convert attack_type to use shared_from_this instead of instrusive_ptrs

src/scripting/lua_unit_attacks.cpp

@@ -81,7 +81,7 @@ attack_type& luaW_checkweapon(lua_State* L, int idx)
 }
 
 template<typename T>
-using attack_ptr_in = boost::intrusive_ptr<typename utils::const_clone<attack_type, typename std::remove_pointer<T>::type>::type>;
+using attack_ptr_in = std::shared_ptr<typename utils::const_clone<attack_type, typename std::remove_pointer<T>::type>::type>;
 
 // Note that these two templates are designed on the assumption that T is either unit or unit_type
 template<typename T>
@@ -139,7 +139,7 @@ static attack_itors::iterator get_attack_iter(unit& u, attack_ptr atk)
 {
 	// This is slightly inefficient since it walks the attack list a second time...
 	return std::find_if(u.attacks().begin(), u.attacks().end(), [&atk](const attack_type& atk2) {
-		return &atk2 == atk;
+		return &atk2 == atk.get();
 	});
 }
 

src/units/attack_type.cpp

@@ -60,7 +60,6 @@ attack_type::attack_type(const config& cfg) :
 	parry_(cfg["parry"]),
 	specials_(cfg.child_or_empty("specials"))
 {
-	assert(ref_count == 0);
 	if (description_.empty())
 		description_ = translation::egettext(id_.c_str());
 

src/units/attack_type.hpp

@@ -30,7 +30,7 @@ class unit_ability_list;
 
 //the 'attack type' is the type of attack, how many times it strikes,
 //and how much damage it does.
-class attack_type
+class attack_type : public std::enable_shared_from_this<attack_type>
 {
 public:
 
@@ -126,22 +126,10 @@ private:
 	int movement_used_;
 	int parry_;
 	config specials_;
-	mutable size_t ref_count = 0;
-
-	friend void intrusive_ptr_add_ref(const attack_type* atk) {
-		++atk->ref_count;
-	}
-
-	friend void intrusive_ptr_release(const attack_type* atk) {
-		assert(atk->ref_count < 1000000);
-		if(--atk->ref_count == 0) {
-			delete atk;
-		}
-	}
 };
 
-using attack_ptr = boost::intrusive_ptr<attack_type>;
-using const_attack_ptr = boost::intrusive_ptr<const attack_type>;
+using attack_ptr = std::shared_ptr<attack_type>;
+using const_attack_ptr = std::shared_ptr<const attack_type>;
 using attack_list = std::vector<attack_ptr>;
 using attack_itors = boost::iterator_range<boost::indirect_iterator<attack_list::iterator>>;
 using const_attack_itors = boost::iterator_range<boost::indirect_iterator<attack_list::const_iterator>>;

src/units/unit.cpp

@@ -974,7 +974,7 @@ void unit::advance_to(const unit_type &u_type,
 	emit_zoc_ = new_type.has_zoc();
 	attacks_.clear();
 	std::transform(new_type.attacks().begin(), new_type.attacks().end(), std::back_inserter(attacks_), [](const attack_type& atk) {
-		return new attack_type(atk);
+		return std::make_shared<attack_type>(atk);
 	});
 	unit_value_ = new_type.cost();