fix #K4063 - "back on ground" given at odd time

Moving over at item that's resting on ice gives a message about there
being ice present and then about the item, whether mention_decor is On
or Off.  With it On, you'll get a message about being back on solid
ground as soon as you leave the ice.  With it Off you wouldn't get
that at all if not levitating; that's the basic no-mention_decor
behavior for ice.  However, if you were levitating, you would get a
delayed "back on solid ground" message when moving over some other
object, which might occur quite a bit later.  Autopickup handling is
calling describe_decor() when the hero is levitating and some of that
wasn't appropriate for no-mention_decor.

This issue has been present since I first implemented mention_decor,
not introduced by recent back_on_ground() changes.

doc/fixes3-7-0.txt

@@ -1801,6 +1801,10 @@ add 'X' as a potential context-sensitive item-action for uwep and uswapwep
 monsters weren't noticing hero's possession or lack of magic resistance when
 	hero getting zapped by a wand of striking was or wasn't resisted
 discard monsters' observations about hero's resistances when saving bones
+autopickup while levitating shares code with 'mention_decor'; after being told
+	about ice covered by an object, moving over some other object later
+	when mention_decor is Off could give "you are back on solid ground"
+	long after leaving the ice
 
 
 Fixes to 3.7.0-x Platform and/or Interface Problems Exposed Via git Repository

src/hack.c

@@ -2831,7 +2831,6 @@ pooleffects(
                 You("leave the %s...", hliquid("water")); /* oops! */
             } else {
                 back_on_ground(FALSE);
-                iflags.last_msg = PLNMSG_BACK_ON_GROUND;
             }
         } else if (Is_waterlevel(&u.uz)) {
             still_inwater = TRUE;

src/pickup.c

@@ -299,14 +299,16 @@ void
 force_decor(boolean via_probing)
 {
     /* we don't want describe_decor() to defer feedback if hero is fumbling
-       with 1 turn left, or for ice_descr() to skip thawing details if hero
+       with 1 turn left until next slip_or_trip(), or for ice_descr() to
-       is probing when levitating while blind (those will be skipped for
+       omit thawing details if hero is probing when levitating while blind
-       look_here() and farlook() or autodescribe); we can't control that by
+       (those will be skipped for look_here() and farlook() or autodescribe);
-       temporarily tweaking properties because that could become noticeable
+       we can't control that by temporarily tweaking properties because that
-       if status gets updated while decor feedback is being delivered */
+       could become noticeable if status gets updated while decor feedback
+       is being delivered */
     gd.decor_fumble_override = TRUE;
     gd.decor_levitate_override = via_probing;
-    /* force current terrain to be different from previous location */
+    /* force current terrain to be different from previous location, or
+       uninteresting if previous location was actually inside solid stone */
     iflags.prev_decor = STONE;
     (void) describe_decor();
     gd.decor_fumble_override = gd.decor_levitate_override = FALSE;
@@ -314,9 +316,12 @@ force_decor(boolean via_probing)
 }
 
 void
-deferred_decor(boolean setup) /* True: deferring, False: catching up */
+deferred_decor(
+    boolean setup) /* True: deferring, False: catching up */
 {
-    if (setup) {
+    if (!flags.mention_decor) {
+        iflags.defer_decor = FALSE;
+    } else if (setup) {
         iflags.defer_decor = TRUE;
     } else {
         (void) describe_decor();
@@ -334,14 +339,17 @@ describe_decor(void)
     const char *dfeature;
     int ltyp;
 
-    if ((HFumbling & TIMEOUT) == 1L && !iflags.defer_decor
+    if ((HFumbling & TIMEOUT) == 1L /* about to slip_or_trip */
+        && !iflags.defer_decor
         && !gd.decor_fumble_override) { /* probe_decor() */
         /*
-         * Work around a message sequencing issue:  avoid
+         * Work around a message sequencing issue if Fumbling's periodic
+         * timeout is about to kick in:  avoid the combination
          *  |You are back on floor.
          *  |You trip over <object>.  or  You flounder.
          * when the trip is being caused by moving on ice as hero
-         * steps off ice onto non-ice.
+         * steps off ice onto non-ice.  Defer the back-on-floor part if
+         * that is about to happen.
          */
         deferred_decor(TRUE);
         return FALSE;
@@ -378,7 +386,7 @@ describe_decor(void)
                 Strcpy(fbuf, dfeature);
             Sprintf(outbuf, "%s.", upstart(fbuf));
         }
-        if (ltyp == ICE)
+        if (ltyp == ICE && flags.mention_decor)
             Norep("%s", outbuf);
         else
             pline("%s", outbuf);
@@ -391,7 +399,11 @@ describe_decor(void)
             }
         }
     }
-    iflags.prev_decor = ltyp;
+    /* describe_decor() is normally called when moving onto a different
+       type of terrain, but it is also called by pickup() even when
+       mention_decor is Off if hero can't reach floor; only adapt the next
+       describe_decor() by what has just occurred in this one when it's On */
+    iflags.prev_decor = flags.mention_decor ? ltyp : STONE;
     return res;
 }
 

src/timeout.c

@@ -1138,9 +1138,7 @@ slip_or_trip(void)
     struct obj *otmp = vobj_at(u.ux, u.uy), *otmp2;
     const char *what;
     char buf[BUFSZ];
-    boolean on_foot = TRUE;
+    boolean on_foot = !u.usteed;
-    if (u.usteed)
-        on_foot = FALSE;
 
     if (otmp && on_foot && !u.uinwater && is_pool(u.ux, u.uy))
         otmp = 0;
@@ -1179,11 +1177,14 @@ slip_or_trip(void)
         /* is fumbling from ice alone? */
         boolean ice_only = !(EFumbling || (HFumbling & ~FROMOUTSIDE));
 
-        pline("%s %s%s on the ice.",
+        pline("%s %s%s %s the ice.",
               u.usteed ? upstart(x_monnam(u.usteed, ARTICLE_THE, (char *) 0,
                                           SUPPRESS_SADDLE, FALSE))
                        : "You",
-              rn2(2) ? "slip" : "slide", on_foot ? "" : "s");
+              rn2(2) ? "slip" : "slide", on_foot ? "" : "s",
+              /* sometimes slipping due to ice occurs during turn that hero
+                 has just moved off the ice; phrase things differently then */
+              is_ice(u.ux, u.uy) ? "on" : "off");
         /* fumbling outside of ice while mounted always causes the hero to
            fall from the saddle, so to avoid a counterintuitive effect where
            ice makes riding _less_ hazardous, unconditionally dismount if

src/trap.c

@@ -4728,6 +4728,7 @@ back_on_ground(boolean rescued)
         you_are_back = flags.verbose ? "You are back" : "Back";
     }
     pline("%s %s %s.", you_are_back, preposit, surf);
+    iflags.last_msg = PLNMSG_BACK_ON_GROUND;
 }
 
 /* life-saving or divine rescue has attempted to get the hero out of hostile