This seems to work now (<[]> behaves like ):
$ perl6 -e 'say so "a" ~~ /<[]>/'
False
$ perl6 -e 'say so "abc" ~~ /a <[]>/'
False
$ perl6 -e 'say so "" ~~ /<[]>/'
False
I added two tests to S05-mass/stdrules.t with commit
https://github.com/perl6/roast/commit/9bad4dd1af
I'm closing this ticket
# New Ticket Created by "Carl Mäsak"
# Please include the string: [perl #109674]
# in the subject line of all future correspondence about this issue.
# https://rt.perl.org:443/rt3/Ticket/Display.html?id=109674 >
nom: say so 'a' ~~ /<[]>/
nom ce5cca: OUTPUT«===SORRY!===StopIteration»
std: