string ranges: bug: ranges of length 1.

* lib.c (seq_iter_init_with_info): String ranges are
inclusive. We must not assume at a range whose endpoints are
the same is empty; we must check that case for the endpoints
being strings.

* tests/012/seq.tl: New tests.

1 files changed, 11 insertions, 1 deletions

diff --git a/lib.c b/lib.c
index b4971191..11cf3340 100644
--- a/lib.c
+++ b/lib.c
@@ -1060,7 +1060,17 @@ void seq_iter_init_with_info(val self, seq_iter_t *it, seq_info_t si)
         /* fallthrough */
       default:
         unsup_obj(self, it->inf.obj);
-      } else {
+      } else switch (type(rf)) {
+      case LIT:
+      case STR:
+      case LSTR:
+        it->ui.vn = copy_str(rf);
+        it->ul.vbound = rt;
+        it->ops = &si_range_str_ops;
+        if (eql(length_str(rf), length_str(rt)))
+          break;
+        unsup_obj(self, it->inf.obj);
+      default:
         seq_iter_init_with_info(self, it, seq_info(nil));
         break;
       }