master 7c17bd2a6d 1/2: New time-equal-p test

[Paul Eggert]

branch: master
commit 7c17bd2a6d8d7cf710051cd7ca00260c1e557609
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    New time-equal-p test
    
    * test/src/timefns-tests.el (time-equal-p-NaN-NaN): New test.
---
 src/timefns.c             | 3 ++-
 test/src/timefns-tests.el | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/timefns.c b/src/timefns.c
index 6cfb787af8..b061be0a78 100644
--- a/src/timefns.c
+++ b/src/timefns.c
@@ -1221,7 +1221,8 @@ time_cmp (Lisp_Object a, Lisp_Object b)
 
   /* Compare nil to nil correctly, and handle other eq values quicker
      while we're at it.  Compare here rather than earlier, to handle
-     NaNs and check formats.  */
+     NaNs.  This means (time-equal-p X X) does not signal an error if
+     X is not a valid time value, but that's OK.  */
   if (EQ (a, b))
     return 0;
 
diff --git a/test/src/timefns-tests.el b/test/src/timefns-tests.el
index 1b49e0622f..e7c464472d 100644
--- a/test/src/timefns-tests.el
+++ b/test/src/timefns-tests.el
@@ -169,6 +169,10 @@ a fixed place on the right and are padded on the left."
 (ert-deftest time-equal-p-nil-nil ()
   (should (time-equal-p nil nil)))
 
+(ert-deftest time-equal-p-NaN-NaN ()
+  (let ((x 0.0e+NaN))
+    (should (not (time-equal-p x x)))))
+
 (ert-deftest time-arith-tests ()
   (let ((time-values (list 0 -1 1 0.0 -0.0 -1.0 1.0
                           most-negative-fixnum most-positive-fixnum