Re: master d0c77a1: Remove some assumptions about timestamp format

[Paul Eggert <eggert@cs.ucla.edu>]

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Michael Albinus wrote:
> Shouldn't this be `time-equal-p', as we have already `time-less-p'?

Thanks, as a Scheme refugee I never can remember which predicates should end in 
"-p" vs "p" vs nothing. I installed the attached.

> Tramp (and other functions) must check, whether a given time value
> is the "don't know" value. Therefore,
> 
> (time-equal time-value 0.0e+NaN)
> 
> must return t, if time-value is a NaN. And what if either value is a
> float infinity?

It appears that NaN isn't what Tramp wants. As a time value, NaN should work 
like floating-point NaN does; it should never compare numerically equal to 
anything, not even to itself (anything else would lead to even more confusion 
than what we already have :-). I hope that my other suggestion for Tramp 
suffices, so that we don't need to worry about what happens with NaNs in 
comparisons.

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From 857c2c271080ef62e57128f531cee6e974ca28fb Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 28 Sep 2018 10:32:41 -0700
Subject: [PATCH] Rename time-equal to time-equal-p

This is for consistency with time-less-p.
* doc/lispref/os.texi (Time Calculations), etc/NEWS:
* src/editfns.c (Ftime_equal_p, syms_of_editfns):
* test/lisp/emacs-lisp/timer-tests.el (timer-test-multiple-of-time):
Rename.
---
 doc/lispref/os.texi                 | 2 +-
 etc/NEWS                            | 2 +-
 src/editfns.c                       | 4 ++--
 test/lisp/emacs-lisp/timer-tests.el | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi
index 400e6bb45c..8ce5a5ed6d 100644
--- a/doc/lispref/os.texi
+++ b/doc/lispref/os.texi
@@ -1739,7 +1739,7 @@ Time Calculations
 The result is @code{nil} if either argument is a NaN.
 @end defun
 
-@defun time-equal t1 t2
+@defun time-equal-p t1 t2
 This returns @code{t} if @var{t1} and @var{t2} are equal time values.
 The result is @code{nil} if either argument is a NaN.
 @end defun
diff --git a/etc/NEWS b/etc/NEWS
index 4dd4260b29..e6508eb60b 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -957,7 +957,7 @@ infinities and NaNs too, and propagate them or return nil like
 floating-point operators do.
 
 +++
-** New function 'time-equal' compares time values for equality.
+** New function 'time-equal-p' compares time values for equality.
 
 ** define-minor-mode automatically documents the meaning of ARG.
 
diff --git a/src/editfns.c b/src/editfns.c
index acd80bbf31..daea746387 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1676,7 +1676,7 @@ See `current-time-string' for the various forms of a time value.  */)
   return time_cmp (t1, t2) < 0 ? Qt : Qnil;
 }
 
-DEFUN ("time-equal", Ftime_equal, Stime_equal, 2, 2, 0,
+DEFUN ("time-equal-p", Ftime_equal_p, Stime_equal_p, 2, 2, 0,
        doc: /* Return non-nil if T1 and T2 are equal time values.  */)
   (Lisp_Object t1, Lisp_Object t2)
 {
@@ -5765,7 +5765,7 @@ it to be non-nil.  */);
   defsubr (&Scurrent_time);
   defsubr (&Stime_add);
   defsubr (&Stime_subtract);
-  defsubr (&Stime_equal);
+  defsubr (&Stime_equal_p);
   defsubr (&Stime_less_p);
   defsubr (&Sget_internal_run_time);
   defsubr (&Sformat_time_string);
diff --git a/test/lisp/emacs-lisp/timer-tests.el b/test/lisp/emacs-lisp/timer-tests.el
index 0e40cdf442..c5971ee768 100644
--- a/test/lisp/emacs-lisp/timer-tests.el
+++ b/test/lisp/emacs-lisp/timer-tests.el
@@ -40,7 +40,7 @@
       (should (debug-timer-check)) t))
 
 (ert-deftest timer-test-multiple-of-time ()
-  (should (time-equal
+  (should (time-equal-p
 	   (timer-next-integral-multiple-of-time '(0 0 0 1) (1+ (ash 1 53)))
 	   (list (ash 1 (- 53 16)) 1))))
 
-- 
2.17.1