1 files changed, 8 insertions, 2 deletions
diff --git a/st/ClassInstance.java b/st/ClassInstance.java
index 3de852f..d51446f 100644
--- a/st/ClassInstance.java
+++ b/st/ClassInstance.java
@@ -1,6 +1,8 @@
 package st;
 
 import java.util.ArrayList;
+
+import heat.TypecheckException;
 import misc.*;
 
 public class ClassInstance extends AbstractInstance {
@@ -27,9 +29,13 @@ public class ClassInstance extends AbstractInstance {
         else
             return false;
 
-        if (o.getName().equals(this.getName()))
+        if (o.getName().equals(this.getName())) {
+            MinimalLogger.info(String.format("Found extension end."));
+            if (o.getExtend() != null && o.getExtend().equals(this.getExtend()))
+                throw new TypecheckException(String.format("Recursive extension on %s detected",
+                                                           this.toString()));
             return true;
-        else
+        } else
             MinimalLogger.info(String.format("I (%s) do not have the same name as %s... Checking if I extend...",
                                              this.getName(), o.getName()));