From @geeknik

Perl v5.25.4-25-g109ac34*

./perl -e '0>formline qr oo=>*0'

perl​: sv.c​:1587​: char *Perl_sv_grow(SV *const, STRLEN)​: Assertion `!((((_svcur)->sv_flags & (0x00004000|0x00008000)) == 0x00008000) && (((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVGV || ((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVLV))' failed.
Aborted

#0 0x00007ffff6cf2067 in __GI_raise (sig=sig@​entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c​:56
#1 0x00007ffff6cf3448 in __GI_abort () at abort.c​:89
#2 0x00007ffff6ceb266 in __assert_fail_base (fmt=0x7ffff6e24238 "%s%s%s​:%u​: %s%sAssertion `%s' failed.\n%n",
  assertion=assertion@​entry=0xe038c0 <.str101> "!((((_svcur)->sv_flags & (0x00004000|0x00008000)) == 0x00008000) && (((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVGV || ((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVLV))", file=file@​entry=0xe29ff8 "sv.c", line=line@​entry=1587,
  function=function@​entry=0xe03a80 <__PRETTY_FUNCTION__.Perl_sv_grow> "char *Perl_sv_grow(SV *const, STRLEN)") at assert.c​:92
#3 0x00007ffff6ceb312 in __GI___assert_fail (
  assertion=0xe038c0 <.str101> "!((((_svcur)->sv_flags & (0x00004000|0x00008000)) == 0x00008000) && (((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVGV || ((svtype)((_svcur)->sv_flags & 0xff)) == SVt_PVLV))", file=0xe29ff8 "sv.c", line=1587,
  function=0xe03a80 <__PRETTY_FUNCTION__.Perl_sv_grow> "char *Perl_sv_grow(SV *const, STRLEN)") at assert.c​:101
#4 0x00000000008eff8a in Perl_sv_grow (sv=<optimized out>, newlen=<optimized out>) at sv.c​:1587
#5 0x0000000000909d62 in Perl_sv_setpvn (sv=0x621000010f08, ptr=0x60200000e071 "main​::0", len=7) at sv.c​:4898
#6 0x0000000000a44b76 in Perl_pp_formline () at pp_ctl.c​:699
#7 0x00000000007f26a4 in Perl_runops_debug () at dump.c​:2234
#8 0x00000000005a10c7 in S_run_body (oldscope=<optimized out>) at perl.c​:2525
#9 perl_run (my_perl=<optimized out>) at perl.c​:2448
#10 0x00000000004de6ce in main (argc=<optimized out>, argv=<optimized out>, env=<optimized out>) at perlmain.c​:123

From zefram@fysh.org

Reduces to 'formline "^", *z'. Fixed by
a4031a7.

-zefram

The RT System itself - Status changed from 'new' to 'open'

@iabyn - Status changed from 'open' to 'pending release'

From @khwilliamson

Thank you for filing this report. You have helped make Perl better.

With the release today of Perl 5.26.0, this and 210 other issues have been
resolved.

Perl 5.26.0 may be downloaded via​:
https://metacpan.org/release/XSAWYERX/perl-5.26.0

If you find that the problem persists, feel free to reopen this ticket.

@khwilliamson - Status changed from 'pending release' to 'resolved'