[gnugo-devel] A crash

[Portela Fernando]

Hello,

After a long absence, I've been toying with the engine for
a couple of days. Following just occured to me :

gnugo --quiet -l regression\games\nando\auto022.sgf -L 208


***assertion failure:
E:\gnugo\engine\move_reasons.c:379 - board[pos] == EMPTY near T10***


   A B C D E F G H J K L M N O P Q R S T
19 . . . . . . . . . . . . O X X . . . . 19
18 . . . . . . . . . . . O . O X . . . . 18
17 . O O O O . . . . . . . . O X X . . . 17
16 O O X O X O O . . O . . . O O O X . . 16
15 O X X X X X O . . . . . . . O X X . . 15
14 O X X X O O . . . . . . . O X O X X . 14
13 O O X O O . . . . . . O . . X O X . . 13
12 X O X X O O O O O . . O X O . O X X X 12
11 X X X O O O X X O . X O O X O O O X O 11     WHITE (O) has captured 1 stones
10 . . X X X X X O O O O X X X X X O O O 10     BLACK (X) has captured 0 stones
 9 . . . . X O X X X O O O O X O O O X X 9
 8 . . X . X O O O X O O X X X X O O X . 8
 7 . X O . O X O O X O O O O X X O X X X 7
 6 . X . O . X X O O O X X X X O O X O X 6
 5 . O O . . X O O X O O O X . X O O O X 5
 4 . . O X . X X O X O X X . X X X O O X 4
 3 . X X . . . . X X X . . . . . . X X . 3
 2 . . . . . . . . . . . . . . . . . . . 2
 1 . . . . . . . . . . . . . . . . . . . 1
   A B C D E F G H J K L M N O P Q R S T
gnugo 3.5.4 (seed 1082464238): You stepped on a bug.
Please save this game as an sgf file and mail it to address@hidden
If you can, please also include the debug output above this message.


abnormal program termination


Running under debugger, I've located some uninitialized variables in 
the break-in code. Possibly, the crash is compiler-dependant. See the
appended suggested patch.

Else, the game has another interesting "feature", white's preceding move.
See the suggested testcase.

I'm still in the process of getting that pike script to run correctly
on my Win32 platform (looks like a line-ending problem, anyone has a 
clue?), I'll run regressions as soon as I can.

Cheers,
nando

- initialize variables in recursive_break and recursive_block
- testcase


Index: engine/readconnect.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/readconnect.c,v
retrieving revision 1.74
diff -u -p -r1.74 readconnect.c
--- engine/readconnect.c        12 Apr 2004 15:28:22 -0000      1.74
+++ engine/readconnect.c        20 Apr 2004 14:45:55 -0000
@@ -2883,7 +2883,7 @@ recursive_break(int str, const char goal
   int num_moves;
   float distance = 0.0;
   int k;
-  int xpos;
+  int xpos = NO_MOVE;
   int savemove = NO_MOVE;
   int savecode = 0;
   int tried_moves = 0;
@@ -3039,7 +3039,7 @@ recursive_block(int str, const char goal
   int num_moves;
   float distance = 0.0;
   int k;
-  int xpos;
+  int xpos = NO_MOVE;
   int savemove = NO_MOVE;
   int savecode = 0;
   int tried_moves = 0;

Index: regression/nando.tst
===================================================================
RCS file: /cvsroot/gnugo/gnugo/regression/nando.tst,v
retrieving revision 1.23
diff -u -p -r1.23 nando.tst
--- regression/nando.tst        14 Apr 2004 12:45:47 -0000      1.23
+++ regression/nando.tst        20 Apr 2004 14:45:56 -0000
@@ -165,6 +165,16 @@ loadsgf games/nando/auto021.sgf
 31 connect E18 H19
 #? [0]

+# O12 and Q14 are amalgamated per pattern CC502. The OWL engine
+# thinks that the dragon can simply escape by playing O13 in
+# response to black P13. And unfortunately, no other safeguards
+# prevent the blunder (as of 3.5.5)
+#CATEGORY=ATARI_ATARI (?)
+loadsgf games/nando/auto022.sgf 206
+32 reg_genmove white
+#? [N13|O13]
+
+
 #--------------------------------------------------------------
 # Cascade of chain breakings
 #CATEGORY=TACTICAL_READING


The game record (it seems I'm too dumb to find out how to diff -N it...)
regression/games/nando/auto022.sgf

(;GM[1]FF[4]
SZ[19]
DT[2004-04-20]
PB[Black]
PW[White]
CA[UTF-8]AP[CGoban:2]ST[2]RU[Japanese]KM[6.50]HA[0]
;B[qd];W[dd];B[pp];W[od];B[dp];W[pf];B[oc];W[nc];B[pc];W[nd];B[rf]
;W[jd];B[df];W[fd];B[cd];W[cc];B[ce];W[bc];B[cj];W[pn];B[np];W[qp]
;B[qq];W[qo];B[rq];W[qj];B[jq];W[dn];B[fp];W[cp];B[cq];W[co];B[bq]
;W[ff];B[nn];W[pl];B[nl];W[mi];B[dh];W[ih];B[kk];W[ij];B[il];W[kj]
;B[fn];W[em];B[ek];W[jk];B[ll];W[jl];B[hk];W[jm];B[kn];W[jn];B[io]
;W[ko];B[lp];W[fi];B[sn];W[af];B[gj];W[rn];B[gi];W[fh];B[so];W[nb]
;B[ob];W[ph];B[qg];W[pg];B[bf];W[ae];B[ri];W[qi];B[rh];W[bg];B[na]
;W[ma];B[oa];W[lb];B[lj];W[li];B[cg];W[bh];B[bi];W[in];B[ee];W[gd]
;B[ch];W[ho];B[ip];W[hm];B[fm];W[cm];B[bn];W[bo];B[bm];W[gl];B[gk]
;W[fl];B[el];W[ag];B[be];W[ad];B[ed];W[ec];B[rm];W[gh];B[qm];W[pm]
;B[qn];W[po];B[op];W[eg];B[cl];W[mk];B[nk];W[lk];B[nj];W[lm];B[ml]
;W[kl];B[ln];W[lo];B[mo];W[jo];B[mj];W[ro];B[sp];W[jp];B[hq];W[hp]
;B[iq];W[kk];B[ni];W[nh];B[hi];W[hh];B[qe];W[rj];B[fe];W[ge];B[gp]
;W[go];B[fo];W[hl];B[ik];W[ii];B[gn];W[hn];B[kp];W[mm];B[nm];W[ef]
;B[de];W[dc];B[pe];W[oe];B[oo];W[fk];B[fj];W[ei];B[ej];W[di];B[ci]
;W[oi];B[dj];W[si];B[sh];W[sj];B[qf];W[dg];B[oj];W[pk];B[qh];W[ql]
;B[rl];W[rp];B[pj];W[pi];B[ai];W[km];B[mn];W[bd];B[cf];W[pd];B[sm]
;W[eh];B[rk];W[qk];B[sk];W[on];B[im];W[hj];B[ah];W[gm];B[ki];W[jj]
;B[mh];W[lh];B[om];W[lg];B[ol];W[ok];B[of];W[nf];B[og]
)