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Lexical variable freed too soon #7570

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p5pRT opened this issue Oct 31, 2004 · 4 comments
Closed

Lexical variable freed too soon #7570

p5pRT opened this issue Oct 31, 2004 · 4 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Oct 31, 2004

Migrated from rt.perl.org#32234 (status was 'resolved')

Searchable as RT32234$
@p5pRT
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p5pRT commented Oct 31, 2004

From @btilly

Created by btilly@gmail.com

The following code prints a blank line when I'd expect it to
print the word "inside" on that line. I believe that when you
exit block OUTER, Perl does not notice that$foo still might be
accessed by a closure that has not yet been created and the
inner $foo is therefore freed.

  my $foo = "outside";
  OUTER​: {
  my $foo = "inside";
  sub test {
  return sub {print "$foo\n";};
  }
  }
  test()->();

Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl v5.8.4:

Configured by Debian Project at Wed May 12 00:32:16 EST 2004.

Summary of my perl5 (revision 5 version 8 subversion 4) configuration:
  Platform:
    osname=linux, osvers=2.4.26-ti1211, archname=i386-linux-thread-multi
    uname='linux kosh 2.4.26-ti1211 #1 sat apr 24 14:46:58 est 2004
i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.8.4
-Dsitearch=/usr/local/lib/perl/5.8.4 -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 -Uusesfio -Uusenm
-Duseshrplib -Dlibperl=libperl.so.5.8.4 -Dd_dosuid -des'
    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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
-fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.3.3 (Debian 20040429)', 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='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so.5.8.4
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    


@INC for perl v5.8.4:
    /etc/perl
    /usr/local/lib/perl/5.8.4
    /usr/local/share/perl/5.8.4
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
    /usr/local/lib/perl/5.8.3
    /usr/local/share/perl/5.8.3
    /usr/local/lib/perl/5.8.2
    /usr/local/share/perl/5.8.2
    /usr/local/lib/perl/5.8.0
    /usr/local/share/perl/5.8.0
    .


Environment for perl v5.8.4:
    HOME=/home/tilly
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Oct 31, 2004

From @iabyn

On Sun, Oct 31, 2004 at 09​:29​:55AM -0000, Ben Tilly wrote​:

The following code prints a blank line when I'd expect it to
print the word "inside" on that line. I believe that when you
exit block OUTER, Perl does not notice that$foo still might be
accessed by a closure that has not yet been created and the
inner $foo is therefore freed.

my $foo = "outside";
OUTER​: \{
    my $foo = "inside";
    sub test \{
        return sub \{print "$foo\\n";\};
    \}
\}
test\(\)\->\(\);

Thanks for the report. This has already been fixed in the development
branch of perl, which will eventually be released as 5.10.0.

Dave.

--
"But Sidley Park is already a picture, and a most amiable picture too.
The slopes are green and gentle. The trees are companionably grouped at
intervals that show them to advantage. The rill is a serpentine ribbon
unwound from the lake peaceably contained by meadows on which the right
amount of sheep are tastefully arranged." -- Lady Croom - Arcadia

@p5pRT
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p5pRT commented Oct 31, 2004

The RT System itself - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented May 30, 2008

p5p@spam.wizbit.be - Status changed from 'open' to 'resolved'

@p5pRT p5pRT closed this as completed May 30, 2008
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