fixed bug which could cause a crash when a unit advances

(as reported by Antonio Manrique Perez)

data/scenarios/Dwarven_Doors.cfg

@@ -194,7 +194,40 @@ Defeat:
 			message="There is no time for delay or idle chatter, onward!"
 		[/message]
 		[/command]
+		[command]
+		[set_variable]
+		name=killed_enemies
+		value=false
+		[/set_variable]
+		[/command]
+		[command]
+		[endlevel]
+		result=victory
+		[/endlevel]
+		[/command]
+	[/event]
 
+	[event]
+	name=victory
+		[message]
+		description=Kalenz
+		id=msg11_5b
+		message="We have defeated the foul Orcs guarding this land, but we must continue without rest. More will surely come!"
+		[/message]
+		[message]
+		description=Delfador
+		id=msg11_5c
+		message="Indeed we must not delay. I remember now, the mines in the North-East are the best way to enter!"
+		[/message]
+		[message]
+		speaker=narrator
+		id=msg11_5d
+		message="But Konrad's party was not alone in entering the mines..."
+		[/message]
+	[/event]
+
+	[event]
+	name=victory
 		[command]
 		[unit]
 		side=2
@@ -227,11 +260,6 @@ Defeat:
 		[/message]
 		[/command]
 
-		[command]
-		[endlevel]
-		result=victory
-		[/endlevel]
-		[/command]
 	[/event]
 
 

src/actions.cpp

@@ -808,9 +808,8 @@ unit get_advanced_unit(const game_data& info,
                   std::map<gamemap::location,unit>& units,
                   const gamemap::location& loc, const std::string& advance_to)
 {
-	const std::map<std::string,unit_type>::const_iterator new_type =
-	     info.unit_types.find(advance_to);
-	std::map<gamemap::location,unit>::iterator un = units.find(loc);
+	const std::map<std::string,unit_type>::const_iterator new_type = info.unit_types.find(advance_to);
+	const std::map<gamemap::location,unit>::iterator un = units.find(loc);
 	if(new_type != info.unit_types.end() && un != units.end()) {
 		return unit(&(new_type->second),un->second);
 	} else {
@@ -821,9 +820,10 @@ unit get_advanced_unit(const game_data& info,
 
 void advance_unit(const game_data& info,
                   std::map<gamemap::location,unit>& units,
-                  const gamemap::location& loc, const std::string& advance_to)
+                  gamemap::location loc, const std::string& advance_to)
 {
 	const unit& new_unit = get_advanced_unit(info,units,loc,advance_to);
+	
 	units.erase(loc);
 	units.insert(std::pair<gamemap::location,unit>(loc,new_unit));
 }

src/actions.hpp

@@ -119,9 +119,12 @@ unit get_advanced_unit(const game_data& info,
                   const gamemap::location& loc, const std::string& advance_to);
 
 //function which will advance the unit at loc to 'advance_to'.
+//note that 'loc' is not a reference, because if it were a reference, we couldn't
+//safely pass in a reference to the item in the map that we're going to delete,
+//since deletion would invalidate the reference.
 void advance_unit(const game_data& info,
                   std::map<gamemap::location,unit>& units,
-                  const gamemap::location& loc, const std::string& advance_to);
+                  gamemap::location loc, const std::string& advance_to);
 
 //function which returns true iff the unit at loc is currently affected
 //by leadership. (i.e. has a higher-level 'leadership' unit next to it)

src/dialogs.cpp

@@ -28,7 +28,7 @@ namespace dialogs
 
 void advance_unit(const game_data& info,
                   std::map<gamemap::location,unit>& units,
-                  const gamemap::location& loc,
+                  gamemap::location loc,
                   display& gui, bool random_choice)
 {
 	std::map<gamemap::location,unit>::iterator u = units.find(loc);

src/dialogs.hpp

@@ -21,9 +21,16 @@
 
 namespace dialogs
 {
+//function to handle an advancing unit. If there is only one choice to advance
+//to, the unit will be automatically advanced. If there is a choice, and 'random_choice'
+//is true, then a unit will be selected at random. Otherwise, a dialog will be displayed
+//asking the user what to advance to.
+//
+//note that 'loc' is not a reference, because deleting an item from the units map
+//(when replacing the unit that is being advanced) will possibly invalidate the reference
 void advance_unit(const game_data& info,
                   std::map<gamemap::location,unit>& units,
-				  const gamemap::location& loc,
+				  gamemap::location loc,
 				  display& gui, bool random_choice=false);
 
 void show_objectives(display& disp, config& level_info);