Add command result flag for whether SetResultData was called

Use for tracerestrict validation result fail offset

src/command.cpp

@@ -1390,6 +1390,8 @@ void CommandCost::SetTile(TileIndex tile)
 
 void CommandCost::SetResultData(uint32 result)
 {
+	this->flags |= CCIF_VALID_RESULT;
+
 	if (result == this->GetResultData()) return;
 
 	if (this->AddInlineData(CCIF_INLINE_RESULT)) {

src/command_type.h

@@ -25,6 +25,7 @@ enum CommandCostIntlFlags : uint8 {
 	CCIF_INLINE_EXTRA_MSG         = 1 << 1,
 	CCIF_INLINE_TILE              = 1 << 2,
 	CCIF_INLINE_RESULT            = 1 << 3,
+	CCIF_VALID_RESULT             = 1 << 4,
 };
 DECLARE_ENUM_AS_BIT_SET(CommandCostIntlFlags)
 
@@ -257,6 +258,11 @@ public:
 
 	void SetTile(TileIndex tile);
 
+	bool HasResultData() const
+	{
+		return (this->flags & CCIF_VALID_RESULT);
+	}
+
 	uint32 GetResultData() const
 	{
 		if (this->flags & CCIF_INLINE_RESULT) return this->inl.result;

src/saveload/tracerestrict_sl.cpp

@@ -77,7 +77,7 @@ static void Load_TRRP()
 			char str[4096];
 			char *strend = str + seprintf(str, lastof(str), "Trace restrict program %d: %s\nProgram dump:",
 					index, GetStringPtr(validation_result.GetErrorMessage()));
-			uint fail_offset = validation_result.GetResultData() ^ (1 << 31);
+			uint fail_offset = validation_result.HasResultData() ? validation_result.GetResultData() : UINT32_MAX;
 			for (uint i = 0; i < (uint)prog->items.size(); i++) {
 				if ((i % 3) == 0) {
 					strend += seprintf(strend, lastof(str), "\n%4u:", i);

src/tracerestrict.cpp

@@ -971,7 +971,7 @@ CommandCost TraceRestrictProgram::Validate(const std::vector<TraceRestrictItem>
 
 		auto validation_error = [i](StringID str) -> CommandCost {
 			CommandCost result(str);
-			result.SetResultData((1 << 31) | (uint)i);
+			result.SetResultData((uint)i);
 			return result;
 		};