Fix dynamic interface implementation.

[gob-dx.git] / src / main.c

diff --git a/src/main.c b/src/main.c
index 424f12c0fcfd48584e88a4e571d1fe0fb9329ee6..6a0c7911cadee6726195ce40eb05754cb288b28b 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
  * Copyright (C) 1999,2000 the Free Software Foundation.
  * Copyright (C) 2000 Eazel, Inc.
  * Copyright (C) 2001-2011 George (Jiri) Lebl
+ * Copyright © 2019-2020 Nick Bowler
  *
  * Author: George (Jiri) Lebl
  *
@@ -1129,20 +1130,46 @@ add_interfaces (void)
 static void
 add_dynamic_interfaces(void)
 {
-       GList *li;
-       for (li = ((Class *)class)->interfaces;
-            li != NULL;
-            li = li ->next) {
-               char *name = replace_sep (li->data, '_');
-               char *type = make_pre_macro (li->data, "TYPE");
+       GList *li = ((Class *)class)->interfaces;
 
-               out_printf(out,
-                          "\t\tg_type_module_add_interface(\n"
-                          "\t\t\ttype_module,\n"
-                          "\t\t\t%s_type_id,\n"
-                          "\t\t\t%s,\n"
-                          "\t\t\t&%s_info);\n",
-                          funcbase, type, name);
+       if (li) {
+               /*
+                * Hack to work around bug in g_type_module_add_interface,
+                * which will fail to add an interface to types that derive
+                * from something that also implements the same interface.
+                *
+                * The actual GType system does not have any such problem,
+                * and the GTypeModule implementation details relied upon
+                * here have not changed once since the feature was first
+                * implemented almost 20 years ago.
+                */
+               out_printf(out, "\t\tstruct _ModuleInterfaceInfo {\n"
+                               "\t\t\tgboolean loaded;\n"
+                               "\t\t\tGType instance_type;\n"
+                               "\t\t\tGType interface_type;\n"
+                               "\t\t\tGInterfaceInfo info;\n"
+                               "\t\t} *modinfo;\n");
+       }
+
+       for (; li; li = li->next) {
+               char *name = replace_sep(li->data, '_');
+               char *type = make_pre_macro(li->data, "TYPE");
+
+               out_printf(out, "\n"
+                               "\t\tmodinfo = g_malloc(sizeof *modinfo);\n"
+                               "\t\tmodinfo->loaded = TRUE;\n"
+                               "\t\tmodinfo->instance_type = %s_type_id;\n"
+                               "\t\tmodinfo->interface_type = %s;\n"
+                               "\t\tmodinfo->info = %s_info;\n"
+                               "\t\tg_type_add_interface_dynamic\n"
+                               "\t\t\t( modinfo->instance_type\n"
+                               "\t\t\t, modinfo->interface_type\n"
+                               "\t\t\t, G_TYPE_PLUGIN(type_module)\n"
+                               "\t\t\t);\n"
+                               "\t\ttype_module->interface_infos = g_slist_prepend\n"
+                               "\t\t\t( type_module->interface_infos\n"
+                               "\t\t\t, modinfo\n"
+                               "\t\t\t);\n", funcbase, type, name);
 
                g_free(type);
                g_free(name);