+#define __PACKAGE__ "Variable::Magic"
+
+#define R(S) fprintf(stderr, "R(" #S ") = %d\n", SvREFCNT(S))
+
+#define PERL_VERSION_GE(R, V, S) (PERL_REVISION > (R) || (PERL_REVISION == (R) && (PERL_VERSION > (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION >= (S))))))
+
+#define PERL_VERSION_LE(R, V, S) (PERL_REVISION < (R) || (PERL_REVISION == (R) && (PERL_VERSION < (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION <= (S))))))
+
+#define PERL_API_VERSION_GE(R, V, S) (PERL_API_REVISION > (R) || (PERL_API_REVISION == (R) && (PERL_API_VERSION > (V) || (PERL_API_VERSION == (V) && (PERL_API_SUBVERSION >= (S))))))
+
+#define PERL_API_VERSION_LE(R, V, S) (PERL_API_REVISION < (R) || (PERL_API_REVISION == (R) && (PERL_API_VERSION < (V) || (PERL_API_VERSION == (V) && (PERL_API_SUBVERSION <= (S))))))
+
+#ifndef VMG_PERL_PATCHLEVEL
+# ifdef PERL_PATCHNUM
+# define VMG_PERL_PATCHLEVEL PERL_PATCHNUM
+# else
+# define VMG_PERL_PATCHLEVEL 0
+# endif
+#endif
+
+/* --- Compatibility ------------------------------------------------------- */
+
+#ifndef Newx
+# define Newx(v, n, c) New(0, v, n, c)
+#endif
+
+#ifndef SvMAGIC_set
+# define SvMAGIC_set(sv, val) (SvMAGIC(sv) = (val))
+#endif
+
+#ifndef dMY_CXT
+# define MY_CXT vmg_globaldata
+# define dMY_CXT
+# define START_MY_CXT STATIC my_cxt_t MY_CXT;
+# define MY_CXT_INIT
+#endif
+
+#ifndef PERL_MAGIC_ext
+# define PERL_MAGIC_ext '~'
+#endif
+
+#ifndef MGf_COPY
+# define MGf_COPY 0
+#endif
+
+#undef MGf_DUP /* Disable it for now. */
+#ifndef MGf_DUP
+# define MGf_DUP 0
+#endif
+
+#ifndef MGf_LOCAL
+# define MGf_LOCAL 0
+#endif
+
+#if PERL_API_VERSION_GE(5, 10, 0)
+# define VMG_UVAR 1
+#else
+# define VMG_UVAR 0
+#endif
+
+#if (VMG_PERL_PATCHLEVEL >= 25854) || PERL_VERSION_GE(5, 9, 3)
+# define VMG_COMPAT_ARRAY_PUSH_NOLEN 1
+#else
+# define VMG_COMPAT_ARRAY_PUSH_NOLEN 0
+#endif
+
+/* since 5.9.5 - see #43357 */
+#if (VMG_PERL_PATCHLEVEL >= 31473) || PERL_VERSION_GE(5, 9, 5)
+# define VMG_COMPAT_ARRAY_UNDEF_CLEAR 1
+#else
+# define VMG_COMPAT_ARRAY_UNDEF_CLEAR 0
+#endif
+
+#if VMG_UVAR
+
+/* Bug-free mg_magical - see http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-01/msg00036.html */
+STATIC void vmg_mg_magical(pTHX_ SV *sv) {
+#define vmg_mg_magical(S) vmg_mg_magical(aTHX_ (S))
+ const MAGIC* mg;
+ PERL_UNUSED_CONTEXT;
+ if ((mg = SvMAGIC(sv))) {
+ SvRMAGICAL_off(sv);
+ do {
+ const MGVTBL* const vtbl = mg->mg_virtual;
+ if (vtbl) {
+ if (vtbl->svt_get && !(mg->mg_flags & MGf_GSKIP))
+ SvGMAGICAL_on(sv);
+ if (vtbl->svt_set)
+ SvSMAGICAL_on(sv);
+ if (vtbl->svt_clear)
+ SvRMAGICAL_on(sv);
+ }
+ } while ((mg = mg->mg_moremagic));
+ if (!(SvFLAGS(sv) & (SVs_GMG|SVs_SMG)))
+ SvRMAGICAL_on(sv);
+ }
+}
+
+#endif /* VMG_UVAR */
+
+/* --- Context-safe global data -------------------------------------------- */