-#define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth
-#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
-#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
-#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
-#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
-
-#define CVf_CLONE 0x0001 /* anon CV uses external lexicals */
-#define CVf_CLONED 0x0002 /* a clone of one of those */
-#define CVf_ANON 0x0004 /* CvGV() can't be trusted */
-#define CVf_OLDSTYLE 0x0008
-#define CVf_UNIQUE 0x0010 /* can't be cloned */
-#define CVf_NODEBUG 0x0020 /* no DB::sub indirection for this CV
+#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
+# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
+ assert(SvTYPE(_cvdepth) == SVt_PVCV); \
+ &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
+ }))
+#else
+# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32
+#endif
+#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
+#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
+#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
+#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
+
+#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
+#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
+
+#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
+#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
+#define CVf_CLONED 0x0040 /* a clone of one of those */
+#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
+#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
+ * require, eval). */
+#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV