From d1ab8fc161d33b035b8eec775ed62dec6f055ea8 Mon Sep 17 00:00:00 2001
From: wixoa <wixoag@gmail.com>
Date: Wed, 5 Feb 2025 19:02:21 -0500
Subject: [PATCH] Disallow var defines on /world and /list (#2206)

---
 DMCompiler/DM/DMCodeTree.Vars.cs | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/DMCompiler/DM/DMCodeTree.Vars.cs b/DMCompiler/DM/DMCodeTree.Vars.cs
index f7ff73d79c..bc8f31e653 100644
--- a/DMCompiler/DM/DMCodeTree.Vars.cs
+++ b/DMCompiler/DM/DMCodeTree.Vars.cs
@@ -105,7 +105,7 @@ public override bool TryDefineVar(DMCompiler compiler, int pass) {
             if (!compiler.DMObjectTree.TryGetDMObject(owner, out var dmObject))
                 return false;
 
-            if (AlreadyExists(compiler, dmObject)) {
+            if (CheckCantDefine(compiler, dmObject)) {
                 _defined = true;
                 return true;
             }
@@ -162,12 +162,23 @@ private bool HandleInstanceVar(DMCompiler compiler, DMObject dmObject) {
             return true;
         }
 
-        private bool AlreadyExists(DMCompiler compiler, DMObject dmObject) {
-            // "type" and "tag" can only be defined in DMStandard
-            if (VarName is "type" or "tag" && !varDef.Location.InDMStandard) {
-                compiler.Emit(WarningCode.InvalidVarDefinition, varDef.Location,
-                    $"Cannot redefine built-in var \"{VarName}\"");
-                return true;
+        private bool CheckCantDefine(DMCompiler compiler, DMObject dmObject) {
+            if (!compiler.Settings.NoStandard) {
+                var inStandard = varDef.Location.InDMStandard;
+
+                // "type" and "tag" can only be defined in DMStandard
+                if (VarName is "type" or "tag" && !inStandard) {
+                    compiler.Emit(WarningCode.InvalidVarDefinition, varDef.Location,
+                        $"Cannot redefine built-in var \"{VarName}\"");
+                    return true;
+                }
+
+                // Vars on /world and /list can only be defined in DMStandard
+                if ((dmObject.Path == DreamPath.World || dmObject.Path == DreamPath.List) && !inStandard) {
+                    compiler.Emit(WarningCode.InvalidVarDefinition, varDef.Location,
+                        $"Cannot define a var on type {dmObject.Path}");
+                    return true;
+                }
             }
 
             //DMObjects store two bundles of variables; the statics in GlobalVariables and the non-statics in Variables.