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[perl #20558] "Attempt to free unreferenced scalar" in for loop

From:
perlbug-followup
Date:
January 27, 2003 07:27
Subject:
[perl #20558] "Attempt to free unreferenced scalar" in for loop
Message ID:
rt-20558-49729.6.89247501529238@bugs6.perl.org
# New Ticket Created by  jsnell@iki.fi 
# Please include the string:  [perl #20558]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=20558 >


This is a bug report for perl from jsnell@iki.fi,
generated with the help of perlbug 1.34 running under perl v5.8.0.


-----------------------------------------------------------------


Running the following test program results in an "Attempt to free
unreferenced scalar". Problem doesn't appear when "map" is used
instead of "for".

#!perl
@n=1;
@n=1 for @n, @n
__END__

I.e. the same array is first used multiple times in the argument list
of the for loop, and then reassigned inside the loop.
   
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl v5.8.0:

Configured by bhcompile at Sun Sep  1 23:55:07 EDT 2002.

Summary of my perl5 (revision 5.0 version 8 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.4.18-11smp, archname=i386-linux-thread-multi
    uname='linux daffy.perf.redhat.com 2.4.18-11smp #1 smp thu aug 15 06:41:59 edt 2002 i686 i686 i386 gnulinux '
    config_args='-des -Doptimize=-O2 -march=i386 -mcpu=i686 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -march=i386 -mcpu=i686',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/usr/include/gdbm'
    ccversion='', gccversion='3.2 20020822 (Red Hat Linux Rawhide 3.2-5)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lgdbm -ldb -ldl -lm -lpthread -lc -lcrypt -lutil
    perllibs=-lnsl -ldl -lm -lpthread -lc -lcrypt -lutil
    libc=/lib/libc-2.2.92.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.2.92'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/usr/lib/perl5/5.8.0/i386-linux-thread-multi/CORE'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.0:
    /usr/lib/perl5/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/5.8.0
    /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl/5.6.1
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl/5.6.1
    /usr/lib/perl5/vendor_perl
    .

---
Environment for perl v5.8.0:
    HOME=/home/jsnell
    LANG=en_US
    LANGUAGE (unset)
    LC_CTYPE=fi_FI
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/jsnell/bin/common:/home/jsnell/bin/linux:/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/X11R6/bin
    PERL_BADLANG (unset)
    SHELL=/bin/zsh




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