Signature: Break the source into multiple files

The signature module has grown groups of rather unrelated
topics. In order to reduce the complexity, we break up
the source into a number of files.

Reason for this change was building support for selectable
features, which should not get lost in all the unrelated
helper functions.

Task-number: PYSIDE-510
Task-number: PYSIDE-1019
Change-Id: I8e22a91db1882f8c5428b8def13bf9f1cea431fb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

9 files changed, 1549 insertions, 1266 deletions

diff --git a/sources/shiboken2/libshiboken/CMakeLists.txt b/sources/shiboken2/libshiboken/CMakeLists.txt
index dee5dbd21..a53402e0f 100644
--- a/sources/shiboken2/libshiboken/CMakeLists.txt
+++ b/sources/shiboken2/libshiboken/CMakeLists.txt
@@ -57,14 +57,19 @@ sbkstaticstrings.cpp
 bindingmanager.cpp
 threadstatesaver.cpp
 shibokenbuffer.cpp
-signature.cpp
 qapp_macro.cpp
 pep384impl.cpp
 voidptr.cpp
 typespec.cpp
 bufferprocs_py37.cpp
+
 embed/signature_bootstrap_inc.h
 embed/signature_inc.h
+
+signature/signature.cpp
+signature/signature_globals.cpp
+signature/signature_extend.cpp
+signature/signature_helper.cpp
 )
 
 get_numpy_location()
@@ -137,12 +142,15 @@ install(FILES
         shibokenbuffer.h
         sbkpython.h
         pep384impl.h
-        signature.h
         qapp_macro.h
         voidptr.h
         typespec.h
         bufferprocs_py37.h
         "${CMAKE_CURRENT_BINARY_DIR}/sbkversion.h"
+
+        signature.h
+        signature/signature_p.h
+
         DESTINATION include/shiboken2${shiboken2_SUFFIX})
 install(TARGETS libshiboken EXPORT Shiboken2Targets
                             LIBRARY DESTINATION "${LIB_INSTALL_DIR}"
diff --git a/sources/shiboken2/libshiboken/signature.cpp b/sources/shiboken2/libshiboken/signature.cpp
deleted file mode 100644
index 3498829e7..000000000
--- a/sources/shiboken2/libshiboken/signature.cpp
+++ /dev/null
@@ -1,1261 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of Qt for Python.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "basewrapper.h"
-#include "autodecref.h"
-#include "sbkstring.h"
-#include "sbkstaticstrings.h"
-#include "sbkstaticstrings_p.h"
-
-using namespace Shiboken;
-
-extern "C"
-{
-
-/*
- * The documentation is located in file signature_doc.rst
- */
-#include "signature.h"
-#include <structmember.h>
-
-// These constants were needed in former versions of the module:
-#define PYTHON_HAS_QUALNAME             (PY_VERSION_HEX >= 0x03030000)
-#define PYTHON_HAS_WEAKREF_PYCFUNCTION  (PY_VERSION_HEX >= 0x030500A0)
-#define PYTHON_IS_PYTHON3               (PY_VERSION_HEX >= 0x03000000)
-#define PYTHON_HAS_KEYWORDONLY          (PYTHON_IS_PYTHON3)
-#define PYTHON_USES_PERCENT_V_FORMAT    (PYTHON_IS_PYTHON3)
-#define PYTHON_USES_D_COMMON            (PY_VERSION_HEX >= 0x03020000)
-#define PYTHON_HAS_DESCR_REDUCE         (PY_VERSION_HEX >= 0x03040000)
-#define PYTHON_HAS_METH_REDUCE          (PYTHON_HAS_DESCR_REDUCE)
-#define PYTHON_NEEDS_ITERATOR_FLAG      (!PYTHON_IS_PYTHON3)
-#define PYTHON_EXPOSES_METHODDESCR      (PYTHON_IS_PYTHON3)
-#define PYTHON_NO_TYPE_IN_FUNCTIONS     (!PYTHON_IS_PYTHON3 || Py_LIMITED_API)
-#define PYTHON_HAS_INT_AND_LONG         (!PYTHON_IS_PYTHON3)
-
-// These constants are still in use:
-#define PYTHON_USES_UNICODE             (PY_VERSION_HEX >= 0x03000000)
-
-typedef struct safe_globals_struc {
-    // init part 1: get arg_dict
-    PyObject *helper_module;
-    PyObject *arg_dict;
-    PyObject *map_dict;
-    PyObject *value_dict;       // for writing signatures
