Add next order condition variable.

src/lang/english.txt

@@ -2385,6 +2385,7 @@ STR_TRACE_RESTRICT_CONDITIONAL_ENDIF                            :End if
 STR_TRACE_RESTRICT_VARIABLE_TRAIN_LENGTH                        :train length
 STR_TRACE_RESTRICT_VARIABLE_MAX_SPEED                           :max speed
 STR_TRACE_RESTRICT_VARIABLE_CURRENT_ORDER                       :current order
+STR_TRACE_RESTRICT_VARIABLE_NEXT_ORDER                          :next order
 STR_TRACE_RESTRICT_VARIABLE_UNDEFINED                           :undefined
 STR_TRACE_RESTRICT_CONDITIONAL_COMPARE_INTEGER                  :{STRING} {STRING} {STRING} {COMMA} then
 STR_TRACE_RESTRICT_CONDITIONAL_COMPARE_SPEED                    :{STRING} {STRING} {STRING} {VELOCITY} then

src/tracerestrict.cpp

@@ -218,6 +218,20 @@ void TraceRestrictProgram::Execute(const Train* v, TraceRestrictProgramResult& o
 						result = TestOrderCondition(&(v->current_order), item);
 						break;
 
+					case TRIT_COND_NEXT_ORDER: {
+						if (v->orders.list == NULL) break;
+						if (v->orders.list->GetNumOrders() == 0) break;
+
+						const Order *current_order = v->GetOrder(v->cur_real_order_index);
+						for (const Order *order = v->orders.list->GetNext(current_order); order != current_order; order = v->orders.list->GetNext(order)) {
+							if (order->IsGotoOrder()) {
+								result = TestOrderCondition(order, item);
+								break;
+							}
+						}
+						break;
+					}
+
 					default:
 						NOT_REACHED();
 				}
@@ -737,7 +751,8 @@ void TraceRestrictRemoveDestinationID(TraceRestrictOrderCondAuxField type, uint1
 	FOR_ALL_TRACE_RESTRICT_PROGRAMS(prog) {
 		for (size_t i = 0; i < prog->items.size(); i++) {
 			TraceRestrictItem &item = prog->items[i]; // note this is a reference,
-			if (GetTraceRestrictType(item) == TRIT_COND_CURRENT_ORDER) {
+			if (GetTraceRestrictType(item) == TRIT_COND_CURRENT_ORDER ||
+					GetTraceRestrictType(item) == TRIT_COND_NEXT_ORDER) {
 				if (GetTraceRestrictAuxField(item) == type && GetTraceRestrictValue(item) == index) {
 					SetTraceRestrictValueDefault(item, TRVT_ORDER); // this updates the instruction in-place
 				}

src/tracerestrict.h

@@ -83,6 +83,7 @@ enum TraceRestrictItemType {
 	TRIT_COND_TRAIN_LENGTH        = 10,   ///< Test train length
 	TRIT_COND_MAX_SPEED           = 11,   ///< Test train max speed
 	TRIT_COND_CURRENT_ORDER       = 12,   ///< Test train current order (station, waypoint or depot)
+	TRIT_COND_NEXT_ORDER          = 13,   ///< Test train next order (station, waypoint or depot)
 	/* space up to 31 */
 };
 
@@ -251,6 +252,7 @@ static inline TraceRestrictTypePropertySet GetTraceRestrictTypeProperties(TraceR
 				break;
 
 			case TRIT_COND_CURRENT_ORDER:
+			case TRIT_COND_NEXT_ORDER:
 				out.value_type = TRVT_ORDER;
 				out.cond_type = TRCOT_BINARY;
 				break;

src/tracerestrict_gui.cpp

@@ -159,6 +159,7 @@ static const TraceRestrictDropDownListSet *GetTypeDropDownListSet(TraceRestrictI
 		STR_TRACE_RESTRICT_VARIABLE_TRAIN_LENGTH,
 		STR_TRACE_RESTRICT_VARIABLE_MAX_SPEED,
 		STR_TRACE_RESTRICT_VARIABLE_CURRENT_ORDER,
+		STR_TRACE_RESTRICT_VARIABLE_NEXT_ORDER,
 		STR_TRACE_RESTRICT_VARIABLE_UNDEFINED,
 		INVALID_STRING_ID,
 	};
@@ -166,6 +167,7 @@ static const TraceRestrictDropDownListSet *GetTypeDropDownListSet(TraceRestrictI
 		TRIT_COND_TRAIN_LENGTH,
 		TRIT_COND_MAX_SPEED,
 		TRIT_COND_CURRENT_ORDER,
+		TRIT_COND_NEXT_ORDER,
 		TRIT_COND_UNDEFINED,
 	};
 	static const TraceRestrictDropDownListSet set_cond = {