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[ID 20010703.009] Freaky action at a distance with $]
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From:
Simon Cozens
Date:
July 3, 2001 10:15
Subject:
[ID 20010703.009] Freaky action at a distance with $]
Message ID:
E15HTBe-0006ub-00@deep-dark-truthful-mirror.perlhacker.org
This is a bug report for perl from simon@netthink.co.uk,
generated with the help of perlbug 1.33 running under perl v5.6.1.
-----------------------------------------------------------------
[Please enter your report here]
This goes right through up to bleadperl. It's probably a Don't Do
That, Then bug, but...
% perl -le '$]++'
Modification of a read-only value attempted at -e line 1.
Fair enough. Let's defeat it!
% perl -le '$main::{q/]/}++'
% perl -le '$main::{q/]/}++; print $]'
Modification of a read-only value attempted at -e line 1.
Huh?
% perl -le '$main::{q/]/}++; exit; print $]'
Modification of a read-only value attempted at -e line 1.
Oh, come on.
% perl -le 'eval q| $main::{q/]/}++;|; print $@'
% perl -le 'eval q| $main::{q/]/}++;|; print $@; exit; print $]'
Modification of a read-only value attempted at (eval 1) line 1.
The mere presence of another reference to $] during compilation
makes $main::{q/]}++ into a syntax error. I have a vague feeling
this has something to do with GV resolution of special variables
because...
% perl -le 'print $main::{q/]/};'
% perl -le 'print $]; print $main::{q/]/}; print ${$main::{q/]/}}'
5.006001
*main::]
5.006001
Ooh, $] has found its way into main:: !
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=low
---
Site configuration information for perl v5.6.1:
Configured by bod at Mon May 28 15:16:04 EST 2001.
Summary of my perl5 (revision 5.0 version 6 subversion 1) configuration:
Platform:
osname=linux, osvers=2.4.4, archname=i386-linux
uname='linux duende 2.4.4 #1 thu may 17 10:50:53 est 2001 i686 unknown '
config_args='-Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.6.1 -Darchlib=/usr/lib/perl/5.6.1 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.6.1 -Dsitearch=/usr/local/lib/perl/5.6.1 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Dotherlibdirs=/usr/lib/perl5/5.6:/usr/lib/perl5/5.005 -Duseshrplib -Dlibperl=libperl.so.5.6.1 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
useperlio=undef d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
Compiler:
cc='cc', ccflags ='-DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-DDEBIAN -fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='2.95.4 20010506 (Debian prerelease)', 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, usemymalloc=n, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lgdbm -ldbm -ldb -ldl -lm -lc -lcrypt
perllibs=-ldl -lm -lc -lcrypt
libc=/lib/libc-2.2.3.so, so=so, useshrplib=true, libperl=libperl.so.5.6.1
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.6.1:
/usr/local/lib/perl/5.6.1
/usr/local/share/perl/5.6.1
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.6.1
/usr/share/perl/5.6.1
/usr/local/lib/site_perl
/usr/local/lib/perl/5.6.0
/usr/local/share/perl/5.6.0
/usr/lib/perl5/5.6/i386-linux
/usr/lib/perl5/5.6
/usr/lib/perl5/5.005/i386-linux
/usr/lib/perl5/5.005
.
---
Environment for perl v5.6.1:
HOME=/home/simon
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/home/simon/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games:/usr/local/sbin:/usr/sbin:/sbin
PERL_BADLANG (unset)
SHELL=/usr/bin/zsh
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[ID 20010703.009] Freaky action at a distance with $]
by Simon Cozens