ImportHook: verify __import__ was not updated before overwriting it with original value

lostmsu · lostmsu · commit 1985a22c2de5 · 2021-02-25T15:57:45.000-08:00
diff --git a/src/runtime/importhook.cs b/src/runtime/importhook.cs
@@ -61,6 +61,12 @@ static void RestoreImport()
         {
             IntPtr builtins = Runtime.GetBuiltins();
 
+#if DEBUG
+            IntPtr existing = Runtime.PyObject_GetAttr(builtins, PyIdentifier.__import__);
+            System.Diagnostics.Debug.Assert(existing == hook.ptr);
+            Runtime.XDecref(existing);
+#endif
+
             int res = Runtime.PyObject_SetAttr(builtins, PyIdentifier.__import__, py_import);
             PythonException.ThrowIfIsNotZero(res);
             Runtime.XDecref(py_import);
