Status update: It looks like STD's opinion on this has changed:
$ viv -c -e 'sub a (:$b($c)) {say $c}; a(:b<foo>)'
===SORRY!===
Subsignature not allowed after named parameter; please insert whitespace at
(eval) line 1:
------> sub a (:$b⏏($c)) {say $c}; a(:b<foo>)
Parse failed
Rakudo's error messages are different though:
$ perl6-m -e 'sub a (:$b($c)) {say $c}; a(:b<foo>)'
Too few positionals passed; expected 1 argument but got 0 in sub-signature of
parameter $b
in sub a at -e:1
in block <unit> at -e:1
$ perl6-p -e 'sub a (:$b($c)) {say $c}; a(:b<foo>)'
Not enough positional parameters passed; got 0 but expected 1 in sub-signature
of parameter $b
in sub a at -e:1
in block <unit> at -e:1
$ perl6-j -e 'sub a (:$b($c)) {say $c}; a(:b<foo>)'
Flattening named argument must have VMHash REPR
in sub a at -e:1
in block <unit> at -e:1
