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[perl #116577] multicall breaks lexicality of variables
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From:
Zefram
Date:
January 29, 2013 19:46
Subject:
[perl #116577] multicall breaks lexicality of variables
Message ID:
rt-3.6.HEAD-27190-1359488784-1596.116577-75-0@perl.org
# New Ticket Created by Zefram
# Please include the string: [perl #116577]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=116577 >
This is a bug report for perl from zefram@fysh.org,
generated with the help of perlbug 1.39 running under perl 5.10.1.
-----------------------------------------------------------------
[Please describe your issue here]
$ cat t0.pl
use List::Util qw(reduce);
our @q;
sub ggg {
my $x = $a;
push @q, \$x;
1;
}
sub fff { reduce \&ggg, 1, 2, 3; }
fff();
fff();
print $_,"\n" for @q;
$ perl t0.pl
SCALAR(0x1f52fc0)
SCALAR(0x1f52fc0)
SCALAR(0x1f53128)
SCALAR(0x1f53128)
$
ggg() is only getting one $x variable per invocation of reduce(),
whereas it should get one per invocation of ggg(). This seems to be
specific to the multicall mechanism (of which reduce() is the exemplar).
(Actual failure mode that I encountered was a reduce() building up
a chain of closures in which each calls the next. The sharing of
supposedly-lexical variables led to the second closure in the chain
calling itself, resulting in a memory-eating infinite loop.)
Wrapping the entire body of ggg() in a do{} makes the lexical variable
behave properly.
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=medium
---
Site configuration information for perl 5.10.1:
Configured by Debian Project at Tue Dec 11 16:56:50 UTC 2012.
Summary of my perl5 (revision 5 version 10 subversion 1) configuration:
Platform:
osname=linux, osvers=2.6.32-5-amd64, archname=x86_64-linux-gnu-thread-multi
uname='linux brahms 2.6.32-5-amd64 #1 smp sun sep 23 10:07:46 utc 2012 x86_64 gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.10.1 -Dsitearch=/usr/local/lib/perl/5.10.1 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.1 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -g',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.4.5', 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='cc', ldflags =' -fstack-protector -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.11.3.so, so=so, useshrplib=true, libperl=libperl.so.5.10.1
gnulibc_version='2.11.3'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib -fstack-protector'
Locally applied patches:
DEBPKG:debian/arm_thread_stress_timeout - http://bugs.debian.org/501970 Raise the timeout of ext/threads/shared/t/stress.t to accommodate slower build hosts
DEBPKG:debian/cpan_config_path - Set location of CPAN::Config to /etc/perl as /usr may not be writable.
DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
DEBPKG:debian/db_file_ver - http://bugs.debian.org/340047 Remove overly restrictive DB_File version check.
DEBPKG:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.
DEBPKG:debian/enc2xs_inc - http://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
DEBPKG:debian/extutils_hacks - Various debian-specific ExtUtils changes
DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.
DEBPKG:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.
DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.
DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.
DEBPKG:debian/m68k_thread_stress - http://bugs.debian.org/495826 Disable some threads tests on m68k for now due to missing TLS.
DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
DEBPKG:debian/module_build_man_extensions - http://bugs.debian.org/479460 Adjust Module::Build manual page extensions for the Debian Perl policy
DEBPKG:debian/perl_synopsis - http://bugs.debian.org/278323 Rearrange perl.pod
DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
DEBPKG:debian/use_gdbm - Explicitly link against -lgdbm_compat in ODBM_File/NDBM_File.
DEBPKG:fixes/assorted_docs - http://bugs.debian.org/443733 [384f06a] Math::BigInt::CalcEmu documentation grammar fix
DEBPKG:fixes/net_smtp_docs - http://bugs.debian.org/100195 [rt.cpan.org #36038] Document the Net::SMTP 'Port' option
DEBPKG:fixes/processPL - http://bugs.debian.org/357264 [rt.cpan.org #17224] Always use PERLRUNINST when building perl modules.
DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
DEBPKG:fixes/pod2man-index-backslash - http://bugs.debian.org/521256 Escape backslashes in .IX entries
DEBPKG:debian/disable-zlib-bundling - Disable zlib bundling in Compress::Raw::Zlib
DEBPKG:fixes/kfreebsd_cppsymbols - http://bugs.debian.org/533098 [3b910a0] Add gcc predefined macros to $Config{cppsymbols} on GNU/kFreeBSD.
DEBPKG:debian/cpanplus_definstalldirs - http://bugs.debian.org/533707 Configure CPANPLUS to use the site directories by default.
DEBPKG:debian/cpanplus_config_path - Save local versions of CPANPLUS::Config::System into /etc/perl.
DEBPKG:fixes/kfreebsd-filecopy-pipes - http://bugs.debian.org/537555 [16f708c] Fix File::Copy::copy with pipes on GNU/kFreeBSD
DEBPKG:fixes/anon-tmpfile-dir - http://bugs.debian.org/528544 [perl #66452] Honor TMPDIR when open()ing an anonymous temporary file
DEBPKG:fixes/abstract-sockets - http://bugs.debian.org/329291 [89904c0] Add support for Abstract namespace sockets.
