Hi everybody.

I have recently found a problem in resetting `$0' inside a script "sourced"
with the `.' builtin.

Not sure if it's a bug or if it's just me doing something that should not
be done; hopefully you can tell.


Here are some minimal examples exposing the problem:
  
    -*-*-*-

  $ cat main1.zsh
  0=x
  v1=$0
  v2=`echo "$0" | sed 's/x/y/g'`
  echo 0="$0"
  echo v1="$v1"
  echo v2="$v2"

  $ zsh main1.zsh; echo e=$?  # this behaves OK
  0=x
  v1=x
  v2=y
  e=0
  
    -*-*-*-

  $ cat main2.zsh
  . ./inc2.zsh
  echo 0="$0"'
  echo v="$v"
  
  $ cat inc2.zsh
  0=x
  v=$0
  
  $ zsh main2.zsh; echo e=$?  # this causes zsh to crash
  *** glibc detected *** zsh: double free or corruption (!prev): 0x08d91a18 ***              
  ======= Backtrace: =========

  /lib/i686/cmov/libc.so.6[0xb7dd98f4]
  /lib/i686/cmov/libc.so.6(cfree+0x96)[0xb7ddb896]
  zsh[0x80804ba]
  zsh(ingetc+0x1a2)[0x8080cc2]
    ... [CUT] (see the attachement)
  b7f87000-b7f88000 rw-p 0001c000 03:47 3156250   /lib/ld-2.9.so
  bff71000-bff87000 rw-p bffea000 00:00 0    [stack]
  Abortito                                                                                   
  e=134                                      
  
    -*-*-*-

  $ cat main3.zsh
  . ./inc3.zsh
  echo 0="$0"'
  echo v="$v"
  
  $ cat inc3.zsh
  0=x
  v=`echo "$0"`
  
  $ zsh main3.zsh; echo e=$?  # I'd expect $v to be "x", but...
  0=main3.zsh
  v=
  e=0

    -*-*-*-

  $ cat main4.zsh
  . ./inc4.zsh
  echo 0="$0"'
  echo v="$v"
  
  $ cat inc4.zsh
  setopt no_function_argzero
  0=x
  v=`echo "$0"`
  
  $ zsh main4.zsh; echo e=$?  # this causes zsh to crash
  *** glibc detected *** zsh: corrupted double-linked list: 0x0813aa20 ***                    
  ======= Backtrace: =========                                                                
  /lib/i686/cmov/libc.so.6[0xb7dc836f]
  /lib/i686/cmov/libc.so.6[0xb7dc9e6d]
  /lib/i686/cmov/libc.so.6(__libc_malloc+0x95)[0xb7dcbcd5]
  zsh(zalloc+0x24)[0x808de44]
  zsh[0x809e347]
  zsh(parse_event+0x2f)[0x80a3fff]
    ... [CUT] (see the attachement)
  b7f75000-b7f76000 rw-p 0001c000 03:47 3156250   /lib/ld-2.9.so
  bfb60000-bfb76000 rw-p bffea000 00:00 0    [stack]

    -*-*-*-

System information:
 
  $ uname -a 
  Linux bigio 2.6.26-1-686 #1 SMP Sat Jan 10 18:29:31 UTC 2009 i686 GNU/Linux
  $ cat /etc/debian_version
  squeeze/sid
  $ zsh --version 
  zsh 4.3.10 (i686-pc-linux-gnu)
  $ dpkg -l zsh
  ii   zsh   4.3.10-5   A shell with lots of features
  $ dpkg -l libc6
  ii   libc6   2.9-25   GNU C Library: Shared libraries


Regards,
   Stefano