From d6c8b1f63cfc0715e86fb14eeee6d395da3d69d2 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Mon, 4 Apr 2022 23:28:16 +0200
Subject: [PATCH] Fixed #1054 (only an issue in debug builds so far)

---
 src/pya/pya/pyaModule.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/pya/pya/pyaModule.cc b/src/pya/pya/pyaModule.cc
index 21fbc9ac1..6f5f41b7f 100644
--- a/src/pya/pya/pyaModule.cc
+++ b/src/pya/pya/pyaModule.cc
@@ -584,6 +584,14 @@ static std::string extract_python_name (const std::string &name)
 static void
 pya_object_deallocate (PyObject *self)
 {
+  //  This avoids an assertion in debug builds (Python, gcmodule.c - update_refs).
+  //  In short, the GC expects not to see objects with refcount 0 and asserts.
+  //  However, due to triggering of signals or similar, the destructor call below
+  //  may trigger a GC (https://github.com/KLayout/klayout/issues/1054).
+  //  According to the comments this may be turned into a release mode assertion, so
+  //  we better work around it.
+  ++self->ob_refcnt;
+
   PYAObjectBase *p = PYAObjectBase::from_pyobject (self);
   p->~PYAObjectBase ();
   Py_TYPE (self)->tp_free (self);