[glib] tests: Fix GDateTime overflow tests on 32-bit architectures

[Philip Withnall <pwithnall src gnome org>]

commit 30fed3b906f3408aa4fc9a7996fa03cf7b940ebe
Author: Philip Withnall <withnall endlessm com>
Date:   Fri Jun 16 12:42:32 2017 +0100

    tests: Fix GDateTime overflow tests on 32-bit architectures
    
    On architectures where sizeof(glong) == 32 bits, there are no problems
    with overflow when constructing a GDateTime from a GTimeVal. Adjust the
    test for this by basing it on the maximum supported tv_sec value it can
    calculate, rather than a fixed ‘known unsupported’ value.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783841

 glib/tests/gdatetime.c |   35 +++++++++++++++++++++--------------
 1 files changed, 21 insertions(+), 14 deletions(-)
---
diff --git a/glib/tests/gdatetime.c b/glib/tests/gdatetime.c
index db04870..3985445 100644
--- a/glib/tests/gdatetime.c
+++ b/glib/tests/gdatetime.c
@@ -401,7 +401,10 @@ find_maximum_supported_tv_sec (void)
 
 /* Check that trying to create a #GDateTime too far in the future reliably
  * fails. With a #GTimeVal, this is subtle, as the tv_usec are added into the
- * calculation part-way through. */
+ * calculation part-way through.
+ *
+ * This varies a bit between 32- and 64-bit architectures, due to the
+ * differences in the size of glong (tv.tv_sec). */
 static void
 test_GDateTime_new_from_timeval_overflow (void)
 {
@@ -410,29 +413,33 @@ test_GDateTime_new_from_timeval_overflow (void)
 
   g_test_bug ("782089");
 
-  tv.tv_sec = G_MAXLONG;
-  tv.tv_usec = 0;
-
-  dt = g_date_time_new_from_timeval_utc (&tv);
-  g_assert_null (dt);
-
-  dt = g_date_time_new_from_timeval_local (&tv);
-  g_assert_null (dt);
-
   tv.tv_sec = find_maximum_supported_tv_sec ();
   tv.tv_usec = G_USEC_PER_SEC - 1;
 
   g_test_message ("Maximum supported GTimeVal.tv_sec = %lu", tv.tv_sec);
 
+  /* Sanity check: do we support the year 2000? */
+  g_assert_cmpint (tv.tv_sec, >=, 946684800);
+
   dt = g_date_time_new_from_timeval_utc (&tv);
   g_assert_nonnull (dt);
   g_date_time_unref (dt);
 
-  tv.tv_sec++;
-  tv.tv_usec = 0;
+  dt = g_date_time_new_from_timeval_local (&tv);
+  g_assert_nonnull (dt);
+  g_date_time_unref (dt);
 
-  dt = g_date_time_new_from_timeval_utc (&tv);
-  g_assert_null (dt);
+  if (tv.tv_sec < G_MAXLONG)
+    {
+      tv.tv_sec++;
+      tv.tv_usec = 0;
+
+      dt = g_date_time_new_from_timeval_utc (&tv);
+      g_assert_null (dt);
+
+      dt = g_date_time_new_from_timeval_local (&tv);
+      g_assert_null (dt);
+    }
 }
 
 static void