I want to call a function passing NULL for gpointer argument, but python None is not converted to NULL, it stays Py_None instead (which is &_Py_NoneStruct, not NULL).

It can be shown on simple function like g_value_set_intance, which is described in .gir as follows:

      <method name="set_instance" c:identifier="g_value_set_instance">
        <doc xml:whitespace="preserve">Sets @value from an instantiatable type via the
value_table's collect_value() function.</doc>
        <return-value transfer-ownership="none">
          <type name="none" c:type="void"/>
        </return-value>
        <parameters>
          <parameter name="instance" transfer-ownership="none" allow-none="1">
            <doc xml:whitespace="preserve">the instance</doc>
            <type name="gpointer" c:type="gpointer"/>
          </parameter>
        </parameters>
      </method>


So i wrote python script:

from gi.repository import GObject
v = GObject.Value()
v.set_instance(None)

And checked it in gdb (some lines skipped):

Breakpoint 1, g_value_set_instance (value=0x80ff960, instance=0x41a1b8cc) at 

(gdb) bt

+ Trace 228570

(gdb) print &_Py_NoneStruct
$2 = (PyObject *) 0x41a1b8cc

As you can see, argument "instance" was passed as 0x41a1b8cc (Py_None), whereas I wanted to pass NULL.