Codechange: Specify underlying type for all enums excluding those exposed to scripts. (#13383)

src/aircraft.h

@@ -25,7 +25,7 @@ static constexpr int HELICOPTER_HOLD_MAX_FLYING_ALTITUDE = 184; ///< holding fly
 struct Aircraft;
 
 /** An aircraft can be one of those types. */
-enum AircraftSubType {
+enum AircraftSubType : uint8_t {
 	AIR_HELICOPTER = 0, ///< an helicopter
 	AIR_AIRCRAFT   = 2, ///< an airplane
 	AIR_SHADOW     = 4, ///< shadow of the aircraft
@@ -33,7 +33,7 @@ enum AircraftSubType {
 };
 
 /** Flags for air vehicles; shared with disaster vehicles. */
-enum AirVehicleFlags {
+enum AirVehicleFlags : uint8_t {
 	VAF_DEST_TOO_FAR             = 0, ///< Next destination is too far away.
 
 	/* The next two flags are to prevent stair climbing of the aircraft. The idea is that the aircraft

src/aircraft_cmd.cpp

@@ -107,7 +107,7 @@ bool IsValidImageIndex<VEH_AIRCRAFT>(uint8_t image_index)
 }
 
 /** Helicopter rotor animation states */
-enum HelicopterRotorStates {
+enum HelicopterRotorStates : uint8_t {
 	HRS_ROTOR_STOPPED,
 	HRS_ROTOR_MOVING_1,
 	HRS_ROTOR_MOVING_2,

src/airport.h

@@ -25,7 +25,7 @@ static const uint NEW_AIRPORTTILE_OFFSET = 74;               ///< offset of firs
 static const uint INVALID_AIRPORTTILE    = NUM_AIRPORTTILES; ///< id for an invalid airport tile
 
 /** Airport types */
-enum AirportTypes {
+enum AirportTypes : uint8_t {
 	AT_SMALL           =   0, ///< Small airport.
 	AT_LARGE           =   1, ///< Large airport.
 	AT_HELIPORT        =   2, ///< Heli port.
@@ -44,7 +44,7 @@ enum AirportTypes {
 };
 
 /** Flags for airport movement data. */
-enum AirportMovingDataFlags {
+enum AirportMovingDataFlags : uint16_t {
 	AMED_NOSPDCLAMP = 1 << 0, ///< No speed restrictions.
 	AMED_TAKEOFF    = 1 << 1, ///< Takeoff movement.
 	AMED_SLOWTURN   = 1 << 2, ///< Turn slowly (mostly used in the air).
@@ -57,7 +57,7 @@ enum AirportMovingDataFlags {
 };
 
 /** Movement States on Airports (headings target) */
-enum AirportMovementStates {
+enum AirportMovementStates : uint8_t {
 	TO_ALL         =   0, ///< Go in this direction for every target.
 	HANGAR         =   1, ///< Heading for hangar.
 	TERM1          =   2, ///< Heading for terminal 1.
@@ -143,7 +143,7 @@ struct AirportFTAbuildup;
 struct AirportFTAClass {
 public:
 	/** Bitmask of airport flags. */
-	enum Flags {
+	enum Flags : uint8_t {
 		AIRPLANES   = 0x1,                     ///< Can planes land on this airport type?
 		HELICOPTERS = 0x2,                     ///< Can helicopters land on this airport type?
 		ALL         = AIRPLANES | HELICOPTERS, ///< Mask to check for both planes and helicopters.

src/base_media_base.h

@@ -24,7 +24,7 @@ struct ContentInfo;
 /** Structure holding filename and MD5 information about a single file */
 struct MD5File {
 	/** The result of a checksum check */
-	enum ChecksumResult {
+	enum ChecksumResult : uint8_t {
 		CR_UNKNOWN,  ///< The file has not been checked yet
 		CR_MATCH,    ///< The file did exist and the md5 checksum did match
 		CR_MISMATCH, ///< The file did exist, just the md5 checksum did not match
@@ -238,7 +238,7 @@ template <class Tbase_set>
 const char *TryGetBaseSetFile(const ContentInfo *ci, bool md5sum, const Tbase_set *s);
 
 /** Types of graphics in the base graphics set */
-enum GraphicsFileType {
+enum GraphicsFileType : uint8_t {
 	GFT_BASE,     ///< Base sprites for all climates
 	GFT_LOGOS,    ///< Logos, landscape icons and original terrain generator sprites
 	GFT_ARCTIC,   ///< Landscape replacement sprites for arctic
@@ -249,7 +249,7 @@ enum GraphicsFileType {
 };
 
 /** Blitter type for base graphics sets. */
-enum BlitterType {
+enum BlitterType : uint8_t {
 	BLT_8BPP,       ///< Base set has 8 bpp sprites only.
 	BLT_32BPP,      ///< Base set has both 8 bpp and 32 bpp sprites.
 };
@@ -316,7 +316,7 @@ static const uint NUM_SONGS_PLAYLIST  = 32;
 std::optional<std::string> GetMusicCatEntryName(const std::string &filename, size_t entrynum);
 std::optional<std::vector<uint8_t>> GetMusicCatEntryData(const std::string &filename, size_t entrynum);
 
-enum MusicTrackType {
+enum MusicTrackType : uint8_t {
 	MTT_STANDARDMIDI, ///< Standard MIDI file
 	MTT_MPSMIDI,      ///< MPS GM driver MIDI format (contained in a CAT file)
 };

src/base_station_base.h

@@ -34,8 +34,7 @@ struct RoadStopTileData {
 
 /** StationRect - used to track station spread out rectangle - cheaper than scanning whole map */
 struct StationRect : public Rect {
-	enum StationRectMode
-	{
+	enum StationRectMode : uint8_t {
 		ADD_TEST = 0,
 		ADD_TRY,
 		ADD_FORCE

src/blitter/32bpp_sse2.hpp

@@ -38,14 +38,14 @@ public:
 	static_assert(sizeof(MapValue) == 2);
 
 	/** Helper for creating specialised functions for specific optimisations. */
-	enum ReadMode {
+	enum ReadMode : uint8_t {
 		RM_WITH_SKIP,   ///< Use normal code for skipping empty pixels.
 		RM_WITH_MARGIN, ///< Use cached number of empty pixels at begin and end of line to reduce work.
 		RM_NONE,        ///< No specialisation.
 	};
 
 	/** Helper for creating specialised functions for the case where the sprite width is odd or even. */
-	enum BlockType {
+	enum BlockType : uint8_t {
 		BT_EVEN, ///< An even number of pixels in the width; no need for a special case for the last pixel.
 		BT_ODD,  ///< An odd number of pixels in the width; special case for the last pixel.
 		BT_NONE, ///< No specialisation for either case.
@@ -56,7 +56,7 @@ public:
 	 *  - calculations (alpha blending),
 	 *  - heavy branching (remap lookups and animation buffer handling).
 	 */
-	enum SpriteFlags {
+	enum SpriteFlags : uint8_t {
 		SF_NONE        = 0,
 		SF_TRANSLUCENT = 1 << 1, ///< The sprite has at least 1 translucent pixel.
 		SF_NO_REMAP    = 1 << 2, ///< The sprite has no remappable colour pixel.

src/bridge.h

@@ -19,7 +19,7 @@
  * which is used to determine the proper sprite table to use
  * while drawing a given bridge part.
  */
-enum BridgePieces {
+enum BridgePieces : uint8_t {
 	BRIDGE_PIECE_NORTH = 0,
 	BRIDGE_PIECE_SOUTH,
 	BRIDGE_PIECE_INNER_NORTH,

src/build_vehicle_gui.cpp

@@ -1159,7 +1159,7 @@ void GUIEngineListAddChildren(GUIEngineList &dst, const GUIEngineList &src, Engi
 }
 
 /** Enum referring to the Hotkeys in the build vehicle window */
-enum BuildVehicleHotkeys {
+enum BuildVehicleHotkeys : int32_t {
 	BVHK_FOCUS_FILTER_BOX, ///< Focus the edit box for editing the filter string
 };
 

src/cargo_type.h

@@ -80,7 +80,7 @@ static const CargoType CARGO_NO_REFIT = 0xFE; ///< Do not refit cargo of a vehic
 static const CargoType INVALID_CARGO = UINT8_MAX;
 
 /** Mixed cargo types for definitions with cargo that can vary depending on climate. */
-enum MixedCargoType {
+enum MixedCargoType : uint8_t {
 	MCT_LIVESTOCK_FRUIT, ///< Cargo can be livestock or fruit.
 	MCT_GRAIN_WHEAT_MAIZE, ///< Cargo can be grain, wheat or maize.
 	MCT_VALUABLES_GOLD_DIAMONDS, ///< Cargo can be valuables, gold or diamonds.

src/cargopacket.h

@@ -292,7 +292,7 @@ public:
 	typedef typename Tcont::const_reverse_iterator ConstReverseIterator;
 
 	/** Kind of actions that could be done with packets on move. */
-	enum MoveToAction {
+	enum MoveToAction : uint8_t {
 		MTA_BEGIN = 0,
 		MTA_TRANSFER = 0, ///< Transfer the cargo to the station.
 		MTA_DELIVER,      ///< Deliver the cargo to some town or industry.

src/cheat_gui.cpp

@@ -168,7 +168,7 @@ static int32_t ClickChangeMaxHlCheat(int32_t new_value, int32_t)
 }
 
 /** Available cheats. */
-enum CheatNumbers {
+enum CheatNumbers : uint8_t {
 	CHT_MONEY,           ///< Change amount of money.
 	CHT_CHANGE_COMPANY,  ///< Switch company.
 	CHT_EXTRA_DYNAMITE,  ///< Dynamite anything.

src/clear_map.h

@@ -16,7 +16,7 @@
 /**
  * Ground types. Valid densities in comments after the enum.
  */
-enum ClearGround {
+enum ClearGround : uint8_t {
 	CLEAR_GRASS  = 0, ///< 0-3
 	CLEAR_ROUGH  = 1, ///< 3
 	CLEAR_ROCKS  = 2, ///< 3

src/command_type.h

@@ -184,7 +184,7 @@ public:
  *
  * @see _command_proc_table
  */
-enum Commands : uint16_t {
+enum Commands : uint8_t {
 	CMD_BUILD_RAILROAD_TRACK,         ///< build a rail track
 	CMD_REMOVE_RAILROAD_TRACK,        ///< remove a rail track
 	CMD_BUILD_SINGLE_RAIL,            ///< build a single rail track
@@ -371,7 +371,7 @@ enum Commands : uint16_t {
  *
  * This enums defines some flags which can be used for the commands.
  */
-enum DoCommandFlag {
+enum DoCommandFlag : uint16_t {
 	DC_NONE                  = 0x000, ///< no flag is set
 	DC_EXEC                  = 0x001, ///< execute the given command
 	DC_AUTO                  = 0x002, ///< don't allow building on structures
@@ -393,7 +393,7 @@ DECLARE_ENUM_AS_BIT_SET(DoCommandFlag)
  *
  * This enumeration defines flags for the _command_proc_table.
  */
-enum CommandFlags {
+enum CommandFlags : uint16_t {
 	CMD_SERVER    = 0x001, ///< the command can only be initiated by the server
 	CMD_SPECTATOR = 0x002, ///< the command may be initiated by a spectator
 	CMD_OFFLINE   = 0x004, ///< the command cannot be executed in a multiplayer game; single-player only
@@ -410,7 +410,7 @@ enum CommandFlags {
 DECLARE_ENUM_AS_BIT_SET(CommandFlags)
 
 /** Types of commands we have. */
-enum CommandType {
+enum CommandType : uint8_t {
 	CMDT_LANDSCAPE_CONSTRUCTION, ///< Construction and destruction of objects on the map.
 	CMDT_VEHICLE_CONSTRUCTION,   ///< Construction, modification (incl. refit) and destruction of vehicles.
 	CMDT_MONEY_MANAGEMENT,       ///< Management of money, i.e. loans.
@@ -425,7 +425,7 @@ enum CommandType {
 };
 
