Only test SvTAIL when SvVALID

Only use the SvTAIL() macro when we've already confirmed that
the SV is SvVALID() - this is in preparation for removing the
SVpbm_TAIL flag in the next commit

1 files changed, 1 insertions, 0 deletions

diff --git a/sv.h b/sv.h
index c33a9a4c11..e2cf10e373 100644
--- a/sv.h
+++ b/sv.h
@@ -1140,6 +1140,7 @@ object type. Exposed to perl code via Internals::SvREADONLY().
 			    assert(SvTYPE(_svtail) != SVt_PVAV);	\
 			    assert(SvTYPE(_svtail) != SVt_PVHV);	\
 			    assert(!SvSCREAM(_svtail));			\
+			    assert((SvFLAGS(sv) & SVpbm_VALID));    	\
 			    (SvFLAGS(sv) & (SVpbm_TAIL|SVpbm_VALID))	\
 				== (SVpbm_TAIL|SVpbm_VALID);		\
 			})