Remove references to functions defined in unloading defs (#1776)

src/object/C4Def.cpp

@@ -319,11 +319,11 @@ C4Def::~C4Def()
 
 void C4Def::Clear()
 {
+	Script.Clear();
 	C4PropList::Clear();
 
 	Graphics.Clear();
 
-	Script.Clear();
 	StringTable.Clear();
 	if (pClonkNames && fClonkNamesOwned) delete pClonkNames; pClonkNames=NULL;
 	if (pRankNames && fRankNamesOwned) delete pRankNames; pRankNames=NULL;

src/script/C4AulCompiler.cpp

@@ -463,6 +463,7 @@ void C4AulCompiler::PreparseAstVisitor::visit(const ::aul::ast::FunctionDecl *n)
 	C4AulFunc *parent_func = Parent->GetFunc(cname);
 
 	Fn = new C4AulScriptFunc(Parent, target_host, cname, n->loc);
+	host->ownedFunctions.insert(Fn);
 	for (const auto &param : n->params)
 	{
 		Fn->AddPar(param.name.c_str(), param.type);

src/script/C4AulFunc.h

@@ -53,7 +53,7 @@ class C4AulFunc: public C4RefCnt
 public:
 	C4AulFunc(C4PropListStatic * Parent, const char *pName);
 
-	const C4PropListStatic * Parent;
+	C4PropListStatic * Parent;
 	const char * GetName() const { return Name ? Name->GetCStr() : 0; }
 	virtual StdStrBuf GetFullName() const; // get a fully classified name (C4ID::Name) for debug output
 

src/script/C4ScriptHost.cpp

@@ -52,6 +52,7 @@ C4ScriptHost::~C4ScriptHost()
 
 void C4ScriptHost::Clear()
 {
+	UnlinkOwnedFunctions();
 	C4ComponentHost::Clear();
 	ast.reset();
 	Script.Clear();
@@ -70,6 +71,49 @@ void C4ScriptHost::Clear()
 	State = ASS_NONE;
 }
 
+void C4ScriptHost::UnlinkOwnedFunctions()
+{
+	// Remove owned functions from their parents. This solves a problem
+	// where overloading a definition would unload the C4ScriptHost, but
+	// keep around global functions, which then contained dangling pointers.
+	for (auto func : ownedFunctions)
+	{
+		C4PropList *parent = func->Parent;
+		if (parent == GetPropList())
+			continue;
+		assert(parent == &::ScriptEngine);
+		C4Value v;
+		parent->GetPropertyByS(func->Name, &v);
+		if (v.getFunction() == func)
+		{
+			// If the function we're deleting is the top-level function in
+			// the inheritance chain, promote the next one in its stead;
+			// if there is no overloaded function, remove the property.
+			if (func->OwnerOverloaded)
+				parent->SetPropertyByS(func->Name, C4VFunction(func->OwnerOverloaded));
+			else
+				parent->ResetProperty(func->Name);
+		}
+		else
+		{
+			C4AulScriptFunc *func_chain = v.getFunction()->SFunc();
+			assert(func_chain != func);
+			while (func_chain)
+			{
+				// Unlink the removed function from the inheritance chain
+				if (func_chain->OwnerOverloaded == func)
+				{
+					func_chain->OwnerOverloaded = func->OwnerOverloaded;
+					break;
+				}
+				assert(func_chain->OwnerOverloaded && "Removed function not found in inheritance chain");
+				func_chain = func_chain->OwnerOverloaded->SFunc();
+			}
+		}
+	}
+	ownedFunctions.clear();
+}
+
 void C4ScriptHost::Unreg()
 {
 	// remove from list

src/script/C4ScriptHost.h

@@ -54,6 +54,9 @@ public:
 	std::string Translate(const std::string &text) const;
 	std::list<C4ScriptHost *> SourceScripts;
 	StdCopyStrBuf ScriptName; // script name
+
+	void UnlinkOwnedFunctions();
+
 protected:
 	C4ScriptHost();
 	void Unreg(); // remove from list
@@ -83,6 +86,10 @@ protected:
 	C4LangStringTable *stringTable;
 	C4Set<C4Property> LocalValues;
 	C4AulScriptState State; // script state
+
+	// list of all functions generated from code in this script host
+	std::set<C4AulScriptFunc*> ownedFunctions;
+
 	friend class C4AulParse;
 	friend class C4AulProfiler;
 	friend class C4AulScriptEngine;