We'd need to run vapigen on the Totem GIR to generate a VAPI file for the plugins. Apart from that, libpeas will have all the Vala support we need once bug #622664 is fixed.

Created attachment 176497 [details] [review]
re-add the sample vala plugin

I'm using the gir directly from vala, generating the vapi could give a nicer experience (e.g. it won't be blocked by things like bug 635287), but it's more work so unless there is a real problem with using the gir, I'd prefer not to generate a vapi for now)

Doesn't seem to quite work.

Replacing the gtk+-3.0 with Gtk-3.0 (so it uses the GIR for GTK+ rather than the vapi) makes it go a bit further:

Gtk-3.0.gir:19093.7-19093.6: error: `ContainerClass' already contains a definition for `handle_border_width'
      </method>
      
Gtk-3.0.gir:18849.7-18849.6: note: previous definition of `handle_border_width' was here
      </field>
      
Compilation failed: 1 error(s), 0 warning(s)
make: *** [libsample_vala_la_vala.stamp] Error 1

Using gtk+-3.0 as you did means that it'll try to load both the VAPI and the GIR file for GTK+ (as Totem requires the Gtk-3.0 GIR file) and will fail horribly with redefined methods and property names.

I'll try regenerating the GIR file.

I would also prefer that you did this as two separate commits, one reverting the commit that removed the sample-vala plugin, and one that made the necessary changes to make it compile.

This change is also necessary to enable Vala by default:
@@ -324,7 +324,7 @@ AC_MSG_CHECKING([whether Vala plugin support is requested])
 AC_ARG_ENABLE([vala],
        AS_HELP_STRING([--enable-vala],[Enable Vala plugin support]),
        [enable_vala=$enableval],
-       [enable_vala=no])
+       [enable_vala=auto])

Fixed in a single commit with the changes mentioned above.