deregister network event in circuit_validator (lsils#442)

include/mockturtle/algorithms/circuit_validator.hpp

@@ -116,6 +116,7 @@ class circuit_validator
  static_assert( has_foreach_fanout_v<Ntk>, "Ntk does not implement the foreach_fanout method" );
  }
 
+ event_ptr = ntk._events->on_add.size();
  ntk._events->on_add.emplace_back( [&]( const auto& n ) {
  (void)n;
  literals.resize();
@@ -136,6 +137,11 @@ class circuit_validator
  restart();
  }
 
+ ~circuit_validator()
+ {
+ ntk._events->on_add.erase( ntk._events->on_add.begin() + event_ptr );
+ }
+
  /*! \brief Validate functional equivalence of signals `f` and `d`. */
  std::optional<bool> validate( signal const& f, signal const& d )
  {
@@ -698,6 +704,8 @@ class circuit_validator
  bool between_push_pop = false;
  std::vector<node> tmp;
 
+ uint32_t event_ptr;
+
 public:
  std::vector<bool> cex;
 };