Initialize Tablebases::MaxCardinality to 0 to prevent uninitialized variable read in rank_root_moves

src/search.h

@@ -112,11 +112,6 @@ void clear();
 
 } // namespace Search
 
-namespace Tablebases {
-
-extern int MaxCardinality;
-
-}
 namespace Learner {
 
   // A pair of reader and evaluation value. Returned by Learner::search(),Learner::qsearch().

src/syzygy/tbprobe.cpp

@@ -52,7 +52,7 @@
 
 using namespace Tablebases;
 
-int Tablebases::MaxCardinality;
+int Tablebases::MaxCardinality = 0;
 
 namespace {
 

src/syzygy/tbprobe.h

@@ -25,6 +25,8 @@
 
 namespace Tablebases {
 
+extern int MaxCardinality;
+
 enum WDLScore {
     WDLLoss        = -2, // Loss
     WDLBlessedLoss = -1, // Loss, but draw under 50-move rule