Subject: Re: [bug#67670] [PATCH] Revise tests for file mtime resolution again.

From: Karl Berry <[email-masked]>
Date: Mon, 25 Dec 2023 16:39:00 -0700

One more follow-up on this. As we saw from the bug reports for the 1.16i
pretest (67894, 67918), the random parallelization failures were back
after this, when autom4te did not support subsecond-mtimes.

As far as I could tell, what was needed was to add
  am_cv_sleep_fractional_seconds=false
which is what the previous sanity.m4 code did when a non-subsecond
autom4te was detected.

With this, my make (dist)check then started reliably succeeding again.
(Though vastly more slowly, of course.)

--- a/t/ax/test-defs.in
+++ b/t/ax/test-defs.in
@@ -193,6 +193,10 @@ case $MTIME_RESOLUTION in
       :
     else
       MTIME_RESOLUTION=1
+      # we must not sleep for fractional seconds when autom4te does not
+      # support subsecond-mtimes, even when sleep supports it. See bug#67670.
+      am_cv_sleep_fractional_seconds=false
+      export am_cv_sleep_fractional_seconds
     fi
   ;;
 esac

My actual commit has a lot of related verbiage, but that additional
assignment is the only substantive change.

Nothing to do here (comments welcome of course), but just wanted to get
this into the bug archive ... --thanks, karl.