From: Fabian Fichter <ianfab@users.noreply.github.com>
Date: Sun, 10 Nov 2019 16:05:07 +0000 (+0100)
Subject: Mitigate perpetual check blindness
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=52a1faa9b4e7b0e6d07503f159b1556dc4bdad03;p=fairystockfish.git

Mitigate perpetual check blindness

Improve handling of problematic positions in #49.
---

diff --git a/src/position.cpp b/src/position.cpp
index 1eed7d8..7e86ba8 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1915,7 +1915,7 @@ bool Position::has_game_cycle(int ply) const {
 
   int end = captures_to_hand() ? st->pliesFromNull : std::min(st->rule50, st->pliesFromNull);
 
-  if (end < 3 || var->nFoldValue != VALUE_DRAW)
+  if (end < 3 || var->nFoldValue != VALUE_DRAW || var->perpetualCheckIllegal)
     return false;
 
   Key originalKey = st->key;