# The construct ${#?} is ambiguous in POSIX.1-2008: it could be the length
# of $? or it could be $# giving an error in the (impossible) case that it
# is not set.
# We use the former interpretation; it seems more useful.

:
[ "${#?}" = 1 ] || echo '${#?} wrong'
(exit 42)
[ "${#?}" = 2 ] || echo '${#?} wrong'