero */
+    reset_trapset(); /* even if to-be-armed trap obj is accompanying hero */
+    iflags.travelcc.x = iflags.travelcc.y = -1; /* travel destination cache */
+    context.polearm.hitmon = (struct monst *) 0; /* polearm target */
+    /* digging context is level-aware and can actually be resumed if
+       hero returns to the previous level without any intervening dig */
 }
 
 STATIC_OVL void

src/lock.c

@@ -75,7 +75,8 @@ STATIC_PTR int
 picklock(VOID_ARGS)
 {
     if (xlock.box) {
-        if ((xlock.box->ox != u.ux) || (xlock.box->oy != u.uy)) {
+        if (xlock.box->where != OBJ_FLOOR
+            || xlock.box->ox != u.ux || xlock.box->oy != u.uy) {
             return ((xlock.usedtime = 0)); /* you or it moved */
         }
     } else { /* door */
@@ -228,6 +229,14 @@ reset_pick()
     xlock.box = 0;
 }
 
+/* level change; don't reset if hero is carrying xlock.box with him/her */
+void
+maybe_reset_pick()
+{
+    if (!xlock.box || !carried(xlock.box))
+        reset_pick();
+}
+
 /* for doapply(); if player gives a direction or resumes an interrupted
    previous attempt then it costs hero a move even if nothing ultimately
    happens; when told "can't do that" before being asked for direction