* lib.c (lazy_appendv_func, lazy_appendv): Bugfix: append*

was silently ignoring lists after the first atom, instead of
throwing an error. Also, it was not detecting the case that
the last argument is a list which should just be returned,
and instead trying to find its tail in preparation for the
next call to lazy_appendv_func, the consequences being runaway
iteration over an infinite list.

1 files changed, 10 insertions, 2 deletions

diff --git a/lib.c b/lib.c
index 913d2b47..d4cc50cc 100644
--- a/lib.c
+++ b/lib.c
@@ -888,11 +888,15 @@ static val lazy_appendv_func(val env, val lcons)
 
   rplaca(lcons, last);
 
-  if (atom(nonempty)) {
+  if (nilp(lists)) {
     rplacd(lcons, nonempty);
     return nil;
   }
 
+  if (atom(nonempty))
+    uw_throwf(error_s, lit("append*: cannot append to atom ~s"),
+              nonempty, nao);
+
   rplacd(env, lists);
 
   {
@@ -914,9 +918,13 @@ val lazy_appendv(val lists)
       break;
   }
 
-  if (atom(nonempty))
+  if (nilp(lists))
     return nonempty;
 
+  if (atom(nonempty))
+    uw_throwf(error_s, lit("append*: cannot append to atom ~s"),
+              nonempty, nao);
+
   {
     loc ptail = ltail(mkcloc(nonempty));
     set(ptail, make_lazy_cons(func_f1(cons(car(deref(ptail)), lists),