From 2a4d367c0e282d7261b362ba69c87ece4fe33dec Mon Sep 17 00:00:00 2001
From: Manhey Chiu <mchiu@hubspot.com>
Date: Fri, 19 Apr 2024 04:24:07 +0100
Subject: [PATCH] Add undefined variable warning when config enabled

---
 .../jinjava/interpret/JinjavaInterpreter.java | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/main/java/com/hubspot/jinjava/interpret/JinjavaInterpreter.java b/src/main/java/com/hubspot/jinjava/interpret/JinjavaInterpreter.java
index 8e0510aca..66848999d 100644
--- a/src/main/java/com/hubspot/jinjava/interpret/JinjavaInterpreter.java
+++ b/src/main/java/com/hubspot/jinjava/interpret/JinjavaInterpreter.java
@@ -78,6 +78,9 @@ public class JinjavaInterpreter implements PyishSerializable {
 
   public static final String IGNORED_OUTPUT_FROM_EXTENDS_NOTE =
     "ignored_output_from_extends";
+
+  public static final String OUTPUT_UNDEFINED_VARIABLES_ERROR =
+    "OUTPUT_UNDEFINED_VARIABLES_ERROR";
   private final Multimap<String, BlockInfo> blocks = ArrayListMultimap.create();
   private final LinkedList<Node> extendParentRoots = new LinkedList<>();
   private final Map<String, RevertibleObject> revertibleObjects = new HashMap<>();
@@ -585,6 +588,23 @@ public Object retraceVariable(String variable, int lineNumber, int startPosition
         }
       }
       obj = var.resolve(obj);
+    } else {
+      if (getConfig().getFeatures().getActivationStrategy(OUTPUT_UNDEFINED_VARIABLES_ERROR).isActive(getContext())) {
+        addError(
+          new TemplateError(
+            ErrorType.WARNING,
+            ErrorReason.MISSING,
+            ErrorItem.TOKEN,
+            "Undefined variable: '" + variable + "'",
+            null,
+            lineNumber,
+            startPosition,
+            null,
+            BasicTemplateErrorCategory.UNKNOWN,
+            ImmutableMap.of("variable", variable)
+          )
+        );
+      }
     }
     return obj;
   }