Merge branch 'master' into jgrpp

# Conflicts:
#	.github/workflows/ci-build.yml
#	.github/workflows/release-linux.yml
#	.github/workflows/release-macos.yml
#	.github/workflows/release-source.yml
#	.github/workflows/release.yml
#	CMakeLists.txt
#	COMPILING.md
#	src/ai/ai_core.cpp
#	src/ai/ai_gui.cpp
#	src/bridge_gui.cpp
#	src/company_gui.cpp
#	src/console_cmds.cpp
#	src/core/CMakeLists.txt
#	src/core/smallmap_type.hpp
#	src/disaster_vehicle.h
#	src/effectvehicle_base.h
#	src/fontcache.cpp
#	src/game/game_core.cpp
#	src/game/game_gui.cpp
#	src/gamelog.cpp
#	src/gamelog_internal.h
#	src/group_gui.cpp
#	src/linkgraph/linkgraph.h
#	src/misc.cpp
#	src/network/core/config.h
#	src/network/core/udp.cpp
#	src/network/network_chat_gui.cpp
#	src/network/network_content_gui.cpp
#	src/network/network_gui.cpp
#	src/newgrf.cpp
#	src/newgrf_gui.cpp
#	src/newgrf_profiling.cpp
#	src/newgrf_profiling.h
#	src/object_gui.cpp
#	src/openttd.cpp
#	src/openttd.h
#	src/order_gui.cpp
#	src/os/windows/font_win32.cpp
#	src/rail_gui.cpp
#	src/road.cpp
#	src/road_gui.cpp
#	src/saveload/afterload.cpp
#	src/saveload/saveload.h
#	src/script/api/script_controller.cpp
#	src/script/api/script_roadtypelist.cpp
#	src/script/script_config.cpp
#	src/script/script_config.hpp
#	src/script/script_instance.cpp
#	src/script/script_scanner.cpp
#	src/script/squirrel.cpp
#	src/script/squirrel_helper.hpp
#	src/settings_gui.cpp
#	src/settings_internal.h
#	src/settings_type.h
#	src/table/settings/network_private_settings.ini
#	src/timetable_gui.cpp
#	src/vehicle.cpp
#	src/vehicle_base.h
#	src/window_gui.h

src/road.cpp

@@ -146,7 +146,15 @@ bool HasRoadTypeAvail(const CompanyID company, RoadType roadtype)
 		const RoadTypeInfo *rti = GetRoadTypeInfo(roadtype);
 		if (rti->label == 0) return false;
 
-		bool available = (rti->flags & ROTFB_HIDDEN) == 0;
+		/* Not yet introduced at this date. */
+		if (IsInsideMM(rti->introduction_date, 0, MAX_DAY) && rti->introduction_date > _date) return false;
+
+		/*
+		 * Do not allow building hidden road types, except when a town may build it.
+		 * The GS under deity mode, as well as anybody in the editor builds roads that are
+		 * owned by towns. So if a town may build it, it should be buildable by them too.
+		 */
+		bool available = (rti->flags & ROTFB_HIDDEN) == 0 || (rti->flags & ROTFB_TOWN_BUILD) != 0;
 		if (!available && (company == OWNER_TOWN || _game_mode == GM_EDITOR || _generating_world)) {
 			if (roadtype == GetTownRoadType()) return true;
 		}