Fix vehicle accessing the main map during mapgen:

src/map_extras.cpp

@@ -412,9 +412,9 @@ static void mx_helicopter( map &m, const tripoint &abs_sub )
                 break;
         }
         if( !one_in( 4 ) ) {
-            wreckage->smash( 0.8f, 1.2f, 1.0f, point( dice( 1, 8 ) - 5, dice( 1, 8 ) - 5 ), 6 + dice( 1, 10 ) );
+            wreckage->smash( m, 0.8f, 1.2f, 1.0f, point( dice( 1, 8 ) - 5, dice( 1, 8 ) - 5 ), 6 + dice( 1, 10 ) );
         } else {
-            wreckage->smash( 0.1f, 0.9f, 1.0f, point( dice( 1, 8 ) - 5, dice( 1, 8 ) - 5 ), 6 + dice( 1, 10 ) );
+            wreckage->smash( m, 0.1f, 0.9f, 1.0f, point( dice( 1, 8 ) - 5, dice( 1, 8 ) - 5 ), 6 + dice( 1, 10 ) );
         }
     }
 }

src/mapgen.cpp

@@ -6887,7 +6887,7 @@ std::unique_ptr<vehicle> map::add_vehicle_to_map(
             // Try again with the wreckage
             std::unique_ptr<vehicle> new_veh = add_vehicle_to_map( std::move( wreckage ), true );
             if( new_veh != nullptr ) {
-                new_veh->smash();
+                new_veh->smash( *this );
                 return new_veh;
             }
 
@@ -6913,7 +6913,7 @@ std::unique_ptr<vehicle> map::add_vehicle_to_map(
     }
 
     if( needs_smashing ) {
-        veh->smash();
+        veh->smash( *this );
     }
 
     return veh;

src/monmove.cpp

@@ -1902,7 +1902,7 @@ void monster::shove_vehicle( const tripoint &remote_destination,
                     g->m.move_vehicle( veh, shove_destination, veh.face );
                 }
                 veh.move = tileray( point( destination_delta_x, destination_delta_y ) );
-                veh.smash( shove_damage_min, shove_damage_max, 0.10F );
+                veh.smash( g->m, shove_damage_min, shove_damage_max, 0.10F );
             }
         }
     }

src/vehicle.cpp

@@ -88,6 +88,121 @@ const int bat_energy_j = 1000;
 // Point dxs for the adjacent cardinal tiles.
 point vehicles::cardinal_d[5] = { point_west, point_east, point_north, point_south, point_zero };
 
