From zefram@fysh.org

I'd expect the delimiter pairing to work on all "opening punctuation"
graphemes. Like this​:

/^<​:Ps>$/.ACCEPTS("[").Bool
True
"q[foo]".EVAL.perl
"foo"

But if the grapheme consists of a Ps base character plus a combining
diacritic, then it matches <​:Ps> (identifying it as an "opening
punctuation" grapheme), but it doesn't get paired with a corresponding
Pe delimiter​:

/^<​:Ps>$/.ACCEPTS("[\x[308]").Bool
True
"q[\x[308]foo]\x[308]".EVAL.perl
===SORRY!=== Error while compiling /home/zefram/usr/perl/pg/EVAL_5
Couldn't find terminator [? (corresponding [? was at line 1)
at /home/zefram/usr/perl/pg/EVAL_5​:1
------> q[?foo]?^<EOL>
  expecting any of​:
  [?

Not sure whether this is really a bug, but the mismatch between the <​:Ps>
regexp and the scope of delimiter pairing is at least less than awesome.

-zefram

From @samcv

I have made the error much more awesome​:

Starter [̈ is immediately followed by a combining codepoint. Please use [ without a combining glyph ([̈ was at line 1)

Should affect q quoting and s/// as well. Going to close this as resolved.

@samcv - Status changed from 'new' to 'resolved'