[Python-checkins] bpo-41117: Cleanup subtract_refs() (GH-27593)

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https://github.com/python/cpython/commit/c34fa2bb06ea44045af8493dfa414addb2b7ce66
commit: c34fa2bb06ea44045af8493dfa414addb2b7ce66
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2021-08-04T18:09:14+02:00
summary:

bpo-41117: Cleanup subtract_refs() (GH-27593)

subtract_refs() reuses the 'op' variable rather than calling the
FROM_GC() macro twice.

Issue reported by William Pickard.

files:
M Modules/gcmodule.c

diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index e5e5aa3287b0d..2592c397cf2f7 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -479,9 +479,9 @@ subtract_refs(PyGC_Head *containers)
     for (; gc != containers; gc = GC_NEXT(gc)) {
         PyObject *op = FROM_GC(gc);
         traverse = Py_TYPE(op)->tp_traverse;
-        (void) traverse(FROM_GC(gc),
-                       (visitproc)visit_decref,
-                       op);
+        (void) traverse(op,
+                        (visitproc)visit_decref,
+                        op);
     }
 }