printer: [] shouldn't print as [. nil].

* lib.c (obj_print_impl): In the case when dwim
has no args, and the logic short circuits to
a closing brace, bypassing the loop, we should
only use the dot notation if the terminating
atom is other than nil.

* tests/012/readprint.tl: Tests added.

1 files changed, 4 insertions, 2 deletions

diff --git a/lib.c b/lib.c
index f9b6ee30..d17e416f 100644
--- a/lib.c
+++ b/lib.c
@@ -14349,8 +14349,10 @@ val obj_print_impl(val obj, val out, val pretty, struct strm_ctx *ctx)
         if (sym == dwim_s) {
           put_char(chr('['), out);
           if (!have_args) {
-            put_string(lit(". "), out);
-            obj_print_impl(args, out, pretty, ctx);
+            if (args) {
+              put_string(lit(". "), out);
+              obj_print_impl(args, out, pretty, ctx);
+            }
             put_char(chr(']'), out);
             break;
           }