[gjs: 1/3] object: Throw when trying to instantiate an abstract type

[Philip Chimento <pchimento src gnome org>]

commit 92e7dc274ade246bd9b632e37defe71cd15926c4
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Apr 26 21:58:21 2019 +0000

    object: Throw when trying to instantiate an abstract type
    
    Trying to instantiate an abstract type is a fatal error on the
    gobject-level. While this is undoubtably an error, we can handle
    the case more gracefully by detecting the condition and throwing
    an exception instead.
    
    https://gitlab.gnome.org/GNOME/gjs/merge_requests/290

 gi/object.cpp | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gi/object.cpp b/gi/object.cpp
index 1a9cf50c..ad9ee655 100644
--- a/gi/object.cpp
+++ b/gi/object.cpp
@@ -1464,6 +1464,12 @@ ObjectInstance::init_impl(JSContext              *context,
     if (!m_proto->props_to_g_parameters(context, args, &names, &values))
         return false;
 
+    if (G_TYPE_IS_ABSTRACT(gtype())) {
+        gjs_throw(context,
+                  "Cannot instantiate abstract type %s", g_type_name(gtype()));
+        return false;
+    }
+
     /* Mark this object in the construction stack, it
        will be popped in gjs_object_custom_init() later
        down.