Fix storing unhashable subclasses into the __subclasses__ dict

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/EconomicMapStorage.java

@@ -165,6 +165,11 @@ public void putUncached(Object key, Object value) {
         PutNode.putUncached(map, key, PyObjectHashNode.executeUncached(key), value);
     }
 
+    @TruffleBoundary
+    public void putUncached(Object key, long hash, Object value) {
+        PutNode.putUncached(map, key, hash, value);
+    }
+
     @TruffleBoundary
     public void putUncached(int key, Object value) {
         PutNode.putUncached(map, key, PyObjectHashNode.hash(key), value);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/type/TypeNodes.java

@@ -814,6 +814,9 @@ public final List<KeyAndHash> execute(Frame frame, Node inliningTarget, HashingS
                     Object subclassValue = pref.getObject();
                     if (subclassValue == null) {
                         Object key = HashingStorageIteratorKey.executeUncached(storage, it);
+                        // CPython uses the object pointer as the key, but we cannot so we do not
+                        // really know how the hash is arrived at and need to make sure to remove
+                        // the same hash that was stored.
                         long hash = HashingStorageIteratorKeyHash.executeUncached(storage, it);
                         acc.add(new KeyAndHash(key, hash));
                     }
@@ -833,6 +836,10 @@ static void clearEmptyReferences(EconomicMapStorage storage) {
         protected static void addSubclass(PythonAbstractClass base, PythonManagedClass subclass) {
             CompilerAsserts.neverPartOfCompilation();
             PDict dict = executeUncached(base);
+            // CPython uses the object pointer as the key, but we cannot since identity hashes are
+            // not unique. So we need to use the actual weakref as the key here, but not all
+            // classes are hashable. So we use the identity hash code for the map storage hash.
+            long hash = System.identityHashCode(subclass);
             HashingStorage storage = dict.getDictStorage();
             Object weakref = PFactory.createReferenceType(PythonLanguage.get(null), subclass);
             if (!(storage instanceof EconomicMapStorage)) {
@@ -842,7 +849,7 @@ protected static void addSubclass(PythonAbstractClass base, PythonManagedClass s
             } else {
                 clearEmptyReferences((EconomicMapStorage) storage);
             }
-            ((EconomicMapStorage) storage).putUncached(weakref, weakref);
+            ((EconomicMapStorage) storage).putUncached(weakref, hash, weakref);
         }
 
         static final class RemoveSubclassValue extends HashingStorageForEachCallback<PythonManagedClass> {