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returning @+ out of scope loses its value #7192

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p5pRT opened this issue Mar 22, 2004 · 4 comments
Closed

returning @+ out of scope loses its value #7192

p5pRT opened this issue Mar 22, 2004 · 4 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Mar 22, 2004

Migrated from rt.perl.org#27839 (status was 'resolved')

Searchable as RT27839$
@p5pRT
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p5pRT commented Mar 22, 2004

From perl-5.8.0@ton.iguana.be

Created by perl-5.8.0@ton.iguana.be

This was already mentioned on the mailinglist, see
http​://groups.google.com/groups?selm=c26p20$34b$1%40post.home.lunix
In that thread you will also find a possible patch, where it was
unclear if that was the proper place to fix.
I'm re-reporting the bug here so it won't get lost.

perl -wle 'sub f {"ab" =~ /(.)/; print "@​+"; return @​+}; print f'
1 1
Use of uninitialized value in print at -e line 1.
Use of uninitialized value in print at -e line 1.

Ok, I can sort of see what's going on here. the scope with the regex
is left, and @​+ gets restored to it's old value (empty). So my result
still knows it was 2 long, but the values are gone, and I get 2 undefs.

But why didn't I get copies of the values, no longer sensitive to
their origin evaporating ?
(later discussion in the thread shows agreement that it should have)

If I try to sort of do this (as much as possible) with a normal array,
I don't observe the effect​:

perl -wle 'sub DESTROY { $a[0]=1} @​a="a".."c"; sub f { my $a=bless[]; return @​a } print f'
abc

(I was sort of starting to expect 1bc here)

Also notice that things like this DO work, even though $1 is also going
out of scope​:
perl -wle 'sub f {"ab" =~ /(.)/; print "$1"; return $1}; print f'
a
a

Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl v5.8.2:

Configured by ton at Sun Jan  4 19:19:06 CET 2004.

Summary of my perl5 (revision 5.0 version 8 subversion 2) configuration:
  Platform:
    osname=linux, osvers=2.6.0, archname=i686-linux-64int-ld
    uname='linux quasar 2.6.0 #3 thu dec 18 18:22:48 cet 2003 i686 gnulinux '
    config_args=''
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=undef uselongdouble=define
    usemymalloc=y, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -fomit-frame-pointer',
    cppflags='-fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.4.0 20031231 (experimental)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='long double', nvsize=12, 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=-lnsl -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.3.2'
  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 v5.8.2:
    /usr/lib/perl5/5.8.2/i686-linux-64int-ld
    /usr/lib/perl5/5.8.2
    /usr/lib/perl5/site_perl/5.8.2/i686-linux-64int-ld
    /usr/lib/perl5/site_perl/5.8.2
    /usr/lib/perl5/site_perl
    .


Environment for perl v5.8.2:
    HOME=/home/ton
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/ton/bin.Linux:/home/ton/bin:/home/ton/bin.SampleSetup:/usr/local/bin:/usr/local/sbin:/usr/local/jre/bin:/home/oracle/product/9.0.1/bin:/usr/local/ar/bin:/usr/games/bin:/usr/X11R6/bin:/usr/share/bin:/usr/bin:/usr/sbin:/bin:/sbin:.
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Mar 23, 2004

From @rgs

Perl-5.8.0@​Ton.Iguana.Be wrote in perl.perl5.porters :

This was already mentioned on the mailinglist, see
http​://groups.google.com/groups?selm=c26p20$34b$1%40post.home.lunix
In that thread you will also find a possible patch, where it was
unclear if that was the proper place to fix.
I'm re-reporting the bug here so it won't get lost.

perl -wle 'sub f {"ab" =~ /(.)/; print "@​+"; return @​+}; print f'
1 1
Use of uninitialized value in print at -e line 1.
Use of uninitialized value in print at -e line 1.

I committed Hugo's proposed fix for this, along with a test case,
as change #22564.

@p5pRT
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p5pRT commented Mar 23, 2004

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

@p5pRT
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p5pRT commented Mar 23, 2004

@rgs - Status changed from 'open' to 'resolved'

@p5pRT p5pRT closed this as completed Mar 23, 2004
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