IMHO this code example in perlre#Assertions is wrong or am I missing something?

Note that the rule for zero-length matches is modified somewhat, in that contents to the left of \G is not counted when determining the length of the match. Thus the following will not match forever:

   $str = 'ABC';
   pos($str) = 1;
   while (/.\G/g) {
     print $&;
   }
[download]

It will print 'A' and then terminate, as it considers the match to be zero-width, and thus will not match at the same position twice in a row.

The while loop tries to match $_ not $str.

so this works like it should

   use warnings;
   $str = 'ABC';
   pos($str) = 1;
   while ($str=~/.\G/g) {
     print $&;
   }
[download]

BUT what's really confusing me is that pos($str) is empty afterwards!

Now appending this code to the latter

   print pos($str);  #line6
   while ($str=~/.\G/g) {
     print $&;
   }
[download]

produces  Use of uninitialized value in print at ... line 6. and an endless loop!

OK ... now at the same time running this code:

   
use warnings;
$str = 'ABC';
print pos($str);
#   pos($str) = 1;
while ($str=~/.\G/g) {
     print $&;
}
[download]

produces

Use of uninitialized value in print at /home/lanx/B/PL/PM/re_escG.pl l
+ine 2.
Use of uninitialized value $& in print at /home/lanx/B/PL/PM/re_escG.p
+l line 5.
[download]

but no endless loop!

Sorry???

if pos() is uninitialized why does it produce in one case an endless loop and in another it doesn't?

UPDATE: Yes, I know that:

Currently, the "\G" anchor is only fully supported when used to anchor to the start of the pattern.(perlretut)

... but pos() is defined to be the position after the last match, thus in our case with a final \G in the pattern it shouldn't change at all... IMHO there's no reason why this shouldn't work... and most probably this bug in pos is the source of the problem!

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