Template replacement: Show warning if chain not compatible with any rail type

See: #419

src/lang/english.txt

@@ -7211,6 +7211,7 @@ STR_TMPL_TEMPLATE_OVR_RUNNING_COST                              :{BLACK}Estimate
 STR_TMPL_TEMPLATE_OVR_MULTIPLE                                  :{BLACK}{STRING1}{BLACK} {STRING1}
 STR_TMPL_WARNING_FREE_WAGON                                     :{RED}Free Chain: not runnable!
 STR_TMPL_WARNING_VEH_UNAVAILABLE                                :{RED}Train not buildable: vehicle unavailable!
+STR_TMPL_WARNING_VEH_NO_COMPATIBLE_RAIL_TYPE                    :{RED}Train not buildable: chain not compatible with any rail type
 STR_TMPL_GROUP_USES_TEMPLATE                                    :{BLACK}Template in use: {NUM}
 STR_TMP_TEMPLATE_IN_USE                                         :Template is in use
 STR_TMP_TEMPLATE_FROM_PARENT_GROUP                              :Using template from parent group

src/tbtr_template_gui_create.cpp

@@ -308,13 +308,22 @@ public:
 					int y = ScaleGUITrad(4) - this->vscroll->GetPosition();
 					bool buildable = true;
 					Money buy_cost = 0;
+					RailTypes types = static_cast<RailTypes>(UINT64_MAX);
 					for (Train *train = this->virtual_train; train != nullptr; train = train->GetNextUnit()) {
-						if (!IsEngineBuildable(train->engine_type, VEH_TRAIN, train->owner)) buildable = false;
-						buy_cost += Engine::Get(train->engine_type)->GetCost();
+						const Engine *e = Engine::Get(train->engine_type);
+						if (!IsEngineBuildable(train->engine_type, VEH_TRAIN, train->owner)) {
+							buildable = false;
+						} else {
+							types &= (GetRailTypeInfo(e->u.rail.railtype))->compatible_railtypes;
+						}
+						buy_cost += e->GetCost();
 					}
 					if (!buildable) {
 						DrawString(8, r.right, y, STR_TMPL_WARNING_VEH_UNAVAILABLE);
 						y += FONT_HEIGHT_NORMAL;
+					} else if (types == RAILTYPES_NONE) {
+						DrawString(8, r.right, y, STR_TMPL_WARNING_VEH_NO_COMPATIBLE_RAIL_TYPE);
+						y += FONT_HEIGHT_NORMAL;
 					}
 
 					SetDParam(0, STR_TMPL_TEMPLATE_OVR_VALUE_LTBLUE);

src/tbtr_template_gui_main.cpp

@@ -674,15 +674,20 @@ public:
 			}
 
 			bool buildable = true;
+			RailTypes types = static_cast<RailTypes>(UINT64_MAX);
 			for (const TemplateVehicle *u = v; u != nullptr; u = u->GetNextUnit()) {
 				if (!IsEngineBuildable(u->engine_type, VEH_TRAIN, u->owner)) {
 					buildable = false;
 					break;
+				} else {
+					types &= (GetRailTypeInfo(Engine::Get(u->engine_type)->u.rail.railtype))->compatible_railtypes;
 				}
 			}
 			/* Draw a notification string for chains that are not buildable */
 			if (!buildable) {
 				DrawString(left, right - ScaleGUITrad(24), y + ScaleGUITrad(2), STR_TMPL_WARNING_VEH_UNAVAILABLE, TC_RED, SA_CENTER);
+			} else if (types == RAILTYPES_NONE) {
+				DrawString(left, right - ScaleGUITrad(24), y + ScaleGUITrad(2), STR_TMPL_WARNING_VEH_NO_COMPATIBLE_RAIL_TYPE, TC_RED, SA_CENTER);
 			}
 
 			/* Draw the template's length in tile-units */