Make map.set_terrain actually work in the game

src/game_board.cpp

@@ -337,7 +337,11 @@ bool game_board::change_terrain(
 	} else if(mode_str == "overlay") {
 		mode = terrain_type_data::OVERLAY;
 	}
+
+	return change_terrain(loc, terrain, mode, replace_if_failed);
+}
 
+bool game_board::change_terrain(const map_location &loc, const t_translation::terrain_code &terrain, terrain_type_data::merge_mode& mode, bool replace_if_failed) {
 	/*
 	 * When a hex changes from a village terrain to a non-village terrain, and
 	 * a team owned that village it loses that village. When a hex changes from

src/game_board.hpp

@@ -16,6 +16,8 @@
 
 #include "display_context.hpp"
 #include "team.hpp"
+#include "terrain/translation.hpp"
+#include "terrain/type_data.hpp"
 #include "units/map.hpp"
 #include "units/id.hpp"
 #include <optional>
@@ -157,8 +159,8 @@ class game_board : public display_context
 	bool try_add_unit_to_recall_list(const map_location& loc, const unit_ptr u);
 	std::optional<std::string> replace_map(const gamemap & r);
 
-	bool change_terrain(const map_location &loc, const std::string &t,
-	                    const std::string & mode, bool replace_if_failed); //used only by lua and debug commands
+	bool change_terrain(const map_location &loc, const std::string &t, const std::string & mode, bool replace_if_failed); //used only by lua and debug commands
+	bool change_terrain(const map_location &loc, const t_translation::terrain_code &t, terrain_type_data::merge_mode& mode, bool replace_if_failed); //used only by lua and debug commands
 
 	// Global accessor from unit.hpp
 

src/scripting/lua_terrainmap.cpp

@@ -259,7 +259,15 @@ static void impl_merge_terrain(lua_State* L, int idx, gamemap_base& map, map_loc
 	auto ter = t_translation::read_terrain_code(t_str);
 	if(ter.base == t_translation::NO_LAYER && ter.overlay != t_translation::NO_LAYER)
 		mode = terrain_type_data::OVERLAY;
-	map.set_terrain(loc, ter, mode);
+	if(auto gm = dynamic_cast<gamemap*>(&map)) {
+		if(resources::gameboard) {
+			bool result = resources::gameboard->change_terrain(loc, ter, mode, true);
+
+			if(resources::controller) {
+				resources::controller->get_display().needs_rebuild(result);
+			}
+		}
+	} else map.set_terrain(loc, ter, mode);
 }
 
 static int impl_terrainmap_colget(lua_State* L)
@@ -375,7 +383,15 @@ static int intf_set_terrain(lua_State *L)
 		}
 	}
 
-	tm.set_terrain(loc, terrain, mode);
+	if(auto gm = dynamic_cast<gamemap*>(&tm)) {
+		if(resources::gameboard) {
+			bool result = resources::gameboard->change_terrain(loc, terrain, mode, true);
+
+			if(resources::controller) {
+				resources::controller->get_display().needs_rebuild(result);
+			}
+		}
+	} else tm.set_terrain(loc, terrain, mode);
 	return 0;
 }