https://github.com/libsdl-org/autoconf/commit/e8c2d79ec42c70b6e4fa282bc0c024bf42f0585f
From e8c2d79ec42c70b6e4fa282bc0c024bf42f0585f Mon Sep 17 00:00:00 2001
From: Paul Eggert <[EMAIL REDACTED]>
Date: Tue, 31 Aug 2021 17:34:46 -0700
Subject: [PATCH] Add commentary for Time::HiRes patches
---
NEWS | 10 ++++++++++
THANKS | 1 +
lib/Autom4te/FileUtils.pm | 5 +++++
3 files changed, 16 insertions(+)
diff --git a/NEWS b/NEWS
index 3c50ff8a..818ba1f4 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,10 @@ GNU Autoconf NEWS - User visible changes.
* Noteworthy changes in release ?.? (????-??-??) [?]
** Backward incompatibilities
+
+*** Autoconf now requires perl 5.8 (2002) or later.
+ Generated 'configure' scripts continue to run without perl.
+
** New features
** Obsolete features and new warnings
@@ -15,6 +19,12 @@ GNU Autoconf NEWS - User visible changes.
** Notable bug fixes
+*** Autoconf caches now use finer-grained timestamps.
+
+ Autoconf now uses floating-point numbers rather than integers to
+ represent cache file timestamps, thus avoiding some problems where
+ automake incorrectly decides not to regenerate stale caches.
+
* Noteworthy changes in release 2.71 (2021-01-28) [stable]
** Bug fixes, including:
diff --git a/THANKS b/THANKS
index 6ebe7dbd..ec89a9f7 100644
--- a/THANKS
+++ b/THANKS
@@ -33,6 +33,7 @@ Anaïs Bouque anais.bouque@fr.thalesgroup.com
Anders Kaseorg andersk@MIT.EDU
Andreas Buening andreas.buening@nexgo.de
Andreas Jaeger aj@suse.de
+Andreas K. Hüttel dilfridge@gentoo.org
Andreas Schott schott@rzg.mpg.de
Andreas Schwab schwab@linux-m68k.org
Andreas Waechter andreasw@watson.ibm.com
diff --git a/lib/Autom4te/FileUtils.pm b/lib/Autom4te/FileUtils.pm
index 27a5fd91..60b66cd6 100644
--- a/lib/Autom4te/FileUtils.pm
+++ b/lib/Autom4te/FileUtils.pm
@@ -119,6 +119,11 @@ sub mtime ($)
$atime,$mtime,$ctime,$blksize,$blocks) = stat ($file)
or fatal "cannot stat $file: $!";
+ # Unfortunately Time::HiRes converts timestamps to floating-point, and the
+ # rounding error can be several nanoseconds for circa-2021 timestamps.
+ # Perhaps some day Perl will support accurate file timestamps. For now, do
+ # the best we can without going outside Perl.
+
return $mtime;
}