- delete all compile-time symbols for scripting after finishing compiling data.

Even the bare-bones gzdoom.pk3 gets rid of over 2000 symbols this way that otherwise would need to be tracked by the garbage collector.

src/d_main.cpp

@@ -2517,6 +2517,9 @@ void D_DoomMain (void)
 
 		// Create replacements for dehacked pickups
 		FinishDehPatch();
+		
+		// clean up the compiler symbols which are not needed any longer.
+		RemoveUnusedSymbols();
 
 		InitActorNumsFromMapinfo();
 		InitSpawnablesFromMapinfo();

src/dobjtype.cpp

@@ -3898,3 +3898,45 @@ void FNamespaceManager::ReleaseSymbols()
 	GlobalNamespace = nullptr;
 	AllNamespaces.Clear();
 }
+
+// removes all symbols from the symbol tables.
+// After running the compiler these are not needed anymore.
+// Only the namespaces themselves are kept because the type table references them.
+int FNamespaceManager::RemoveSymbols()
+{
+	int count = 0;
+	for (auto ns : AllNamespaces)
+	{
+		count += ns->Symbols.Symbols.CountUsed();
+		ns->Symbols.ReleaseSymbols();
+	}
+	return count;
+}
+
+void RemoveUnusedSymbols()
+{
+	// Global symbols are not needed anymore after running the compiler.
+	int count = Namespaces.RemoveSymbols();
+
+	// We do not need any non-field and non-function symbols in structs and classes anymore.
+	for (size_t i = 0; i < countof(TypeTable.TypeHash); ++i)
+	{
+		for (PType *ty = TypeTable.TypeHash[i]; ty != NULL; ty = ty->HashNext)
+		{
+			if (ty->IsKindOf(RUNTIME_CLASS(PStruct)))
+			{
+				auto it = ty->Symbols.GetIterator();
+				PSymbolTable::MapType::Pair *pair;
+				while (it.NextPair(pair))
+				{
+					if (!pair->Value->IsKindOf(RUNTIME_CLASS(PField)) && !pair->Value->IsKindOf(RUNTIME_CLASS(PFunction)))
+					{
+						ty->Symbols.RemoveSymbol(pair->Value);
+						count++;
+					}
+				}
+			}
+		}
+	}
+	DPrintf(DMSG_SPAMMY, "%d symbols removed after compilation\n", count);
+}

src/dobjtype.h

@@ -76,6 +76,7 @@ class VMFrameStack;
 struct VMValue;
 struct VMReturn;
 class VMFunction;
+struct FNamespaceManager;
 
 // A VM function ------------------------------------------------------------
 
@@ -157,6 +158,7 @@ private:
 	MapType Symbols;
 
 	friend class DObject;
+	friend struct FNamespaceManager;
 };
 
 // A symbol for a compiler tree node ----------------------------------------
@@ -1010,6 +1012,7 @@ struct FNamespaceManager
 	PNamespace *NewNamespace(int filenum);
 	size_t MarkSymbols();
 	void ReleaseSymbols();
+	int RemoveSymbols();
 };
 
 extern FNamespaceManager Namespaces;
@@ -1047,4 +1050,7 @@ inline T *&DObject::PointerVar(FName field)
 {
 	return *(T**)ScriptVar(field, nullptr);	// pointer check is more tricky and for the handful of uses in the DECORATE parser not worth the hassle.
 }
+
+void RemoveUnusedSymbols();
+
 #endif