-    PyObject *feature_dict;     // registry for PySide.support.__feature__
-    // init part 2: run module
-    PyObject *pyside_type_init_func;
-    PyObject *create_signature_func;
-    PyObject *seterror_argument_func;
-    PyObject *make_helptext_func;
-    PyObject *finish_import_func;
-} safe_globals_struc, *safe_globals;
-
-static safe_globals pyside_globals = nullptr;
-
-static PyObject *GetTypeKey(PyObject *ob);
-
-static PyObject *GetSignature_Function(PyObject *, PyObject *);
-static PyObject *GetSignature_TypeMod(PyObject *, PyObject *);
-static PyObject *GetSignature_Wrapper(PyObject *, PyObject *);
-static PyObject *get_signature(PyObject *self, PyObject *args);
-static PyObject *get_signature_intern(PyObject *ob, PyObject *modifier);
-
-static PyObject *PySide_BuildSignatureProps(PyObject *class_mod);
-
-static void init_module_1(void);
-static void init_module_2(void);
-static PyObject *_init_pyside_extension(PyObject * /* self */, PyObject * /* args */);
-
-static PyObject *CreateSignature(PyObject *props, PyObject *key)
-{
-    /*
-     * Here is the new function to create all signatures. It simply calls
-     * into Python and creates a signature object directly.
-     * This is so much simpler than using all the attributes explicitly
-     * to support '_signature_is_functionlike()'.
-     */
-    return PyObject_CallFunction(pyside_globals->create_signature_func,
-                                 const_cast<char *>("(OO)"), props, key);
-}
-
-typedef PyObject *(*signaturefunc)(PyObject *, PyObject *);
-
-static PyObject *_get_written_signature(signaturefunc sf, PyObject *ob, PyObject *modifier)
-{
-    /*
-     * Be a writable Attribute, but have a computed value.
-     *
-     * If a signature has not been written, call the signature function.
-     * If it has been written, return the written value.
-     * After __del__ was called, the function value re-appears.
-     *
-     * Note: This serves also for the new version that does not allow any
-     * assignment if we have a computed value. We only need to check if
-     * a computed value exists and then forbid writing.
-     * See pyside_set___signature
-     */
-    PyObject *ret = PyDict_GetItem(pyside_globals->value_dict, ob);
-    if (ret == nullptr)
-        return ob == nullptr ? nullptr : sf(ob, modifier);
-    Py_INCREF(ret);
-    return ret;
-}
-
-static PyObject *pyside_cf_get___signature__(PyObject *func, PyObject *modifier)
-{
-    init_module_2();
-    return _get_written_signature(GetSignature_Function, func, modifier);
-}
-
-static PyObject *pyside_sm_get___signature__(PyObject *sm, PyObject *modifier)
-{
-    init_module_2();
-    AutoDecRef func(PyObject_GetAttr(sm, PyMagicName::func()));
-    if (Py_TYPE(func) == PepFunction_TypePtr)
-        return PyObject_GetAttr(func, PyMagicName::signature());
-    return _get_written_signature(GetSignature_Function, func, modifier);
-}
-
-static PyObject *_get_class_of_cf(PyObject *ob_cf)
-{
-    PyObject *selftype = PyCFunction_GET_SELF(ob_cf);
-    if (selftype == nullptr) {
-        selftype = PyDict_GetItem(pyside_globals->map_dict, ob_cf);
-        if (selftype == nullptr) {
-            // This must be an overloaded function that we handled special.
-            AutoDecRef special(Py_BuildValue("(OO)", ob_cf, PyName::overload()));
-            selftype = PyDict_GetItem(pyside_globals->map_dict, special);
-            if (selftype == nullptr) {
-                // This is probably a module function. We will return type(None).
