From a1e82aff0fd842b0f09e2cd166560dfda725ba13 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 9 Apr 2023 11:41:57 -0700
Subject: Improve year2038, largefile option processing
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* lib/autoconf/specific.m4 (_AC_SYS_YEAR2038_PROBE)
(_AC_SYS_YEAR2038_ENABLE, _AC_SYS_YEAR2038_OPT_IN)
(AC_SYS_YEAR2038, _AC_SYS_LARGEFILE_PROBE)
(_AC_SYS_LARGEFILE_ENABLE): Do not use enable_largefile to record
whether largefile is required, as ‘./configure
--disable-largefile’ sets enable_largefile=no even if largefile is
required and this disables largefile.  Instead, use a separate
shell variable ac_largefile_required and test it as well.
Similarly for enable_year2038.
(_AC_SYS_LARGEFILE_ENABLE): Omit --disable-largefile help string
if year2038 is required, since largefile is a prereq for year2038.
---
 lib/autoconf/specific.m4 | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/lib/autoconf/specific.m4 b/lib/autoconf/specific.m4
index 5dc00695..1a3f4a65 100644
--- a/lib/autoconf/specific.m4
+++ b/lib/autoconf/specific.m4
@@ -155,10 +155,10 @@ AS_CASE([$ac_cv_sys_year2038_opts],
   ["none needed"], [],
   ["support not detected"],
     [ac_have_year2038=no
-     AS_CASE([$enable_year2038],
-      [required],
+     AS_CASE([$ac_year2038_required,$enable_year2038],
+      [yes,*],
         [AC_MSG_FAILURE([support for timestamps after Jan 2038 is required])],
-      [yes],
+      [*,yes],
         [# If we're not cross compiling and 'touch' works with a large
         # timestamp, then we can presume the system supports wider time_t
         # *somehow* and we just weren't able to detect it.  One common
@@ -209,10 +209,12 @@ AS_CASE([$ac_cv_sys_year2038_opts],
 m4_define([_AC_SYS_YEAR2038_ENABLE],
 [m4_divert_text([DEFAULTS],
   m4_provide_if([AC_SYS_YEAR2038_REQUIRED],
-    [enable_year2038=required],
+    [ac_year2038_required=yes],
+    [ac_year2038_required=no]))dnl
+m4_divert_text([DEFAULTS],
   m4_provide_if([AC_SYS_YEAR2038],
     [enable_year2038=yes],
-    [enable_year2038=no])))]dnl
+    [enable_year2038=no]))]dnl
 [m4_provide_if([AC_SYS_YEAR2038_REQUIRED], [],
 [AC_ARG_ENABLE([year2038],
   m4_provide_if([AC_SYS_YEAR2038],
@@ -231,7 +233,8 @@ m4_define([_AC_SYS_YEAR2038_ENABLE],
 # documented macro.
 AC_DEFUN([_AC_SYS_YEAR2038_OPT_IN],
 [m4_provide_if([_AC_SYS_YEAR2038_PROBE], [], [dnl
-  AS_IF([test "$enable_year2038" != no], [_AC_SYS_YEAR2038_PROBE])
+  AS_IF([test "$ac_year2038_required,$enable_year2038" != no,no],
+    [_AC_SYS_YEAR2038_PROBE])
   AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])
 ])])
 
@@ -244,7 +247,8 @@ AC_DEFUN([AC_SYS_YEAR2038],
 [m4_provide_if([AC_SYS_LARGEFILE_REQUIRED], [],
   [AC_REQUIRE([AC_SYS_LARGEFILE])])]dnl
 [m4_provide_if([_AC_SYS_YEAR2038_PROBE], [], [dnl
-  AS_IF([test "$enable_year2038" != no], [_AC_SYS_YEAR2038_PROBE])
+  AS_IF([test "$ac_year2038_required,$enable_year2038" != no,no],
+    [_AC_SYS_YEAR2038_PROBE])
   AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])
 ])])
 
@@ -326,7 +330,7 @@ AS_CASE([$ac_cv_sys_largefile_opts],
   ["none needed"], [],
   ["support not detected"],
     [ac_have_largefile=no
-     AS_IF([test $enable_largefile = required],
+     AS_IF([test $ac_largefile_required,$ac_year2038_required != no,no],
        [AC_MSG_FAILURE([support for large files is required])])],
 
   ["-D_FILE_OFFSET_BITS=64"],
@@ -358,11 +362,15 @@ _AC_SYS_YEAR2038_OPT_IN
 m4_define([_AC_SYS_LARGEFILE_ENABLE],
 [m4_divert_text([DEFAULTS],
   m4_provide_if([AC_SYS_LARGEFILE_REQUIRED],
-    [enable_largefile=required],
-    [enable_largefile=yes]))]dnl
+    [ac_largefile_required=yes],
+    [ac_largefile_required=no]))dnl
+m4_divert_text([DEFAULTS],
+  [enable_largefile=yes])]dnl
 [m4_provide_if([AC_SYS_LARGEFILE_REQUIRED], [],
-[AC_ARG_ENABLE([largefile],
-  [AS_HELP_STRING([--disable-largefile], [omit support for large files])])])])
+   [m4_provide_if([AC_SYS_YEAR2038_REQUIRED], [],
+      [AC_ARG_ENABLE([largefile],
+         [AS_HELP_STRING([--disable-largefile],
+	    [omit support for large files])])])])])
 
 # AC_SYS_LARGEFILE
 # ----------------
@@ -377,7 +385,8 @@ m4_define([_AC_SYS_LARGEFILE_ENABLE],
 # large files; see also AC_SYS_LARGEFILE_REQUIRED.
 AC_DEFUN([AC_SYS_LARGEFILE],
 [m4_provide_if([_AC_SYS_LARGEFILE_PROBE], [], [dnl
-  AS_IF([test "$enable_largefile" != no], [_AC_SYS_LARGEFILE_PROBE])
+  AS_IF([test "$ac_largefile_required,$enable_largefile,$ac_year2038_required" != no,no,no],
+    [_AC_SYS_LARGEFILE_PROBE])
   AC_CONFIG_COMMANDS_PRE([_AC_SYS_LARGEFILE_ENABLE])
 ])])
 
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