# HG changeset patch
# User terkhen <terkhen@openttd.org>
# Date 2010-07-10 20:18:59
# Node ID 4874828c361b0718fe076f6f7b7225676d597646
# Parent  cc96258f112272b161f72168a5ede26a1566f12b

(svn r20116) -Add: Show an specific error message when trying to convert/remove nonexistant signals.

diff --git a/src/lang/english.txt b/src/lang/english.txt
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -3551,6 +3551,7 @@ STR_ERROR_CAN_T_REMOVE_RAILROAD_TRACK   
 STR_ERROR_CAN_T_REMOVE_SIGNALS_FROM                             :{WHITE}Can't remove signals from here...
 STR_ERROR_SIGNAL_CAN_T_CONVERT_SIGNALS_HERE                     :{WHITE}Can't convert signals here...
 STR_ERROR_THERE_IS_NO_RAILROAD_TRACK                            :{WHITE}...there is no railway track
+STR_ERROR_THERE_ARE_NO_SIGNALS                                  :{WHITE}...there are no signals
 
 STR_ERROR_CAN_T_CONVERT_RAIL                                    :{WHITE}Can't convert railtype here...
 
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -948,7 +948,7 @@ CommandCost CmdBuildSingleSignal(TileInd
 	if (HasBit(p1, 17) && HasSignalOnTrack(tile, track)) return CommandCost();
 
 	/* you can not convert a signal if no signal is on track */
-	if (convert_signal && !HasSignalOnTrack(tile, track)) return CMD_ERROR;
+	if (convert_signal && !HasSignalOnTrack(tile, track)) return_cmd_error(STR_ERROR_THERE_ARE_NO_SIGNALS);
 
 	CommandCost cost;
 	if (!HasSignalOnTrack(tile, track)) {
@@ -1220,7 +1220,11 @@ static CommandCost CmdSignalTrackHelper(
 				had_success = true;
 				total_cost.AddCost(ret);
 			} else {
-				last_error = ret;
+				/* The "No railway" error is the least important one. */
+				if (ret.GetErrorMessage() != STR_ERROR_THERE_IS_NO_RAILROAD_TRACK ||
+						last_error.GetErrorMessage() == INVALID_STRING_ID) {
+					last_error = ret;
+				}
 			}
 		}
 
@@ -1288,7 +1292,7 @@ CommandCost CmdRemoveSingleSignal(TileIn
 		return_cmd_error(STR_ERROR_THERE_IS_NO_RAILROAD_TRACK);
 	}
 	if (!HasSignalOnTrack(tile, track)) {
-		return CMD_ERROR;
+		return_cmd_error(STR_ERROR_THERE_ARE_NO_SIGNALS);
 	}
 	CommandCost ret = EnsureNoTrainOnTrack(tile, track);
 	if (ret.Failed()) return ret;