Joseph Huang

Looks like it's working on chessx-1.5.7b.dmg 2022-05-26 15.5 MB

OKAY: I think then potentially this was fixed in Oct 21, 2021 here https://github.com/Isarhamster/chessx/blame/0d19c71dafaa595670c15010befbafcadb15e574/src/database/tablebase.cpp The old version relies on dtm which isn't always available in the Sygyzy tablebases https://github.com/Isarhamster/chessx/blob/9086a00e2d433eb2ec3d1dd2c0bac2fdb0e46ad0/src/database/tablebase.cpp

So then, let's see if it's a display issue https://github.com/Isarhamster/chessx/blob/5e34a5508201078033453be8995c66394db35d5f/src/gui/analysiswidget.cpp#L510 Expecting... score = 45 // from bestScore dtm = false // because: -0x800 < score < 0x800 ... Notably, during the bug we're showing all the other alternative moves but they all have dtz = 0 and dtm = 0 So somehow, int result = bestScore ? (bestScore > 0) ? 1:-1:0; is evaluating to 0?

Inspecting the code directly https://github.com/Isarhamster/chessx/blob/5e34a5508201078033453be8995c66394db35d5f/src/database/tablebase.cpp#L138 and comparing to the API results: http://tablebase.lichess.ovh/standard?fen=7q/7P/1K6/1p6/8/3Q4/k7/8 w - - 29 81 we can expect... jdtm.isNull() == true dtz == 45 bestScore == 45 (bestScore > 0) ? 1:-1 = 1 bestScore ? (bestScore > 0) ? 1:-1 : 0 === bestScore ? 1 : 0 = 1 result = 1 ... moves[0]:xjdtm.isNull() == true moves[0]:xdtz == -44 moves[0]:xbestScore...

Okay, according to https://github.com/Isarhamster/chessx/blob/5e34a5508201078033453be8995c66394db35d5f/src/database/tablebase.cpp#L84 the Sygyzy API being used is https://github.com/lichess-org/lila-tablebase Loading http://tablebase.lichess.ovh/standard?fen=7q/7P/1K6/1p6/8/3Q4/k7/8 w - - 29 81 directly in the browser correctly shows "win" which means the bug is somewhere in the ChessX receiving code

Inspecting the code directly https://github.com/Isarhamster/chessx/blob/5e34a5508201078033453be8995c66394db35d5f/src/database/tablebase.cpp#L138 and comparing to the API results: http://tablebase.lichess.ovh/standard?fen=7q/7P/1K6/1p6/8/3Q4/k7/8 w - - 29 81 we can expect... jdtm.isNull() == true dtz == 45 bestScore == 45 (bestScore > 0) ? 1:-1 = 1 bestScore ? (bestScore > 0) ? 1:-1 : 0 === bestScore ? 1 : 0 = 1 result = 1 ... moves[0]:xjdtm.isNull() == true moves[0]:xdtz == -44 moves[0]:xbestScore...

Okay, according to https://github.com/Isarhamster/chessx/blob/5e34a5508201078033453be8995c66394db35d5f/src/database/tablebase.cpp#L84 the Sygyzy API being used is https://github.com/lichess-org/lila-tablebase Loading http://tablebase.lichess.ovh/standard?fen=7q/7P/1K6/1p6/8/3Q4/k7/8 w - - 29 81 directly in the browser still shows draw

Reproduced on 1.5.0.0 WIN64 MSVC13 Qt5.12.3 also (I had to restart ChessX after changing the "Use online tablebase servers" setting)