Codechange: Use enum class for RailGroundType.

src/newgrf_commons.cpp

@@ -350,7 +350,7 @@ uint32_t GetTerrainType(TileIndex tile, TileContext context)
 					/* During map generation the snowstate may not be valid yet, as the tileloop may not have run yet. */
 					if (_generating_world) goto genworld; // we do not care about foundations here
 					RailGroundType ground = GetRailGroundType(tile);
-					has_snow = (ground == RAIL_GROUND_ICE_DESERT || (context == TCX_UPPER_HALFTILE && ground == RAIL_GROUND_HALF_SNOW));
+					has_snow = (ground == RailGroundType::SnowOrDesert || (context == TCX_UPPER_HALFTILE && ground == RailGroundType::HalfTileSnow));
 					break;
 				}