Fix #10574 -- revert the change and don't list unavailable road types to game script.

src/road.cpp

@@ -112,7 +112,17 @@ bool HasRoadTypeAvail(const CompanyID company, RoadType roadtype)
 {
 	if (company == OWNER_DEITY || company == OWNER_TOWN || _game_mode == GM_EDITOR || _generating_world) {
 		const RoadTypeInfo *rti = GetRoadTypeInfo(roadtype);
-		return rti->label != 0 && (rti->flags & ROTFB_HIDDEN) == 0;
+		if (rti->label == 0) return false;
+
+		/* Not yet introduced at this date. */
+		if (IsInsideMM(rti->introduction_date, 0, MAX_DATE) && rti->introduction_date > TimerGameCalendar::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.
+		 */
+		return (rti->flags & ROTFB_HIDDEN) == 0 || (rti->flags & ROTFB_TOWN_BUILD) != 0;
 	} else {
 		const Company *c = Company::GetIfValid(company);
 		if (c == nullptr) return false;

src/road.h

@@ -39,14 +39,14 @@ enum RoadTypeFlags {
 	ROTF_NO_LEVEL_CROSSING,                                ///< Bit number for disabling level crossing
 	ROTF_NO_HOUSES,                                        ///< Bit number for setting this roadtype as not house friendly
 	ROTF_HIDDEN,                                           ///< Bit number for hidden from construction.
-	ROTF_TOWN_BUILD,                                       ///< Bit number for allowing towns to build this roadtype. Does not override ROTF_HIDDEN.
+	ROTF_TOWN_BUILD,                                       ///< Bit number for allowing towns to build this roadtype.
 
 	ROTFB_NONE = 0,                                        ///< All flags cleared.
 	ROTFB_CATENARY          = 1 << ROTF_CATENARY,          ///< Value for drawing a catenary.
 	ROTFB_NO_LEVEL_CROSSING = 1 << ROTF_NO_LEVEL_CROSSING, ///< Value for disabling a level crossing.
 	ROTFB_NO_HOUSES         = 1 << ROTF_NO_HOUSES,         ///< Value for for setting this roadtype as not house friendly.
 	ROTFB_HIDDEN            = 1 << ROTF_HIDDEN,            ///< Value for hidden from construction.
-	ROTFB_TOWN_BUILD        = 1 << ROTF_TOWN_BUILD,        ///< Value for allowing towns to build this roadtype. Does not override ROTFB_HIDDEN.
+	ROTFB_TOWN_BUILD        = 1 << ROTF_TOWN_BUILD,        ///< Value for allowing towns to build this roadtype.
 };
 DECLARE_ENUM_AS_BIT_SET(RoadTypeFlags)
 

src/script/api/script_roadtypelist.cpp

@@ -18,6 +18,6 @@ ScriptRoadTypeList::ScriptRoadTypeList(ScriptRoad::RoadTramTypes rtts)
 	EnforceDeityOrCompanyModeValid_Void();
 	for (RoadType rt = ROADTYPE_BEGIN; rt != ROADTYPE_END; rt++) {
 		if (!HasBit(rtts, GetRoadTramType(rt))) continue;
-		if (ScriptCompanyMode::IsDeity() || ::HasRoadTypeAvail(ScriptObject::GetCompany(), rt)) this->AddItem(rt);
+		if (::HasRoadTypeAvail(ScriptObject::GetCompany(), rt)) this->AddItem(rt);
 	}
 }