+// For reference what each function is supposed to do, see their implementation in
+// @ref DefaultRemovePartHandler. Add compatible code for it into @ref MapgenRemovePartHandler,
+// if needed.
+class RemovePartHandler
+{
+    public:
+        virtual ~RemovePartHandler() = default;
+
+        virtual void unboard( const tripoint &loc ) = 0;
+        virtual void add_item_or_charges( const tripoint &loc, item it ) = 0;
+        virtual void set_transparency_cache_dirty( int z ) = 0;
+        virtual void removed( vehicle &veh, int part ) = 0;
+        virtual void spawn_animal_from_part( item &base, const tripoint &loc ) = 0;
+};
+
+class DefaultRemovePartHandler : public RemovePartHandler
+{
+    public:
+        ~DefaultRemovePartHandler() override = default;
+
+        void unboard( const tripoint &loc ) override {
+            g->m.unboard_vehicle( loc );
+        }
+        void add_item_or_charges( const tripoint &loc, item it ) override {
+            g->m.add_item_or_charges( loc, std::move( it ) );
+        }
+        void set_transparency_cache_dirty( const int z ) override {
+            g->m.set_transparency_cache_dirty( z );
+        }
+        void removed( vehicle &veh, const int part ) override {
+            // If the player is currently working on the removed part, stop them as it's futile now.
+            const player_activity &act = g->u.activity;
+            if( act.id() == activity_id( "ACT_VEHICLE" ) && act.moves_left > 0 && act.values.size() > 6 ) {
+                if( veh_pointer_or_null( g->m.veh_at( tripoint( act.values[0], act.values[1],
+                                                    g->u.posz() ) ) ) == &veh ) {
+                    if( act.values[6] >= part ) {
+                        g->u.cancel_activity();
+                        add_msg( m_info, _( "The vehicle part you were working on has gone!" ) );
+                    }
+                }
+            }
+            // @todo maybe do this for all the nearby NPCs as well?
+
+            if( g->u.get_grab_type() == OBJECT_VEHICLE && g->u.grab_point == veh.global_part_pos3( part ) ) {
+                if( veh.parts_at_relative( veh.parts[part].mount, false ).empty() ) {
+                    add_msg( m_info, _( "The vehicle part you were holding has been destroyed!" ) );
+                    g->u.grab( OBJECT_NONE );
+                }
+            }
+
+            g->m.dirty_vehicle_list.insert( &veh );
+        }
+        void spawn_animal_from_part( item &base, const tripoint &loc ) override {
+            tripoint target = loc;
+            bool spawn = true;
+            if( !g->is_empty( target ) ) {
+                std::vector<tripoint> valid;
+                for( const tripoint &dest : g->m.points_in_radius( target, 1 ) ) {
+                    if( g->is_empty( dest ) ) {
+                        valid.push_back( dest );
+                    }
+                }
+                if( valid.empty() ) {
+                    spawn = false;
+                } else {
+                    target = random_entry( valid );
+                }
+            }
+            base.release_monster( target, spawn );
+        }
+};
+
+class MapgenRemovePartHandler : public RemovePartHandler
+{
+    private:
+        map &m;
+
+    public:
+        MapgenRemovePartHandler( map &m ) : m( m ) { }
+
+        ~MapgenRemovePartHandler() override = default;
+
+        void unboard( const tripoint &/*loc*/ ) override {
+            debugmsg( "Tried to unboard during mapgen!" );
+            // Ignored. Will almost certainly not be called anyway, because
+            // there are no creatures that could have been mounted during mapgen.
+        }
+        void add_item_or_charges( const tripoint &loc, item it ) override {
+            if( !m.inbounds( loc ) ) {
+                debugmsg( "Tried to put item %s on invalid tile %d,%d,%d during mapgen!", it.tname(), loc.x, loc.y,
+                          loc.z );
+                tripoint copy = loc;
+                m.clip_to_bounds( copy );
+                assert( m.inbounds( copy ) ); // prevent infinite recursion
+                add_item_or_charges( copy, std::move( it ) );
+                return;
+            }
+            m.add_item_or_charges( loc, std::move( it ) );
+        }
+        void set_transparency_cache_dirty( const int /*z*/ ) override {
+            // Ignored for now. We don't initialize the transparency cache in mapgen anyway.
+        }
+        void removed( vehicle &veh, const int /*part*/ ) override {
+            // @todo check if this is necessary, it probably isn't during mapgen
+            m.dirty_vehicle_list.insert( &veh );
+        }
+        void spawn_animal_from_part( item &/*base*/, const tripoint &/*loc*/ ) override {
+            debugmsg( "Tried to spawn animal from vehicle part during mapgen!" );
+            // Ignored. The base item will not be changed and will spawn as is:
+            // still containing the animal.
+            // This should not happend during mapgen anyway.
+            // @todo *if* this actually happens: create a spawn point for the animal instead.
+        }
+};
+
 // Vehicle stack methods.
 vehicle_stack::iterator vehicle_stack::erase( vehicle_stack::const_iterator it )
 {
@@ -693,7 +808,7 @@ void vehicle::do_autodrive()
  * (ie, any spot with multiple frames) will be completely destroyed, as that
  * was the collision point.
  */
-void vehicle::smash( float hp_percent_loss_min, float hp_percent_loss_max,
+void vehicle::smash( map &m, float hp_percent_loss_min, float hp_percent_loss_max,
                      float percent_of_parts_to_affect, point damage_origin, float damage_size )
 {
     for( auto &part : parts ) {
@@ -734,6 +849,8 @@ void vehicle::smash( float hp_percent_loss_min, float hp_percent_loss_max,
             }
         }
     }
+
+    std::unique_ptr<RemovePartHandler> handler_ptr;
     // clear out any duplicated locations
     for( int p = static_cast<int>( parts.size() ) - 1; p >= 0; p-- ) {
         vehicle_part &part = parts[ p ];
@@ -749,7 +866,18 @@ void vehicle::smash( float hp_percent_loss_min, float hp_percent_loss_max,
             if( ( part_info( p ).location.empty() &&
                   part_info( p ).get_id() == part_info( other_p ).get_id() ) ||
                 ( part_info( p ).location == part_info( other_p ).location ) ) {
-                remove_part( other_p );
+                // Deferred creation of the handler to here so it is only created when actually needed.
+                if( !handler_ptr ) {
+                    // This is a heuristic: we just assume the default handler is good enough when called
+                    // on the main game map. And assume that we run from some mapgen code if called on
+                    // another instance.
+                    if( g && &g->m == &m ) {
+                        handler_ptr = std::make_unique<DefaultRemovePartHandler>();
+                    } else {
+                        handler_ptr = std::make_unique<MapgenRemovePartHandler>( m );
+                    }
+                }
+                remove_part( other_p, *handler_ptr );
             }
         }
     }
@@ -1700,8 +1828,19 @@ bool vehicle::merge_rackable_vehicle( vehicle *carry_veh, const std::vector<int>
  * Mark a part as removed from the vehicle.
  * @return bool true if the vehicle's 0,0 point shifted.
  */
-bool vehicle::remove_part( int p )
+bool vehicle::remove_part( const int p )
 {
+    DefaultRemovePartHandler handler;
+    return remove_part( p, handler );
+}
+
+bool vehicle::remove_part( const int p, RemovePartHandler &handler )
+{
+    // NOTE: Don't access g or g->m or anything from it directly here.
+    // Forward all access to the handler.
+    // There are currently two implementations of it:
+    // - one for normal game play (vehicle is on the main map g->m),
+    // - one for mapgen (vehicle is on a temporary map used only during mapgen).
     if( p >= static_cast<int>( parts.size() ) ) {
         debugmsg( "Tried to remove part %d but only %d parts!", p, parts.size() );
         return false;
@@ -1717,13 +1856,8 @@ bool vehicle::remove_part( int p )
     const tripoint part_loc = global_part_pos3( p );
 
