From [Unknown Contact. See original ticket]

On Fri Aug 08 11​:52​:10 2014, khw wrote​:

Now fixed by 842a9d2
which I vote to backport into 5.20.1

Thank you. It gets my vote, too.

On Sat Aug 02 20​:07​:50 2014, public@​khwilliamson.com wrote​:

Not having looked into this at all, but knowing that 5.20.1 is due
this
month, if this were to get into that release, would that be a good
enough workaround?

Yes, that would be okay. However, I would still like to get my module working with 5.20.0 if possible, so I have some questions​:

$ perl5.21.3 -Mre=debug -e 'my $a = "rdvark"; $a =~ /(?=[A-Za-z0-9_])a*?/g;'
...
stclass ANYOF[0-9A-Z_a-z] minlen 0
...
$ perl5.21.3 -Mre=debug -e 'my $a = "rdvark"; $a =~ /(?{})(?=[A-Za-z0-9_])a*?/g;'
...
stclass ANYOF[a] minlen 0 with eval
...

(These one-liners are from before the fix.)

It seems that the stclass optimisation is behaving differently depending on the presence or absence of an eval. (I find that surprising. I thought the optimisation would just be turned on or off.)

What can I add to the pattern to turn off the optimisation altogether? Under what circumstances does this bug occur? (I.e., where does (?=) have to be in the pattern, etc.) Is it only with (?=...) or does it apply to other assertions, too?

--

Father Chrysostomos