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List:       perl5-porters
Subject:    [perl #31403] Assignments inside lists misbehave
From:       "jerabek () math ! cas ! cz (via RT)" <perlbug-followup () perl ! org>
Date:       2004-08-31 13:02:16
Message-ID: rt-3.0.11-31403-95090.11.297250999822 () perl ! org
[Download RAW message or body]

# New Ticket Created by  jerabek@math.cas.cz 
# Please include the string:  [perl #31403]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=31403 >


This is a bug report for perl from jerabek@math.cas.cz,
generated with the help of perlbug 1.34 running under perl v5.8.3.


-----------------------------------------------------------------
[Please enter your report here]

When a variable followed by an assignment to the same variable are
both interpolated in a list, the result is bogus.

Specifically, the original length of an array is preserved, but the
slots are filled using the new value of the variable, repeated if the
new value is shorter.

(I hope the examples are more clear than the description.)

[~]% perl -e '@a = (1, 2, 3, 4, 5); @b = (@a, (@a = (8, 9))); print "@b\n"'
8 9 8 9 8 8 9
[~]% perl -e '$a = 1; @b = ($a, ($a += 2)); print "@b\n"'
3 3

Notice that this affects in particular the common "reverse comma"
idiom ($a, ...)[0].

Cheers,
Emil Jerabek

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl v5.8.3:

Configured by bhcompile at Tue Mar 23 20:55:12 EST 2004.

Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
  Platform:
    osname=linux, osvers=2.4.21-9.elsmp, archname=i386-linux-thread-multi
    uname='linux bugs.devel.redhat.com 2.4.21-9.elsmp #1 smp thu jan 8 17:08:56 est \
2004 i686 i686 i386 gnulinux '  config_args='-des -Doptimize=-O2 -g -pipe -march=i386 \
-mcpu=i686 -Dversion=5.8.3 -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 -Dinc_version_list=5.8.2 5.8.1 5.8.0'  \
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 -DTHREADS_HAVE_PIDS -DDEBUGGING \
-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 \
-I/usr/include/gdbm',  optimize='-O2 -g -pipe -march=i386 -mcpu=i686',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING \
-fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'  ccversion='', \
gccversion='3.3.2 20031218 (Red Hat Linux 3.3.2-5)', 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 -lcrypt -lutil -lpthread -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic \
-Wl,-rpath,/usr/lib/perl5/5.8.3/i386-linux-thread-multi/CORE'  cccdlflags='-fPIC', \
lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.3:
    /usr/lib/perl5/5.8.3/i386-linux-thread-multi
    /usr/lib/perl5/5.8.3
    /usr/lib/perl5/site_perl/5.8.3/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.2/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.3
    /usr/lib/perl5/site_perl/5.8.2
    /usr/lib/perl5/site_perl/5.8.1
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.2/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.3
    /usr/lib/perl5/vendor_perl/5.8.2
    /usr/lib/perl5/vendor_perl/5.8.1
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl
    .

---
Environment for perl v5.8.3:
    HOME=/home/emil
    LANG=cs_CZ.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/kerberos/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/local/bin:/home/emil/bin:/usr/java/j2re1.4.2_03/bin
  PERL_BADLANG (unset)
    SHELL=/bin/zsh


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