codegen: Fix vfunc signature of delegate-typed property in interface

codegen/valagtypemodule.vala

@@ -2161,6 +2161,8 @@ public class Vala.GTypeModule : GErrorModule {
 						for (int dim = 1; dim <= array_type.rank; dim++) {
 							vdeclarator.add_parameter (new CCodeParameter (get_array_length_cname ("result", dim), length_ctype));
 						}
+					} else if ((prop.property_type is DelegateType) && get_ccode_delegate_target (prop) && ((DelegateType) prop.property_type).delegate_symbol.has_target) {
+						vdeclarator.add_parameter (new CCodeParameter (get_delegate_target_cname ("result"), "gpointer*"));
 					}
 
 					var vdecl = new CCodeDeclaration (creturn_type);
@@ -2184,6 +2186,8 @@ public class Vala.GTypeModule : GErrorModule {
 						for (int dim = 1; dim <= array_type.rank; dim++) {
 							vdeclarator.add_parameter (new CCodeParameter (get_array_length_cname ("value", dim), length_ctype));
 						}
+					} else if ((prop.property_type is DelegateType) && get_ccode_delegate_target (prop) && ((DelegateType) prop.property_type).delegate_symbol.has_target) {
+						vdeclarator.add_parameter (new CCodeParameter (get_delegate_target_cname ("value"), "gpointer"));
 					}
 
 					var vdecl = new CCodeDeclaration ("void");

tests/Makefile.am

@@ -333,6 +333,7 @@ TESTS = \
 	objects/interfaces.vala \
 	objects/interface-generics.vala \
 	objects/interface-property-base-access.vala \
+	objects/interface-property-delegate.vala \
 	objects/interface-virtual-override.vala \
 	objects/methods.vala \
 	objects/paramspec.vala \

tests/objects/interface-property-delegate.vala

@@ -0,0 +1,29 @@
+delegate void FooFunc ();
+
+interface IFoo {
+	public abstract unowned FooFunc prop { get; set; }
+}
+
+class Foo : IFoo {
+	public unowned FooFunc prop { get; set; }
+}
+
+class Bar {
+	public bool reached;
+
+	public Bar () {
+		var foo = new Foo ();
+		foo.prop = bar;
+
+		foo.prop ();
+	}
+
+	void bar () {
+		reached = true;
+	}
+}
+
+void main () {
+	var bar = new Bar ();
+	assert (bar.reached);
+}