Re: [gnugo-devel] bug report

[Gunnar Farnebäck]

On 07/04/11 13:19, Hendrik Baier wrote:
> ***assertion failure:
> board.c:1173 - board[pos] == EMPTY near C2***
> [...]

Thanks for the report. I can reproduce the crash and have made a patch
to fix it, appended below. It can also be found at
http://trac.gnugo.org/gnugo/ticket/229

/Gunnar

diff --git a/patterns/helpers.c b/patterns/helpers.c
index 9381a61..5e5a0b2 100644
--- a/patterns/helpers.c
+++ b/patterns/helpers.c
@@ -502,18 +502,27 @@ backfill_helper(int apos, int bpos, int cpos)
   int color = board[cpos];
   int other = OTHER_COLOR(color);
   int dpos  = NO_MOVE;
+  int move_found = 0;

   if (TRYMOVE(apos, color)) {
     if (TRYMOVE(bpos, other)) {
       if (attack(cpos, NULL) && find_defense(cpos, &dpos)) {
-       set_minimum_move_value(dpos, 0.1);
-       TRACE("%o...setting min move value of %1m to 0.1\n", dpos);
+       move_found = 1;
       }
       popgo();
     }
     popgo();
   }

+  /* It might happen that the tried moves changed the board
+   * significantly. Verify that dpos is playable also without those
+   * moves.
+   */
+  if (move_found && board[dpos] == EMPTY && is_legal(dpos, color)) {
+    set_minimum_move_value(dpos, 0.1);
+    TRACE("%o...setting min move value of %1m to 0.1\n", dpos);
+  }
+
   return 0;
 }