-                selftype = Py_None;
-            }
-        }
-    }
-
-    PyObject *obtype_mod = (PyType_Check(selftype) || PyModule_Check(selftype))
-                           ? selftype
-                           : reinterpret_cast<PyObject *>(Py_TYPE(selftype));
-    Py_INCREF(obtype_mod);
-    return obtype_mod;
-}
-
-static PyObject *_get_class_of_sm(PyObject *ob_sm)
-{
-    AutoDecRef func(PyObject_GetAttr(ob_sm, PyMagicName::func()));
-    return _get_class_of_cf(func);
-}
-
-static PyObject *_get_class_of_descr(PyObject *ob)
-{
-    return PyObject_GetAttr(ob, PyMagicName::objclass());
-}
-
-static PyObject *GetClassOrModOf(PyObject *ob)
-{
-    /*
-     * Return the type or module of a function or type.
-     * The purpose is finally to use the name of the object.
-     */
-    if (PyType_Check(ob)) {
-        // PySide-928: The type case must do refcounting like the others as well.
-        Py_INCREF(ob);
-        return ob;
-    }
-    if (PyType_IsSubtype(Py_TYPE(ob), &PyCFunction_Type))
-        return _get_class_of_cf(ob);
-    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
-        return _get_class_of_sm(ob);
-    if (Py_TYPE(ob) == PepMethodDescr_TypePtr)
-        return _get_class_of_descr(ob);
-    if (Py_TYPE(ob) == &PyWrapperDescr_Type)
-        return _get_class_of_descr(ob);
-    Py_FatalError("unexpected type in GetClassOrModOf");
-    return nullptr;
-}
-
-static PyObject *get_funcname(PyObject *ob)
-{
-    PyObject *func = ob;
-    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
-        func = PyObject_GetAttr(ob, PyMagicName::func());
-    else
-        Py_INCREF(func);
-    PyObject *func_name = PyObject_GetAttr(func, PyMagicName::name());
-    Py_DECREF(func);
-    if (func_name == nullptr)
-        Py_FatalError("unexpected name problem in compute_name_key");
-    return func_name;
-}
-
-static PyObject *compute_name_key(PyObject *ob)
-{
-    if (PyType_Check(ob))
-        return GetTypeKey(ob);
-    AutoDecRef func_name(get_funcname(ob));
-    AutoDecRef type_key(GetTypeKey(GetClassOrModOf(ob)));
-    return Py_BuildValue("(OO)", type_key.object(), func_name.object());
-}
-
-static int build_name_key_to_func(PyObject *obtype)
-{
-    auto *type = reinterpret_cast<PyTypeObject *>(obtype);
-    PyMethodDef *meth = type->tp_methods;
-
-    if (meth == nullptr)
-        return 0;
-
-    AutoDecRef type_key(GetTypeKey(obtype));
-    for (; meth->ml_name != nullptr; meth++) {
-        AutoDecRef func(PyCFunction_NewEx(meth, obtype, nullptr));
-        AutoDecRef func_name(get_funcname(func));
-        AutoDecRef name_key(Py_BuildValue("(OO)", type_key.object(), func_name.object()));
-        if (func.isNull() || name_key.isNull()
-            || PyDict_SetItem(pyside_globals->map_dict, name_key, func) < 0)
-            return -1;
-    }
-    return 0;
-}
-
-static PyObject *name_key_to_func(PyObject *ob)
-{
-    /*
-     * We build a mapping from name_key to function.
-     * This could also be computed directly, but the Limited API
-     * makes this impossible. So we always build our own mapping.
