(svn r25882) -Change [FS#5766]: Don't offer subsidies for auto-distributed cargo.

src/subsidy.cpp

@@ -348,7 +348,10 @@ bool FindSubsidyTownCargoRoute()
 	}
 
 	/* Avoid using invalid NewGRF cargoes. */
-	if (!CargoSpec::Get(cid)->IsValid()) return false;
+	if (!CargoSpec::Get(cid)->IsValid() ||
+			_settings_game.linkgraph.GetDistributionType(cid) != DT_MANUAL) {
+		return false;
+	}
 
 	/* Quit if the percentage transported is large enough. */
 	if (src_town->GetPercentTransported(cid) > SUBSIDY_MAX_PCT_TRANSPORTED) return false;
@@ -388,8 +391,13 @@ bool FindSubsidyIndustryCargoRoute()
 	}
 
 	/* Quit if no production in this industry
-	 * or if the pct transported is already large enough */
-	if (total == 0 || trans > SUBSIDY_MAX_PCT_TRANSPORTED || cid == CT_INVALID) return false;
+	 * or if the pct transported is already large enough
+	 * or if the cargo is automatically distributed */
+	if (total == 0 || trans > SUBSIDY_MAX_PCT_TRANSPORTED ||
+			cid == CT_INVALID ||
+			_settings_game.linkgraph.GetDistributionType(cid) != DT_MANUAL) {
+		return false;
+	}
 
 	SourceID src = src_ind->index;
 
@@ -480,7 +488,16 @@ void SubsidyMonthlyLoop()
 		}
 	}
 
-	if (modified) RebuildSubsidisedSourceAndDestinationCache();
+	if (modified) {
+		RebuildSubsidisedSourceAndDestinationCache();
+	} else if (_settings_game.linkgraph.distribution_pax != DT_MANUAL &&
+			   _settings_game.linkgraph.distribution_mail != DT_MANUAL &&
+			   _settings_game.linkgraph.distribution_armoured != DT_MANUAL &&
+			   _settings_game.linkgraph.distribution_default != DT_MANUAL) {
+		/* Return early if there are no manually distributed cargoes and if we
+		 * don't need to invalidate the subsidies window. */
+		return;
+	}
 
 	bool passenger_subsidy = false;
 	bool town_subsidy = false;
@@ -488,7 +505,7 @@ void SubsidyMonthlyLoop()
 
 	int random_chance = RandomRange(16);
 
-	if (random_chance < 2) {
+	if (random_chance < 2 && _settings_game.linkgraph.distribution_pax == DT_MANUAL) {
 		/* There is a 1/8 chance each month of generating a passenger subsidy. */
 		int n = 1000;