[gnumeric] DATEDIF: fix problem across bogus 1900-02-29.

[Morten Welinder <mortenw src gnome org>]

commit aa5baf3452062647bf0b0de0e237e12f75eaaed0
Author: Morten Welinder <terra gnome org>
Date:   Tue Dec 8 14:26:13 2009 -0500

    DATEDIF: fix problem across bogus 1900-02-29.

 NEWS                        |    1 +
 plugins/fn-date/ChangeLog   |    5 +++++
 plugins/fn-date/functions.c |    7 ++++---
 3 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/NEWS b/NEWS
index b449ec0..c4b9d53 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,7 @@ Morten:
 	* Fix selection problem.  [#601107]
 	* Automate solver testing.
 	* Fix SUMIF problem.  [#603671]
+	* Fix DATEDIF problem across bogus 1900-02-29.  [#599461]
 
 --------------------------------------------------------------------------
 Gnumeric 1.9.16
diff --git a/plugins/fn-date/ChangeLog b/plugins/fn-date/ChangeLog
index 29be780..e8ae5fa 100644
--- a/plugins/fn-date/ChangeLog
+++ b/plugins/fn-date/ChangeLog
@@ -1,3 +1,8 @@
+2009-12-08  Morten Welinder  <terra gnome org>
+
+	* functions.c (gnumeric_datedif): Go via GDate, even for "d" case.
+	Fixes #599461 and a few other things.
+
 2009-11-29  Morten Welinder <terra gnome org>
 
 	* Release 1.9.16
diff --git a/plugins/fn-date/functions.c b/plugins/fn-date/functions.c
index 19de7b4..6e14992 100644
--- a/plugins/fn-date/functions.c
+++ b/plugins/fn-date/functions.c
@@ -323,15 +323,16 @@ gnumeric_datedif (GnmFuncEvalInfo *ei, GnmValue const * const *argv)
 
 	if (date1 > date2)
 		return value_new_error_NUM (ei->pos);
-	if (!strcmp (opt, "d"))
-		return value_new_int (date2 - date1);
 
 	go_date_serial_to_g (&d1, date1, conv);
 	go_date_serial_to_g (&d2, date2, conv);
 	if (!g_date_valid (&d1) || !g_date_valid (&d2))
 		return value_new_error_VALUE (ei->pos);
 
-	if (!strcmp (opt, "m"))
+	if (!strcmp (opt, "d"))
+		return value_new_int (g_date_get_julian (&d2) -
+				      g_date_get_julian (&d1));
+	else if (!strcmp (opt, "m"))
 		return value_new_int (go_date_g_months_between (&d1, &d2));
 	else if (!strcmp (opt, "y"))
 		return value_new_int (go_date_g_years_between (&d1, &d2));