Thanks, good catch. 'altzone' too. These variables were
changed from 'long' to 'time_t' back in 1987, but (as you note)
that's incompatible with common practice on the rare hosts where
time_t is not 'long', so we should change them back, as follows
(pushed into the experimental repository on Github):
>From 6e770de05814b2fec6bc54bc0bace0d7f431fa04 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 24 Sep 2013 18:42:34 -0700
Subject: [PATCH] Port to x32 by fixing type incompatibility with POSIX.
Reported by Elliott Hughes in
<http://mm.icann.org/pipermail/tz/2013-September/020376.html>.
* localtime.c (timezone) [USG_COMPAT]:
(altzone) [ALTZONE]: Now long, not time_t.
* strftime.c (_fmt): Use long, not int, to store timezone.
* NEWS: Document this.
---
NEWS | 10 ++++++++++
localtime.c | 4 ++--
strftime.c | 2 +-
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/NEWS b/NEWS
index c1e8ba3..355aea6 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,16 @@ Unreleased, experimental changes
Palestine will fall back at 00:00, not 01:00. (Thanks to Steffen Thorsen.)
+ Changes affecting API
+
+ The types of the global variables 'timezone' and 'altzone' (if present)
+ have been changed back to 'long'. This is required for 'timezone'
+ by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
+ These variables were originally 'long' in the tz code, but were
+ mistakenly changed to 'time_t' in 1987; nobody reported the
+ incompatibility until now. The difference matters on x32, where
+ 'long' is 32 bits and 'time_t' is 64. (Thanks to Elliott Hughes.)
+
Changes affecting the build procedure
Avoid long strings in leapseconds.awk to work around a mawk bug.
diff --git a/localtime.c b/localtime.c
index f2004b5..8c8edf3 100644
--- a/localtime.c
+++ b/localtime.c
@@ -215,12 +215,12 @@ char * tzname[2] = {
static struct tm tm;
#ifdef USG_COMPAT
-time_t timezone = 0;
+long timezone = 0;
int daylight = 0;
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
-time_t altzone = 0;
+long altzone = 0;
#endif /* defined ALTZONE */
static int_fast32_t
diff --git a/strftime.c b/strftime.c
index aba3d33..c324f1b 100644
--- a/strftime.c
+++ b/strftime.c
@@ -492,7 +492,7 @@ label:
continue;
case 'z':
{
- int diff;
+ long diff;
char const * sign;
if (t->tm_isdst < 0)
--
1.8.1.2