 /** Different command pause levels. */
-enum CommandPauseLevel {
+enum CommandPauseLevel : uint8_t {
 	CMDPL_NO_ACTIONS,      ///< No user actions may be executed.
 	CMDPL_NO_CONSTRUCTION, ///< No construction actions may be executed.
 	CMDPL_NO_LANDSCAPING,  ///< No landscaping actions may be executed.

src/company_gui.cpp

@@ -2208,7 +2208,7 @@ struct CompanyWindow : Window
 	CompanyWidgets query_widget;
 
 	/** Display planes in the company window. */
-	enum CompanyWindowPlanes {
+	enum CompanyWindowPlanes : uint8_t {
 		/* Display planes of the #WID_C_SELECT_VIEW_BUILD_HQ selection widget. */
 		CWP_VB_VIEW = 0,  ///< Display the view button
 		CWP_VB_BUILD,     ///< Display the build button

src/company_manager_face.h

@@ -16,7 +16,7 @@
 #include "company_type.h"
 
 /** The gender/race combinations that we have faces for */
-enum GenderEthnicity {
+enum GenderEthnicity : uint8_t {
 	GENDER_FEMALE    = 0, ///< This bit set means a female, otherwise male
 	ETHNICITY_BLACK  = 1, ///< This bit set means black, otherwise white
 
@@ -29,7 +29,7 @@ enum GenderEthnicity {
 DECLARE_ENUM_AS_BIT_SET(GenderEthnicity) ///< See GenderRace as a bitset
 
 /** Bitgroups of the CompanyManagerFace variable */
-enum CompanyManagerFaceVariable {
+enum CompanyManagerFaceVariable : uint8_t {
 	CMFV_GENDER,
 	CMFV_ETHNICITY,
 	CMFV_GEN_ETHN,

src/console_cmds.cpp

@@ -1959,7 +1959,7 @@ static std::vector<std::pair<std::string_view, NetworkAuthorizedKeys *>> _consol
 	{ "server", &_settings_client.network.server_authorized_keys },
 };
 
-enum ConNetworkAuthorizedKeyAction {
+enum ConNetworkAuthorizedKeyAction : uint8_t {
 	CNAKA_LIST,
 	CNAKA_ADD,
 	CNAKA_REMOVE,

src/console_internal.h

@@ -16,7 +16,7 @@ static const uint ICON_CMDLN_SIZE     = 1024; ///< maximum length of a typed in
 static const uint ICON_MAX_STREAMSIZE = 2048; ///< maximum length of a totally expanded command
 
 /** Return values of console hooks (#IConsoleHook). */
-enum ConsoleHookResult {
+enum ConsoleHookResult : uint8_t {
 	CHR_ALLOW,    ///< Allow command execution.
 	CHR_DISALLOW, ///< Disallow command execution.
 	CHR_HIDE,     ///< Hide the existence of the command.

src/console_type.h

@@ -13,7 +13,7 @@
 #include "gfx_type.h"
 
 /** Modes of the in-game console. */
-enum IConsoleModes {
+enum IConsoleModes : uint8_t {
 	ICONSOLE_FULL,   ///< In-game console is opened, whole screen.
 	ICONSOLE_OPENED, ///< In-game console is opened, upper 1/3 of the screen.
 	ICONSOLE_CLOSED, ///< In-game console is closed.

src/core/pool_type.hpp

@@ -13,7 +13,7 @@
 #include "enum_type.hpp"
 
 /** Various types of a pool. */
-enum PoolType {
+enum PoolType : uint8_t {
 	PT_NONE    = 0x00, ///< No pool is selected.
 	PT_NORMAL  = 0x01, ///< Normal pool containing game objects.
 	PT_NCLIENT = 0x02, ///< Network client pools.

src/currency.h

@@ -23,7 +23,7 @@ static constexpr TimerGameCalendar::Year MIN_EURO_YEAR{2000}; ///< The earliest
  * savegame compatibility and in order to refer to them quickly, especially
  * for referencing the custom one.
  */
-enum Currencies {
+enum Currencies : uint8_t {
 	CURRENCY_GBP,       ///< British Pound
 	CURRENCY_USD,       ///< US Dollar
 	CURRENCY_EUR,       ///< Euro

src/depot_gui.cpp

@@ -436,7 +436,7 @@ struct DepotWindow : Window {
 		const Vehicle *wagon;
 	};
 
-	enum DepotGUIAction {
+	enum DepotGUIAction : uint8_t {
 		MODE_ERROR,
 		MODE_DRAG_VEHICLE,
 		MODE_SHOW_VEHICLE,

src/direction_type.h

@@ -55,7 +55,7 @@ DECLARE_INCREMENT_DECREMENT_OPERATORS(Direction)
  *       modulo DIR_END or use the #ChangeDirDiff(DirDiff, DirDiff) function.
  * @see ChangeDirDiff(DirDiff, DirDiff)
  */
-enum DirDiff {
+enum DirDiff : uint8_t {
 	DIRDIFF_SAME    = 0,    ///< Both directions faces to the same direction
 	DIRDIFF_45RIGHT = 1,    ///< Angle of 45 degrees right
 	DIRDIFF_90RIGHT = 2,    ///< Angle of 90 degrees right
@@ -92,7 +92,7 @@ DECLARE_ENUM_AS_ADDABLE(DiagDirection)
  *
  * @see DirDiff
  */
-enum DiagDirDiff {
+enum DiagDirDiff : uint8_t {
 	DIAGDIRDIFF_BEGIN   = 0,        ///< Used for iterations
 	DIAGDIRDIFF_SAME    = 0,        ///< Same directions
 	DIAGDIRDIFF_90RIGHT = 1,        ///< 90 degrees right

src/disaster_vehicle.h

@@ -13,7 +13,7 @@
 #include "vehicle_base.h"
 
 /** Different sub types of disaster vehicles. */
-enum DisasterSubType {
+enum DisasterSubType : uint8_t {
 	ST_ZEPPELINER,               ///< Zeppelin, crashes at airports.
 	ST_ZEPPELINER_SHADOW,        ///< Shadow of the zeppelin.
 	ST_SMALL_UFO,                ///< Small UFO, tries to find a road vehicle to destroy.

src/driver.h

@@ -35,7 +35,7 @@ public:
 	virtual ~Driver() = default;
 
 	/** The type of driver */
-	enum Type {
+	enum Type : uint8_t {
 		DT_BEGIN = 0, ///< Helper for iteration
 		DT_MUSIC = 0, ///< A music driver, needs to be before sound to properly shut down extmidi forked music players
 		DT_SOUND,     ///< A sound driver

src/economy_type.h

@@ -57,7 +57,7 @@ struct Economy {
 };
 
 /** Score categories in the detailed performance rating. */
-enum ScoreID {
+enum ScoreID : uint8_t {
 	SCORE_BEGIN      = 0,
 	SCORE_VEHICLES   = 0,
 	SCORE_STATIONS   = 1,
@@ -71,11 +71,16 @@ enum ScoreID {
 	SCORE_TOTAL      = 9,  ///< This must always be the last entry
 	SCORE_END        = 10, ///< How many scores are there..
 
-	SCORE_MAX = 1000,      ///< The max score that can be in the performance history
-	/* the scores together of score_info is allowed to be more! */
+
 };
 DECLARE_INCREMENT_DECREMENT_OPERATORS(ScoreID)
 
+/**
+ * The max score that can be in the performance history.
+ * The scores together of score_info is allowed to be more!
+ */
+static constexpr int SCORE_MAX = 1000;
+
 /** Data structure for storing how the score is computed for a single score id. */
 struct ScoreInfo {
 	int needed; ///< How much you need to get the perfect score
@@ -195,7 +200,7 @@ using Expenses = std::array<Money, EXPENSES_END>;
 /**
  * Categories of a price bases.
  */
-enum PriceCategory {
+enum PriceCategory : uint8_t {
 	PCAT_NONE,         ///< Not affected by difficulty settings
 	PCAT_RUNNING,      ///< Price is affected by "vehicle running cost" difficulty setting
 	PCAT_CONSTRUCTION, ///< Price is affected by "construction cost" difficulty setting

src/effectvehicle_func.h

@@ -13,7 +13,7 @@
 #include "vehicle_type.h"
 
 /** Effect vehicle types */
-enum EffectVehicleType {
+enum EffectVehicleType : uint8_t {
 	EV_CHIMNEY_SMOKE            =  0, ///< Smoke of power plant (industry).
 	EV_STEAM_SMOKE              =  1, ///< Smoke of steam engines.
 	EV_DIESEL_SMOKE             =  2, ///< Smoke of diesel engines.

src/engine_type.h

@@ -90,7 +90,7 @@ struct ShipVehicleInfo {
  * If bit 0 is 0 then it is a helicopter, otherwise it is a plane
  * in which case bit 1 tells us whether it's a big(fast) plane or not.
  */
-enum AircraftSubTypeBits {
+enum AircraftSubTypeBits : uint8_t {
 	AIR_HELI = 0,
 	AIR_CTOL = 1, ///< Conventional Take Off and Landing, i.e. planes
 	AIR_FAST = 2
@@ -168,7 +168,7 @@ struct EngineInfo {
 /**
  * EngineInfo.misc_flags is a bitmask, with the following values
  */
-enum EngineMiscFlags {
+enum EngineMiscFlags : uint8_t {
 	EF_RAIL_TILTS = 0, ///< Rail vehicle tilts in curves
 	EF_ROAD_TRAM  = 0, ///< Road vehicle is a tram/light rail vehicle
 	EF_USES_2CC   = 1, ///< Vehicle uses two company colours
@@ -183,7 +183,7 @@ enum EngineMiscFlags {
 /**
  * Engine.flags is a bitmask, with the following values.
  */
-enum EngineFlags {
+enum EngineFlags : uint8_t {
 	ENGINE_AVAILABLE         = 1, ///< This vehicle is available to everyone.
 	ENGINE_EXCLUSIVE_PREVIEW = 2, ///< This vehicle is in the exclusive preview stage, either being used or being offered to a company.
 };

src/error.h

@@ -20,7 +20,7 @@
 struct GRFFile;
 
 /** Message severity/type */
-enum WarningLevel {
+enum WarningLevel : uint8_t {
 	WL_INFO,     ///< Used for DoCommand-like (and some non-fatal AI GUI) errors/information
 	WL_WARNING,  ///< Other information
 	WL_ERROR,    ///< Errors (eg. saving/loading failed)

src/fileio_func.h

@@ -60,7 +60,7 @@ class TarScanner : FileScanner {
 	uint DoScan(Subdirectory sd);
 public:
 	/** The mode of tar scanning. */
-	enum Mode {
+	enum Mode : uint8_t {
 		NONE     = 0,      ///< Scan nothing.
 		BASESET  = 1 << 0, ///< Scan for base sets.
 		NEWGRF   = 1 << 1, ///< Scan for non-base sets.

src/fileio_type.h

@@ -13,7 +13,7 @@
 #include "core/enum_type.hpp"
 
 /** The different abstract types of files that the system knows about. */
-enum AbstractFileType {
+enum AbstractFileType : uint8_t {
 	FT_NONE,      ///< nothing to do
 	FT_SAVEGAME,  ///< old or new savegame
 	FT_SCENARIO,  ///< old or new scenario
@@ -26,7 +26,7 @@ enum AbstractFileType {
 };
 
 /** Kinds of files in each #AbstractFileType. */
-enum DetailedFileType {
+enum DetailedFileType : uint8_t {
 	/* Save game and scenario files. */
 	DFT_OLD_GAME_FILE, ///< Old save game or scenario file.
 	DFT_GAME_FILE,     ///< Save game or scenario file.
@@ -50,7 +50,7 @@ enum DetailedFileType {
 };
 
