[gdk-pixbuf] init: Improve error message for missing cache file

[Benjamin Otte <otte src gnome org>]

commit 463e97de9a0339a60be8da506ddff156619bd69b
Author: John Spencer <maillist-gtk barfooze de>
Date:   Sat Nov 3 17:43:21 2012 +0100

    init: Improve error message for missing cache file
    
    People on IRC were rightly pointing out that the fix is easy once you
    know it. So why wouldn't gdk-pixbuf print it?
    
    Also reinstate the warning. The pixdata module is always loaded so we
    need to expect one existing module.

 gdk-pixbuf/gdk-pixbuf-io.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/gdk-pixbuf/gdk-pixbuf-io.c b/gdk-pixbuf/gdk-pixbuf-io.c
index 411ceb6..59bc1ee 100644
--- a/gdk-pixbuf/gdk-pixbuf-io.c
+++ b/gdk-pixbuf/gdk-pixbuf-io.c
@@ -512,9 +512,13 @@ gdk_pixbuf_io_init (void)
         channel = g_io_channel_new_file (filename, "r",  &error);
         if (!channel) {
                 /* Don't bother warning if we have some built-in loaders */
-                if (file_formats == NULL)
-                        g_warning ("Cannot open pixbuf loader module file '%s': %s",
-                                   filename, error->message);
+                if (file_formats == NULL || file_formats->next == NULL)
+                        g_warning ("Cannot open pixbuf loader module file '%s': %s\n\n"
+                                   "This likely means that your installation is broken.\n"
+                                   "Try running the command\n"
+                                   "  gdk-pixbuf-query-loaders > %s\n"
+                                   "to make things work again for the time being.",
+                                   filename, error->message, filename);
                 g_string_free (tmp_buf, TRUE);
                 g_free (filename);
                 return;