Bug: Illegal move in version 0.3.0

[rwbc]

I am still following progress of Megalodon (which isn't very easy due to lots of commits).

My last compilation of version 0.3.0 finally played much better than those before, but I still caught an illegal move already in game 1. (played 6 games vs. Alouette 0.14)

BTW the source for 0.3.0 had the wrong version number in uci id, it still showed 0.2.6.

[Event "Test@CuteCGdv"]
[Site "RWBC-CAPPUCCINO Win7U64 Q8200 2.33Ghz + Nvidia GT 710"]
[Date "2021.04.01"]
[Round "1"]
[White "Megalodon_030-64"]
[Black "Alouette_014-64"]
[Result "0-1"]
[ECO "A86"]
[GameDuration "00:00:41"]
[GameEndTime "2021-04-01T12:09:43.455 Mitteleuropäische Sommerzeit"]
[GameStartTime "2021-04-01T12:09:01.765 Mitteleuropäische Sommerzeit"]
[Opening "Dutch"]
[PlyCount "32"]
[Termination "illegal move"]
[TimeControl "40/120"]
[Variation "Leningrad Variation"]

1. d4 {book} f5 {book}
2. c4 {book} Nf6 {book}
3. g3 {book} g6 {book}
4. Bg2 {-0.89/5 2.45} Ng4
5. f3 {+0.08/5 2.50} Nf6
6. Bg5 {-0.44/5 2.55} Nh5
7. g4 {-0.08/5 2.62} h6
8. gxh5 {+0.96/5 2.67} hxg5
9. hxg6 {+1.29/5 2.74} Nc6
10. g7 {+13.46/5 2.83} Bxg7
11. e3 {-0.21/5 2.90} O-O
12. Nd2 {-0.21/5 3.00} d6
13. f4 {-0.21/5 3.08} gxf4
14. Bd5+ {+1.70/5 3.20} e6
15. Bxc6 {+0.34/5 3.31} fxe3
16. Bf3 {+1.60/5 3.45} exd2+ {White makes an illegal move: g1e2}
0-1

[rwbc]

This bug seems still there in version 0.3.2 (my compilation)

Below is analysis from Megalodon 0.3.2 with feeding the pgn (while analysing) one ply before the illegal move happened:

dep score   nodes   time    (not shown:  tbhits knps    seldep)
  6  -2.70  11.1M   0:36.16 h2h4 g7d4 g1e2 d4b2 h1g1 g8h8 
  5  -0.05  1.15M   0:03.59 g1e2 d8h4 e2g3 g7d4 f3b7 
  4  -1.29  65805   0:00.22 g1e2 g8h8 e2f4 g7d4 
  3  -0.13  10705   0:00.02 e1f1 g7d4 f3b7 
  2  -1.29  527     0:00.00 g1e2 g7d4 
  1  +0.84  31      0:00.00 f3b7 

[rwbc]

I thought this was already fixed? BTW very strange moves with the Q from move 12 'til the illegal end.

[Event "Test@CuteCGdv"]
[Site "RWBC-CAPPUCCINO Win7U64 Q8200 2.33Ghz + Nvidia GT 710"]
[Date "2021.04.03"]
[Round "6"]
[White "Megalodon_033r2046-64"]
[Black "Zoe_01"]
[Result "0-1"]
[ECO "B20"]
[GameDuration "00:00:28"]
[GameEndTime "2021-04-03T12:10:02.072 Mitteleuropäische Sommerzeit"]
[GameStartTime "2021-04-03T12:09:33.278 Mitteleuropäische Sommerzeit"]
[Opening "Sicilian defense"]
[PlyCount "28"]
[Termination "illegal move"]
[TimeControl "40/60"]

1. e4 {book} c5 {book} 2. d3 {book} g6 {book} 3. f4 {book} Bg7 {book}
4. Be3 {+0.06/3 0.38s} Bxb2 {+1.85/6 2.96s} 5. Nd2 {-4.56/5 0.37s}
Nf6 {+3.05/5 2.02s} 6. Rb1 {-2.88/5 0.37s} Bd4 {-0.80/6 2.12s}
7. Bxd4 {-1.44/5 0.38s} cxd4 {-1.10/6 2.11s} 8. Ngf3 {+0.32/3 0.38s}
d5 {-1.00/6 3.22s} 9. exd5 {-1.18/5 0.39s} Nxd5 {+0.20/6 3.02s}
10. g3 {+1.24/3 0.38s} Nc3 {+2.00/6 3.58s} 11. Qc1 {-1.68/3 0.40s}
Nxb1 {+6.40/5 1.40s} 12. Qb2 {-3.39/5 0.42s} Nc3 {+4.30/6 1.90s}
13. Qxc3 {-3.18/5 0.41s} dxc3 {+14.70/5 0.54s} 14. Ne5 {-8.52/3 0.41s}
cxd2+ {+18.00/5 1.13s, White makes an illegal move: f1g2} 0-1

[phuang1024]

I also experienced strange blunders with Megalodon. I think it should be fixed in 6dffa5b46afa2ab257df1cbfabb3e8641f94f7b7, which reduced the imbalance eval weight.