DEBPKG:fixes/hurd_cppsymbols - http://bugs.debian.org/544307 [eeb92b7] Add gcc predefined macros to $Config{cppsymbols} on GNU/Hurd.
DEBPKG:fixes/autodie-flock - http://bugs.debian.org/543731 Allow for flock returning EAGAIN instead of EWOULDBLOCK on linux/parisc
DEBPKG:fixes/archive-tar-instance-error - http://bugs.debian.org/539355 [rt.cpan.org #48879] Separate Archive::Tar instance error strings from each other
DEBPKG:fixes/positive-gpos - http://bugs.debian.org/545234 [perl #69056] [c584a96] Fix \\G crash on first match
DEBPKG:debian/devel-ppport-ia64-optim - http://bugs.debian.org/548943 Work around an ICE on ia64
DEBPKG:fixes/trie-logic-match - http://bugs.debian.org/552291 [perl #69973] [0abd0d7] Fix a DoS in Unicode processing [CVE-2009-3626]
DEBPKG:fixes/hppa-thread-eagain - http://bugs.debian.org/554218 make the threads-shared test suite more robust, fixing failures on hppa
DEBPKG:fixes/crash-on-undefined-destroy - http://bugs.debian.org/564074 [perl #71952] [1f15e67] Fix a NULL pointer dereference when looking for a DESTROY method
DEBPKG:fixes/tainted-errno - http://bugs.debian.org/574129 [perl #61976] [be1cf43] fix an errno stringification bug in taint mode
DEBPKG:fixes/safe-upgrade - http://bugs.debian.org/582978 Upgrade Safe.pm to 2.25, fixing CVE-2010-1974
DEBPKG:fixes/tell-crash - http://bugs.debian.org/578577 [f4817f3] Fix a tell() crash on bad arguments.
DEBPKG:fixes/format-write-crash - http://bugs.debian.org/579537 [perl #22977] [421f30e] Fix a crash in format/write
DEBPKG:fixes/arm-alignment - http://bugs.debian.org/289884 [f1c7503] Prevent gcc from optimizing the alignment test away on armel
DEBPKG:fixes/fcgi-test - Fix a failure in CGI/t/fast.t when FCGI is installed
DEBPKG:fixes/hurd-ccflags - http://bugs.debian.org/587901 Make hints/gnu.sh append to $ccflags rather than overriding them
DEBPKG:debian/squelch-locale-warnings - http://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
DEBPKG:fixes/lc-numeric-docs - http://bugs.debian.org/379329 [perl #78452] [903eb63] LC_NUMERIC documentation fixes
DEBPKG:fixes/lc-numeric-sprintf - http://bugs.debian.org/601549 [perl #78632] [b3fd614] Fix sprintf not to ignore LC_NUMERIC with constants
DEBPKG:fixes/concat-stack-corruption - http://bugs.debian.org/596105 [perl #78674] [e3393f5] Fix stack pointer corruption in pp_concat() with 'use encoding'
DEBPKG:fixes/cgi-multiline-header - http://bugs.debian.org/606995 [CVE-2010-2761 CVE-2010-4410 CVE-2010-4411] CGI.pm MIME boundary and multiline header vulnerabilities
DEBPKG:fixes/casing-taint-cve-2011-1487 - http://bugs.debian.org/622817 [perl #87336] fix unwanted taint laundering in lc(), uc() et al.
DEBPKG:fixes/safe-reval-rdo-cve-2010-1447 - [PATCH] Wrap by default coderefs returned by rdo and reval
DEBPKG:fixes/encode-heap-overflow - [PATCH] Fix decode_xs n-byte heap-overflow security bug in
DEBPKG:fixes/digest_eval_hole - Close the eval \"require $module\" security hole in
DEBPKG:fixes/unregister_signal_handler - [PATCH] main: Unregister signal handler before destroying my_perl
DEBPKG:fixes/CVE-2012-5195 - avoid calling memset with a negative count
DEBPKG:fixes/CVE-2012-5526 - [PATCH 1/4] CR escaping for P3P header
DEBPKG:fixes/storable-security-warning - [PATCH] add a note about security concerns in Storable
DEBPKG:patchlevel - http://bugs.debian.org/567489 List packaged patches for 5.10.1-17squeeze4 in patchlevel.h
---
@INC for perl 5.10.1:
/etc/perl
/usr/local/lib/perl/5.10.1
/usr/local/share/perl/5.10.1
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.10
/usr/share/perl/5.10
/usr/local/lib/site_perl
.
---
Environment for perl 5.10.1:
HOME=/home/zefram
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/home/zefram/pub/x86_64-unknown-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/bin:/usr/local/bin:/usr/games
PERL_BADLANG (unset)
SHELL=/usr/bin/zsh
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[perl #116577] multicall breaks lexicality of variables
by Zefram