The Regional Indicator Symbols seem to get mangled when flipped sometimes

[thundergnat]

The Problem

The Regional Indicator Symbols (Flag emoji) sometimes work as expected when flipped, sometimes not.

say my $um = '🇬🇧 is not 🇧🇬';
say $um.flip;

Output:
🇬🇧 is not 🇧🇬
🇬🇧 ton si 🇬🇧

 "🇬 🇧🇧🇬".flip.say;

Output:
🇬🇧🇧 🇬

Tested on Camelia ce5a011 (see http://colabti.org/irclogger/irclogger_log/perl6?date=2018-08-10#l896)

and on random dev build:
2018.06-255-gd471bf7 built on MoarVM version 2018.06-314-g4199a95

[AlexDaniel]

This used to work in the past.

Bisected: (2017-06-10) 56e71d5

[thundergnat]

That second one might fall under the DIHWIDT clause, but I really thought the first should work.

[samcv]

Will have to take a look at this. It looks like the code that tries to count if we have 2 or 3 Regional Indicators and segment them is buggy. I'm guessing that it's not resetting the count and so it causes a break after the third Regional Indicator it sees (since RI are segmented at 2 or at 3 codepoints).

[samcv]

I have fixed this bug in MoarVM/MoarVM@829b8ee70 see commit information for full description on the issue. rakudo/nqp should be bumped to get the fix once Travis is clean on MoarVM

[samcv]

Tests have been added here: Raku/roast@0a5ff6b

Going to close the issue now. It can be reopened but I believe this issue and other bugs I found with regional indicators have now been fixed 👍