#! perl -slw
use strict;
use warnings;

use Inline C => <<'__EOI__';

SV* f(SV* sv, I32 pos, I32 len) {
    SV* targ = newSV_type(SVt_PVLV);
    sv_magic(targ, NULL, PERL_MAGIC_substr, NULL, 0);
    LvTYPE(targ)    = 'x';
    LvTARG(targ)    = SvREFCNT_inc_simple(sv);
    LvTARGOFF(targ) = pos;
    LvTARGLEN(targ) = len;
    return targ;
}

__EOI__
use Devel::Peek qw( Dump );

sub f :lvalue;

my $x = "abcde";
my $r = ++f($x,2,1);
Dump $r;
print $x;

__END__
C:\test>ike2-lv.pl
SV = PVNV(0x3da9db8) at 0x277920
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x3f044c8 "d"\0
  CUR = 1
  LEN = 8
abdde