I think perl's clobbering or removing backreferences somewhere, and you're trying to access \1 after perl's done something else with it.
If $1 is assigned to a temp var within dofunc, the code no longer dumps core. Below is my test, and output...

#!/usr/bin/perl -w
use strict;
my $weeping;
print doFunc( "AABBCC",0 );  
print doFunc( "AAAABBBBCCCC",0 );  

 sub doFunc {
    my( $theParam,$depth) = @_;
    print STDERR "\ndofunc($theParam)\n";
    my $re;
    $re = ${['(.+)$weeping']}[$depth]||'(.+)($weeping)';     
    print STDERR join"\n", $theParam =~ /$re/g,undef;
    $theParam =~ s/$re/&doFunc($weeping,$depth+1)/ge;
    $weeping=$1;
    ++$theParam;
    print STDERR "=$theParam\n";
    return $theParam;
}

[download]


and this gives us 

dofunc(AABBCC)
=AABBCD
AABBCD
dofunc(AAAABBBBCCCC)
=AAAABBBBCCCD
AAAABBBBCCCD

[download]


Now, if you'll excuse me, I need to go wash my hands compulsively :-)
update so what output do you expect, out of curiosity?

In reply to Re: recursive s///g core dumps by boo_radley
in thread recursive s///g core dumps by I0

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.