Re: [PATCH] up_to_date_p: treat equal mtime as outdated.

    Probably best to leave it, as is, and mark it as known-to-be-unused at
    least via comment.

How does the text below look for an explanation?

(By the way, I noticed that FileUtils.pm, unlike the other *.pm in
lib/Automake, doesn't have an =over 4 ... =back around all the other
items, causing pod2text to complain. I'll fix that too unless there is
some magical reason for it.)

--- a/lib/Automake/FileUtils.pm
+++ b/lib/Automake/FileUtils.pm
@@ -181,7 +181,20 @@ sub update_file ($$;$)
 
 =item C<up_to_date_p ($file, @dep)>
 
-Is C<$file> more recent than C<@dep>?
+Is C<$file> strictly more recent than C<@dep>?
+If mtimes are equal, returns true.
+
+This function is not used anywhere in Automake.  Where it is used is in
+C<autom4te>, which is part of Autoconf.  And its use there poses a
+problem with respect to subsecond timestamps, as discussed at
+L<https://lists.gnu.org/archive/html/automake-patches/2020-04/msg00000.html>
+(thread continues into May).  The best approach seems to be to leave this
+function alone, and have C<autom4te> use a different test, one which is
+not part of Automake.
+
+Although we would like to remove this function from Automake, since it's
+not used, that would break older versions of Autoconf, which seems
+gratuitious. So we leave it, unchanged.
 
 =cut
 

compile finished at Sat May  9 18:09:15 2020