Glib: Use callback functions with C linkageglibmm-2-76

* gio/src/cancellable.ccg: Add TODO comment.
* glib/glibmm/class.cc: Call custom_class_base_finalize_function() and
custom_class_init_function() via local functions with C linkage.
* glib/glibmm/extraclassinit.h: Point out in the class documentation that
the class init and instance init functions shall have C linkage.
* glib/glibmm/main.[cc|h]: Call prepare_vfunc(), check_vfunc() and
dispatch_vfunc() via local functions with C linkage.
* glib/glibmm/objectbase.cc: Call destroy_notify_callback()
via a local function with C linkage.
* glib/glibmm/propertyproxy_base.cc: Call PropertyProxyConnectionNode::
callback() and destroy_notify_handler() via local functions with C linkage.
* glib/glibmm/signalproxy.cc: Call SignalProxyNormal::slot0_void_callback()
and SignalProxyConnectionNode::destroy_notify_handler() via local functions
with C linkage.
* glib/src/binding.ccg: Add extern "C".
* glib/src/bytearray.ccg: Add a TODO comment.
* glib/src/markup.ccg: Call functions in the vfunc table via local
functions with C linkage.
* glib/src/optioncontext.ccg: Add extern "C".
* glib/src/optiongroup.ccg: Call post_parse_callback() and
option_arg_callback() via local functions with C linkage.

Part of issue #1

1 files changed, 29 insertions, 2 deletions

diff --git a/glib/glibmm/class.cc b/glib/glibmm/class.cc
index 31f92c61..5344f381 100644
--- a/glib/glibmm/class.cc
+++ b/glib/glibmm/class.cc
@@ -21,6 +21,30 @@
 #include <glibmm/interface.h>
 #include <glibmm/private/interface_p.h>
 
+namespace
+{
+// C++ linkage
+using BaseFinalizeFuncType = void (*)(void*);
+using ClassInitFuncType = void (*)(void*, void*);
+
+BaseFinalizeFuncType p_custom_class_base_finalize_function;
+ClassInitFuncType p_custom_class_init_function;
+
+extern "C"
+{
+// From functions with C linkage, to private static member functions with C++ linkage
+static void Class_custom_class_base_finalize_function(void* g_class)
+{
+  p_custom_class_base_finalize_function(g_class);
+}
+
+static void Class_custom_class_init_function(void* g_class, void* class_data)
+{
+  p_custom_class_init_function(g_class, class_data);
+}
+} // extern "C"
+} // anonymous namespace
+
 namespace Glib
 {
 
@@ -128,11 +152,14 @@ Class::clone_custom_type(
       all_class_init_funcs->insert(all_class_init_funcs->end(),
         class_init_funcs->begin(), class_init_funcs->end());
 
+    p_custom_class_base_finalize_function = &Class::custom_class_base_finalize_function;
+    p_custom_class_init_function = &Class::custom_class_init_function;
+
     const GTypeInfo derived_info = {
       class_size,
       nullptr, // base_init
-      &Class::custom_class_base_finalize_function, // base_finalize
-      &Class::custom_class_init_function,
+      &Class_custom_class_base_finalize_function, // base_finalize
+      &Class_custom_class_init_function,
       nullptr, // class_finalize
       all_class_init_funcs, // class_data
       instance_size,