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[perl #126928] local $! = $!; does not work as expected, does notrestore

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From:
Chad Granum
Date:
December 15, 2015 20:35
Subject:
[perl #126928] local $! = $!; does not work as expected, does notrestore
Message ID:
rt-4.0.18-29932-1450211698-0.126928-75-0@perl.org
# New Ticket Created by  Chad Granum 
# Please include the string:  [perl #126928]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=126928 >


This is a bug report for perl from exodist7@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.22.0.


-----------------------------------------------------------------

local $! = $! will set $! to 0, and will not restore it at the end of the
scope.

Sample code:

    $! = 100;
    print '$! == ' . int($!) . "\n";
    {
        local $! = $!;
        print '$! == ' . int($!) . "\n";
    }
    print '$! == ' . int($!) . "\n";

Output:

    $! == 100
    $! == 0
    $! == 0

You can work around the issue by replacing 'local $! = $!' with 'local $! =
int($!)' or with 'my $x = $!; local $! = $x;'. Using 'local $!' without
assinging a value to it also works as expected in that it restores the old
value at the end of the scope.

I am not sure if this is truly a bug, but it is certainly unexpected.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.22.0:

Configured by exodist at Wed Jul 29 11:56:27 PDT 2015.

Summary of my perl5 (revision 5 version 22 subversion 0) configuration:

  Platform:
    osname=linux, osvers=3.13.0-44-generic,
archname=x86_64-linux-thread-multi
    uname='linux work 3.13.0-44-generic #73-ubuntu smp tue dec 16 00:22:43
utc 2014 x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/exodist/perl5/perlbrew/perls/main
-Dusethreads -Aeval:scriptdir=/home/exodist/perl5/perlbrew/perls/main/bin'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe
-fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.8.4', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678,
doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16,
longdblkind=3
    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 /usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
/usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib
/usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
-fstack-protector'


---
@INC for perl 5.22.0:
    /home/exodist/.perlbrew/libs/main@exodist
/lib/perl5/x86_64-linux-thread-multi
    /home/exodist/.perlbrew/libs/main@exodist/lib/perl5

/home/exodist/perl5/perlbrew/perls/main/lib/site_perl/5.22.0/x86_64-linux-thread-multi
    /home/exodist/perl5/perlbrew/perls/main/lib/site_perl/5.22.0

/home/exodist/perl5/perlbrew/perls/main/lib/5.22.0/x86_64-linux-thread-multi
    /home/exodist/perl5/perlbrew/perls/main/lib/5.22.0
    .

---
Environment for perl 5.22.0:
    HOME=/home/exodist
    LANG=en_US.UTF-8
    LANGUAGE=en_US
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/exodist/.perlbrew/libs/main@exodist
/bin:/home/exodist/perl5/perlbrew/bin:/home/exodist/perl5/perlbrew/perls/main/bin:/home/exodist/bin:/home/exodist/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
    PERL5LIB=/home/exodist/.perlbrew/libs/main@exodist/lib/perl5
    PERLBREW_BASHRC_VERSION=0.66
    PERLBREW_HOME=/home/exodist/.perlbrew
    PERLBREW_LIB=exodist
    PERLBREW_MANPATH=/home/exodist/.perlbrew/libs/main@exodist
/man:/home/exodist/perl5/perlbrew/perls/main/man
    PERLBREW_PATH=/home/exodist/.perlbrew/libs/main@exodist
/bin:/home/exodist/perl5/perlbrew/bin:/home/exodist/perl5/perlbrew/perls/main/bin
    PERLBREW_PERL=main
    PERLBREW_ROOT=/home/exodist/perl5/perlbrew
    PERLBREW_VERSION=0.66
    PERL_BADLANG (unset)
    PERL_LOCAL_LIB_ROOT=/home/exodist/.perlbrew/libs/main@exodist
    PERL_MB_OPT=--install_base /home/exodist/.perlbrew/libs/main@exodist
    PERL_MM_OPT=INSTALL_BASE=/home/exodist/.perlbrew/libs/main@exodist
    SHELL=/usr/bin/zsh


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