split, split*: fix poor behavior for beyond-length indices.

* lib.c (split_func, split_Star_func): Ignore indices greater
than the length of the sequence, the same as negative indices
are ignored which don't become nonnegative after adding the
length.

* tests/012/seq.tl: Fix questionable test cases, which
now confirm the right behavior.

1 files changed, 8 insertions, 6 deletions

diff --git a/lib.c b/lib.c
index 4e21108b..eb4c9b8c 100644
--- a/lib.c
+++ b/lib.c
@@ -4240,19 +4240,20 @@ static val partition_func(val base, val lcons)
 static val split_func(val base, val lcons)
 {
   us_cons_bind (seq, indices, lcons);
-  val len = nil;
+  val le = nil;
 
   for (;;) {
     if (iter_more(indices)) {
+      val len = if3(le, le, le = length(seq));
       val raw_index = iter_item(indices);
       val index = if3((!opt_compat || opt_compat > 170) && minusp(raw_index),
-                      plus(raw_index, if3(len, len, len = length(seq))),
+                      plus(raw_index, len),
                       raw_index);
       val index_rebased = minus(index, base);
 
       indices = iter_step(indices);
 
-      if (minusp(index_rebased)) {
+      if (minusp(index_rebased) || gt(index_rebased, len)) {
         continue;
       } else {
         val first = sub(seq, zero, index_rebased);
@@ -4282,19 +4283,20 @@ static val split_func(val base, val lcons)
 static val split_star_func(val base, val lcons)
 {
   us_cons_bind (seq, indices, lcons);
-  val len = nil;
+  val le = nil;
 
   for (;;) {
     if (iter_more(indices)) {
+      val len = if3(le, le, le = length(seq));
       val raw_index = iter_item(indices);
       val index = if3((!opt_compat || opt_compat > 170) && minusp(raw_index),
-                      plus(raw_index, if3(len, len, len = length(seq))),
+                      plus(raw_index, len),
                       raw_index);
       val index_rebased = minus(index, base);
 
       indices = iter_step(indices);
 
-      if (minusp(index_rebased)) {
+      if (minusp(index_rebased) || gt(index_rebased, len)) {
         continue;
       } else {
         val first = sub(seq, zero, index_rebased);