[gnumeric] MStyle: check that empty styles' hash values are zero.

[Morten Welinder <mortenw src gnome org>]

commit 605a65b2ae53b996e6f10f5168c1468aeea83e82
Author: Morten Welinder <terra gnome org>
Date:   Tue Jun 16 11:50:10 2009 -0400

    MStyle: check that empty styles' hash values are zero.

 ChangeLog    |    3 +++
 src/mstyle.c |   10 ++++++++++
 2 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 8e51909..8b7495f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2009-06-16  Morten Welinder  <terra gnome org>
 
+	* src/mstyle.c (gnm_style_update): Verify that empty styles have
+	hash values all zero.
+
 	* src/sstest.c (test_insdel_rowcol_names): Explicitly define
 	Print_Area to be whole sheet.  Fixes test again.
 
diff --git a/src/mstyle.c b/src/mstyle.c
index 82dfe33..8a8c9e4 100644
--- a/src/mstyle.c
+++ b/src/mstyle.c
@@ -256,6 +256,16 @@ gnm_style_update (GnmStyle *style)
 	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
 
 	style->hash_key = hash;
+
+	if (G_UNLIKELY (style->set == 0)) {
+		/*
+		 * gnm_style_new and gnm_style_dup both assume that the
+		 * correct hash values (both of them) for the empty style
+		 * is zero.
+		 */
+		g_assert (style->hash_key == 0);
+		g_assert (style->hash_key_xl == 0);
+	}
 }
 
 guint