[glib] Clarify type transformability and comparability

[Matthias Clasen <matthiasc src gnome org>]

commit deb8a9325b2f3c82f92746583baa7bd2a6552bd1
Author: A. Walton <awalton gnome org>
Date:   Thu Aug 29 23:33:58 2013 -0700

    Clarify type transformability and comparability
    
    If two GValues are transformable, it implies they are compatible,
    so you do not need to check for compatibility yourself. Bump the
    documentation to reflect this fact.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707111

 gobject/gvalue.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/gobject/gvalue.c b/gobject/gvalue.c
index 280969e..ee40842 100644
--- a/gobject/gvalue.c
+++ b/gobject/gvalue.c
@@ -466,7 +466,9 @@ g_value_register_transform_func (GType           src_type,
  * @dest_type: Target type.
  *
  * Check whether g_value_transform() is able to transform values
- * of type @src_type into values of type @dest_type.
+ * of type @src_type into values of type @dest_type. Note that for
+ * the types to be transformable, they must be compatible and a
+ * transform function must be registered.
  *
  * Returns: %TRUE if the transformation is possible, %FALSE otherwise.
  */