Monsters see and remember when others trigger traps

No longer will there be a conga line of hill orcs stepping into
the same arrow trap one after another.

doc/fixes3-7-0.txt

@@ -1013,6 +1013,7 @@ when breaking a wand of sleep hits the hero with the explosion, don't describe
 	that as "the sleep ray hits you"
 expose fuz tester to wizard-mode as #fuzzer extended command
 monsters which cannot move due to boulders or walls try to escape
+intelligent monsters see and remember when others trigger traps
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository

include/extern.h

@@ -1653,6 +1653,7 @@ extern void monstseesu(unsigned long);
 extern boolean resist_conflict(struct monst *);
 extern boolean mon_knows_traps(struct monst *, int);
 extern void mon_learns_traps(struct monst *, int);
+extern void mons_see_trap(struct trap *);
 
 /* ### monmove.c ### */
 

src/mondata.c

@@ -1396,4 +1396,24 @@ mon_learns_traps(struct monst *mtmp, int ttyp)
         mtmp->mtrapseen |= (1L << (ttyp - 1));
 }
 
+/* monsters see a trap trigger, and remember it */
+void
+mons_see_trap(struct trap *ttmp)
+{
+    struct monst *mtmp;
+    coordxy tx = ttmp->tx, ty = ttmp->ty;
+    int maxdist = levl[tx][ty].lit ? 7*7 : 2;
+
+    for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
+        if (is_animal(mtmp->data) || mindless(mtmp->data)
+            || !haseyes(mtmp->data) || !mtmp->mcansee)
+            continue;
+        if (dist2(mtmp->mx, mtmp->my, tx, ty) > maxdist)
+            continue;
+        if (!m_cansee(mtmp, tx, ty))
+            continue;
+        mon_learns_traps(mtmp, ttmp->ttyp);
+    }
+}
+
 /*mondata.c*/

src/monmove.c

@@ -1269,6 +1269,7 @@ m_move(register struct monst* mtmp, register int after)
         register struct obj *otmp;
         register coordxy xx, yy;
         coordxy oomx, oomy, lmx, lmy;
+        struct trap *ttmp;
 
         /* cut down the search radius if it thinks character is closer. */
         if (distmin(mtmp->mux, mtmp->muy, omx, omy) < SQSRCHRADIUS
@@ -1321,6 +1322,16 @@ m_move(register struct monst* mtmp, register int after)
                         || (is_lava(xx, yy) && !likes_lava(ptr)))
                         continue;
 
+                    /* ignore obj if there's a trap and monster knows it */
+                    if ((ttmp = t_at(xx, yy)) != 0
+                        && mon_knows_traps(mtmp, ttmp->ttyp)) {
+                        if (gx == xx && gy == yy) {
+                            gx = mtmp->mux;
+                            gy = mtmp->muy;
+                        }
+                        continue;
+                    }
+
                     if (((likegold && otmp->oclass == COIN_CLASS)
                          || (likeobjs && index(practical, otmp->oclass)
                              && (otmp->otyp != CORPSE

src/trap.c

@@ -2553,6 +2553,7 @@ dotrap(struct trap *trap, unsigned trflags)
 
     if (u.usteed)
         mon_learns_traps(u.usteed, ttype);
+    mons_see_trap(trap);
 
     /*
      * Note:
@@ -3271,6 +3272,7 @@ mintrap(struct monst *mtmp, unsigned mintrapflags)
         }
 
         mon_learns_traps(mtmp, tt);
+        mons_see_trap(trap);
 
         /* Monster is aggravated by being trapped by you.
            Recognizing who made the trap isn't completely