From @cpansprout

$ ./perl -Ilib -le 'substr $#_, 0, 0, "234"; print $#_;'
234
$ ./perl -Ilib -le 'sub _​:lvalue{$#_} substr _, 0, 0, "234"; print $#_'
-1

I would expect 234 from both one-liners.

I suspect +sub​:lvalue { substr lvalue_sub() }->()=3 has similar problems.

Flags​:
  category=core
  severity=low

Site configuration information for perl 5.17.5​:

Configured by sprout at Sat Sep 22 18​:51​:23 PDT 2012.

Summary of my perl5 (revision 5 version 17 subversion 5) configuration​:
  Snapshot of​: 451f421
  Platform​:
  osname=darwin, osvers=10.5.0, archname=darwin-2level
  uname='darwin pint.local 10.5.0 darwin kernel version 10.5.0​: fri nov 5 23​:20​:39 pdt 2010; root​:xnu-1504.9.17~1release_i386 i386 '
  config_args='-de -Dusedevel -DDEBUGGING'
  hint=recommended, useposix=true, d_sigaction=define
  useithreads=undef, usemultiplicity=undef
  useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
  use64bitint=undef, use64bitall=undef, uselongdouble=undef
  usemymalloc=n, bincompat5005=undef
  Compiler​:
  cc='cc', ccflags ='-fno-common -DPERL_DARWIN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include',
  optimize='-O3 -g',
  cppflags='-fno-common -DPERL_DARWIN -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
  ccversion='', gccversion='4.2.1 (Apple Inc. build 5664)', gccosandvers=''
  intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
  alignbytes=8, prototype=define
  Linker and Libraries​:
  ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-protector -L/usr/local/lib'
  libpth=/usr/local/lib /usr/lib
  libs=-ldbm -ldl -lm -lutil -lc
  perllibs=-ldl -lm -lutil -lc
  libc=, so=dylib, useshrplib=false, libperl=libperl.a
  gnulibc_version=''
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
  cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -fstack-protector'

Locally applied patches​:
 

@​INC for perl 5.17.5​:
  /usr/local/lib/perl5/site_perl/5.17.5/darwin-2level
  /usr/local/lib/perl5/site_perl/5.17.5
  /usr/local/lib/perl5/5.17.5/darwin-2level
  /usr/local/lib/perl5/5.17.5
  /usr/local/lib/perl5/site_perl
  .

Environment for perl 5.17.5​:
  DYLD_LIBRARY_PATH (unset)
  HOME=/Users/sprout
  LANG=en_US.UTF-8
  LANGUAGE (unset)
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/usr/bin​:/bin​:/usr/sbin​:/sbin​:/usr/local/bin​:/usr/X11/bin​:/usr/local/bin
  PERL_BADLANG (unset)
  SHELL=/bin/bash

From @Leont

On Sun, Oct 14, 2012 at 10​:17 PM, Father Chrysostomos
<perlbug-followup@​perl.org> wrote​:

$ ./perl -Ilib -le 'substr $#_, 0, 0, "234"; print $#_;'
234
$ ./perl -Ilib -le 'sub _​:lvalue{$#_} substr _, 0, 0, "234"; print $#_'
-1

I would expect 234 from both one-liners.

I suspect +sub​:lvalue { substr lvalue_sub() }->()=3 has similar problems.

«perl -le 'my $foo; sub _ : lvalue{$foo} substr _, 0, 0, "234"; print
$foo'» works for me, while «perl -le 'sub _ : lvalue{$#a} substr _,
0, 0, "234"; print $#a'» does not. This looks $#array related to me.

Leon

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

From @b2gills

On Sun, Oct 14, 2012 at 3​:17 PM, Father Chrysostomos
<perlbug-followup@​perl.org> wrote​:

# New Ticket Created by Father Chrysostomos
# Please include the string​: [perl #115258]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=115258 >

$ ./perl -Ilib -le 'substr $#_, 0, 0, "234"; print $#_;'
234
$ ./perl -Ilib -le 'sub _​:lvalue{$#_} substr _, 0, 0, "234"; print $#_'
-1

I would expect 234 from both one-liners.

While you are correct that there is a bug here, your test doesn't expose it.

That is because you are referencing two different @​_ arrays;

$ perl -Ilib -le 'sub _​:lvalue{$#_} _ = "234"; print $#_'
-1
$ perl -Ilib -le 'sub _​:lvalue{$#a} _ = "234"; print $#a'
234

This one is affected by the bug.

$ perl -Ilib -le 'sub _​:lvalue{$#a} substr _, 0, 0, "234"; print $#a'
-1

From Eirik-Berg.Hanssen@allverden.no

On Sun, Oct 14, 2012 at 10​:17 PM, Father Chrysostomos <
perlbug-followup@​perl.org> wrote​:

$ ./perl -Ilib -le 'substr $#_, 0, 0, "234"; print $#_;'
234
$ ./perl -Ilib -le 'sub _​:lvalue{$#_} substr _, 0, 0, "234"; print $#_'
-1

I would expect 234 from both one-liners.

  I wouldn't, since $#_ is a bad example, given that @​_ (and hence $#_) is
local to the sub – observe​:

eirik@​bluebird[22​:49​:59]$ perl -Ilib -le '@​a=9; sub f​:lvalue{$#a} f="234";
print $#a'
234
eirik@​bluebird[22​:50​:09]$ perl -Ilib -le '@​_=9; sub f​:lvalue{$#_} f="234";
print $#_'
0
eirik@​bluebird[22​:50​:23]~$

  But the problem with substr persists also with better examples​:

eirik@​bluebird[22​:50​:23]$ perl -Ilib -le 'sub f​:lvalue{$#a} substr f, 0,
0, "234"; print $#a'
-1
eirik@​bluebird[22​:51​:49]$

Eirik

From zefram@fysh.org

Fixed in commit 19a8de4.

-zefram

@cpansprout - Status changed from 'open' to 'resolved'