 /** Operation performed on the file. */
-enum SaveLoadOperation {
+enum SaveLoadOperation : uint8_t {
 	SLO_CHECK,   ///< Load file for checking and/or preview.
 	SLO_LOAD,    ///< File is being loaded.
 	SLO_SAVE,    ///< File is being saved.
@@ -70,7 +70,7 @@ enum SaveLoadOperation {
  * Values are a combination of #AbstractFileType and #DetailedFileType.
  * @see GetAbstractFileType GetDetailedFileType
  */
-enum FiosType {
+enum FiosType : uint16_t {
 	FIOS_TYPE_DRIVE  = MAKE_FIOS_TYPE(FT_NONE, DFT_FIOS_DRIVE),
 	FIOS_TYPE_PARENT = MAKE_FIOS_TYPE(FT_NONE, DFT_FIOS_PARENT),
 	FIOS_TYPE_DIR    = MAKE_FIOS_TYPE(FT_NONE, DFT_FIOS_DIR),
@@ -112,7 +112,7 @@ inline DetailedFileType GetDetailedFileType(FiosType fios_type)
 /**
  * The different kinds of subdirectories OpenTTD uses
  */
-enum Subdirectory {
+enum Subdirectory : uint8_t {
 	BASE_DIR,      ///< Base directory for all subdirectories
 	SAVE_DIR,      ///< Base directory for all savegames
 	AUTOSAVE_DIR,  ///< Subdirectory of save for autosaves
@@ -136,7 +136,7 @@ enum Subdirectory {
 /**
  * Types of searchpaths OpenTTD might use
  */
-enum Searchpath : unsigned {
+enum Searchpath : uint8_t {
 	SP_FIRST_DIR,
 	SP_WORKING_DIR = SP_FIRST_DIR, ///< Search in the working directory
 #ifdef USE_XDG

src/fios.h

@@ -19,7 +19,7 @@
 
 
 /** Special values for save-load window for the data parameter of #InvalidateWindowData. */
-enum SaveLoadInvalidateWindowData {
+enum SaveLoadInvalidateWindowData : uint8_t {
 	SLIWD_RESCAN_FILES,          ///< Rescan all files (when changed directory, ...)
 	SLIWD_SELECTION_CHANGES,     ///< File selection has changed (user click, ...)
 	SLIWD_FILTER_CHANGES,        ///< The filename filter has changed (via the editbox)
@@ -91,7 +91,7 @@ public:
 	const FiosItem *FindItem(const std::string_view file);
 };
 
-enum SortingBits {
+enum SortingBits : uint8_t {
 	SORT_ASCENDING  = 0,
 	SORT_DESCENDING = 1,
 	SORT_BY_DATE    = 0,

src/framerate_type.h

@@ -44,7 +44,7 @@
  * @note When adding new elements here, make sure to also update all other locations depending on the length and order of this enum.
  * See <em>Adding new measurements</em> above.
  */
-enum PerformanceElement {
+enum PerformanceElement : uint8_t {
 	PFE_FIRST = 0,
 	PFE_GAMELOOP = 0,  ///< Speed of gameloop processing.
 	PFE_GL_ECONOMY,    ///< Time spent processing cargo movement

src/game/game_text.hpp

@@ -13,7 +13,7 @@
 #include "../strings_type.h"
 
 struct StringParam {
-	enum ParamType {
+	enum ParamType : uint8_t {
 		UNUSED,
 		RAW_STRING,
 		STRING,

src/genworld.h

@@ -14,7 +14,7 @@
 #include <thread>
 
 /** Constants related to world generation */
-enum LandscapeGenerator {
+enum LandscapeGenerator : uint8_t {
 	/* Order of these enums has to be the same as in lang/english.txt
 	 * Otherwise you will get inconsistent behaviour. */
 	LG_ORIGINAL     = 0,  ///< The original landscape generator
@@ -24,7 +24,7 @@ enum LandscapeGenerator {
 static const uint32_t GENERATE_NEW_SEED = UINT32_MAX; ///< Create a new random seed
 
 /** Modes for GenerateWorld */
-enum GenWorldMode {
+enum GenWorldMode : uint8_t {
 	GWM_NEWGAME   = 0, ///< Generate a map for a new game
 	GWM_EMPTY     = 1, ///< Generate an empty map (sea-level)
 	GWM_RANDOM    = 2, ///< Generate a random map for SE
@@ -32,7 +32,7 @@ enum GenWorldMode {
 };
 
 /** Smoothness presets. */
-enum TgenSmoothness {
+enum TgenSmoothness : uint8_t {
 	TGEN_SMOOTHNESS_BEGIN,      ///< First smoothness value.
 	TGEN_SMOOTHNESS_VERY_SMOOTH = TGEN_SMOOTHNESS_BEGIN, ///< Smoothness preset 'very smooth'.
 	TGEN_SMOOTHNESS_SMOOTH,     ///< Smoothness preset 'smooth'.
@@ -66,7 +66,7 @@ struct GenWorldInfo {
 };
 
 /** Current stage of world generation process */
-enum GenWorldProgress {
+enum GenWorldProgress : uint8_t {
 	GWP_MAP_INIT,    ///< Initialize/allocate the map, start economy
 	GWP_LANDSCAPE,   ///< Create the landscape
 	GWP_RIVER,       ///< Create the rivers

src/genworld_gui.cpp

@@ -43,7 +43,7 @@
 extern void MakeNewgameSettingsLive();
 
 /** Enum for the modes we can generate in. */
-enum GenerateLandscapeWindowMode {
+enum GenerateLandscapeWindowMode : uint8_t {
 	GLWM_GENERATE,  ///< Generate new game.
 	GLWM_HEIGHTMAP, ///< Load from heightmap.
 	GLWM_SCENARIO,  ///< Generate flat land.

src/gfx_type.h

@@ -24,7 +24,7 @@ struct PalSpriteID {
 	PaletteID pal;    ///< The palette (use \c PAL_NONE) if not needed)
 };
 
-enum WindowKeyCodes {
+enum WindowKeyCodes : uint16_t {
 	WKC_SHIFT = 0x8000,
 	WKC_CTRL  = 0x4000,
 	WKC_ALT   = 0x2000,
@@ -239,7 +239,7 @@ static_assert(sizeof(Colour) == sizeof(uint32_t));
 
 
 /** Available font sizes */
-enum FontSize {
+enum FontSize : uint8_t {
 	FS_NORMAL, ///< Index of the normal font in the font tables.
 	FS_SMALL,  ///< Index of the small font in the font tables.
 	FS_LARGE,  ///< Index of the large font in the font tables.
@@ -291,7 +291,7 @@ DECLARE_INCREMENT_DECREMENT_OPERATORS(Colours)
 DECLARE_ENUM_AS_ADDABLE(Colours)
 
 /** Colour of the strings, see _string_colourmap in table/string_colours.h or docs/ottd-colourtext-palette.png */
-enum TextColour {
+enum TextColour : uint16_t {
 	TC_BEGIN       = 0x00,
 	TC_FROMSTRING  = 0x00,
 	TC_BLUE        = 0x00,
@@ -328,14 +328,14 @@ static constexpr uint8_t PALETTE_ANIM_SIZE = 28; ///< number of animated colours
 static constexpr uint8_t PALETTE_ANIM_START = 227; ///< Index in  the _palettes array from which all animations are taking places (table/palettes.h)
 
 /** Define the operation GfxFillRect performs */
-enum FillRectMode {
+enum FillRectMode : uint8_t {
 	FILLRECT_OPAQUE,  ///< Fill rectangle with a single colour
 	FILLRECT_CHECKER, ///< Draw only every second pixel, used for greying-out
 	FILLRECT_RECOLOUR, ///< Apply a recolour sprite to the screen content
 };
 
 /** Palettes OpenTTD supports. */
-enum PaletteType {
+enum PaletteType : uint8_t {
 	PAL_DOS,        ///< Use the DOS palette.
 	PAL_WINDOWS,    ///< Use the Windows palette.
 };
@@ -364,14 +364,14 @@ struct Palette {
 };
 
 /** Modes for 8bpp support */
-enum Support8bpp {
+enum Support8bpp : uint8_t {
 	S8BPP_NONE = 0, ///< No support for 8bpp by OS or hardware, force 32bpp blitters.
 	S8BPP_SYSTEM,   ///< No 8bpp support by hardware, do not try to use 8bpp video modes or hardware palettes.
 	S8BPP_HARDWARE, ///< Full 8bpp support by OS and hardware.
 };
 
 	/** How to align the to-be drawn text. */
-enum StringAlignment {
+enum StringAlignment : uint8_t {
 	SA_LEFT        = 0 << 0, ///< Left align the text.
 	SA_HOR_CENTER  = 1 << 0, ///< Horizontally center the text.
 	SA_RIGHT       = 2 << 0, ///< Right align the text (must be a single bit).

src/goal_gui.cpp

@@ -31,7 +31,7 @@
 #include "safeguards.h"
 
 /** Goal list columns. */
-enum GoalColumn {
+enum GoalColumn : uint8_t {
 	GC_GOAL = 0, ///< Goal text column.
 	GC_PROGRESS, ///< Goal progress column.
 };

src/ground_vehicle.hpp

@@ -18,7 +18,7 @@
 #include "widgets/vehicle_widget.h"
 
 /** What is the status of our acceleration? */
-enum AccelStatus {
+enum AccelStatus : uint8_t {
 	AS_ACCEL, ///< We want to go faster, if possible of course.
 	AS_BRAKE, ///< We want to stop.
 };
@@ -51,7 +51,7 @@ struct GroundVehicleCache {
 };
 
 /** Ground vehicle flags. */
-enum GroundVehicleFlags {
+enum GroundVehicleFlags : uint8_t {
 	GVF_GOINGUP_BIT              = 0,  ///< Vehicle is currently going uphill. (Cached track information for acceleration)
 	GVF_GOINGDOWN_BIT            = 1,  ///< Vehicle is currently going downhill. (Cached track information for acceleration)
 	GVF_SUPPRESS_IMPLICIT_ORDERS = 2,  ///< Disable insertion and removal of automatic orders until the vehicle completes the real order.

src/group_gui.cpp

@@ -190,7 +190,7 @@ void BuildGuiGroupList(GUIGroupList &dst, bool fold, Owner owner, VehicleType ve
 class VehicleGroupWindow : public BaseVehicleListWindow {
 private:
 	/* Columns in the group list */
-	enum ListColumns {
+	enum ListColumns : uint8_t {
 		VGC_FOLD,          ///< Fold / Unfold button.
 		VGC_NAME,          ///< Group name.
 		VGC_PROTECT,       ///< Autoreplace protect icon.

src/heightmap.h

@@ -16,7 +16,7 @@
  * Order of these enums has to be the same as in lang/english.txt
  * Otherwise you will get inconsistent behaviour.
  */
-enum HeightmapRotation {
+enum HeightmapRotation : uint8_t {
 	HM_COUNTER_CLOCKWISE, ///< Rotate the map counter clockwise 45 degrees
 	HM_CLOCKWISE,         ///< Rotate the map clockwise 45 degrees
 };

src/industry.h

@@ -306,7 +306,7 @@ extern IndustryBuildData _industry_builder;
 
 
 /** Special values for the industry list window for the data parameter of #InvalidateWindowData. */
-enum IndustryDirectoryInvalidateWindowData {
+enum IndustryDirectoryInvalidateWindowData : uint8_t {
 	IDIWD_FORCE_REBUILD,
 	IDIWD_PRODUCTION_CHANGE,
 	IDIWD_FORCE_RESORT,

src/industry_gui.cpp

@@ -58,14 +58,14 @@ bool _ignore_restrictions;
 std::bitset<NUM_INDUSTRYTYPES> _displayed_industries; ///< Communication from the industry chain window to the smallmap window about what industries to display.
 
