Help with GtkBuilder memory leak

[Giovanni Panozzo <giovanni panozzo it>]

I'm trying to identify some memory leaks of my application using 
-fsanitize=address of GCC.

But really I came to a point where all seems to be inside GTK.
Here is my small test program, compile

----- builderleak.c -------------------------------------

#include <gtk/gtk.h>

GtkApplicationWindow *w;

static void
activate (GtkApplication* app,
          gpointer        user_data)
{
        GtkBuilder* b;
        b = gtk_builder_new_from_file("builderleak.glade");
        w = GTK_APPLICATION_WINDOW(gtk_builder_get_object(b, "mainwin"));
        g_object_set(w, "application", app, NULL);

}

int
main (int    argc,
      char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.builderleak", 
G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}
----------------------------------------------
----- builderleak.glade ----------------------
<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.20.0 -->
<interface>
  <requires lib="gtk+" version="3.20"/>
  <object class="GtkApplicationWindow" id="mainwin">
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <child>
      <object class="GtkLabel">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="label" translatable="yes">label</property>
      </object>
    </child>
  </object>
</interface>
--------------------------------------------------

Just compile the above builderleak.c with

gcc `pkg-config --cflags gtk+-3.0` -o builderleak builderleak.c 
`pkg-config --libs gtk+-3.0` -fsanitize=address

[tested on current Arch Linux, with gtk3 3.20.6-1]

And execute it.

When closing the main window, the application will exit, but the address 
sanitizer will shows you a lot of memory leaks of objects allocated by 
libfontconfig.

Here is part of the address sanitizer output:

=================================================================
==14900==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 1280 byte(s) in 2 object(s) allocated from:
    #0 0x7f56220d8120 in __interceptor_realloc 
/build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:59
    #1 0x7f561d86fb9a  (/usr/lib/libfontconfig.so.1+0x1db9a)

Indirect leak of 3168 byte(s) in 99 object(s) allocated from:
    #0 0x7f56220d7d58 in __interceptor_malloc 
/build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:38
    #1 0x7f561d85e0ef  (/usr/lib/libfontconfig.so.1+0xc0ef)

Indirect leak of 1340 byte(s) in 114 object(s) allocated from:
    #0 0x7f56220d7d58 in __interceptor_malloc 
/build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:38
    #1 0x7f561f854ab9 in __strdup (/usr/lib/libc.so.6+0x7dab9)
...


Just swap the internal GtkLabel widget with a GtkDrawingArea, and all 
memory leaks.

The question is: is my program which is causing all these memory leaks ? 
Why ?


Thank you