     // Unboard any entities standing on removed boardable parts
-    if( part_flag( p, "BOARDABLE" ) ) {
-        std::vector<int> bp = boarded_parts();
-        for( auto &elem : bp ) {
-            if( elem == p ) {
-                g->m.unboard_vehicle( part_loc );
-            }
-        }
+    if( part_flag( p, "BOARDABLE" ) && parts[p].has_flag( vehicle_part::passenger_flag ) ) {
+        handler.unboard( part_loc );
     }
 
     // If `p` has flag `parent_flag`, remove child with flag `child_flag`
@@ -1733,9 +1867,8 @@ bool vehicle::remove_part( int p )
         if( part_flag( p, parent_flag ) ) {
             int dep = part_with_feature( p, child_flag, false );
             if( dep >= 0 ) {
-                item it = parts[dep].properties_to_item();
-                g->m.add_item_or_charges( part_loc, it );
-                remove_part( dep );
+                handler.add_item_or_charges( part_loc, parts[dep].properties_to_item() );
+                remove_part( dep, handler );
                 return true;
             }
         }
@@ -1745,31 +1878,16 @@ bool vehicle::remove_part( int p )
     // if a windshield is removed (usually destroyed) also remove curtains
     // attached to it.
     if( remove_dependent_part( "WINDOW", "CURTAIN" ) || part_flag( p, VPFLAG_OPAQUE ) ) {
-        g->m.set_transparency_cache_dirty( sm_pos.z );
+        handler.set_transparency_cache_dirty( sm_pos.z );
     }
 
     remove_dependent_part( "SEAT", "SEATBELT" );
     remove_dependent_part( "BATTERY_MOUNT", "NEEDS_BATTERY_MOUNT" );
 