 /** Cargo suffix type (for which window is it requested) */
-enum CargoSuffixType {
+enum CargoSuffixType : uint8_t {
 	CST_FUND,  ///< Fund-industry window
 	CST_VIEW,  ///< View-industry window
 	CST_DIR,   ///< Industry-directory window
 };
 
 /** Ways of displaying the cargo. */
-enum CargoSuffixDisplay {
+enum CargoSuffixDisplay : uint8_t {
 	CSD_CARGO,             ///< Display the cargo without sub-type (cb37 result 401).
 	CSD_CARGO_AMOUNT,      ///< Display the cargo and amount (if useful), but no sub-type (cb37 result 400 or fail).
 	CSD_CARGO_TEXT,        ///< Display then cargo and supplied string (cb37 result 800-BFF).
@@ -138,7 +138,7 @@ static void GetCargoSuffix(uint cargo, CargoSuffixType cst, const Industry *ind,
 	}
 }
 
-enum CargoSuffixInOut {
+enum CargoSuffixInOut : uint8_t {
 	CARGOSUFFIX_OUT = 0,
 	CARGOSUFFIX_IN  = 1,
 };
@@ -789,14 +789,14 @@ static inline bool IsProductionAlterable(const Industry *i)
 class IndustryViewWindow : public Window
 {
 	/** Modes for changing production */
-	enum Editability {
+	enum Editability : uint8_t {
 		EA_NONE,              ///< Not alterable
 		EA_MULTIPLIER,        ///< Allow changing the production multiplier
 		EA_RATE,              ///< Allow changing the production rates
 	};
 
 	/** Specific lines in the info panel */
-	enum InfoLine {
+	enum InfoLine : uint8_t {
 		IL_NONE,              ///< No line
 		IL_MULTIPLIER,        ///< Production multiplier
 		IL_RATE1,             ///< Production rate of cargo 1
@@ -1334,7 +1334,7 @@ static bool CargoFilter(const Industry * const *industry, const std::pair<CargoT
 static GUIIndustryList::FilterFunction * const _industry_filter_funcs[] = { &CargoFilter };
 
 /** Enum referring to the Hotkeys in the industry directory window */
-enum IndustryDirectoryHotkeys {
+enum IndustryDirectoryHotkeys : int32_t {
 	IDHK_FOCUS_FILTER_BOX, ///< Focus the filter box
 };
 /**
@@ -1986,7 +1986,7 @@ static WindowDesc _industry_cargoes_desc(
 );
 
 /** Available types of field. */
-enum CargoesFieldType {
+enum CargoesFieldType : uint8_t {
 	CFT_EMPTY,       ///< Empty field.
 	CFT_SMALL_EMPTY, ///< Empty small field (for the header).
 	CFT_INDUSTRY,    ///< Display industry.

src/industry_map.h

@@ -19,7 +19,7 @@
  * They all are pointing toward array _industry_draw_tile_data, in table/industry_land.h
  * How to calculate the correct position ? GFXid << 2 | IndustryStage (0 to 3)
  */
-enum IndustryGraphics {
+enum IndustryGraphics : uint8_t {
 	GFX_COAL_MINE_TOWER_NOT_ANIMATED   =   0,
 	GFX_COAL_MINE_TOWER_ANIMATED       =   1,
 	GFX_POWERPLANT_CHIMNEY             =   8,

src/industrytype.h

@@ -19,7 +19,7 @@
 #include "newgrf_commons.h"
 
 /** Available types of industry lifetimes. */
-enum IndustryLifeType {
+enum IndustryLifeType : uint8_t {
 	INDUSTRYLIFE_BLACK_HOLE =      0, ///< Like power plants and banks
 	INDUSTRYLIFE_EXTRACTIVE = 1 << 0, ///< Like mines
 	INDUSTRYLIFE_ORGANIC    = 1 << 1, ///< Like forests
@@ -30,7 +30,7 @@ enum IndustryLifeType {
  * Available procedures to check whether an industry may build at a given location.
  * @see CheckNewIndustryProc, _check_new_industry_procs[]
  */
-enum CheckProc {
+enum CheckProc : uint8_t {
 	CHECK_NOTHING,    ///< Always succeeds.
 	CHECK_FOREST,     ///< %Industry should be build above snow-line in arctic climate.
 	CHECK_REFINERY,   ///< %Industry should be positioned near edge of the map.
@@ -44,7 +44,7 @@ enum CheckProc {
 };
 
 /** How was the industry created */
-enum IndustryConstructionType {
+enum IndustryConstructionType : uint8_t {
 	ICT_UNKNOWN,          ///< in previous game version or without newindustries activated
 	ICT_NORMAL_GAMEPLAY,  ///< either by user or random creation process
 	ICT_MAP_GENERATION,   ///< during random map creation
@@ -52,7 +52,7 @@ enum IndustryConstructionType {
 };
 
 /** Various industry behaviours mostly to represent original TTD specialities */
-enum IndustryBehaviour {
+enum IndustryBehaviour : uint32_t {
 	INDUSTRYBEH_NONE                  =      0,
 	INDUSTRYBEH_PLANT_FIELDS          = 1 << 0,  ///< periodically plants fields around itself (temp and arctic farms)
 	INDUSTRYBEH_CUT_TREES             = 1 << 1,  ///< cuts trees and produce first output cargo from them (lumber mill)
@@ -79,7 +79,7 @@ enum IndustryBehaviour {
 DECLARE_ENUM_AS_BIT_SET(IndustryBehaviour)
 
 /** Flags for miscellaneous industry tile specialities */
-enum IndustryTileSpecialFlags {
+enum IndustryTileSpecialFlags : uint8_t {
 	INDTILE_SPECIAL_NONE                  = 0,
 	INDTILE_SPECIAL_NEXTFRAME_RANDOMBITS  = 1 << 0, ///< Callback 0x26 needs random bits
 	INDTILE_SPECIAL_ACCEPTS_ALL_CARGO     = 1 << 1, ///< Tile always accepts all cargoes the associated industry accepts

src/ini_type.h

@@ -13,7 +13,7 @@
 #include "fileio_type.h"
 
 /** Types of groups */
-enum IniGroupType {
+enum IniGroupType : uint8_t {
 	IGT_VARIABLES = 0, ///< Values of the form "landscape = hilly".
 	IGT_LIST      = 1, ///< A list of values, separated by \n and terminated by the next group block.
 	IGT_SEQUENCE  = 2, ///< A list of uninterpreted lines, terminated by the next group block.

src/intro_gui.cpp

@@ -135,7 +135,7 @@ struct SelectGameWindow : public Window {
 				vc.delay = std::stoi(match[3].str()) * 1000; // milliseconds
 
 				/* Parse flags from second matching group. */
-				enum IdType {
+				enum IdType : uint8_t {
 					ID_NONE, ID_VEHICLE
 				} id_type = ID_NONE;
 				for (char c : match[2].str()) {

src/landscape_type.h

@@ -14,7 +14,7 @@
 typedef uint8_t LandscapeID; ///< Landscape type. @see LandscapeType
 
 /** Landscape types */
-enum LandscapeType {
+enum LandscapeType : uint8_t {
 	LT_TEMPERATE  = 0,
 	LT_ARCTIC     = 1,
 	LT_TROPIC     = 2,

src/linkgraph/linkgraph_type.h

@@ -44,7 +44,7 @@ enum DistributionType : uint8_t {
  * Refreshing a link makes just sure a minimum capacity is kept. Increasing
  * actually adds the given capacity.
  */
-enum EdgeUpdateMode {
+enum EdgeUpdateMode : uint8_t {
 	EUM_INCREASE     = 1,      ///< Increase capacity.
 	EUM_REFRESH      = 1 << 1, ///< Refresh capacity.
 	EUM_RESTRICTED   = 1 << 2, ///< Use restricted link.

src/linkgraph/refresh.h

@@ -25,7 +25,7 @@ protected:
 	 * Various flags about properties of the last examined link that might have
 	 * an influence on the next one.
 	 */
-	enum RefreshFlags {
+	enum RefreshFlags : uint8_t {
 		USE_NEXT,     ///< There was a conditional jump. Try to use the given next order when looking for a new one.
 		HAS_CARGO,    ///< Consist could leave the last stop where it could interact with cargo carrying cargo (i.e. not an "unload all" + "no loading" order).
 		WAS_REFIT,    ///< Consist was refit since the last stop where it could interact with cargo.

src/main_gui.cpp

@@ -178,7 +178,7 @@ static constexpr NWidgetPart _nested_main_window_widgets[] = {
 	NWidget(NWID_VIEWPORT, INVALID_COLOUR, WID_M_VIEWPORT), SetResize(1, 1),
 };
 
-enum {
+enum GlobalHotKeys : int32_t {
 	GHK_QUIT,
 	GHK_ABANDON,
 	GHK_CONSOLE,

src/misc_gui.cpp

@@ -42,7 +42,7 @@
 #include "safeguards.h"
 
 /** Method to open the OSK. */
-enum OskActivation {
+enum OskActivation : uint8_t {
 	OSKA_DISABLED,           ///< The OSK shall not be activated at all.
 	OSKA_DOUBLE_CLICK,       ///< Double click on the edit box opens OSK.
 	OSKA_SINGLE_CLICK,       ///< Single click after focus click opens OSK.

src/music/midi.h

@@ -20,7 +20,7 @@ struct SMFHeader {
 };
 
 /** MIDI status byte codes */
-enum MidiStatus {
+enum MidiStatus : uint8_t {
 	/* Bytes with top bit unset are data bytes i.e. not status bytes */
 	/* Channel status messages, require channel number in lower nibble */
 	MIDIST_NOTEOFF     = 0x80,
@@ -55,7 +55,7 @@ enum MidiStatus {
  * MIDI controller numbers.
  * Complete list per General MIDI, missing values are not defined.
  */
-enum MidiController {
+enum MidiController : uint8_t {
 	/* Standard continuous controllers (MSB control) */
 	MIDICT_BANKSELECT        =   0,
 	MIDICT_MODWHEEL          =   1,
@@ -141,7 +141,7 @@ enum MidiController {
 
 
 /** Well-known MIDI system exclusive message values for use with the MidiGetStandardSysexMessage function. */
-enum class MidiSysexMessage {
+enum class MidiSysexMessage : uint8_t {
 	/** Reset device to General MIDI defaults */
 	ResetGM,
 	/** Reset device to (Roland) General Standard defaults */

src/music/midifile.cpp

@@ -520,7 +520,7 @@ struct MpsMachine {
 	MidiFile &target;     ///< recipient of data
 
 	/** Overridden MIDI status codes used in the data format */
-	enum MpsMidiStatus {
+	enum MpsMidiStatus : uint8_t {
 		MPSMIDIST_SEGMENT_RETURN = 0xFD, ///< resume playing master track from stored position
 		MPSMIDIST_SEGMENT_CALL   = 0xFE, ///< store current position of master track playback, and begin playback of a segment
 		MPSMIDIST_ENDSONG        = 0xFF, ///< immediately end the song

src/music_gui.cpp

@@ -47,7 +47,7 @@ struct MusicSystem {
 	};
 	typedef std::vector<PlaylistEntry> Playlist;
 
-	enum PlaylistChoices {
+	enum PlaylistChoices : uint8_t {
 		PLCH_ALLMUSIC,
 		PLCH_OLDSTYLE,
 		PLCH_NEWSTYLE,

src/network/core/address.h

@@ -183,7 +183,7 @@ public:
  *
  * Sorting will prefer entries at the top of this list above ones at the bottom.
  */
-enum ServerAddressType {
+enum ServerAddressType : uint8_t {
 	SERVER_ADDRESS_DIRECT,      ///< Server-address is based on an hostname:port.
 	SERVER_ADDRESS_INVITE_CODE, ///< Server-address is based on an invite code.
 };

src/network/core/core.h

@@ -20,7 +20,7 @@ bool NetworkCoreInitialize();
 void NetworkCoreShutdown();
 
 /** Status of a network client; reasons why a client has quit */
-enum NetworkRecvStatus {
+enum NetworkRecvStatus : uint8_t {
 	NETWORK_RECV_STATUS_OKAY,             ///< Everything is okay.
 	NETWORK_RECV_STATUS_DESYNC,           ///< A desync did occur.
 	NETWORK_RECV_STATUS_NEWGRF_MISMATCH,  ///< We did not have the required NewGRFs.

