[perl #119071] Misdiagnosed regex infinite recursion

On Mon Jul 29 10:22:42 2013, nicholas wrote:
> On Mon, Jul 29, 2013 at 07:20:13PM +0200, demerphq wrote:
> > On 29 July 2013 18:17, Philip Hazel <perlbug-followup@perl.org>
> wrote:
> 
> > > $ perl -e 'x =~ /(?:(a(*SKIP)b)){0}(?:(?1)|ac)/'
> > > Infinite recursion in regex at -e line 1.
> > >
> > > As far as I can see, there is no infinite recursion here.
> Capturing group
> > > number 1 is (a(*SKIP)b) and that does not do any recursing, so
> calling
> > > it via (?1) is just a single recursion.
> >
> > This looks to me like another example of {0} => NOTHING optimization
> > not playing nicely with recursive patterns.
> 
> Yes, caused by commit 3018b823898645e44b8c37c70ac5c6302b031381
> 
> Fixed by commit 2e3a23da260a7ec5d61b81cb34c38de5e528b41d
> 
> Nicholas Clark
> 


$ ./perl -Ilib -v | head -3 | tail -2This is perl 5, version 19,
subversion 3 (v5.19.3 (v5.19.2-208-g5c24ac0)) built for darwin-2level

$ ./perl -Ilib -E 'if (x =~ /(?:(a(*SKIP)b)){0}(?:(?1)|ac)/) {say "yes"}
else { say "no"};'
no


Is this ticket closable?

---
via perlbug:  queue: perl5 status: open
https://rt.perl.org:443/rt3/Ticket/Display.html?id=119071

• [perl #119071] Misdiagnosed regex infinite recursion by Philip Hazel
• Re: [perl #119071] Misdiagnosed regex infinite recursion by demerphq
• Re: [perl #119071] Misdiagnosed regex infinite recursion by Nicholas Clark
• [perl #119071] Misdiagnosed regex infinite recursion by James E Keenan via RT
• [perl #119071] Misdiagnosed regex infinite recursion by James E Keenan via RT
• Re: [perl #119071] Misdiagnosed regex infinite recursion by demerphq