From victor@drawall.cc

Created by victor@drawall.cc

How to reproduce
----------------

perl5.23.4 -e '/.{1}??/'

Note​: /.{1}?+/ gives the same results, but no other quantifier combination.

Expected behavior
-----------------

Perl should die with the following diagnostic​:

Nested quantifiers in regex; marked by <-- HERE in m/.{1}?? <-- HERE / at -e line 1.

Actual behavior
---------------

Perl terminates normally.

Affected versions
-----------------

Current blead (0fa1f7e) is affected.
perl5.22.0 is affected
perl5.20.2 is affected
perl5.18.4 is NOT affected
perl5.16.3 is NOT affected.

Flags:
    category=core
    severity=low

This perlbug was built using Perl 5.23.4 - Fri Oct  2 19:59:39 CEST 2015
It is being executed now by  Perl 5.23.4 - Tue Sep 22 21:18:14 CEST 2015.

Site configuration information for perl 5.23.4:

Configured by grimy at Tue Sep 22 21:18:14 CEST 2015.

Summary of my perl5 (revision 5 version 23 subversion 4) configuration:
  Commit id: 2d9b5f101563ac9fee41e6ca496f79db6222d2e3
  Platform:
    osname=linux, osvers=4.0.7-2-arch, archname=x86_64-linux
    uname='linux localhost 4.0.7-2-arch #1 smp preempt tue jun 30
07:50:21 utc 2015 x86_64 gnulinux '
    config_args='-ds -e -Dusedevel'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fwrapv -fno-strict-aliasing -pipe
-fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fwrapv -fno-strict-aliasing -pipe
-fstack-protector-strong -I/usr/local/include'
    ccversion='', gccversion='5.1.0', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8,
byteorder=12345678, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define,
longdblsize=16, longdblkind=3
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib
/usr/lib/gcc/x86_64-unknown-linux-gnu/5.1.0/include-fixed /usr/lib
/lib/../lib /usr/lib/../lib /lib /lib64 /usr/lib64
    libs=-lpthread -lnsl -lnm -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
-lgdbm_compat
    perllibs=-lpthread -lnsl -lnm -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.21.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.21'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
-fstack-protector-strong'



@INC for perl 5.23.4:
    /usr/local/lib/perl5/site_perl/5.23.4/x86_64-linux
    /usr/local/lib/perl5/site_perl/5.23.4
    /usr/local/lib/perl5/5.23.4/x86_64-linux
    /usr/local/lib/perl5/5.23.4
    /usr/local/lib/perl5/site_perl
    .


Environment for perl 5.23.4:
    HOME=/home/grimy
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/grimy/bin:/home/grimy/.nvim/scripts:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/opt/plan9/bin
    PERL_BADLANG (unset)
    SHELL (unset)

From @iabyn

On Fri, Oct 02, 2015 at 12​:59​:09PM -0700, Victor ADAM wrote​:

# New Ticket Created by Victor ADAM
# Please include the string​: [perl #126253]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=126253 >

This is a bug report for perl from victor@​drawall.cc,
generated with the help of perlbug 1.40 running under perl 5.23.4.

-----------------------------------------------------------------
[Please describe your issue here]

How to reproduce
----------------

perl5.23.4 -e '/.{1}??/'

Note​: /.{1}?+/ gives the same results, but no other quantifier combination.

But it warns​:

$ perl5200 -we'"a" =~ /.{1}??/'
Useless use of greediness modifier '?' in regex; marked by <-- HERE in m/.{1}? <-- HERE ?/ at -e line 1.
$

--
My Dad used to say 'always fight fire with fire', which is probably why
he got thrown out of the fire brigade.

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

From @iabyn

On Mon, Oct 05, 2015 at 09​:18​:29AM +0100, Dave Mitchell wrote​:

On Fri, Oct 02, 2015 at 12​:59​:09PM -0700, Victor ADAM wrote​:

# New Ticket Created by Victor ADAM
# Please include the string​: [perl #126253]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=126253 >

This is a bug report for perl from victor@​drawall.cc,
generated with the help of perlbug 1.40 running under perl 5.23.4.

-----------------------------------------------------------------
[Please describe your issue here]

How to reproduce
----------------

perl5.23.4 -e '/.{1}??/'

Note​: /.{1}?+/ gives the same results, but no other quantifier combination.

But it warns​:

$ perl5200 -we'"a" =~ /.{1}??/'
Useless use of greediness modifier '?' in regex; marked by <-- HERE in m/.{1}? <-- HERE ?/ at -e line 1.
$

Victor pointed out to me offlist that that should still die. Bisecting
shows that up until the following commit, /.{1}??/ croaked with

  Nested quantifiers in regex; ...

and now its silently accepted.

commit 4fa6dd1
Author​: Karl Williamson <public@​khwilliamson.com>
Date​: Fri Dec 6 15​:50​:52 2013 -0700

  PATCH​: [Perl #42957] Suggesting warning for useless greediness operator
 
  This adds the requested warning. Now we'll see if anything breaks as a
  result.

--
Modern art​:
  "That's easy, I could have done that!"
  "Ah, but you didn't!"

From @khwilliamson

Thanks for the report, fixed by commit
d54288e

--
Karl Williamson

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

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