Codechange: Check NewGRF feature is defined before processing any sprite group mapping.

Previously this was checked after loading ids, or repeatedly checked for
each item.

src/newgrf.cpp

@@ -5706,6 +5706,11 @@ static void CanalMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void StationMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->stations == nullptr) {
+		grfmsg(1, "StationMapSpriteGroup: No stations defined, skipping");
+		return;
+	}
+
 	uint8 *stations = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		stations[i] = buf->ReadByte();
@@ -5758,6 +5763,11 @@ static void StationMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void TownHouseMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->housespec == nullptr) {
+		grfmsg(1, "TownHouseMapSpriteGroup: No houses defined, skipping");
+		return;
+	}
+
 	uint8 *houses = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		houses[i] = buf->ReadByte();
@@ -5770,11 +5780,6 @@ static void TownHouseMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "TownHouseMapSpriteGroup")) return;
 
-	if (_cur.grffile->housespec == nullptr) {
-		grfmsg(1, "TownHouseMapSpriteGroup: No houses defined, skipping");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		HouseSpec *hs = _cur.grffile->housespec[houses[i]];
 
@@ -5789,6 +5794,11 @@ static void TownHouseMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void IndustryMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->industryspec == nullptr) {
+		grfmsg(1, "IndustryMapSpriteGroup: No industries defined, skipping");
+		return;
+	}
+
 	uint8 *industries = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		industries[i] = buf->ReadByte();
@@ -5801,11 +5811,6 @@ static void IndustryMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "IndustryMapSpriteGroup")) return;
 
-	if (_cur.grffile->industryspec == nullptr) {
-		grfmsg(1, "IndustryMapSpriteGroup: No industries defined, skipping");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		IndustrySpec *indsp = _cur.grffile->industryspec[industries[i]];
 
@@ -5820,6 +5825,11 @@ static void IndustryMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void IndustrytileMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->indtspec == nullptr) {
+		grfmsg(1, "IndustrytileMapSpriteGroup: No industry tiles defined, skipping");
+		return;
+	}
+
 	uint8 *indtiles = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		indtiles[i] = buf->ReadByte();
@@ -5832,11 +5842,6 @@ static void IndustrytileMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "IndustrytileMapSpriteGroup")) return;
 
-	if (_cur.grffile->indtspec == nullptr) {
-		grfmsg(1, "IndustrytileMapSpriteGroup: No industry tiles defined, skipping");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		IndustryTileSpec *indtsp = _cur.grffile->indtspec[indtiles[i]];
 
@@ -5998,6 +6003,11 @@ static void RoadTypeMapSpriteGroup(ByteReader *buf, uint8 idcount, RoadTramType
 
 static void AirportMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->airportspec == nullptr) {
+		grfmsg(1, "AirportMapSpriteGroup: No airports defined, skipping");
+		return;
+	}
+
 	uint8 *airports = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		airports[i] = buf->ReadByte();
@@ -6010,11 +6020,6 @@ static void AirportMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "AirportMapSpriteGroup")) return;
 
-	if (_cur.grffile->airportspec == nullptr) {
-		grfmsg(1, "AirportMapSpriteGroup: No airports defined, skipping");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		AirportSpec *as = _cur.grffile->airportspec[airports[i]];
 
@@ -6029,6 +6034,11 @@ static void AirportMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void AirportTileMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->airtspec == nullptr) {
+		grfmsg(1, "AirportTileMapSpriteGroup: No airport tiles defined, skipping");
+		return;
+	}
+
 	uint8 *airptiles = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		airptiles[i] = buf->ReadByte();
@@ -6041,11 +6051,6 @@ static void AirportTileMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "AirportTileMapSpriteGroup")) return;
 
-	if (_cur.grffile->airtspec == nullptr) {
-		grfmsg(1, "AirportTileMapSpriteGroup: No airport tiles defined, skipping");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		AirportTileSpec *airtsp = _cur.grffile->airtspec[airptiles[i]];
 
@@ -6060,6 +6065,11 @@ static void AirportTileMapSpriteGroup(ByteReader *buf, uint8 idcount)
 
 static void RoadStopMapSpriteGroup(ByteReader *buf, uint8 idcount)
 {
+	if (_cur.grffile->roadstops == nullptr) {
+		grfmsg(1, "RoadStopMapSpriteGroup: No roadstops defined, skipping");
+		return;
+	}
+
 	uint8 *roadstops = AllocaM(uint8, idcount);
 	for (uint i = 0; i < idcount; i++) {
 		roadstops[i] = buf->ReadByte();
@@ -6089,11 +6099,6 @@ static void RoadStopMapSpriteGroup(ByteReader *buf, uint8 idcount)
 	uint16 groupid = buf->ReadWord();
 	if (!IsValidGroupID(groupid, "RoadStopMapSpriteGroup")) return;
 
-	if (_cur.grffile->roadstops == nullptr) {
-		grfmsg(0, "RoadStopMapSpriteGroup: No roadstops defined, skipping.");
-		return;
-	}
-
 	for (uint i = 0; i < idcount; i++) {
 		RoadStopSpec *roadstopspec = _cur.grffile->roadstops == nullptr ? nullptr : _cur.grffile->roadstops[roadstops[i]];