bpo-34042: Fix dict.copy() to maintain correct total refcount (GH-8119)

(cherry picked from commit 0b75228700e0077d8bf2636e74733389514b4b2f)

Co-authored-by: Yury Selivanov <yury@magic.io>

diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-07-05-15-51-29.bpo-34042.Gr9XUH.rst b/Misc/NEWS.d/next/Core and Builtins/2018-07-05-15-51-29.bpo-34042.Gr9XUH.rst
new file mode 100644 (file)
index 0000000..fd1730d
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-07-05-15-51-29.bpo-34042.Gr9XUH.rst
@@ -0,0 +1,2 @@
+Fix dict.copy() to maintain correct total refcount (as reported by
+sys.gettotalrefcount()).

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 7a1bcebec6fdfd30b4ffe108f6540e65313c64b9..828eb99e2d03220a9c0948c870d9725c2f2ba0e0 100644 (file)
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -656,6 +656,13 @@ clone_combined_dict(PyDictObject *orig)
         /* Maintain tracking. */
         _PyObject_GC_TRACK(new);
     }
+
+    /* Since we copied the keys table we now have an extra reference
+       in the system.  Manually call _Py_INC_REFTOTAL to signal that
+       we have it now; calling DK_INCREF would be an error as
+       keys->dk_refcnt is already set to 1 (after memcpy). */
+    _Py_INC_REFTOTAL;
+
     return (PyObject *)new;
 }