Bizarre copy of HASH in list assignment...

[Manfred Lotz]

Hi there,
I have a script where I use croak and somebody else using that script
gets

Bizarre copy of HASH in list assignment
at /usr/share/perl/5.20/Carp.pm line 228.

I get a message like this, instead:

Variable b has empty value! at ./x.pl line 23.
main::myfunc() called at ./x.pl line 8

which is what should happen.

Any idea what this message means? I'm not able to reproduce it.

Here a minimal example:

#! /usr/bin/perl

use strict;
use warnings;

use Carp;

myfunc();



sub myfunc {
my %vars = (
'a' => 'some val',
'b' => q{},
);

while ( my ( $key, $val ) = each %vars ) {
if ( not defined $val ) {
croak "No value given for $key";
}
if ( $val eq q{} ) {
croak "Variable $key has empty value!";
}
}
return;
}


--
Manfred

[Shlomi Fish]

Hi Manfred,

This code looks fine to me (except for some \t|4-space-indent mixup, which is
relatively minor). I cannot reproduce the reported problem here
( perl-5.20.1-8.mga5 on Mageia Linux x86-64 5 - I'm getting something similar
to what you are getting).

Can you please ask your friend for:

1. Operating system + version.

2. The perl 5 distribution and its version.

3. Version of Carp.pm and the surrounding lines.

4. Other parameters of their environment.

Maybe this way we'll be able to reproduce it.

Regards,

Shlomi Fish

--
-----------------------------------------------------------------
Shlomi Fish http://www.shlomifish.org/
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Please reply to list if it's a mailing list post - http://shlom.in/reply .

[Andy Bach]

On Tue, Mar 31, 2015 at 3:28 AM, Manfred Lotz <manfre...@arcor.de> wrote:

Bizarre copy of HASH in list assignment
at /usr/share/perl/5.20/Carp.pm line 228.

Hmm:
http://stackoverflow.com/questions/6217317/bizarre-copy-of-unknown-in-subroutine-entry

which suggests:

A "Bizarre copy" occurs when Perl's stack is corrupted or contains non-scalars. It occurs as the result of bugs in Perl itself or in XS modules. (Brian Gerard's example exercises one of a long list of known bugs related to the stack not being ref-counted.)

You could isolate the problem by adding the following to the anon sub:

...

--

a

Andy Bach,
afb...@gmail.com
608 658-1890 cell
608 261-5738 wk

[Manfred Lotz]

Hi Shlomi,
it took me a while to get back to it.

The versions of the two systems where the error came up are:

1.
Slackware 14.0, kernel 3.2.29-smp
"This is perl 5, version 16, subversion 3 (v5.16.3) built for
i486-linux-thread-multi" Carp.pm:
our $VERSION = '1.26';

2.
Debian testing ("Debian 3.16.7-ckt7-1 (2015-03-01) i686")
This is perl 5, version 20, subversion 2 (v5.20.2) built for
i586-linux-gnu-thread-multi-64int

Carp.pm:
our $VERSION = '1.3301';


From what Andy said I think it is not easy to reproduce the error. I
was not successful when trying it out on my system with the same Perl
(perhaps a different patch level, though), and the same data. At least,
I'm sure it is not reproducible using a minimal example.


I don't know if this setting has any influence:

main( @ARGV ) unless caller();

sub main {
...
}

sub ...


I just worked around by using warn/die again.


--
Manfred