Tracerestrict GUI: Refactor string handling for realistic braking warning

src/lang/english.txt

@@ -3242,7 +3242,6 @@ STR_TRACE_RESTRICT_VARIABLE_PBS_ENTRY_SIGNAL                    :PBS entry signa
 STR_TRACE_RESTRICT_VARIABLE_PBS_ENTRY_SIGNAL_LONG               :entered signal of PBS block
 STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL                  :PBS end signal
 STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL_LONG             :signal at current end of PBS reservation
-STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL_LONG_WARN        :signal at current end of PBS reservation {PUSH_COLOUR}{RED}(requires realistic braking){POP_COLOUR}
 STR_TRACE_RESTRICT_VARIABLE_TRAIN_GROUP                         :train group
 STR_TRACE_RESTRICT_VARIABLE_TRAIN_SLOT                          :train in slot
 STR_TRACE_RESTRICT_VARIABLE_SLOT_OCCUPANCY                      :slot occupancy
@@ -3461,6 +3460,7 @@ STR_TRACE_RESTRICT_UNSHARE_TOOLTIP                              :{BLACK}Stop sha
 STR_TRACE_RESTRICT_SIGNAL_GUI_TOOLTIP                           :{BLACK}Routefinding restriction
 STR_TRACE_RESTRICT_INSTRUCTION_LIST_TOOLTIP                     :{BLACK}Click an instruction to select it{}Ctrl+Click to scroll to the instruction's target (if any)
 STR_TRACE_RESTRICT_HIGHLIGHT_TOOLTIP                            :{BLACK}Toggle highlighting all signals sharing this program
+STR_TRACE_RESTRICT_WARNING_REQUIRES_REALISTIC_BRAKING           :{STRING} {PUSH_COLOUR}{RED}(requires realistic braking){POP_COLOUR}
 STR_TRACE_RESTRICT_ERROR_CAN_T_INSERT_ITEM                      :{WHITE}Can't insert instruction
 STR_TRACE_RESTRICT_ERROR_CAN_T_MODIFY_ITEM                      :{WHITE}Can't modify instruction
 STR_TRACE_RESTRICT_ERROR_CAN_T_REMOVE_ITEM                      :{WHITE}Can't remove instruction

src/tracerestrict_gui.cpp

@@ -1207,18 +1207,28 @@ static void DrawInstructionString(const TraceRestrictProgram *prog, TraceRestric
 						SetDParam(3, TileX(tile));
 						SetDParam(4, TileY(tile));
 					}
+					auto insert_warning = [&](StringID warning) {
+						char buf[256];
+						int64 args_array[] = { (int64)GetDParam(1) };
+						StringParameters tmp_params(args_array);
+						char *end = GetStringWithArgs(buf, warning, &tmp_params, lastof(buf));
+						_temp_special_strings[0].assign(buf, end);
+						SetDParam(1, SPECSTR_TEMP_START);
+					};
 					switch (static_cast<TraceRestrictPBSEntrySignalAuxField>(GetTraceRestrictAuxField(item))) {
 						case TRPESAF_VEH_POS:
 							SetDParam(1, STR_TRACE_RESTRICT_VARIABLE_PBS_ENTRY_SIGNAL_LONG);
 							break;
 
 						case TRPESAF_RES_END:
-							SetDParam(1, _settings_game.vehicle.train_braking_model == TBM_REALISTIC ? STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL_LONG : STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL_LONG_WARN);
+							SetDParam(1, STR_TRACE_RESTRICT_VARIABLE_PBS_RES_END_SIGNAL_LONG);
+							if (_settings_game.vehicle.train_braking_model != TBM_REALISTIC) insert_warning(STR_TRACE_RESTRICT_WARNING_REQUIRES_REALISTIC_BRAKING);
 							break;
 
 						default:
 							NOT_REACHED();
 					}
+
 					break;
 				}