The regexp engine should check SV flags rather than SV type for

determining if something is a reference, because under the debugger
the value returned by the swash code is SVt_PVMG.
Not doing this has the side effect of repeatedly reassigning the
same array element, which causes destructors to fire on the reassignment
which in turn causes &utf8::DESTROY to run outside of the pseudo-safety
of save_re_context, which under the debugger involves re-entering the
regexp engine, which causes corruption of the regexp engine's global
state.

p4raw-id: //depot/perl@26228

diff --git a/regexec.c b/regexec.c
index 6e234a2..ec13139 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -4668,7 +4668,7 @@ Perl_regclass_swash(pTHX_ register const regnode* node, bool doinit, SV** listsv
             * documentation of these array elements. */
 
            si = *ary;
-           a  = SvTYPE(ary[1]) == SVt_RV   ? &ary[1] : 0;
+           a  = SvROK(ary[1]) ? &ary[1] : 0;
            b  = SvTYPE(ary[2]) == SVt_PVAV ? &ary[2] : 0;
 
            if (a)