Fix assertion failure with $#a=\1

If the array has been freed and a reference is then assigned to
the arylen scalar and then get-magic is called on that scalar,
Perl_magic_getarylen misbehaves.  SvOK_off is not sufficient if
arbitrary values can be assigned by Perl code.  Globs, refs and
regexps (among others) need special handling, which sv_setsv
knows how to do.

1 files changed, 1 insertions, 1 deletions

diff --git a/mg.c b/mg.c
index 5403f67dfd..305817c76f 100644
--- a/mg.c
+++ b/mg.c
@@ -2020,7 +2020,7 @@ Perl_magic_getarylen(pTHX_ SV *sv, const MAGIC *mg)
     if (obj) {
 	sv_setiv(sv, AvFILL(obj));
     } else {
-	SvOK_off(sv);
+	sv_setsv(sv, NULL);
     }
     return 0;
 }