Merge pull request CleverRaven#83385 from inogenous/prevent-segfault-when-cancelling-completed-butchery

Prevent segfault when cancelling butchery

Author: inogenous

src/activity_actor.cpp

@@ -9139,14 +9139,11 @@ void butchery_activity_actor::do_turn( player_activity &act, Character &you )
     }
 
     if( this_bd->progress >= this_bd->time_to_butcher ) {
+        const butchery_data bd_copy = *this_bd;
+        bd.pop_back();
         // this corpse is done
-        destroy_the_carcass( *this_bd, you );
-        if( bd.empty() ) {
-            act.moves_left = 0;
-            return;
-        } else {
-            bd.pop_back();
-        }
+        destroy_the_carcass( bd_copy, you );
+        // WARNING: destroy_the_carcass might spill acid, which gives the player the option to cancel this activity. If so, then `this` might be invalidated, along with all `butchery_data` elements. So here we need to be sure to not use either of those after this call.
     } else {
         this_bd->progress += 1_seconds;
         // Uses max(1, ..) to prevent it going all the way to zero, which would stop the activity by the general `activity_actor` handling.

src/butchery.cpp

@@ -1175,7 +1175,7 @@ void destroy_the_carcass( const butchery_data &bd, Character &you )
     you.recoil = MAX_RECOIL;
 
     get_event_bus().send<event_type::character_butchered_corpse>( you.getID(),
-            corpse_item.get_mtype()->id, "ACT_" + io::enum_to_string<butcher_type>( bd.b_type ) );
+            corpse->id, "ACT_" + io::enum_to_string<butcher_type>( action ) );
 
 }