src/network/core/tcp.h

@@ -20,7 +20,7 @@
 #include <thread>
 
 /** The states of sending the packets. */
-enum SendPacketsState {
+enum SendPacketsState : uint8_t {
 	SPS_CLOSED,      ///< The connection got closed.
 	SPS_NONE_SENT,   ///< The buffer is still full, so no (parts of) packets could be sent.
 	SPS_PARTLY_SENT, ///< The packets are partly sent; there are more packets to be sent in the queue.
@@ -80,7 +80,7 @@ private:
 	 * game-thread, and not at another random time where we might not have the
 	 * lock on the game-state.
 	 */
-	enum class Status {
+	enum class Status : uint8_t {
 		Init,       ///< TCPConnecter is created but resolving hasn't started.
 		Resolving,  ///< The hostname is being resolved (threaded).
 		Failure,    ///< Resolving failed.

src/network/core/tcp_admin.h

@@ -70,7 +70,7 @@ enum PacketAdminType : uint8_t {
 };
 
 /** Status of an admin. */
-enum AdminStatus {
+enum AdminStatus : uint8_t {
 	ADMIN_STATUS_INACTIVE,      ///< The admin is not connected nor active.
 	ADMIN_STATUS_AUTHENTICATE,  ///< The admin is connected and working on authentication.
 	ADMIN_STATUS_ACTIVE,        ///< The admin is active.
@@ -78,7 +78,7 @@ enum AdminStatus {
 };
 
 /** Update types an admin can register a frequency for */
-enum AdminUpdateType {
+enum AdminUpdateType : uint8_t {
 	ADMIN_UPDATE_DATE,            ///< Updates about the date of the game.
 	ADMIN_UPDATE_CLIENT_INFO,     ///< Updates about the information of clients.
 	ADMIN_UPDATE_COMPANY_INFO,    ///< Updates about the generic information of companies.
@@ -93,7 +93,7 @@ enum AdminUpdateType {
 };
 
 /** Update frequencies an admin can register. */
-enum AdminUpdateFrequency {
+enum AdminUpdateFrequency : uint8_t {
 	ADMIN_FREQUENCY_POLL      = 0x01, ///< The admin can poll this.
 	ADMIN_FREQUENCY_DAILY     = 0x02, ///< The admin gets information about this on a daily basis.
 	ADMIN_FREQUENCY_WEEKLY    = 0x04, ///< The admin gets information about this on a weekly basis.
@@ -105,7 +105,7 @@ enum AdminUpdateFrequency {
 DECLARE_ENUM_AS_BIT_SET(AdminUpdateFrequency)
 
 /** Reasons for removing a company - communicated to admins. */
-enum AdminCompanyRemoveReason {
+enum AdminCompanyRemoveReason : uint8_t {
 	ADMIN_CRR_MANUAL,    ///< The company is manually removed.
 	ADMIN_CRR_AUTOCLEAN, ///< The company is removed due to autoclean.
 	ADMIN_CRR_BANKRUPT,  ///< The company went belly-up.

src/network/core/tcp_content_type.h

@@ -15,7 +15,7 @@
 #include "../../3rdparty/md5/md5.h"
 
 /** The values in the enum are important; they are used as database 'keys' */
-enum ContentType {
+enum ContentType : uint8_t {
 	CONTENT_TYPE_BEGIN         = 1, ///< Helper to mark the begin of the types
 	CONTENT_TYPE_BASE_GRAPHICS = 1, ///< The content consists of base graphics
 	CONTENT_TYPE_NEWGRF        = 2, ///< The content consists of a NewGRF
@@ -44,14 +44,14 @@ enum PacketContentType : uint8_t {
 };
 
 /** Unique identifier for the content. */
-enum ContentID {
-	INVALID_CONTENT_ID = UINT32_MAX, ///< Sentinel for invalid content.
-};
+using ContentID = uint32_t;
+
+static constexpr ContentID INVALID_CONTENT_ID = UINT32_MAX; ///< Sentinel for invalid content.
 
 /** Container for all important information about a piece of content. */
 struct ContentInfo {
 	/** The state the content can be in. */
-	enum State {
+	enum State : uint8_t {
 		UNSELECTED,     ///< The content has not been selected
 		SELECTED,       ///< The content has been manually selected
 		AUTOSELECTED,   ///< The content has been selected as dependency

src/network/core/tcp_coordinator.h

@@ -49,7 +49,7 @@ enum PacketCoordinatorType : uint8_t {
 /**
  * The type of connection the Game Coordinator can detect we have.
  */
-enum ConnectionType {
+enum ConnectionType : uint8_t {
 	CONNECTION_TYPE_UNKNOWN,  ///< The Game Coordinator hasn't informed us yet what type of connection we have.
 	CONNECTION_TYPE_ISOLATED, ///< The Game Coordinator failed to find a way to connect to your server. Nobody will be able to join.
 	CONNECTION_TYPE_DIRECT,   ///< The Game Coordinator can directly connect to your server.
@@ -60,7 +60,7 @@ enum ConnectionType {
 /**
  * The type of error from the Game Coordinator.
  */
-enum NetworkCoordinatorErrorType {
+enum NetworkCoordinatorErrorType : uint8_t {
 	NETWORK_COORDINATOR_ERROR_UNKNOWN,              ///< There was an unknown error.
 	NETWORK_COORDINATOR_ERROR_REGISTRATION_FAILED,  ///< Your request for registration failed.
 	NETWORK_COORDINATOR_ERROR_INVALID_INVITE_CODE,  ///< The invite code given is invalid.

src/network/network_client.h

@@ -21,7 +21,7 @@ private:
 	uint8_t token = 0; ///< The token we need to send back to the server to prove we're the right client.
 
 	/** Status of the connection with the server. */
-	enum ServerStatus {
+	enum ServerStatus : uint8_t {
 		STATUS_INACTIVE,      ///< The client is not connected nor active.
 		STATUS_JOIN,          ///< We are trying to join a server.
 		STATUS_AUTH_GAME,     ///< Last action was requesting game (server) password.

src/network/network_content_gui.cpp

@@ -320,7 +320,7 @@ struct ContentListFilterData {
 };
 
 /** Filter criteria for NetworkContentListWindow. */
-enum ContentListFilterCriteria {
+enum ContentListFilterCriteria : uint8_t {
 	CONTENT_FILTER_TEXT = 0,        ///< Filter by query sting
 	CONTENT_FILTER_TYPE_OR_SELECTED,///< Filter by being of displayed type or selected for download
 };

src/network/network_crypto.h

@@ -222,7 +222,7 @@ public:
 class NetworkAuthenticationClientHandler : public NetworkAuthenticationHandler {
 public:
 	/** The processing result of receiving a request. */
-	enum RequestResult {
+	enum RequestResult : uint8_t {
 		AWAIT_USER_INPUT, ///< We have requested some user input, but must wait on that.
 		READY_FOR_RESPONSE, ///< We do not have to wait for user input, and can immediately respond to the server.
 		INVALID, ///< We have received an invalid request.
@@ -258,7 +258,7 @@ public:
 class NetworkAuthenticationServerHandler : public NetworkAuthenticationHandler {
 public:
 	/** The processing result of receiving a response. */
-	enum ResponseResult {
+	enum ResponseResult : uint8_t {
 		AUTHENTICATED, ///< The client was authenticated successfully.
 		NOT_AUTHENTICATED, ///< All authentications for this handler have been exhausted.
 		RETRY_NEXT_METHOD, ///< The client failed to authenticate, but there is another method to try.

src/network/network_crypto_internal.h

@@ -49,7 +49,7 @@ using X25519Mac = std::array<uint8_t, X25519_MAC_SIZE>;
 using X25519KeyExchangeMessage = std::array<uint8_t, X25519_KEY_EXCHANGE_MESSAGE_SIZE>;
 
 /** The side of the key exchange. */
-enum class X25519KeyExchangeSide {
+enum class X25519KeyExchangeSide : uint8_t {
 	CLIENT, ///< We are the client.
 	SERVER, ///< We are the server.
 };

src/network/network_gamelist.h

@@ -15,7 +15,7 @@
 #include "network_type.h"
 
 /** The status a server can be in. */
-enum NetworkGameListStatus {
+enum NetworkGameListStatus : uint8_t {
 	NGLS_OFFLINE, ///< Server is offline (or cannot be queried).
 	NGLS_ONLINE,  ///< Server is online.
 	NGLS_FULL,    ///< Server is full and cannot be queried.

src/network/network_gui.cpp

@@ -1313,7 +1313,7 @@ static WindowDesc _client_list_desc(
  * The possibly entries in a DropDown for an admin.
  * Client and companies are mixed; they just have to be unique.
  */
-enum DropDownAdmin {
+enum DropDownAdmin : uint8_t {
 	DD_CLIENT_ADMIN_KICK,
 	DD_CLIENT_ADMIN_BAN,
 	DD_COMPANY_ADMIN_RESET,

src/network/network_gui.h

@@ -38,7 +38,7 @@ struct NetworkCompanyInfo : NetworkCompanyStats {
 	std::string clients;      ///< The clients that control this company (Name1, name2, ..)
 };
 
-enum NetworkRelayWindowCloseData {
+enum NetworkRelayWindowCloseData : uint8_t {
 	NRWCD_UNHANDLED = 0, ///< Relay request is unhandled.
 	NRWCD_HANDLED = 1, ///< Relay request is handled, either by user or by timeout.
 };

src/network/network_internal.h

@@ -40,7 +40,7 @@
 typedef class ServerNetworkGameSocketHandler NetworkClientSocket;
 
 /** Status of the clients during joining. */
-enum NetworkJoinStatus {
+enum NetworkJoinStatus : uint8_t {
 	NETWORK_JOIN_STATUS_CONNECTING,
 	NETWORK_JOIN_STATUS_AUTHORIZING,
 	NETWORK_JOIN_STATUS_WAITING,

src/network/network_server.h

@@ -50,7 +50,7 @@ protected:
 
 public:
 	/** Status of a client */
-	enum ClientStatus {
+	enum ClientStatus : uint8_t {
 		STATUS_INACTIVE,      ///< The client is not connected nor active.
 		STATUS_AUTH_GAME,     ///< The client is authorizing with game (server) password.
 		STATUS_IDENTIFY,      ///< The client is identifying itself.

src/network/network_survey.h

@@ -24,7 +24,7 @@ protected:
 	bool IsCancelled() const override { return false; }
 
 public:
-	enum class Reason {
+	enum class Reason : uint8_t {
 		PREVIEW, ///< User is previewing the survey result.
 		LEAVE, ///< User is leaving the game (but not exiting the application).
 		EXIT, ///< User is exiting the application.

src/network/network_type.h

@@ -25,7 +25,7 @@ static const uint MAX_CLIENT_SLOTS = 256;
 /**
  * Vehicletypes in the order they are send in info packets.
  */
-enum NetworkVehicleType {
+enum NetworkVehicleType : uint8_t {
 	NETWORK_VEH_TRAIN = 0,
 	NETWORK_VEH_LORRY,
 	NETWORK_VEH_BUS,
@@ -87,7 +87,7 @@ DECLARE_ENUM_AS_ADDABLE(DestType)
  * Actions that can be used for NetworkTextMessage.
  * @warning The values of the enum items are part of the admin network API. Only append at the end.
  */
-enum NetworkAction {
+enum NetworkAction : uint8_t {
 	NETWORK_ACTION_JOIN,
 	NETWORK_ACTION_LEAVE,
 	NETWORK_ACTION_SERVER_MESSAGE,
@@ -107,7 +107,7 @@ enum NetworkAction {
  * The error codes we send around in the protocols.
  * @warning The values of the enum items are part of the admin network API. Only append at the end.
  */
-enum NetworkErrorCode {
+enum NetworkErrorCode : uint8_t {
 	NETWORK_ERROR_GENERAL, // Try to use this one like never
 
