Just don't mess with the debugger's own namesspace DB:: !

I don't understand the purpose of all those indirections anyway.

Cleaning up the code helps:

#!/usr/bin/perl
use strict;
use warnings;

$|=1;

print "1\n"; 


sub caller_args {             # NB: renamed
    my ($level) = @_;
    {
        package DB;
        () = caller( ( $level || 0 ) + 1 );
    }
    wantarray ? @DB::args : [@DB::args]; 
      # NB: returning a ref \@DB::args was dangerous
}

sub tst {
    local $\="\n";
    print "\@_ = @_";
    print "called_args = ", join (" ", caller_args(0));
}

tst(1..3);
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See caller for details.

w/o debuger

> perl tst.pl 
1
@_ = 1 2 3
called_args = 1 2 3
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with debugger

> perl -d tst.pl 

Loading DB routines from perl5db.pl version 1.3
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(tst.pl:5):    $|=1;
  DB<100> n
main::(tst.pl:7):    print "1\n";
  DB<100> 
1
main::(tst.pl:25):    tst(1..3);
  DB<100> 
@_ = 1 2 3
called_args = 1 2 3
Debugged program terminated.  Use q to quit or R to restart,
  use o inhibit_exit to avoid stopping after program termination,
  h q, h R or h o to get additional info.
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