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[perl #117457] '/' must follow a numeric type in unpack, inconsistent message

From:
perlbug @ plan9 . de
Date:
April 3, 2013 05:39
Subject:
[perl #117457] '/' must follow a numeric type in unpack, inconsistent message
Message ID:
rt-3.6.HEAD-28177-1364967573-1087.117457-75-0@perl.org
# New Ticket Created by  perlbug@plan9.de 
# Please include the string:  [perl #117457]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=117457 >



This is a bug report for perl from perlbug@plan9.de,
generated with the help of perlbug 1.39 running under perl 5.16.3.


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

It seems pack and unpack work very inconsistently with '/':

   join ":", unpack "(w/a)*", pack "(w/a)*", 12, 13
   => 12:13
   join ":", unpack "(w/a)*", pack "(w/a)*"
   =>  (empty string)

In this case, everything works as advertised - the () group gobbles up all
remaining values when unpacking, even when there are none.

This changes when something precedes it:

   join ":", unpack "C (w/a)*", pack "C (w/a)*", 1, 2, 3
   => 1:2:3
   join ":", unpack "C (w/a)*", pack "C (w/a)*", 1
   => '/' must follow a numeric type in unpack at -e line 1.

Expected for the last case would be just the value "1".

In addition to having different behaviour when something precedes to
(w/a)* unpack expression or not, the error message is quite confusing, as
clearly, '/' follows a numeric type in this case.

I checked perl 5.8.9, 5.14.2, and 5.16.3, and all are consistently
inconsistent in the same way.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.16.3:

Configured by Marc Lehmann at Wed Mar 13 11:30:24 CET 2013.

Summary of my perl5 (revision 5 version 16 subversion 3) configuration:
   
  Platform:
    osname=linux, osvers=3.2.0-4-amd64, archname=x86_64-linux
    uname='linux cerebro 3.2.0-4-amd64 #1 smp debian 3.2.35-2 x86_64 gnulinux '
    config_args='-Duselargefiles -Duse64bitint -Dusemymalloc=n -Dstatic_ext=Fcntl -Dcc=gcc -Dccflags=-DPERL_DISABLE_PMC -DPERL_ARENA_SIZE=16376 -USITEARCH_EXP -USITELIB_EXP -UARCHLIB_EXP -D_GNU_SOURCE  -I/opt/include -ggdb -gdwarf-2 -g3 -Doptimize=-O6 -fno-asynchronous-unwind-tables -fno-strict-aliasing -Dcccdlflags=-fPIC -Dldflags=-L/opt/perl/lib -L/opt/lib -Dlibs=-ldl -lm -lcrypt -Dprefix=/opt/perl -Dprivlib=/opt/perl/lib/perl5 -Darchlib=/opt/perl/lib/perl5 -Uusevendorprefix -Dsiteprefix=/opt/perl -Dsitelib=/opt/perl/lib/perl5 -Dsitearch=/opt/perl/lib/perl5 -Dsitebin=/opt/perl/bin -Dman1dir=/opt/perl/man/man1 -Dman3dir=/opt/perl/man/man3 -Dsiteman1dir=/opt/perl/man/man1 -Dsiteman3dir=/opt/perl/man/man3 -Dman1ext=1 -Dman3ext=3 -Dpager=/usr/bin/less -Uafs -Uusesfio -Uusenm -Uuseshrplib -Ud_dosuid -Dusethreads=undef -Duse5005threads=undef -Duseithreads=undef -Dusemultiplicity=undef -Demail=perl-binary@plan9.de -Dcf_email=perl-binary@plan9.de -Dcf_by=Marc Lehmann -Dlocincpth=/o
 pt/perl/include /opt/include -Dmyhostname=localhost -Dmultiarch=undef -Dbin=/opt/perl/bin -Dxxxusedevel -DxxxDEBUGGING -Dxxxuse_debugging_perl -Dxxxuse_debugmalloc -dEs'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-DPERL_DISABLE_PMC -DPERL_ARENA_SIZE=16376 -USITEARCH_EXP -USITELIB_EXP -UARCHLIB_EXP -D_GNU_SOURCE -I/opt/include -ggdb -gdwarf-2 -g3 -fno-strict-aliasing -pipe -I/opt/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O6 -fno-asynchronous-unwind-tables -fno-strict-aliasing',
    cppflags='-DPERL_DISABLE_PMC -DPERL_ARENA_SIZE=16376 -USITEARCH_EXP -USITELIB_EXP -UARCHLIB_EXP -D_GNU_SOURCE -I/opt/include -ggdb -gdwarf-2 -g3 -fno-strict-aliasing -pipe -I/opt/include'
    ccversion='', gccversion='4.7.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags ='-L/opt/perl/lib -L/opt/lib -L/usr/local/lib'
    libpth=/usr/local/lib /lib/x86_64-linux-gnu /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-ldl -lm -lcrypt
    perllibs=-ldl -lm -lcrypt
    libc=, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.13'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O6 -fno-asynchronous-unwind-tables -fno-strict-aliasing -L/opt/perl/lib -L/opt/lib -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl 5.16.3:
    /root/src/sex
    /root/pserv/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    .

---
Environment for perl 5.16.3:
    HOME=/root
    LANG (unset)
    LANGUAGE (unset)
    LC_CTYPE=en_US.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/root/s2:/root/s:/opt/bin:/opt/sbin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/X11/bin:/usr/games:/usr/local/bin:/usr/local/sbin:/root/pserv:.
    PERL5LIB=/root/src/sex:/root/pserv/lib/perl5
    PERL5_CPANPLUS_CONFIG=/root/.cpanplus/config
    PERLDB_OPTS=ornaments=0
    PERL_ANYEVENT_DBI_TESTS=1
    PERL_ANYEVENT_LOOP_TESTS=1
    PERL_ANYEVENT_NET_TESTS=1
    PERL_BADLANG (unset)
    PERL_UNICODE=E
    SHELL=/bin/bash




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