 	/* Signals from clients */

src/newgrf.cpp

@@ -314,7 +314,7 @@ static const uint NUM_STATIONS_PER_GRF = UINT16_MAX - 1;
 /** Temporary engine data used when loading only */
 struct GRFTempEngineData {
 	/** Summary state of refittability properties */
-	enum Refittability {
+	enum Refittability : uint8_t {
 		UNSET    =  0,  ///< No properties assigned. Default refit masks shall be activated.
 		EMPTY,          ///< GRF defined vehicle as not-refittable. The vehicle shall only carry the default cargo.
 		NONEMPTY,       ///< GRF defined the vehicle as refittable. If the refitmask is empty after translation (cargotypes not available), disable the vehicle.
@@ -997,7 +997,7 @@ static void ConvertTTDBasePrice(uint32_t base_pointer, const char *error_locatio
 }
 
 /** Possible return values for the FeatureChangeInfo functions */
-enum ChangeInfoResult {
+enum ChangeInfoResult : uint8_t {
 	CIR_SUCCESS,    ///< Variable was parsed and read
 	CIR_DISABLED,   ///< GRF was disabled due to error
 	CIR_UNHANDLED,  ///< Variable was parsed but unread

src/newgrf.h

@@ -23,7 +23,7 @@
  * List of different canal 'features'.
  * Each feature gets an entry in the canal spritegroup table
  */
-enum CanalFeature {
+enum CanalFeature : uint8_t {
 	CF_WATERSLOPE,
 	CF_LOCKS,
 	CF_DIKES,
@@ -42,7 +42,7 @@ struct CanalProperties {
 	uint8_t flags;          ///< Flags controlling display.
 };
 
-enum GrfLoadingStage {
+enum GrfLoadingStage : uint8_t {
 	GLS_FILESCAN,
 	GLS_SAFETYSCAN,
 	GLS_LABELSCAN,
@@ -54,7 +54,7 @@ enum GrfLoadingStage {
 
 DECLARE_INCREMENT_DECREMENT_OPERATORS(GrfLoadingStage)
 
-enum GrfMiscBit {
+enum GrfMiscBit : uint8_t {
 	GMB_DESERT_TREES_FIELDS    = 0, // Unsupported.
 	GMB_DESERT_PAVED_ROADS     = 1,
 	GMB_FIELD_BOUNDING_BOX     = 2, // Unsupported.
@@ -64,7 +64,7 @@ enum GrfMiscBit {
 	GMB_SECOND_ROCKY_TILE_SET  = 6,
 };
 
-enum GrfSpecFeature {
+enum GrfSpecFeature : uint8_t {
 	GSF_TRAINS,
 	GSF_ROADVEHICLES,
 	GSF_SHIPS,
@@ -159,14 +159,14 @@ struct GRFFile : ZeroedMemoryAllocator {
 	}
 };
 
-enum ShoreReplacement {
+enum ShoreReplacement : uint8_t {
 	SHORE_REPLACE_NONE,       ///< No shore sprites were replaced.
 	SHORE_REPLACE_ACTION_5,   ///< Shore sprites were replaced by Action5.
 	SHORE_REPLACE_ACTION_A,   ///< Shore sprites were replaced by ActionA (using grass tiles for the corner-shores).
 	SHORE_REPLACE_ONLY_NEW,   ///< Only corner-shores were loaded by Action5 (openttd(w/d).grf only).
 };
 
-enum TramReplacement {
+enum TramReplacement : uint8_t {
 	TRAMWAY_REPLACE_DEPOT_NONE,       ///< No tram depot graphics were loaded.
 	TRAMWAY_REPLACE_DEPOT_WITH_TRACK, ///< Electrified depot graphics with tram track were loaded.
 	TRAMWAY_REPLACE_DEPOT_NO_TRACK,   ///< Electrified depot graphics without tram track were loaded.

src/newgrf_act5.h

@@ -11,7 +11,7 @@
 #define NEWGRF_ACT5_H
 
 /** The type of action 5 type. */
-enum Action5BlockType {
+enum Action5BlockType : uint8_t {
 	A5BLOCK_FIXED,                ///< Only allow replacing a whole block of sprites. (TTDP compatible)
 	A5BLOCK_ALLOW_OFFSET,         ///< Allow replacing any subset by specifiing an offset.
 	A5BLOCK_INVALID,              ///< unknown/not-implemented type

src/newgrf_airport.h

@@ -67,7 +67,7 @@ public:
 };
 
 /** List of default airport classes. */
-enum AirportClassID {
+enum AirportClassID : uint8_t {
 	APC_BEGIN     = 0,  ///< Lowest valid airport class id
 	APC_SMALL     = 0,  ///< id for small airports class
 	APC_LARGE,          ///< id for large airports class
@@ -80,7 +80,7 @@ enum AirportClassID {
 DECLARE_INCREMENT_DECREMENT_OPERATORS(AirportClassID)
 
 /** TTDP airport types. Used to map our types to TTDPatch's */
-enum TTDPAirportType {
+enum TTDPAirportType : uint8_t {
 	ATP_TTDP_SMALL,    ///< Same as AT_SMALL
 	ATP_TTDP_LARGE,    ///< Same as AT_LARGE
 	ATP_TTDP_HELIPORT, ///< Same as AT_HELIPORT

src/newgrf_animation_type.h

@@ -23,7 +23,7 @@ struct AnimationInfo {
 };
 
 /** Animation triggers for station. */
-enum StationAnimationTrigger {
+enum StationAnimationTrigger : uint8_t {
 	SAT_BUILT,         ///< Trigger tile when built.
 	SAT_NEW_CARGO,     ///< Trigger station on new cargo arrival.
 	SAT_CARGO_TAKEN,   ///< Trigger station when cargo is completely taken.
@@ -34,7 +34,7 @@ enum StationAnimationTrigger {
 };
 
 /** Animation triggers of the industries. */
-enum IndustryAnimationTrigger {
+enum IndustryAnimationTrigger : uint8_t {
 	IAT_CONSTRUCTION_STATE_CHANGE,  ///< Trigger whenever the construction state changes.
 	IAT_TILELOOP,                   ///< Trigger in the periodic tile loop.
 	IAT_INDUSTRY_TICK,              ///< Trigger every tick.
@@ -43,7 +43,7 @@ enum IndustryAnimationTrigger {
 };
 
 /** Animation triggers for airport tiles */
-enum AirpAnimationTrigger {
+enum AirpAnimationTrigger : uint8_t {
 	AAT_BUILT,                   ///< Triggered when the airport is built (for all tiles at the same time).
 	AAT_TILELOOP,                ///< Triggered in the periodic tile loop.
 	AAT_STATION_NEW_CARGO,       ///< Triggered when new cargo arrives at the station (for all tiles at the same time).
@@ -53,7 +53,7 @@ enum AirpAnimationTrigger {
 };
 
 /** Animation triggers for objects. */
-enum ObjectAnimationTrigger {
+enum ObjectAnimationTrigger : uint8_t {
 	OAT_BUILT,     ///< Triggered when the object is built (for all tiles at the same time).
 	OAT_TILELOOP,  ///< Triggered in the periodic tile loop.
 	OAT_256_TICKS, ///< Triggered every 256 ticks (for all tiles at the same time).

src/newgrf_callbacks.h

@@ -17,7 +17,7 @@
  * industry, etc.
  * Names are formatted as CBID_<CLASS>_<CALLBACK>
  */
-enum CallbackID {
+enum CallbackID : uint16_t {
 	/** Set when using the callback resolve system, but not to resolve a callback. */
 	CBID_NO_CALLBACK                     = 0x00,
 
@@ -297,7 +297,7 @@ enum CallbackID {
  * Callback masks for vehicles, indicates which callbacks are used by a vehicle.
  * Some callbacks are always used and don't have a mask.
  */
-enum VehicleCallbackMask {
+enum VehicleCallbackMask : uint8_t {
 	CBM_VEHICLE_VISUAL_EFFECT  = 0, ///< Visual effects and wagon power (trains, road vehicles and ships)
 	CBM_VEHICLE_LENGTH         = 1, ///< Vehicle length (trains and road vehicles)
 	CBM_VEHICLE_LOAD_AMOUNT    = 2, ///< Load amount
@@ -313,7 +313,7 @@ enum VehicleCallbackMask {
 /**
  * Callback masks for stations.
  */
-enum StationCallbackMask {
+enum StationCallbackMask : uint8_t {
 	CBM_STATION_AVAIL                = 0, ///< Availability of station in construction window
 	CBM_STATION_DRAW_TILE_LAYOUT     = 1, ///< Use callback to select a tile layout to use when drawing.
 	CBM_STATION_ANIMATION_NEXT_FRAME = 2, ///< Use a custom next frame callback
@@ -324,7 +324,7 @@ enum StationCallbackMask {
 /**
  * Callback masks for road stops.
  */
-enum RoadStopCallbackMask {
+enum RoadStopCallbackMask : uint8_t {
 	CBM_ROAD_STOP_AVAIL                = 0, ///< Availability of road stop in construction window
 	CBM_ROAD_STOP_ANIMATION_NEXT_FRAME = 1, ///< Use a custom next frame callback
 	CBM_ROAD_STOP_ANIMATION_SPEED      = 2, ///< Customize the animation speed of the road stop
@@ -333,7 +333,7 @@ enum RoadStopCallbackMask {
 /**
  * Callback masks for houses.
  */
-enum HouseCallbackMask {
+enum HouseCallbackMask : uint8_t {
 	CBM_HOUSE_ALLOW_CONSTRUCTION        =  0, ///< decide whether the house can be built on a given tile
 	CBM_HOUSE_ANIMATION_NEXT_FRAME      =  1, ///< decides next animation frame
 	CBM_HOUSE_ANIMATION_START_STOP      =  2, ///< periodically start/stop the animation
@@ -352,14 +352,14 @@ enum HouseCallbackMask {
 /**
  * Callback masks for canals.
  */
-enum CanalCallbackMask {
+enum CanalCallbackMask : uint8_t {
 	CBM_CANAL_SPRITE_OFFSET       = 0, ///< Enable add sprite offset callback
 };
 
 /**
  * Callback masks for cargoes.
  */
-enum CargoCallbackMask {
+enum CargoCallbackMask : uint8_t {
 	CBM_CARGO_PROFIT_CALC         = 0, ///< custom profit calculation
 	CBM_CARGO_STATION_RATING_CALC = 1, ///< custom station rating for this cargo type
 };
@@ -367,7 +367,7 @@ enum CargoCallbackMask {
 /**
  * Callback masks for Industries
  */
-enum IndustryCallbackMask {
+enum IndustryCallbackMask : uint8_t {
 	CBM_IND_PROBABILITY               =  0, ///< industry availability/probability callback
 	CBM_IND_PRODUCTION_CARGO_ARRIVAL  =  1, ///< call production callback when cargo arrives at the industry
 	CBM_IND_PRODUCTION_256_TICKS      =  2, ///< call production callback every 256 ticks
@@ -388,7 +388,7 @@ enum IndustryCallbackMask {
 /**
  * Callback masks for industry tiles
  */
-enum IndustryTileCallbackMask {
+enum IndustryTileCallbackMask : uint8_t {
 	CBM_INDT_ANIM_NEXT_FRAME          = 0,  ///< decides next animation frame
 	CBM_INDT_ANIM_SPEED               = 1,  ///< decides animation speed
 	CBM_INDT_CARGO_ACCEPTANCE         = 2,  ///< decides amount of cargo acceptance
@@ -401,7 +401,7 @@ enum IndustryTileCallbackMask {
 /**
  * Callback masks for objects
  */
-enum ObjectCallbackMask {
+enum ObjectCallbackMask : uint8_t {
 	CBM_OBJ_SLOPE_CHECK               =  0, ///< decides slope suitability
 	CBM_OBJ_ANIMATION_NEXT_FRAME      =  1, ///< decides next animation frame
 	CBM_OBJ_ANIMATION_SPEED           =  2, ///< decides animation speed
@@ -413,7 +413,7 @@ enum ObjectCallbackMask {
 /**
  * Callback masks for airport tiles
  */
-enum AirportTileCallbackMask {
+enum AirportTileCallbackMask : uint8_t {
 	CBM_AIRT_ANIM_NEXT_FRAME          = 0,  ///< decides next animation frame
 	CBM_AIRT_ANIM_SPEED               = 1,  ///< decides animation speed
 	CBM_AIRT_SHAPE_CHECK              = 4,  ///< decides slope suitability

src/newgrf_canal.h

@@ -14,7 +14,7 @@
 #include "tile_type.h"
 
 /** Flags controlling the display of canals. */
-enum CanalFeatureFlag {
+enum CanalFeatureFlag : uint8_t {
 	CFF_HAS_FLAT_SPRITE = 0, ///< Additional flat ground sprite in the beginning.
 };
 

src/newgrf_commons.h

@@ -20,7 +20,7 @@
 #include "company_type.h"
 
 /** Context for tile accesses */
-enum TileContext {
+enum TileContext : uint8_t {
 	TCX_NORMAL,         ///< Nothing special.
 	TCX_UPPER_HALFTILE, ///< Querying information about the upper part of a tile with halftile foundation.
 	TCX_ON_BRIDGE,      ///< Querying information about stuff on the bridge (via some bridgehead).
@@ -29,7 +29,7 @@ enum TileContext {
 /**
  * Flags to enable register usage in sprite layouts.
  */
-enum TileLayoutFlags {
+enum TileLayoutFlags : uint8_t {
 	TLF_NOTHING           = 0x00,
 
 	TLF_DODRAW            = 0x01,   ///< Only draw sprite if value of register TileLayoutRegisters::dodraw is non-zero.
@@ -49,7 +49,7 @@ enum TileLayoutFlags {
 	TLF_KNOWN_FLAGS       = 0xFF,   ///< Known flags. Any unknown set flag will disable the GRF.
 
