After some discussion it was decided to let that fail with X::Comp::NYI for now:
$ perl6 -e 'say $?FILE; { my constant $?FILE = "foo"; say $?FILE }'
===SORRY!=== Error while compiling -e
Constants with a '?' twigil not yet implemented. Sorry.
at -e:1
------> say $?FILE; { my constant $?FILE = "foo"⏏; say $?FILE }
See the discussion at #perl6 from 2015-08-17 (around
http://irclog.perlgeek.de/perl6/2015-08-17#i_11069350; search for af61bb2,
82ea784 and f58a726 to get more background).
I added a test to S32-exceptions/misc.t with commit
https://github.com/perl6/roast/commit/a5831ca942.
I'm closing this ticket as 'resolved'.
