Fix bugs when rounding to bignums

Also, since Emacs historically reported a range error when
rounding operations overflowed, do that consistently for all
bignum overflows.
* doc/lispref/errors.texi (Standard Errors):
* doc/lispref/numbers.texi (Integer Basics): Document range errors.
* src/alloc.c (range_error): Rename from integer_overflow.
All uses changed.
* src/floatfns.c (rounding_driver): When the result of a floating
point rounding operation does not fit into a fixnum, put it
into a bignum instead of always signaling an range error.
* test/src/floatfns-tests.el (divide-extreme-sign):
These tests now return the mathematically-correct answer
instead of signaling an error.
(bignum-round): Check that integers round to themselves.

1 files changed, 8 insertions, 4 deletions

diff --git a/test/src/floatfns-tests.el b/test/src/floatfns-tests.el
index 592efce359d..d41b08f7965 100644
--- a/test/src/floatfns-tests.el
+++ b/test/src/floatfns-tests.el
@@ -20,10 +20,10 @@
 (require 'ert)
 
 (ert-deftest divide-extreme-sign ()
-  (should-error (ceiling most-negative-fixnum -1.0))
-  (should-error (floor most-negative-fixnum -1.0))
-  (should-error (round most-negative-fixnum -1.0))
-  (should-error (truncate most-negative-fixnum -1.0)))
+  (should (= (ceiling most-negative-fixnum -1.0) (- most-negative-fixnum)))
+  (should (= (floor most-negative-fixnum -1.0) (- most-negative-fixnum)))
+  (should (= (round most-negative-fixnum -1.0) (- most-negative-fixnum)))
+  (should (= (truncate most-negative-fixnum -1.0) (- most-negative-fixnum))))
 
 (ert-deftest logb-extreme-fixnum ()
   (should (= (logb most-negative-fixnum) (1+ (logb most-positive-fixnum)))))
@@ -66,6 +66,10 @@
                   (1+ most-positive-fixnum)
                   (* most-positive-fixnum most-positive-fixnum))))
     (dolist (n ns)
+      (should (= n (ceiling n)))
+      (should (= n (floor n)))
+      (should (= n (round n)))
+      (should (= n (truncate n)))
       (dolist (d ns)
         (let ((q (/ n d))
               (r (% n d))