     // Release any animal held by the part
     if( parts[p].has_flag( vehicle_part::animal_flag ) ) {
-        tripoint target = part_loc;
-        bool spawn = true;
-        if( !g->is_empty( target ) ) {
-            std::vector<tripoint> valid;
-            for( const tripoint &dest : g->m.points_in_radius( target, 1 ) ) {
-                if( g->is_empty( dest ) ) {
-                    valid.push_back( dest );
-                }
-            }
-            if( valid.empty() ) {
-                spawn = false;
-            } else {
-                target = random_entry( valid );
-            }
-        }
         item base = item( parts[p].get_base() );
-        base.release_monster( target, spawn );
+        handler.spawn_animal_from_part( base, part_loc );
         parts[p].set_base( base );
         parts[p].remove_flag( vehicle_part::animal_flag );
     }
@@ -1807,41 +1925,20 @@ bool vehicle::remove_part( int p )
     parts[p].removed = true;
     removed_part_count++;
 
-    // If the player is currently working on the removed part, stop them as it's futile now.
-    const player_activity &act = g->u.activity;
-    if( act.id() == activity_id( "ACT_VEHICLE" ) && act.moves_left > 0 && act.values.size() > 6 ) {
-        if( veh_pointer_or_null( g->m.veh_at( tripoint( act.values[0], act.values[1],
-                                              g->u.posz() ) ) ) == this ) {
-            if( act.values[6] >= p ) {
-                g->u.cancel_activity();
-                add_msg( m_info, _( "The vehicle part you were working on has gone!" ) );
-            }
-        }
-    }
+    handler.removed( *this, p );
 
     const point &vp_mount = parts[p].mount;
     const auto iter = labels.find( label( vp_mount ) );
-    const bool no_label = iter != labels.end();
-    const bool grab_found = g->u.get_grab_type() == OBJECT_VEHICLE && g->u.grab_point == part_loc;
-    // Checking these twice to avoid calling the relatively expensive parts_at_relative() unnecessarily.
-    if( no_label || grab_found ) {
-        if( parts_at_relative( vp_mount, false ).empty() ) {
-            if( no_label ) {
-                labels.erase( iter );
-            }
-            if( grab_found ) {
-                add_msg( m_info, _( "The vehicle part you were holding has been destroyed!" ) );
-                g->u.grab( OBJECT_NONE );
-            }
-        }
+    if( iter != labels.end() && parts_at_relative( vp_mount, false ).empty() ) {
+        labels.erase( iter );
     }
 
     for( auto &i : get_items( p ) ) {
         // Note: this can spawn items on the other side of the wall!
+        // @todo fix this ^^
         tripoint dest( part_loc + point( rng( -3, 3 ), rng( -3, 3 ) ) );
-        g->m.add_item_or_charges( dest, i );
+        handler.add_item_or_charges( dest, i );
     }
-    g->m.dirty_vehicle_list.insert( this );
     refresh();
     coeff_air_changed = true;
     return shift_if_needed();

src/vehicle.h

@@ -40,6 +40,7 @@ class Creature;
 class nc_color;
 class player;
 class npc;
+class map;
 class vehicle;
 class vehicle_part_range;
 class JsonIn;
@@ -524,6 +525,8 @@ struct label : public point {
     std::string text;
 };
 
+class RemovePartHandler;
+
 /**
  * A vehicle as a whole with all its components.
  *
@@ -720,9 +723,8 @@ class vehicle
         void init_state( int init_veh_fuel, int init_veh_status );
 
         // damages all parts of a vehicle by a random amount
-        void smash( float hp_percent_loss_min = 0.1f, float hp_percent_loss_max = 1.2f,
-                    float percent_of_parts_to_affect = 1.0f, point damage_origin = point_zero,
-                    float damage_size = 0 );
+        void smash( map &m, float hp_percent_loss_min = 0.1f, float hp_percent_loss_max = 1.2f,
+                    float percent_of_parts_to_affect = 1.0f, point damage_origin = point_zero, float damage_size = 0 );
 
         void serialize( JsonOut &json ) const;
         void deserialize( JsonIn &jsin );
@@ -804,6 +806,13 @@ class vehicle
         // merge a previously found single tile vehicle into this vehicle
         bool merge_rackable_vehicle( vehicle *carry_veh, const std::vector<int> &rack_parts );
 
+        /**
+         * @param handler A class that receives various callbacks, e.g. for placing items.
+         * This handler is different when called during mapgen (when items need to be placed
+         * on the temporary mapgen map), and when called during normal game play (when items
+         * go on the main map g->m).
+         */
+        bool remove_part( int p, RemovePartHandler &handler );
         bool remove_part( int p );
         void part_removal_cleanup();