Argument Clinic uses original name of Python parameter in generated code for custom (format code "O&") converter even if the parameter was renamed.

Example:

/*[clinic input]
test
    filename as path: object(converter="PyUnicode_FSConverter")
    /
[clinic start generated code]*/

Generated code:

static PyObject *
test(PyModuleDef *module, PyObject *arg)
{
    PyObject *return_value = NULL;
    PyObject *path;

    if (!PyUnicode_FSConverter(arg, &filename))
        goto exit;
    return_value = test_impl(module, path);

exit:
    return return_value;
}

This is caused by your "meth_o inline" code, which isn't checked in yet.  A clean checkout of CPython trunk generates this correct code:

    if (!PyArg_Parse(arg, "O&:test", PyUnicode_FSConverter, &path))

Maybe you don't need to use bugs.python.org as your personal bug tracker; maybe you don't need to add me to your private bugs.

You are right. Sorry for the noise.