bug fix: static variable

Author: Catoverflow

ROBDD.cpp

@@ -1,7 +1,7 @@
 #include "ROBDD.hpp"
 #include <vector>
 int yyparse();
-
+ROBDD *T;
 ROBDD::ROBDD()
 {
     this->zero = new BDD_node({0, nullptr, nullptr});

ROBDD.hpp

@@ -35,5 +35,4 @@
         // delete nodes with references count = 0
         void trim();
     };
-    static ROBDD *T;
 #endif

expression.y

@@ -1,12 +1,13 @@
 %{
 #include <iostream>
 #include <string>
+#include "ROBDD.hpp"
 int yylex(void);
 void yyerror(const char *s);
+extern ROBDD *T;
 %}
 
 %code requires {
-#include <memory>
 #include "ROBDD.hpp"
 }