 	/** Flags which are still required after loading the GRF. */
-	TLF_DRAWING_FLAGS     = ~TLF_CUSTOM_PALETTE,
+	TLF_DRAWING_FLAGS     = TLF_KNOWN_FLAGS & ~TLF_CUSTOM_PALETTE,
 
 	/** Flags which do not work for the (first) ground sprite. */
 	TLF_NON_GROUND_FLAGS  = TLF_BB_XY_OFFSET | TLF_BB_Z_OFFSET | TLF_CHILD_X_OFFSET | TLF_CHILD_Y_OFFSET,

src/newgrf_config.h

@@ -17,7 +17,7 @@
 #include "3rdparty/md5/md5.h"
 
 /** GRF config bit flags */
-enum GCF_Flags {
+enum GCF_Flags : uint8_t {
 	GCF_SYSTEM,     ///< GRF file is an openttd-internal system grf
 	GCF_UNSAFE,     ///< GRF file is unsafe for static usage
 	GCF_STATIC,     ///< GRF file is used statically (can be used in any MP game)
@@ -29,7 +29,7 @@ enum GCF_Flags {
 };
 
 /** Status of GRF */
-enum GRFStatus {
+enum GRFStatus : uint8_t {
 	GCS_UNKNOWN,      ///< The status of this grf file is unknown
 	GCS_DISABLED,     ///< GRF file is disabled
 	GCS_NOT_FOUND,    ///< GRF file was not found in the local cache
@@ -38,7 +38,7 @@ enum GRFStatus {
 };
 
 /** Encountered GRF bugs */
-enum GRFBugs {
+enum GRFBugs : uint8_t {
 	GBUG_VEH_LENGTH,        ///< Length of rail vehicle changes when not inside a depot
 	GBUG_VEH_REFIT,         ///< Articulated vehicles carry different cargoes resp. are differently refittable than specified in purchase list
 	GBUG_VEH_POWERED_WAGON, ///< Powered wagon changed poweredness state when not inside a depot
@@ -47,14 +47,14 @@ enum GRFBugs {
 };
 
 /** Status of post-gameload GRF compatibility check */
-enum GRFListCompatibility {
+enum GRFListCompatibility : uint8_t {
 	GLC_ALL_GOOD,   ///< All GRF needed by game are present
 	GLC_COMPATIBLE, ///< Compatible (eg. the same ID, but different checksum) GRF found in at least one case
 	GLC_NOT_FOUND,  ///< At least one GRF couldn't be found (higher priority than GLC_COMPATIBLE)
 };
 
 /** Information that can/has to be stored about a GRF's palette. */
-enum GRFPalette {
+enum GRFPalette : uint8_t {
 	GRFP_USE_BIT     = 0,   ///< The bit used for storing the palette to use.
 	GRFP_GRF_OFFSET  = 2,   ///< The offset of the GRFP_GRF data.
 	GRFP_GRF_SIZE    = 2,   ///< The size of the GRFP_GRF data.
@@ -202,7 +202,7 @@ struct GRFConfig {
 using GRFConfigList = GRFConfig *;
 
 /** Method to find GRFs using FindGRFConfig */
-enum FindGRFConfigMode {
+enum FindGRFConfigMode : uint8_t {
 	FGCM_EXACT,       ///< Only find Grfs matching md5sum
 	FGCM_COMPATIBLE,  ///< Find best compatible Grf wrt. desired_version
 	FGCM_NEWEST,      ///< Find newest Grf

src/newgrf_debug.h

@@ -15,7 +15,7 @@
 #include "vehicle_type.h"
 
 /** Current state of spritepicker */
-enum NewGrfDebugSpritePickerMode {
+enum NewGrfDebugSpritePickerMode : uint8_t {
 	SPM_NONE,
 	SPM_WAIT_CLICK,
 	SPM_REDRAW,

src/newgrf_debug_gui.cpp

@@ -77,7 +77,7 @@ static inline uint GetInspectWindowNumber(GrfSpecFeature feature, uint index)
  * The type of a property to show. This is used to
  * provide an appropriate representation in the GUI.
  */
-enum NIType {
+enum NIType : uint8_t {
 	NIT_INT,   ///< The property is a simple integer
 	NIT_CARGO, ///< The property is a cargo
 };

src/newgrf_engine.cpp

@@ -94,7 +94,7 @@ static int MapOldSubType(const Vehicle *v)
 
 
 /* TTDP style aircraft movement states for GRF Action 2 Var 0xE2 */
-enum TTDPAircraftMovementStates {
+enum TTDPAircraftMovementStates : uint8_t {
 	AMS_TTDP_HANGAR,
 	AMS_TTDP_TO_HANGAR,
 	AMS_TTDP_TO_PAD1,
@@ -230,7 +230,7 @@ static uint8_t MapAircraftMovementState(const Aircraft *v)
 
 
 /* TTDP style aircraft movement action for GRF Action 2 Var 0xE6 */
-enum TTDPAircraftMovementActions {
+enum TTDPAircraftMovementActions : uint8_t {
 	AMA_TTDP_IN_HANGAR,
 	AMA_TTDP_ON_PAD1,
 	AMA_TTDP_ON_PAD2,

src/newgrf_engine.h

@@ -46,7 +46,7 @@ struct VehicleScopeResolver : public ScopeResolver {
 /** Resolver for a vehicle (chain) */
 struct VehicleResolverObject : public ResolverObject {
 	/** Application of 'wagon overrides'. */
-	enum WagonOverride {
+	enum WagonOverride : uint8_t {
 		WO_NONE,     //!< Resolve no wagon overrides.
 		WO_UNCACHED, //!< Resolve wagon overrides.
 		WO_CACHED,   //!< Resolve wagon overrides using TrainCache::cached_override.
@@ -103,13 +103,13 @@ bool UsesWagonOverride(const Vehicle *v);
 int GetVehicleProperty(const Vehicle *v, PropertyID property, int orig_value, bool is_signed = false);
 int GetEngineProperty(EngineID engine, PropertyID property, int orig_value, const Vehicle *v = nullptr, bool is_signed = false);
 
-enum class BuildProbabilityType {
+enum class BuildProbabilityType : uint8_t {
 	Reversed = 0,
 };
 
 bool TestVehicleBuildProbability(Vehicle *v, EngineID engine, BuildProbabilityType type);
 
-enum VehicleTrigger {
+enum VehicleTrigger : uint8_t {
 	VEHICLE_TRIGGER_NEW_CARGO     = 0x01,
 	/* Externally triggered only for the first vehicle in chain */
 	VEHICLE_TRIGGER_DEPOT         = 0x02,

src/newgrf_generic.h

@@ -17,7 +17,7 @@
 struct SpriteGroup;
 
 /** AI events for asking the NewGRF for information. */
-enum AIConstructionEvent {
+enum AIConstructionEvent : uint8_t {
 	AICE_TRAIN_CHECK_RAIL_ENGINE     = 0x00, ///< Check if we should build an engine
 	AICE_TRAIN_CHECK_ELRAIL_ENGINE   = 0x01, ///< Check if we should build an engine
 	AICE_TRAIN_CHECK_MONORAIL_ENGINE = 0x02, ///< Check if we should build an engine

src/newgrf_house.h

@@ -109,7 +109,7 @@ bool CanDeleteHouse(TileIndex tile);
 
 bool NewHouseTileLoop(TileIndex tile);
 
-enum HouseTrigger {
+enum HouseTrigger : uint8_t {
 	/* The tile of the house has been triggered during the tileloop. */
 	HOUSE_TRIGGER_TILE_LOOP     = 0x01,
 	/*

src/newgrf_industries.h

@@ -68,7 +68,7 @@ struct IndustriesResolverObject : public ResolverObject {
 };
 
 /** When should the industry(tile) be triggered for random bits? */
-enum IndustryTrigger {
+enum IndustryTrigger : uint8_t {
 	/** Triggered each tile loop */
 	INDUSTRY_TRIGGER_TILELOOP_PROCESS = 1,
 	/** Triggered (whole industry) each 256 ticks */
@@ -78,7 +78,7 @@ enum IndustryTrigger {
 };
 
 /** From where has callback #CBID_INDUSTRY_PROBABILITY been called */
-enum IndustryAvailabilityCallType {
+enum IndustryAvailabilityCallType : uint8_t {
 	IACT_MAPGENERATION,    ///< during random map generation
 	IACT_RANDOMCREATION,   ///< during creation of random ingame industry
 	IACT_USERCREATION,     ///< from the Fund/build window

src/newgrf_industrytiles.h

@@ -67,7 +67,7 @@ bool StartStopIndustryTileAnimation(const Industry *ind, IndustryAnimationTrigge
 
 
 /** Available industry tile triggers. */
-enum IndustryTileTrigger {
+enum IndustryTileTrigger : uint8_t {
 	INDTILE_TRIGGER_TILE_LOOP       = 0x01, ///< The tile of the industry has been triggered during the tileloop.
 	INDUSTRY_TRIGGER_INDUSTRY_TICK  = 0x02, ///< The industry has been triggered via its tick.
 	INDUSTRY_TRIGGER_RECEIVED_CARGO = 0x04, ///< Cargo has been delivered.

src/newgrf_properties.h

@@ -15,7 +15,7 @@
  * Names are formatted as PROP_<CLASS>_<NAME>
  * @todo Currently the list only contains properties which are used more than once in the code. I.e. they are available for callback 0x36.
  */
-enum PropertyID {
+enum PropertyID : uint8_t {
 	PROP_VEHICLE_LOAD_AMOUNT                    = 0x07, ///< Loading speed
 
 	PROP_TRAIN_SPEED                            = 0x09, ///< Max. speed: 1 unit = 1/1.6 mph = 1 km-ish/h

src/newgrf_roadstop.h

@@ -34,7 +34,7 @@ enum RoadStopClassID : uint16_t {
 DECLARE_INCREMENT_DECREMENT_OPERATORS(RoadStopClassID)
 
 /* Some Triggers etc. */
-enum RoadStopRandomTrigger {
+enum RoadStopRandomTrigger : uint8_t {
 	RSRT_NEW_CARGO,       ///< Trigger roadstop on arrival of new cargo.
 	RSRT_CARGO_TAKEN,     ///< Trigger roadstop when cargo is completely taken.
 	RSRT_VEH_ARRIVES,     ///< Trigger roadstop when road vehicle arrives.
@@ -66,7 +66,7 @@ enum RoadStopDrawMode : uint8_t {
 };
 DECLARE_ENUM_AS_BIT_SET(RoadStopDrawMode)
 
-enum RoadStopSpecFlags {
+enum RoadStopSpecFlags : uint8_t {
 	RSF_CB141_RANDOM_BITS       = 0, ///< Callback 141 needs random bits.
 	RSF_NO_CATENARY             = 2, ///< Do not show catenary.
 	RSF_DRIVE_THROUGH_ONLY      = 3, ///< Stop is drive-through only.
@@ -76,7 +76,7 @@ enum RoadStopSpecFlags {
 	RSF_DRAW_MODE_REGISTER      = 8, ///< Read draw mode from register 0x100.
 };
 
-enum RoadStopView {
+enum RoadStopView : uint8_t {
 	RSV_BAY_NE                  = 0, ///< Bay road stop, facing Northeast
 	RSV_BAY_SE                  = 1, ///< Bay road stop, facing Southeast
 	RSV_BAY_SW                  = 2, ///< Bay road stop, facing Southwest

src/newgrf_sound.h

@@ -15,7 +15,7 @@
 #include "vehicle_type.h"
 
 /** Events at which a sound might be played. */
-enum VehicleSoundEvent {
+enum VehicleSoundEvent : uint8_t {
 	VSE_START         = 1, ///< Vehicle starting, i.e. leaving, the station.
 	VSE_TUNNEL        = 2, ///< Train entering a tunnel.
 	VSE_BREAKDOWN     = 3, ///< Vehicle breaking down.

src/newgrf_station.cpp

@@ -49,7 +49,7 @@ template class NewGRFClass<StationSpec, StationClassID, STAT_CLASS_MAX>;
 
 static const uint NUM_STATIONSSPECS_PER_STATION = 255; ///< Maximum number of parts per station.
 
