VarAction2: Fix calculated result groups being incorrectly pruned

src/newgrf.cpp

@@ -5526,7 +5526,7 @@ static const SpriteGroup *GetGroupFromGroupID(byte setid, byte type, uint16 grou
 	while (result != nullptr) {
 		if (result->type == SGT_DETERMINISTIC) {
 			const DeterministicSpriteGroup *sg = static_cast<const DeterministicSpriteGroup *>(result);
-			if (sg->adjusts.size() == 0 || (sg->adjusts.size() == 1 && sg->adjusts[0].variable == 0x1A && (sg->adjusts[0].operation == DSGA_OP_ADD || sg->adjusts[0].operation == DSGA_OP_RST))) {
+			if (sg->GroupMayBeBypassed()) {
 				/* Deterministic sprite group can be trivially resolved, skip it */
 				uint32 value = (sg->adjusts.size() == 1) ? EvaluateDeterministicSpriteGroupAdjust(sg->size, sg->adjusts[0], nullptr, 0, UINT_MAX) : 0;
 				result = sg->default_group;

src/newgrf_spritegroup.cpp

@@ -286,7 +286,7 @@ void DeterministicSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) co
 	}
 
 	auto check_1A_range = [&]() -> bool {
-		if (this->adjusts.size() == 0 || (this->adjusts.size() == 1 && this->adjusts[0].variable == 0x1A && (this->adjusts[0].operation == DSGA_OP_ADD || this->adjusts[0].operation == DSGA_OP_RST))) {
+		if (this->GroupMayBeBypassed()) {
 			/* Not clear why some GRFs do this, perhaps a way of commenting out a branch */
 			uint32 value = (this->adjusts.size() == 1) ? EvaluateDeterministicSpriteGroupAdjust(this->size, this->adjusts[0], nullptr, 0, UINT_MAX) : 0;
 			for (const auto &range : this->ranges) {
@@ -442,6 +442,14 @@ void DeterministicSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) co
 	}
 }
 
+bool DeterministicSpriteGroup::GroupMayBeBypassed() const
+{
+	if (this->calculated_result) return false;
+	if (this->adjusts.size() == 0) return true;
+	if ((this->adjusts.size() == 1 && this->adjusts[0].variable == 0x1A && (this->adjusts[0].operation == DSGA_OP_ADD || this->adjusts[0].operation == DSGA_OP_RST))) return true;
+	return false;
+}
+
 void CallbackResultSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) const
 {
 	if (op.mode == ACOM_FIND_CB_RESULT) op.cb_result_found = true;

src/newgrf_spritegroup.h

@@ -316,6 +316,7 @@ struct DeterministicSpriteGroup : SpriteGroup {
 	const SpriteGroup *error_group; // was first range, before sorting ranges
 
 	void AnalyseCallbacks(AnalyseCallbackOperation &op) const override;
+	bool GroupMayBeBypassed() const;
 
 protected:
 	const SpriteGroup *Resolve(ResolverObject &object) const override;