bpo-36389: Add _PyObject_CheckConsistency() function (GH-12803)

Add a new _PyObject_CheckConsistency() function which can be used to
help debugging. The function is available in release mode.

Add a 'check_content' parameter to _PyDict_CheckConsistency().

2 files changed, 19 insertions, 0 deletions

diff --git a/Include/cpython/object.h b/Include/cpython/object.h
index 64d196a..ba52a48 100644
--- a/Include/cpython/object.h
+++ b/Include/cpython/object.h
@@ -446,6 +446,21 @@ PyAPI_FUNC(void) _PyObject_AssertFailed(
     int line,
     const char *function);
 
+/* Check if an object is consistent. For example, ensure that the reference
+   counter is greater than or equal to 1, and ensure that ob_type is not NULL.
+
+   Call _PyObject_AssertFailed() if the object is inconsistent.
+
+   If check_content is zero, only check header fields: reduce the overhead.
+
+   The function always return 1. The return value is just here to be able to
+   write:
+
+   assert(_PyObject_CheckConsistency(obj, 1)); */
+PyAPI_FUNC(int) _PyObject_CheckConsistency(
+    PyObject *op,
+    int check_content);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index a88b626..c955953 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -10,6 +10,10 @@ extern "C" {
 
 #include "pycore_pystate.h"   /* _PyRuntime */
 
+PyAPI_FUNC(int) _PyType_CheckConsistency(PyTypeObject *type);
+PyAPI_FUNC(int) _PyUnicode_CheckConsistency(PyObject *op, int check_content);
+PyAPI_FUNC(int) _PyDict_CheckConsistency(PyObject *mp, int check_content);
+
 /* Tell the GC to track this object.
  *
  * NB: While the object is tracked by the collector, it must be safe to call the