arybase.xs: Check that $[ is in the main stash

Check that $[ is in the main stash before doing anything magical with
$[=1.  This can only be in another stash if some other XS module has
overridden the check functions to change $[ to $foo::[.  But robust-
ness is good, right?

diff --git a/ext/arybase/arybase.xs b/ext/arybase/arybase.xs
index 5c653e3..7cee0dc 100644 (file)
--- a/ext/arybase/arybase.xs
+++ b/ext/arybase/arybase.xs
@@ -137,6 +137,7 @@ STATIC bool ab_op_is_dollar_bracket(pTHX_ OP *o) {
  return o->op_type == OP_RV2SV && (o->op_flags & OPf_KIDS)
   && (c = cUNOPx(o)->op_first)
   && c->op_type == OP_GV
+  && GvSTASH(cGVOPx_gv(c)) == PL_defstash
   && strEQ(GvNAME(cGVOPx_gv(c)), "[");
 }