add missing _has() methods for capability fields

Author: dwrensha

capnpc/src/codegen.rs

@@ -1348,6 +1348,7 @@ fn generate_haser(
             | type_::Data(())
             | type_::List(_)
             | type_::Struct(_)
+            | type_::Interface(_)
             | type_::AnyPointer(_) => {
                 if is_reader {
                     interior.push(Line(format!(

capnpc/test/test.capnp

@@ -129,7 +129,7 @@ struct TestAllTypes {
   dataField      @13 : Data;
   structField    @14 : TestAllTypes;
   enumField      @15 : TestEnum;
-  interfaceField @16 : Void;  # TODO
+  interfaceField @16 : EmptyInterface;
 
   voidList      @17 : List(Void);
   boolList      @18 : List(Bool);
@@ -147,7 +147,7 @@ struct TestAllTypes {
   dataList      @30 : List(Data);
   structList    @31 : List(TestAllTypes);
   enumList      @32 : List(TestEnum);
-  interfaceList @33 : List(Void);  # TODO
+  interfaceList @33 : List(EmptyInterface);
 }
 
 struct TestDefaults {

capnpc/test/test_util.rs

@@ -199,6 +199,7 @@ check_test_message_impl(($mod:ident::$typ:ident) => (
                                                                 .get_text_field().unwrap());
                 }
                 assert!(Ok(TestEnum::Baz) == sub_reader.reborrow().get_enum_field());
+                assert_eq!(false, sub_reader.reborrow().has_interface_field());
                 assert_eq!(3, sub_reader.reborrow().get_void_list().unwrap().len());
 
                 {