(svn r25553) -Fix [FS#5530]: provide a warning when no vehicles are available, and tell what to do in that case

src/engine.cpp

@@ -30,6 +30,7 @@
 #include "company_base.h"
 #include "vehicle_func.h"
 #include "articulated_vehicles.h"
+#include "error.h"
 
 #include "table/strings.h"
 #include "table/engines.h"
@@ -1098,3 +1099,25 @@ bool IsEngineRefittable(EngineID engine)
 	CargoID default_cargo = e->GetDefaultCargoType();
 	return default_cargo != CT_INVALID && ei->refit_mask != 1U << default_cargo;
 }
+
+/**
+ * Check for engines that have an appropriate availability.
+ */
+void CheckEngines()
+{
+	const Engine *e;
+	Date min_date = INT32_MAX;
+
+	FOR_ALL_ENGINES(e) {
+		if (!e->IsEnabled()) continue;
+
+		/* We have an available engine... yay! */
+		if (e->flags & ENGINE_AVAILABLE && e->company_avail != 0) return;
+
+		/* Okay, try to find the earliest date. */
+		min_date = min(min_date, e->info.base_intro);
+	}
+
+	SetDParam(0, min_date);
+	ShowErrorMessage(STR_ERROR_NO_VEHICLES_AVAILABLE, STR_ERROR_NO_VEHICLES_AVAILABLE_EXPLANATION, WL_WARNING);
+}

src/engine_func.h

@@ -18,6 +18,7 @@
 
 void SetupEngines();
 void StartupEngines();
+void CheckEngines();
 
 /* Original engine data counts and offsets */
 extern const uint8 _engine_counts[4];

src/lang/english.txt

@@ -4316,6 +4316,9 @@ STR_ERROR_CAN_T_CHANGE_SERVICING                                :{WHITE}Can't ch
 
 STR_ERROR_VEHICLE_IS_DESTROYED                                  :{WHITE}... vehicle is destroyed
 
+STR_ERROR_NO_VEHICLES_AVAILABLE                                 :{WHITE}No vehicles are available yet
+STR_ERROR_NO_VEHICLES_AVAILABLE_EXPLANATION                     :{WHITE}Start a new game after {DATE_SHORT} or use a NewGRF that provides early vehicles
+
 # Specific vehicle errors
 STR_ERROR_CAN_T_MAKE_TRAIN_PASS_SIGNAL                          :{WHITE}Can't make train pass signal at danger...
 STR_ERROR_CAN_T_REVERSE_DIRECTION_TRAIN                         :{WHITE}Can't reverse direction of train...

src/openttd.cpp

@@ -926,6 +926,7 @@ static void MakeNewGameDone()
 
 	if (_settings_client.gui.pause_on_newgame) DoCommandP(0, PM_PAUSED_NORMAL, 1, CMD_PAUSE);
 
+	CheckEngines();
 	MarkWholeScreenDirty();
 }