Fix a rare, but nasty desync caused by a unit selection (or lack ther…

…eof) (#1174)

Thanks @6AKU66 for discovering this one.

rts/System/Object.cpp

@@ -54,14 +54,25 @@ CObject::~CObject()
 	assert(!detached);
 	detached = true;
 
-	for (const auto& p: listenersDepTbl) {
-		assert(p.first >= DEPENDENCE_ATTACKER && p.first < DEPENDENCE_COUNT);
-		assert(p.second < listeners.size());
-
-		for (CObject* obj: listeners[p.second]) {
+	// NB: listenersDepTbl must be iterated sequentially
+	// due to the presence of obj->DependentDied(this);
+	// The order of naive iteration becomes undefined in
+	// case "unsynced" dependencies like DEPENDENCE_SELECTED
+	// are present in listenersDepTbl
+	// Ex: can't use `for (const auto& p : listenersDepTbl) {}`
+	for (std::underlying_type_t<DependenceType> dt = DEPENDENCE_ATTACKER, cnt = 0; dt < DEPENDENCE_COUNT && cnt < listenersDepTbl.size(); ++dt) {
+		const auto it = listenersDepTbl.find(dt);
+		if (it == listenersDepTbl.end())
+			continue;
+
+		++cnt;
+
+		assert(it->second < listeners.size());
+
+		for (CObject* obj: listeners[it->second]) {
 			obj->DependentDied(this);
 
-			const auto jt = obj->listeningDepTbl.find(p.first);
+			const auto jt = obj->listeningDepTbl.find(it->first);
 
 			if (jt == obj->listeningDepTbl.end())
 				continue;

rts/System/Object.h

@@ -5,6 +5,7 @@
 
 #include <atomic>
 #include <functional>
+#include <type_traits>
 #include <vector>
 
 #include "ObjectDependenceTypes.h"
@@ -125,8 +126,8 @@ class CObject
 	template<size_t N> void FilterListening(const TObjFilterPred& fp, std::array<int, N>& ids) const { FilterDepObjects(listening, fp, ids); }
 
 protected:
-	spring::unordered_map<int, size_t> listenersDepTbl; // maps dependence-type to index into listeners
-	spring::unordered_map<int, size_t> listeningDepTbl; // maps dependence-type to index into listening
+	spring::unordered_map<std::underlying_type_t<DependenceType>, size_t> listenersDepTbl; // maps dependence-type to index into listeners
+	spring::unordered_map<std::underlying_type_t<DependenceType>, size_t> listeningDepTbl; // maps dependence-type to index into listening
 
 	TDependenceMap listeners;
 	TDependenceMap listening;

rts/System/ObjectDependenceTypes.h

@@ -9,7 +9,7 @@
 // AddDeathDependence / DeleteDeathDependence calls in order not to risk a crash. With dependence types this can never happen, i.e.
 // DeleteDeathDependence(object, DEPENDENCE_ATTACKER) can be called a hundred times without any risk of losing some other type of dependence.
 // Dependence types also makes it easy to detect deletion of non-existent dependence types, and output a warning for debugging purposes.
-enum DependenceType {
+enum DependenceType : uint8_t {
 	DEPENDENCE_ATTACKER,
 	DEPENDENCE_BUILD,
 	DEPENDENCE_BUILDER,
@@ -21,14 +21,9 @@ enum DependenceType {
 	DEPENDENCE_INTERCEPTABLE,
 	DEPENDENCE_INTERCEPTTARGET,
 	DEPENDENCE_LASTCOLWARN,
-	DEPENDENCE_LIGHT,
 	DEPENDENCE_ORDERTARGET,
 	DEPENDENCE_RECLAIM,
-	DEPENDENCE_REPULSE,
-	DEPENDENCE_REPULSED,
 	DEPENDENCE_RESURRECT,
-	DEPENDENCE_SELECTED,
-	DEPENDENCE_SOLIDONTOP,
 	DEPENDENCE_TARGET,
 	DEPENDENCE_TARGETUNIT,
 	DEPENDENCE_TERRAFORM,
@@ -37,6 +32,13 @@ enum DependenceType {
 	DEPENDENCE_WAITCMD,
 	DEPENDENCE_WEAPON,
 	DEPENDENCE_WEAPONTARGET,
+	DEPENDENCE_REPULSE,
+	DEPENDENCE_REPULSED,
+	DEPENDENCE_SOLIDONTOP,
+	// unsynced, keep them last
+	DEPENDENCE_LIGHT,
+	DEPENDENCE_SELECTED,
+
 	DEPENDENCE_NONE,
 	DEPENDENCE_COUNT
 };