From @bbkr

[13​:30] <bbkr> std​: /$'x'/
[13​:30] <p6eval> std 32120​: OUTPUT«�[31m===�[0mSORRY!�[31m===�[0mâ�¤Unrecognized
regex metacharacter (must be quoted to match literally) at /tmp/Z7pZBmmNfW
line 1​:â�¤------> �[32m/$�[33mâ���[31m'x'/�[0mâ�¤Can't call method "from" on
unblessed reference at STD.pm line 53782.â�¤FAILED 00​:01 116mâ�¤Â»

[13​:30] <bbkr> rakudo​: /$'x'/
[13​:30] <p6eval> rakudo f8e959​: ( no output )

From @diakopter

On Tue Aug 31 04​:32​:18 2010, pawel.pabian@​implix.com wrote​:

[13​:30] <bbkr> std​: /$'x'/
[13​:30] <p6eval> std 32120​:
OUTPUT«�[31m===�[0mSORRY!�[31m===�[0m�Unrecognized
regex metacharacter (must be quoted to match literally) at
/tmp/Z7pZBmmNfW
line 1​:â�¤------> �[32m/$�[33mâ���[31m'x'/�[0mâ�¤Can't call method "from" on
unblessed reference at STD.pm line 53782.â�¤FAILED 00​:01 116mâ�¤Â»

[13​:30] <bbkr> rakudo​: /$'x'/
[13​:30] <p6eval> rakudo f8e959​: ( no output )

correctly errors now. marking testneeded.

17​:46 <diakopter> rakudo​: /$'x'/
17​:46 <p6eval> rakudo 024843​: OUTPUT«===SORRY!===â�¤Non-declarative sigil
is missing its
  nameâ�¤at /tmp/R6NXpe2G4M​:1â�¤Â»

The RT System itself - Status changed from 'new' to 'open'

From @bbkr

I'm not sure this is resolved.

STD error​:
Unrecognized regex metacharacter $ (must be quoted to match literally)...

Rakudo error​:
Non-declarative sigil is missing its name...

Both failures should have the same reason. Otherwise it can be compared to ridiculous situation
where someone says "my car is not working because it has broken gearbox" and you reply "I
have the same car because mine is not working due to broken radio" :)

From @usev6

Nowadays this is parsed by STD and Rakudo (on Moar, Parrot and JVM)​:

$ viv -c -e "/$'x'/"
syntax OK

$ perl6 -e "/$'x'/"
$ perl6 -e "say (/$'x'/).perl"
regex (Mu​: *%_) { #`(Regex|70560384) ... }

I added a test to S05-metasyntax/unknown.t with commit Raku/roast@72709f1783

I'm closing this ticket now. If you think this is not solved (maybe even STD gets it wrong now?), please reopen.

@usev6 - Status changed from 'open' to 'resolved'