More refcounting fixes

src/runtime/builtin_modules/builtins.cpp

@@ -1137,6 +1137,8 @@ extern "C" PyObject* PyErr_NewException(char* name, PyObject* _base, PyObject* d
         _base = Exception;
     if (dict == NULL)
         dict = new BoxedDict();
+    else
+        Py_INCREF(dict);
 
     try {
         char* dot_pos = strchr(name, '.');
@@ -1149,11 +1151,13 @@ extern "C" PyObject* PyErr_NewException(char* name, PyObject* _base, PyObject* d
         BoxedClass* base = static_cast<BoxedClass*>(_base);
 
         if (PyDict_GetItemString(dict, "__module__") == NULL) {
-            PyDict_SetItemString(dict, "__module__", boxString(llvm::StringRef(name, dot_pos - name)));
+            PyDict_SetItemString(dict, "__module__", autoDecref(boxString(llvm::StringRef(name, dot_pos - name))));
         }
         checkAndThrowCAPIException();
 
-        Box* cls = runtimeCall(type_cls, ArgPassSpec(3), boxedName, BoxedTuple::create({ base }), dict, NULL, NULL);
+        Box* cls = runtimeCall(type_cls, ArgPassSpec(3), boxedName, autoDecref(BoxedTuple::create({ base })), dict, NULL, NULL);
+        Py_DECREF(boxedName);
+        Py_DECREF(dict);
         return cls;
     } catch (ExcInfo e) {
         // PyErr_NewException isn't supposed to fail, and callers sometimes take advantage of that

src/runtime/capi.cpp

@@ -878,10 +878,12 @@ extern "C" void PyErr_SetExcInfo(PyObject* type, PyObject* value, PyObject* trac
 }
 
 extern "C" void PyErr_SetString(PyObject* exception, const char* string) noexcept {
-    PyErr_SetObject(exception, boxString(string));
+    PyErr_SetObject(exception, autoDecref(boxString(string)));
 }
 
 extern "C" void PyErr_SetObject(PyObject* exception, PyObject* value) noexcept {
+    Py_XINCREF(exception);
+    Py_XINCREF(value);
     PyErr_Restore(exception, value, NULL);
 }
 

src/runtime/dict.cpp

@@ -329,9 +329,18 @@ extern "C" PyObject* PyDict_GetItem(PyObject* dict, PyObject* key) noexcept {
     ASSERT(PyDict_Check(dict) || dict->cls == attrwrapper_cls, "%s", getTypeName(dict));
     if (PyDict_Check(dict)) {
         BoxedDict* d = static_cast<BoxedDict*>(dict);
-        return d->getOrNull(key);
+
+        /* preserve the existing exception */
+        PyObject* err_type, *err_value, *err_tb;
+        PyErr_Fetch(&err_type, &err_value, &err_tb);
+        Box* b = d->getOrNull(key);
+        /* ignore errors */
+        PyErr_Restore(err_type, err_value, err_tb);
+        return b;
     }
 
+    assert(0 && "check refcounting");
+
     auto&& tstate = _PyThreadState_Current;
     if (tstate != NULL && tstate->curexc_type != NULL) {
         /* preserve the existing exception */
@@ -392,7 +401,7 @@ extern "C" int PyDict_Next(PyObject* op, Py_ssize_t* ppos, PyObject** pkey, PyOb
 
 extern "C" PyObject* PyDict_GetItemString(PyObject* dict, const char* key) noexcept {
     if (dict->cls == attrwrapper_cls)
-        return unwrapAttrWrapper(dict)->getattr(internStringMortal(key));
+        return unwrapAttrWrapper(dict)->getattr(autoDecref(internStringMortal(key)));
 
     Box* key_s;
     try {
@@ -400,7 +409,7 @@ extern "C" PyObject* PyDict_GetItemString(PyObject* dict, const char* key) noexc
     } catch (ExcInfo e) {
         abort();
     }
-    return PyDict_GetItem(dict, key_s);
+    return PyDict_GetItem(dict, autoDecref(key_s));
 }
 
 Box* dictSetitem(BoxedDict* self, Box* k, Box* v) {

src/runtime/hiddenclass.cpp

@@ -79,6 +79,7 @@ HiddenClass* HiddenClass::getOrMakeChild(BoxedString* attr) {
     static StatCounter num_hclses("num_hidden_classes");
     num_hclses.log();
 
+    // XXX: need to hold a ref to the string (or maybe we don't if we can hook the un-interning)
     HiddenClass* rtn = new HiddenClass(this);
     rtn->attr_offsets[attr] = this->attributeArraySize();
     this->children[attr] = rtn;

src/runtime/types.cpp

@@ -2142,7 +2142,7 @@ public:
         internStringMortalInplace(key);
 
         self->b->setattr(key, value, NULL);
-        return None;
+        Py_RETURN_NONE;
     }
 
     static int ass_sub(PyDictObject* mp, PyObject* v, PyObject* w) noexcept {
@@ -2154,6 +2154,7 @@ public:
                 res = AttrWrapper::setitem((Box*)mp, v, w);
             }
             assert(res == None);
+            Py_DECREF(res);
         } catch (ExcInfo e) {
             setCAPIException(e);
             return -1;
@@ -2259,7 +2260,7 @@ public:
             self->b->delattr(key, NULL);
         else
             raiseExcHelper(KeyError, "'%s'", key->data());
-        return None;
+        Py_RETURN_NONE;
     }
 
     static Box* str(Box* _self) {

src/runtime/util.cpp

@@ -77,7 +77,7 @@ void boundSliceWithLength(i64* start_out, i64* stop_out, i64 start, i64 stop, i6
 
 Box* boxStringOrNone(const char* s) {
     if (s == NULL) {
-        return None;
+        return incref(None);
     } else {
         return boxString(s);
     }