-enum TriggerArea {
+enum TriggerArea : uint8_t {
 	TA_TILE,
 	TA_PLATFORM,
 	TA_WHOLE,

src/newgrf_station.h

@@ -93,7 +93,7 @@ enum StationClassID : uint16_t {
 /** Allow incrementing of StationClassID variables */
 DECLARE_INCREMENT_DECREMENT_OPERATORS(StationClassID)
 
-enum StationSpecFlags {
+enum StationSpecFlags : uint8_t {
 	SSF_SEPARATE_GROUND,      ///< Use different sprite set for ground sprites.
 	SSF_DIV_BY_STATION_SIZE,  ///< Divide cargo amount by station size.
 	SSF_CB141_RANDOM_BITS,    ///< Callback 141 needs random bits.
@@ -102,7 +102,7 @@ enum StationSpecFlags {
 };
 
 /** Randomisation triggers for stations */
-enum StationRandomTrigger {
+enum StationRandomTrigger : uint8_t {
 	SRT_NEW_CARGO,        ///< Trigger station on new cargo arrival.
 	SRT_CARGO_TAKEN,      ///< Trigger station when cargo is completely taken.
 	SRT_TRAIN_ARRIVES,    ///< Trigger platform when train arrives.

src/newgrf_storage.h

@@ -17,7 +17,7 @@
 /**
  * Mode switches to the behaviour of persistent storage array.
  */
-enum PersistentStorageMode {
+enum PersistentStorageMode : uint8_t {
 	PSM_ENTER_GAMELOOP,   ///< Enter the gameloop, changes will be permanent.
 	PSM_LEAVE_GAMELOOP,   ///< Leave the gameloop, changes will be temporary.
 	PSM_ENTER_COMMAND,    ///< Enter command scope, changes will be permanent.

src/newgrf_text.cpp

@@ -39,7 +39,7 @@
  * the grf base will not be used in order to find the string, but rather for
  * jumping from standard langID scheme to the new one.
  */
-enum GRFBaseLanguages {
+enum GRFBaseLanguages : uint8_t {
 	GRFLB_AMERICAN    = 0x01,
 	GRFLB_ENGLISH     = 0x02,
 	GRFLB_GERMAN      = 0x04,
@@ -48,7 +48,7 @@ enum GRFBaseLanguages {
 	GRFLB_GENERIC     = 0x80,
 };
 
-enum GRFExtendedLanguages {
+enum GRFExtendedLanguages : uint8_t {
 	GRFLX_AMERICAN    = 0x00,
 	GRFLX_ENGLISH     = 0x01,
 	GRFLX_GERMAN      = 0x02,

src/news_type.h

@@ -103,7 +103,7 @@ DECLARE_ENUM_AS_BIT_SET(NewsFlag)
 /**
  * News display options
  */
-enum NewsDisplay {
+enum NewsDisplay : uint8_t {
 	ND_OFF,        ///< Only show a reminder in the status bar
 	ND_SUMMARY,    ///< Show ticker
 	ND_FULL,       ///< Show newspaper

src/openttd.h

@@ -15,7 +15,7 @@
 #include "core/enum_type.hpp"
 
 /** Mode which defines the state of the game. */
-enum GameMode {
+enum GameMode : uint8_t {
 	GM_MENU,
 	GM_NORMAL,
 	GM_EDITOR,
@@ -23,7 +23,7 @@ enum GameMode {
 };
 
 /** Mode which defines what mode we're switching to. */
-enum SwitchMode {
+enum SwitchMode : uint8_t {
 	SM_NONE,
 	SM_NEWGAME,           ///< New Game --> 'Random game'.
 	SM_RESTARTGAME,       ///< Restart --> 'Random game' with current settings.
@@ -42,7 +42,7 @@ enum SwitchMode {
 };
 
 /** Display Options */
-enum DisplayOptions {
+enum DisplayOptions : uint8_t {
 	DO_SHOW_TOWN_NAMES     = 0, ///< Display town names.
 	DO_SHOW_STATION_NAMES  = 1, ///< Display station names.
 	DO_SHOW_SIGNS          = 2, ///< Display signs.

src/order_gui.cpp

@@ -477,7 +477,7 @@ static Order GetOrderCmdFromTile(const Vehicle *v, TileIndex tile)
 }
 
 /** Hotkeys for order window. */
-enum {
+enum OrderHotKeys : int32_t {
 	OHK_SKIP,
 	OHK_DELETE,
 	OHK_GOTO,
@@ -534,7 +534,7 @@ enum {
 struct OrdersWindow : public Window {
 private:
 	/** Under what reason are we using the PlaceObject functionality? */
-	enum OrderPlaceObjectState {
+	enum OrderPlaceObjectState : uint8_t {
 		OPOS_NONE,
 		OPOS_GOTO,
 		OPOS_CONDITIONAL,
@@ -543,7 +543,7 @@ private:
 	};
 
 	/** Displayed planes of the #NWID_SELECTION widgets. */
-	enum DisplayPane {
+	enum DisplayPane : uint8_t {
 		/* WID_O_SEL_TOP_ROW_GROUNDVEHICLE */
 		DP_GROUNDVEHICLE_ROW_NORMAL      = 0, ///< Display the row for normal/depot orders in the top row of the train/rv order window.
 		DP_GROUNDVEHICLE_ROW_CONDITIONAL = 1, ///< Display the row for conditional orders in the top row of the train/rv order window.

src/order_type.h

@@ -49,7 +49,7 @@ enum OrderType : uint8_t {
 /**
  * Flags related to the unloading order.
  */
-enum OrderUnloadFlags {
+enum OrderUnloadFlags : uint8_t {
 	OUF_UNLOAD_IF_POSSIBLE = 0,      ///< Unload all cargo that the station accepts.
 	OUFB_UNLOAD            = 1 << 0, ///< Force unloading all cargo onto the platform, possibly not getting paid.
 	OUFB_TRANSFER          = 1 << 1, ///< Transfer all cargo onto the platform.
@@ -59,7 +59,7 @@ enum OrderUnloadFlags {
 /**
  * Flags related to the loading order.
  */
-enum OrderLoadFlags {
+enum OrderLoadFlags : uint8_t {
 	OLF_LOAD_IF_POSSIBLE = 0,      ///< Load as long as there is cargo that fits in the train.
 	OLFB_FULL_LOAD       = 1 << 1, ///< Full load all cargoes of the consist.
 	OLF_FULL_LOAD_ANY    = 3,      ///< Full load a single cargo of the consist.
@@ -69,7 +69,7 @@ enum OrderLoadFlags {
 /**
  * Non-stop order flags.
  */
-enum OrderNonStopFlags {
+enum OrderNonStopFlags : uint8_t {
 	ONSF_STOP_EVERYWHERE                  = 0, ///< The vehicle will stop at any station it passes and the destination.
 	ONSF_NO_STOP_AT_INTERMEDIATE_STATIONS = 1, ///< The vehicle will not stop at any stations it passes except the destination.
 	ONSF_NO_STOP_AT_DESTINATION_STATION   = 2, ///< The vehicle will stop at any station it passes except the destination.
@@ -80,7 +80,7 @@ enum OrderNonStopFlags {
 /**
  * Where to stop the trains.
  */
-enum OrderStopLocation {
+enum OrderStopLocation : uint8_t {
 	OSL_PLATFORM_NEAR_END = 0, ///< Stop at the near end of the platform
 	OSL_PLATFORM_MIDDLE   = 1, ///< Stop at the middle of the platform
 	OSL_PLATFORM_FAR_END  = 2, ///< Stop at the far end of the platform
@@ -90,7 +90,7 @@ enum OrderStopLocation {
 /**
  * Reasons that could cause us to go to the depot.
  */
-enum OrderDepotTypeFlags {
+enum OrderDepotTypeFlags : uint8_t {
 	ODTF_MANUAL          = 0,      ///< Manually initiated order.
 	ODTFB_SERVICE        = 1 << 0, ///< This depot order is because of the servicing limit.
 	ODTFB_PART_OF_ORDERS = 1 << 1, ///< This depot order is because of a regular order.
@@ -99,7 +99,7 @@ enum OrderDepotTypeFlags {
 /**
  * Actions that can be performed when the vehicle enters the depot.
  */
-enum OrderDepotActionFlags {
+enum OrderDepotActionFlags : uint8_t {
 	ODATF_SERVICE_ONLY   = 0,      ///< Only service the vehicle.
 	ODATFB_HALT          = 1 << 0, ///< Service the vehicle and then halt it.
 	ODATFB_NEAREST_DEPOT = 1 << 1, ///< Send the vehicle to the nearest depot.
@@ -110,7 +110,7 @@ DECLARE_ENUM_AS_BIT_SET(OrderDepotActionFlags)
 /**
  * Variables (of a vehicle) to 'cause' skipping on.
  */
-enum OrderConditionVariable {
+enum OrderConditionVariable : uint8_t {
 	OCV_LOAD_PERCENTAGE,    ///< Skip based on the amount of load
 	OCV_RELIABILITY,        ///< Skip based on the reliability
 	OCV_MAX_SPEED,          ///< Skip based on the maximum speed
@@ -125,7 +125,7 @@ enum OrderConditionVariable {
 /**
  * Comparator for the skip reasoning.
  */
-enum OrderConditionComparator {
+enum OrderConditionComparator : uint8_t {
 	OCC_EQUALS,      ///< Skip if both values are equal
 	OCC_NOT_EQUALS,  ///< Skip if both values are not equal
 	OCC_LESS_THAN,   ///< Skip if the value is less than the limit
@@ -157,7 +157,7 @@ enum ModifyOrderFlags : uint8_t {
 /**
  * Depot action to switch to when doing a #MOF_DEPOT_ACTION.
  */
-enum OrderDepotAction {
+enum OrderDepotAction : uint8_t {
 	DA_ALWAYS_GO, ///< Always go to the depot
 	DA_SERVICE,   ///< Service only if needed
 	DA_STOP,      ///< Go to the depot and stop there

src/os/macosx/string_osx.cpp

@@ -36,7 +36,7 @@ extern "C" {
 		CTRunDelegateGetWidthCallback   getWidth;
 	} CTRunDelegateCallbacks;
 
-	enum {
+	enum : int32_t {
 		kCTRunDelegateVersion1 = 1,
 		kCTRunDelegateCurrentVersion = kCTRunDelegateVersion1
 	};