[vala] girparser: Ensure interfaces have at least one instantiable prerequisite

[Jürg Billeter <juergbi src gnome org>]

commit 65bc5e64725900961ec7a1bd2d670f8fd20241b1
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Wed Jul 21 14:12:20 2010 +0100

    girparser: Ensure interfaces have at least one instantiable prerequisite
    
    When parsing a GIR file, add a prerequisite on GLib.Object to interfaces
    which don't have an instantiable prerequisite specified in the GIR file,
    as g-ir-scanner considers this prerequisite to be implicit.
    
    Fixes bug 624923.

 vala/valagirparser.vala |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/vala/valagirparser.vala b/vala/valagirparser.vala
index 1e2ed82..bf1d33e 100644
--- a/vala/valagirparser.vala
+++ b/vala/valagirparser.vala
@@ -801,6 +801,18 @@ public class Vala.GirParser : CodeVisitor {
 			}
 		}
 
+		// ensure we have at least one instantiable prerequisite (GLib.Object)
+		bool has_instantiable_prereq = false;
+		foreach (DataType prereq in iface.get_prerequisites ()) {
+			if (prereq.data_type is Class) {
+				has_instantiable_prereq = true;
+				break;
+			}
+		}
+
+		if (!has_instantiable_prereq)
+			iface.add_prerequisite (new ObjectType ((ObjectTypeSymbol) glib_ns.scope.lookup ("Object")));
+
 		// virtual method merging
 		foreach (Method m in vmethods) {
 			var symbol = iface.scope.lookup (m.name);