perl -MO=Deparse -e '@a = qw (a bc def); print "before: @a\n"; $"=q; print
 "after: @a\n";'

Output:
@a = ('a', 'bc', 'def');          # ok, I agree
print "before: @a\n";             # yep, still with ya
$" = ' print "after: @a\\n"';     # whoa, this is unexpected
-e syntax OK                      # good news, I guess