pybind11/pytypes.h inc_ref(), dec_ref() PyGILState_Check() **excluding** nullptr

Guarded by `PYBIND11_ASSERT_GIL_HELD_INCREF_DECREF`

Author: rwgk

include/pybind11/detail/common.h

@@ -259,6 +259,11 @@
 #    endif
 #endif
 
+#if !defined(NDEBUG) && !defined(PY_ASSERT_GIL_HELD_INCREF_DECREF)                                \
+    && !defined(PYBIND11_ASSERT_GIL_HELD_INCREF_DECREF)
+#    define PYBIND11_ASSERT_GIL_HELD_INCREF_DECREF
+#endif
+
 // #define PYBIND11_STR_LEGACY_PERMISSIVE
 // If DEFINED, pybind11::str can hold PyUnicodeObject or PyBytesObject
 //             (probably surprising and never documented, but this was the

include/pybind11/pytypes.h

@@ -246,6 +246,11 @@ class handle : public detail::object_api<handle> {
     const handle &inc_ref() const & {
 #ifdef PYBIND11_HANDLE_REF_DEBUG
         inc_ref_counter(1);
+#endif
+#if defined(PYBIND11_ASSERT_GIL_HELD_INCREF_DECREF)
+        if (m_ptr != nullptr && !PyGILState_Check()) {
+            throw std::runtime_error("pybind11::handle::inc_ref() PyGILState_Check() failure.");
+        }
 #endif
         Py_XINCREF(m_ptr);
         return *this;
@@ -257,6 +262,11 @@ class handle : public detail::object_api<handle> {
         this function automatically. Returns a reference to itself.
     \endrst */
     const handle &dec_ref() const & {
+#if defined(PYBIND11_ASSERT_GIL_HELD_INCREF_DECREF)
+        if (m_ptr != nullptr && !PyGILState_Check()) {
+            throw std::runtime_error("pybind11::handle::dec_ref() PyGILState_Check() failure.");
+        }
+#endif
         Py_XDECREF(m_ptr);
         return *this;
     }