-     */
-    AutoDecRef name_key(compute_name_key(ob));
-    if (name_key.isNull())
-        Py_RETURN_NONE;
-
-    PyObject *ret = PyDict_GetItem(pyside_globals->map_dict, name_key);
-    if (ret == nullptr) {
-        // do a lazy initialization
-        AutoDecRef type_key(GetTypeKey(GetClassOrModOf(ob)));
-        PyObject *type = PyDict_GetItem(pyside_globals->map_dict,
-                                        type_key);
-        if (type == nullptr)
-            Py_RETURN_NONE;
-        assert(PyType_Check(type));
-        if (build_name_key_to_func(type) < 0)
-            return nullptr;
-        ret = PyDict_GetItem(pyside_globals->map_dict, name_key);
-    }
-    Py_XINCREF(ret);
-    return ret;
-}
-
-static PyObject *pyside_md_get___signature__(PyObject *ob_md, PyObject *modifier)
-{
-    init_module_2();
-    AutoDecRef func(name_key_to_func(ob_md));
-    if (func.object() == Py_None)
-        return Py_None;
-    if (func.isNull())
-        Py_FatalError("missing mapping in MethodDescriptor");
-    return pyside_cf_get___signature__(func, modifier);
-}
-
-static PyObject *pyside_wd_get___signature__(PyObject *ob, PyObject *modifier)
-{
-    init_module_2();
-    return _get_written_signature(GetSignature_Wrapper, ob, modifier);
-}
-
-static PyObject *pyside_tp_get___signature__(PyObject *obtype_mod, PyObject *modifier)
-{
-    init_module_2();
-    return _get_written_signature(GetSignature_TypeMod, obtype_mod, modifier);
-}
-
-// forward
-static PyObject *GetSignature_Cached(PyObject *props, PyObject *func_kind, PyObject *modifier);
-
-// Helper for __qualname__ which might not always exist in Python 2 (type).
-static PyObject *_get_qualname(PyObject *ob)
-{
-    // We support __qualname__ for types, only.
-    assert(PyType_Check(ob));
-    PyObject *name = PyObject_GetAttr(ob, PyMagicName::qualname());
-    if (name == nullptr) {
-        PyErr_Clear();
-        name = PyObject_GetAttr(ob, PyMagicName::name());
-    }
-    return name;
-}
-
-static PyObject *GetTypeKey(PyObject *ob)
-{
-    assert(PyType_Check(ob) || PyModule_Check(ob));
-    /*
-     * We obtain a unique key using the module name and the type name.
-     *
-     * The type name is a bit funny when modules are nested.
-     * Example:
-     *
-     * "sample.Photon.ValueIdentity" is a class.
-     *   name:   "ValueIdentity"
-     *   module: "sample.Photon"
-     *
-     * This is the PyCFunction behavior, as opposed to Python functions.
-     */
-    // PYSIDE-1286: We use correct __module__ and __qualname__, now.
-    AutoDecRef module_name(PyObject_GetAttr(ob, PyMagicName::module()));
-    if (module_name.isNull()) {
-        // We have no module_name because this is a module ;-)
-        PyErr_Clear();
-        module_name.reset(PyObject_GetAttr(ob, PyMagicName::name()));
-        return Py_BuildValue("O", module_name.object());
-    }
-    AutoDecRef class_name(_get_qualname(ob));
-    if (class_name.isNull()) {
-        Py_FatalError("Signature: missing class name in GetTypeKey");
-        return nullptr;
-    }
-    return Py_BuildValue("(OO)", module_name.object(), class_name.object());
-}
-
-static PyObject *empty_dict = nullptr;
-
-static PyObject *TypeKey_to_PropsDict(PyObject *type_key, PyObject *obtype)
-{
-    PyObject *dict = PyDict_GetItem(pyside_globals->arg_dict, type_key);
-    if (dict == nullptr) {
-        if (empty_dict == nullptr)
-            empty_dict = PyDict_New();
-        dict = empty_dict;
-    }
-    if (!PyDict_Check(dict))
-        dict = PySide_BuildSignatureProps(type_key);
-    return dict;
-}
-
-static PyObject *GetSignature_Function(PyObject *obfunc, PyObject *modifier)
-{
-    // make sure that we look into PyCFunction, only...
