Squash some MSVC warnings

src/ai/formula/callable_objects.cpp

@@ -394,11 +394,8 @@ variant set_unit_var_callable::execute_self(variant ctxt) {
 }
 
 variant fallback_callable::execute_self(variant) {
-//	if(get_recursion_count() < recursion_counter::MAX_COUNTER_VALUE) {
-		//we want give control of the side to human for the rest of this turn
-		throw fallback_ai_to_human_exception();
-//	}
-	return variant(false);
+	// We want give control of the side to human for the rest of this turn
+	throw fallback_ai_to_human_exception();
 }
 
 }

src/gui/dialogs/editor/custom_tod.cpp

@@ -257,7 +257,7 @@ const time_of_day& custom_tod::get_selected_tod() const
 	try {
 		return times_.at(current_tod_);
 	} catch(std::out_of_range&) {
-		assert(false && "Attempted to fetch a non-existant ToD!");
+		throw std::string("Attempted to fetch a non-existant ToD!");
 	}
 }
 

src/scripting/game_lua_kernel.cpp

@@ -1461,6 +1461,7 @@ int game_lua_kernel::impl_end_level_data_set(lua_State* L)
 static int impl_end_level_data_collect(lua_State* L)
 {
 	end_level_data* data = static_cast<end_level_data*>(lua_touserdata(L, 1));
+	data; // Suppress an erroneous MSVC warning (a destructor call doesn't count as a reference)
 	data->~end_level_data();
 	return 0;
 }

src/scripting/lua_gui2.cpp

@@ -435,10 +435,10 @@ int intf_set_dialog_value(lua_State* L)
 			std::vector<int> selected_vec = lua_check<std::vector<int>>(L, 1);
 			std::set<int> selected(selected_vec.begin(), selected_vec.end());
 			for(unsigned i = 0; i < list->get_item_count(); i++) {
-				list->select_row(i, selected.count(i + 1));
+				list->select_row(i, selected.count(i + 1) > 0);
 			}
 			for(unsigned i = 0; i < list->get_item_count(); i++) {
-				list->select_row(i, selected.count(i + 1));
+				list->select_row(i, selected.count(i + 1) > 0);
 			}
 		} else {
 			int v = luaL_checkinteger(L, 1);

src/units/unit.hpp

@@ -846,10 +846,10 @@ class unit
 	{
 		template<typename T>
 		typename std::enable_if<!std::is_same<int, T>::value, std::string>::type
-		operator()(T& v) const
+		operator()(T&) const
 		{
 			// Any special upkeep type should have an associated @ref type getter in its helper struct.
-			return v.type();
+			return T::type();
 		}
 
 		std::string operator()(int v) const