bpo-35059: Enhance _PyObject_GC_TRACK() macros (GH-20931)

* Rename _PyObject_GC_TRACK_impl() to _PyObject_GC_TRACK()
* Rename _PyObject_GC_UNTRACK_impl() to _PyObject_GC_UNTRACK()
* Omit filename and lineno parameters if NDEBUG is defined.

Author: vstinner

Include/internal/pycore_object.h

@@ -53,6 +53,8 @@ _PyObject_InitVar(PyVarObject *op, PyTypeObject *typeobj, Py_ssize_t size)
 
 
 /* Tell the GC to track this object.
+ *
+ * The object must not be tracked by the GC.
  *
  * NB: While the object is tracked by the collector, it must be safe to call the
  * ob_traverse method.
@@ -61,20 +63,24 @@ _PyObject_InitVar(PyVarObject *op, PyTypeObject *typeobj, Py_ssize_t size)
  * because it's not object header.  So we don't use _PyGCHead_PREV() and
  * _PyGCHead_SET_PREV() for it to avoid unnecessary bitwise operations.
  *
- * The PyObject_GC_Track() function is the public version of this macro.
+ * See also the public PyObject_GC_Track() function.
  */
-static inline void _PyObject_GC_TRACK_impl(const char *filename, int lineno,
-                                           PyObject *op)
+static inline void _PyObject_GC_TRACK(
+// The preprocessor removes _PyObject_ASSERT_FROM() calls if NDEBUG is defined
+#ifndef NDEBUG
+    const char *filename, int lineno,
+#endif
+    PyObject *op)
 {
     _PyObject_ASSERT_FROM(op, !_PyObject_GC_IS_TRACKED(op),
                           "object already tracked by the garbage collector",
-                          filename, lineno, "_PyObject_GC_TRACK");
+                          filename, lineno, __func__);
 
     PyGC_Head *gc = _Py_AS_GC(op);
     _PyObject_ASSERT_FROM(op,
                           (gc->_gc_prev & _PyGC_PREV_MASK_COLLECTING) == 0,
                           "object is in generation which is garbage collected",
-                          filename, lineno, "_PyObject_GC_TRACK");
+                          filename, lineno, __func__);
 
     PyThreadState *tstate = _PyThreadState_GET();
     PyGC_Head *generation0 = tstate->interp->gc.generation0;
@@ -85,24 +91,26 @@ static inline void _PyObject_GC_TRACK_impl(const char *filename, int lineno,
     generation0->_gc_prev = (uintptr_t)gc;
 }
 
-#define _PyObject_GC_TRACK(op) \
-    _PyObject_GC_TRACK_impl(__FILE__, __LINE__, _PyObject_CAST(op))
-
 /* Tell the GC to stop tracking this object.
  *
  * Internal note: This may be called while GC. So _PyGC_PREV_MASK_COLLECTING
  * must be cleared. But _PyGC_PREV_MASK_FINALIZED bit is kept.
  *
  * The object must be tracked by the GC.
  *
- * The PyObject_GC_UnTrack() function is the public version of this macro.
+ * See also the public PyObject_GC_UnTrack() which accept an object which is
+ * not tracked.
  */
-static inline void _PyObject_GC_UNTRACK_impl(const char *filename, int lineno,
-                                             PyObject *op)
+static inline void _PyObject_GC_UNTRACK(
+// The preprocessor removes _PyObject_ASSERT_FROM() calls if NDEBUG is defined
+#ifndef NDEBUG
+    const char *filename, int lineno,
+#endif
+    PyObject *op)
 {
     _PyObject_ASSERT_FROM(op, _PyObject_GC_IS_TRACKED(op),
                           "object not tracked by the garbage collector",
-                          filename, lineno, "_PyObject_GC_UNTRACK");
+                          filename, lineno, __func__);
 
     PyGC_Head *gc = _Py_AS_GC(op);
     PyGC_Head *prev = _PyGCHead_PREV(gc);
@@ -113,8 +121,20 @@ static inline void _PyObject_GC_UNTRACK_impl(const char *filename, int lineno,
     gc->_gc_prev &= _PyGC_PREV_MASK_FINALIZED;
 }
 
-#define _PyObject_GC_UNTRACK(op) \
-    _PyObject_GC_UNTRACK_impl(__FILE__, __LINE__, _PyObject_CAST(op))
+// Macros to accept any type for the parameter, and to automatically pass
+// the filename and the filename (if NDEBUG is not defined) where the macro
+// is called.
+#ifdef NDEBUG
+#  define _PyObject_GC_TRACK(op) \
+        _PyObject_GC_TRACK(_PyObject_CAST(op))
+#  define _PyObject_GC_UNTRACK(op) \
+        _PyObject_GC_UNTRACK(_PyObject_CAST(op))
+#else
+#  define _PyObject_GC_TRACK(op) \
+        _PyObject_GC_TRACK(__FILE__, __LINE__, _PyObject_CAST(op))
+#  define _PyObject_GC_UNTRACK(op) \
+        _PyObject_GC_UNTRACK(__FILE__, __LINE__, _PyObject_CAST(op))
+#endif
 
 #ifdef Py_REF_DEBUG
 extern void _PyDebug_PrintTotalRefs(void);