Some regex quantifiers don't work as expected

[jmaslak]

The Problem

This regex, demonstrated here, returns true when it shouldn't (I think!).

This is a golfed exampe -

perl6 -e 'say "aaa" ~~ m/(a ** {2..*}) ** 2..*/'

Output:

[0] red:jmaslak$ perl6 -e 'say "aaa" ~~ m/(a ** {2..*}) ** 2..*/'
｢aaa｣
 0 => ｢a｣
 0 => ｢aa｣
[0] red:jmaslak$

Note perl6 -e 'say "aaa" ~~ m/(a ** 2..*) ** 2..*/' does what I would expect it to do (returns false). So does perl6 -e 'say "aaa" ~~ m/(a ** 2..*) ** {2..*}/'

Expected Behavior

Expected behaviro is returning false.

Actual Behavior

Returns a true value.

Steps to Reproduce

perl6 -e 'say "aaa" ~~ m/(a ** {2..*}) ** 2..*/'

Environment

• Operating system: Ubuntu 16.04
• Compiler version (perl6 -v): 2008.06 6.c

[ugexe]

It works with the :ratchet adverb. So probably a result of { } ( See the answer here )

[lizmat]

So, can we close this ticket? Or should we work on documentation?

[jnthn]

@lizmat No, I think it's a backtracking bug, and :ratchet doesn't do backtracking, so "hides" the bug.