Fix e66cec8f86: Permit loading of industry production callback with invalid cargo type.

It is only an error if the invalid result is actually used. This will be silently ignored at the moment.
It is still an error if a duplicate cargo type is returned.

src/lang/english.txt

@@ -3002,7 +3002,7 @@ STR_NEWGRF_ERROR_GRM_FAILED                                     :Requested GRF r
 STR_NEWGRF_ERROR_FORCEFULLY_DISABLED                            :{1:RAW_STRING} was disabled by {2:RAW_STRING}
 STR_NEWGRF_ERROR_INVALID_SPRITE_LAYOUT                          :Invalid/unknown sprite layout format (sprite {3:NUM})
 STR_NEWGRF_ERROR_LIST_PROPERTY_TOO_LONG                         :Too many elements in property value list (sprite {3:NUM}, property {4:HEX})
-STR_NEWGRF_ERROR_INDPROD_CALLBACK                               :Invalid industry production callback (sprite {3:NUM}, "{1:RAW_STRING}")
+STR_NEWGRF_ERROR_INDPROD_CALLBACK                               :Invalid industry production callback (sprite {3:NUM}, "{2:RAW_STRING}")
 
 # NewGRF related 'general' warnings
 STR_NEWGRF_POPUP_CAUTION_CAPTION                                :{WHITE}Caution!
@@ -3034,6 +3034,7 @@ STR_NEWGRF_BUGGY                                                :{WHITE}NewGRF '
 STR_NEWGRF_BUGGY_ARTICULATED_CARGO                              :{WHITE}Cargo/refit information for '{1:ENGINE}' differs from purchase list after construction. This might cause autorenew/-replace to fail refitting correctly
 STR_NEWGRF_BUGGY_ENDLESS_PRODUCTION_CALLBACK                    :{WHITE}'{1:STRING}' caused an endless loop in the production callback
 STR_NEWGRF_BUGGY_UNKNOWN_CALLBACK_RESULT                        :{WHITE}Callback {1:HEX} returned unknown/invalid result {2:HEX}
+STR_NEWGRF_BUGGY_INVALID_CARGO_PRODUCTION_CALLBACK              :{WHITE}'{1:STRING}' returned invalid cargo type in the production callback at {2:HEX}
 
 # 'User removed essential NewGRFs'-placeholders for stuff without specs
 STR_NEWGRF_INVALID_CARGO                                        :<invalid cargo>

src/newgrf.cpp

@@ -5005,7 +5005,12 @@ static void NewSpriteGroup(ByteReader *buf)
 						for (uint i = 0; i < group->num_input; i++) {
 							byte rawcargo = buf->ReadByte();
 							CargoID cargo = GetCargoTranslation(rawcargo, _cur.grffile);
-							if (std::find(group->cargo_input, group->cargo_input + i, cargo) != group->cargo_input + i) {
+							if (cargo == CT_INVALID) {
+								/* The mapped cargo is invalid. This is permitted at this point,
+								 * as long as the result is not used. Mark it invalid so this
+								 * can be tested later. */
+								group->version = 0xFF;
+							} else if (std::find(group->cargo_input, group->cargo_input + i, cargo) != group->cargo_input + i) {
 								GRFError *error = DisableGrf(STR_NEWGRF_ERROR_INDPROD_CALLBACK);
 								error->data = stredup("duplicate input cargo");
 								return;
@@ -5022,7 +5027,10 @@ static void NewSpriteGroup(ByteReader *buf)
 						for (uint i = 0; i < group->num_output; i++) {
 							byte rawcargo = buf->ReadByte();
 							CargoID cargo = GetCargoTranslation(rawcargo, _cur.grffile);
-							if (std::find(group->cargo_output, group->cargo_output + i, cargo) != group->cargo_output + i) {
+							if (cargo == CT_INVALID) {
+								/* Mark this result as invalid to use */
+								group->version = 0xFF;
+							} else if (std::find(group->cargo_output, group->cargo_output + i, cargo) != group->cargo_output + i) {
 								GRFError *error = DisableGrf(STR_NEWGRF_ERROR_INDPROD_CALLBACK);
 								error->data = stredup("duplicate output cargo");
 								return;

src/newgrf_industries.cpp

@@ -605,6 +605,17 @@ void IndustryProductionCallback(Industry *ind, int reason)
 		if (tgroup == NULL || tgroup->type != SGT_INDUSTRY_PRODUCTION) break;
 		const IndustryProductionSpriteGroup *group = (const IndustryProductionSpriteGroup *)tgroup;
 
+		if (group->version == 0xFF) {
+			/* Result was marked invalid on load, display error message */
+			SetDParamStr(0, spec->grf_prop.grffile->filename);
+			SetDParam(1, spec->name);
+			SetDParam(2, ind->location.tile);
+			ShowErrorMessage(STR_NEWGRF_BUGGY, STR_NEWGRF_BUGGY_INVALID_CARGO_PRODUCTION_CALLBACK, WL_WARNING);
+
+			/* abort the function early, this error isn't critical and will allow the game to continue to run */
+			break;
+		}
+
 		bool deref = (group->version >= 1);
 
 		if (group->version < 2) {

src/newgrf_spritegroup.h

@@ -277,7 +277,7 @@ struct TileLayoutSpriteGroup : SpriteGroup {
 struct IndustryProductionSpriteGroup : SpriteGroup {
 	IndustryProductionSpriteGroup() : SpriteGroup(SGT_INDUSTRY_PRODUCTION) {}
 
-	uint8 version;
+	uint8 version;                              ///< Production callback version used, or 0xFF if marked invalid
 	uint8 num_input;                            ///< How many subtract_input values are valid
 	int16 subtract_input[INDUSTRY_NUM_INPUTS];  ///< Take this much of the input cargo (can be negative, is indirect in cb version 1+)
 	CargoID cargo_input[INDUSTRY_NUM_INPUTS];   ///< Which input cargoes to take from (only cb version 2)