iter-step: don't step through improper list terminators.

The issue is that iter-step will traverse (1 2 . 3)
into the 3, and then that is valid iterator which
continues via 4, 5, 6, ...

This affects the each operator family which use
iter-step.

* lib.c (iter_step): Handle CONS and LCONS specially now. If
the next object pulled via cdr is not a cons, and not nil,
then throw an error. The default case now only possibly
handles list-like sequences. Here we do something more generic
and expensive: we enforce that the next iterator must
be nil, or else a list-like sequence.

0 files changed, 0 insertions, 0 deletions