Handle weird cases like (ceil 0 0.0)

* src/floatfns.c (double_integer_scale): Distinguish Inf from NaN.
(rounding_driver): Handle (ceil 0 0.0) and (ceil 0 1.0e+INF).
* test/src/floatfns-tests.el (special-round): Add tests for
weird cases like this.

Avoid crash with (floor 0 0.0)
* src/floatfns.c (rounding_driver): Signal an arithmetic
error if divisor is 0.0 or -0.0, instead of crashing.

1 files changed, 11 insertions, 13 deletions

diff --git a/test/src/floatfns-tests.el b/test/src/floatfns-tests.el
index 7f1d4691bf0..0eef3de75f7 100644
--- a/test/src/floatfns-tests.el
+++ b/test/src/floatfns-tests.el
@@ -106,19 +106,17 @@
                           (zerop (% (round n d) 2)))))))))))
 
 (ert-deftest special-round ()
-  (let ((ns '(-1e+INF 1e+INF -1 1 -1e+NaN 1e+NaN)))
-    (dolist (n ns)
-      (unless (<= (abs n) 1)
-        (should-error (ceiling n))
-        (should-error (floor n))
-        (should-error (round n))
-        (should-error (truncate n)))
-      (dolist (d ns)
-        (unless (<= (abs (/ n d)) 1)
-          (should-error (ceiling n d))
-          (should-error (floor n d))
-          (should-error (round n d))
-          (should-error (truncate n d)))))))
+  (dolist (f '(ceiling floor round truncate))
+    (let ((ns '(-1e+INF 1e+INF -1 -0.0 0.0 0 1 -1e+NaN 1e+NaN)))
+      (dolist (n ns)
+        (if (not (<= (abs n) 1))
+            (should-error (funcall f n))
+          (should (= n (funcall f n)))
+          (dolist (d '(-1e+INF 1e+INF))
+            (should (eq 0 (funcall f n d)))))
+        (dolist (d ns)
+          (when (or (zerop d) (= (abs n) 1e+INF) (not (= n n)) (not (= d d)))
+            (should-error (funcall f n d))))))))
 
 (ert-deftest big-round ()
   (should (= (floor 54043195528445955 3)