Fix #1679

Author: cowtowncoder

release-notes/VERSION

@@ -11,6 +11,7 @@ Project: jackson-databind
 #1658: Infinite recursion when deserializing a class extending a Map,
   with a recursive value type
  (reported by Kevin G)
+#1679: `StackOverflowError` in Dynamic `StdKeySerializer`
 
 2.8.9 (12-Jun-2017)
 

src/main/java/com/fasterxml/jackson/databind/ser/std/StdKeySerializers.java

@@ -207,6 +207,13 @@ public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType t
         protected JsonSerializer<Object> _findAndAddDynamic(PropertySerializerMap map,
                 Class<?> type, SerializerProvider provider) throws JsonMappingException
         {
+            // 27-Jun-2017, tatu: [databind#1679] Need to avoid StackOverflowError...
+            if (type == Object.class) {
+                // basically just need to call `toString()`, easiest way:
+                JsonSerializer<Object> ser = new Default(Default.TYPE_TO_STRING, type);
+                _dynamicSerializers = map.newWith(type, ser);
+                return ser;
+            }
             PropertySerializerMap.SerializerAndMapResult result =
                     // null -> for now we won't keep ref or pass BeanProperty; could change
                     map.findAndAddKeySerializer(type, provider, null);

src/test/java/com/fasterxml/jackson/failing/KeySerializers1679Test.java renamed to src/test/java/com/fasterxml/jackson/databind/ser/KeySerializers1679Test.java

@@ -1,4 +1,4 @@
-package com.fasterxml.jackson.failing;
+package com.fasterxml.jackson.databind.ser;
 
 import java.util.*;
 
@@ -18,8 +18,8 @@ public class KeySerializers1679Test extends BaseMapTest
     public void testRecursion1679() throws Exception
     {
         Map<Object, Object> objectMap = new HashMap<Object, Object>();
-        objectMap.put(new Object(), new Object());
+        objectMap.put(new Object(), "foo");
         String json = MAPPER.writeValueAsString(objectMap);
-        assertEquals("{}", json);
+        assertNotNull(json);
     }
 }