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[perl #119797] lvalue sub shows "Bizarre copy of ARRAY in block exit" in very specific case.

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September 15, 2013 10:08
[perl #119797] lvalue sub shows "Bizarre copy of ARRAY in block exit" in very specific case.
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# New Ticket Created by  GlitchMr 
# Please include the string:  [perl #119797]
# in the subject line of all future correspondence about this issue. 
# <URL: >

This is a bug report for perl from,
generated with the help of perlbug 1.39 running under perl 5.18.1.

[Please describe your issue here]

Following code involving lvalue shows "Bizarre copy of ARRAY in block
exit". I've experimented with it, and it seems to happen with any
array (lexical or global), as long the `if` condition involves array
somehow, and returns false (for example, `if (@array, 0)`), and `else`
block returns `@array` without `return` keyword.

    # The subroutine has to be declared as lvalue, so you can write to
    # it in order to trigger the bug.
    sub array : lvalue {
        # This test has to involve @array somehow, but fail.
        if (@array) {
            # The contents of if block don't matter, so I left this
            # block empty. It just has to exist.
        else {
            # The else condition has to return @array. Return keyword
            # cannot be used for this bug to trigger.
    # Now, to trigger the bug, it's enough to write to array.
    (array) = ();

[Please do not change anything below this line]
Site configuration information for perl 5.18.1:

Configured by nobody at Tue Aug 13 13:22:58 CEST 2013.

Summary of my perl5 (revision 5 version 18 subversion 1) configuration:
    osname=linux, osvers=3.10.5-1-arch,
    uname='linux mnt-chroots-arch-extra-x86_64-flo-64 3.10.5-1-arch #1
    smp preempt mon aug 5 08:04:22 cest 2013 x86_64 gnulinux '
    config_args='-des -Dusethreads -Duseshrplib -Doptimize=-march=x86-64
    -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4
    -Dprefix=/usr -Dvendorprefix=/usr
    -Dscriptdir=/usr/bin/core_perl -Dsitescript=/usr/bin/site_perl
    -Dvendorscript=/usr/bin/vendor_perl -Dinc_version_list=none
    -Dman1ext=1perl -Dman3ext=3perl -Dcccdlflags='-fPIC'
    -Dlddlflags=-shared -Wl,-O1,--sort-common,--as-needed,-z,relro
    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
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing
    -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
    optimize='-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
    -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.8.1 20130725 (prerelease)',
    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',
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags ='-Wl,-O1,--sort-common,--as-needed,-z,relro
    -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/../lib /usr/lib/../lib /lib /usr/lib
    /lib64 /usr/lib64
    libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/, so=so, useshrplib=true,
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E
    cccdlflags='-fPIC', lddlflags='-shared
    -Wl,-O1,--sort-common,--as-needed,-z,relro -L/usr/local/lib

Locally applied patches:

@INC for perl 5.18.1:

Environment for perl 5.18.1:
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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