Describe why we don't have to guard against PL_dirty in vmg_mgwiz_free()

[perl/modules/Variable-Magic.git] / Magic.xs

diff --git a/Magic.xs b/Magic.xs
index 0e9ff74ef9f3aac4a394392d0a54cd8497cc2330..9aabb411d9a158cd52f5ed0127f3fad00ab1226d 100644 (file)
--- a/Magic.xs
+++ b/Magic.xs
@@ -160,9 +160,11 @@ STATIC SV *vmg_clone(pTHX_ SV *sv, tTHX owner) {
  * reverted to dev-5.11 as 9cdcb38b */
 #if VMG_HAS_PERL_MAINT(5, 8, 9, 28160) || VMG_HAS_PERL_MAINT(5, 9, 3, 25854) || VMG_HAS_PERL(5, 10, 0)
 # ifndef VMG_COMPAT_ARRAY_PUSH_NOLEN
-/* This branch should only apply for perls before the official 5.11.0 release.
- * Makefile.PL takes care of the higher ones. */
-#  define VMG_COMPAT_ARRAY_PUSH_NOLEN 1
+#  if VMG_HAS_PERL(5, 11, 0)
+#   define VMG_COMPAT_ARRAY_PUSH_NOLEN 0
+#  else
+#   define VMG_COMPAT_ARRAY_PUSH_NOLEN 1
+#  endif
 # endif
 # ifndef VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID
 #  define VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID 1
@@ -447,6 +449,15 @@ STATIC void vmg_mgwiz_free(pTHX_ MGWIZ *w) {
  if (!w)
   return;
 
+ /* We reach this point in dirty state when ptable_free() is called from the
+  * atexit cleanup callback, and that the global table still holds a live
+  * wizard. This happens before all the SV bodies are freed, so all the wizard
+  * callbacks are still alive (as they are referenced by the undead wizard).
+  * Hence it is safe to decrement their refcount. Later on, the wizard free
+  * callback itself will trigger when the wizard body is reaped, but it will
+  * be skipped as it guards against dirty state - which is good since nothing
+  * has to be done anymore at that point. */
+
  SvREFCNT_dec(w->cb_data);
  SvREFCNT_dec(w->cb_get);
  SvREFCNT_dec(w->cb_set);