-    if (Py_TYPE(obfunc) == PepFunction_TypePtr)
-        Py_RETURN_NONE;
-    AutoDecRef obtype_mod(GetClassOrModOf(obfunc));
-    AutoDecRef type_key(GetTypeKey(obtype_mod));
-    if (type_key.isNull())
-        Py_RETURN_NONE;
-    PyObject *dict = TypeKey_to_PropsDict(type_key, obtype_mod);
-    if (dict == nullptr)
-        return nullptr;
-    AutoDecRef func_name(PyObject_GetAttr(obfunc, PyMagicName::name()));
-    PyObject *props = !func_name.isNull() ? PyDict_GetItem(dict, func_name) : nullptr;
-    if (props == nullptr)
-        Py_RETURN_NONE;
-
-    int flags = PyCFunction_GET_FLAGS(obfunc);
-    PyObject *func_kind;
-    if (PyModule_Check(obtype_mod))
-        func_kind = PyName::function();
-    else if (flags & METH_CLASS)
-        func_kind = PyName::classmethod();
-    else if (flags & METH_STATIC)
-        func_kind = PyName::staticmethod();
-    else
-        func_kind = PyName::method();
-    return GetSignature_Cached(props, func_kind, modifier);
-}
-
-static PyObject *GetSignature_Wrapper(PyObject *ob, PyObject *modifier)
-{
-    AutoDecRef func_name(PyObject_GetAttr(ob, PyMagicName::name()));
-    AutoDecRef objclass(PyObject_GetAttr(ob, PyMagicName::objclass()));
-    AutoDecRef class_key(GetTypeKey(objclass));
-    if (func_name.isNull() || objclass.isNull() || class_key.isNull())
-        return nullptr;
-    PyObject *dict = TypeKey_to_PropsDict(class_key, objclass);
-    if (dict == nullptr)
-        return nullptr;
-    PyObject *props = PyDict_GetItem(dict, func_name);
-    if (props == nullptr)
-        Py_RETURN_NONE;
-    return GetSignature_Cached(props, PyName::method(), modifier);
-}
-
-static PyObject *GetSignature_TypeMod(PyObject *ob, PyObject *modifier)
-{
-    AutoDecRef ob_name(PyObject_GetAttr(ob, PyMagicName::name()));
-    AutoDecRef ob_key(GetTypeKey(ob));
-
-    PyObject *dict = TypeKey_to_PropsDict(ob_key, ob);
-    if (dict == nullptr)
-        return nullptr;
-    PyObject *props = PyDict_GetItem(dict, ob_name);
-    if (props == nullptr)
-        Py_RETURN_NONE;
-    return GetSignature_Cached(props, PyName::method(), modifier);
-}
-
-static PyObject *GetSignature_Cached(PyObject *props, PyObject *func_kind, PyObject *modifier)
-{
-    // Special case: We want to know the func_kind.
-    if (modifier) {
-#if PYTHON_USES_UNICODE
-        PyUnicode_InternInPlace(&modifier);
-#else
-        PyString_InternInPlace(&modifier);
-#endif
-        if (modifier == PyMagicName::func_kind())
-            return Py_BuildValue("O", func_kind);
-    }
-
-    AutoDecRef key(modifier == nullptr ? Py_BuildValue("O", func_kind)
-                                       : Py_BuildValue("(OO)", func_kind, modifier));
-    PyObject *value = PyDict_GetItem(props, key);
-    if (value == nullptr) {
-        // we need to compute a signature object
-        value = CreateSignature(props, key);
-        if (value != nullptr) {
-            if (PyDict_SetItem(props, key, value) < 0)
-                // this is an error
-                return nullptr;
-        }
-        else {
-            // key not found
-            Py_RETURN_NONE;
-        }
-    }
-    return Py_INCREF(value), value;
-}
-
-static const char *PySide_CompressedSignaturePackage[] = {
-#include "embed/signature_inc.h"
-    };
-
-static const unsigned char PySide_SignatureLoader[] = {
-#include "embed/signature_bootstrap_inc.h"
-    };
-
-// This function will be inserted into __builtins__.
-static PyMethodDef init_methods[] = {
-    {"_init_pyside_extension", (PyCFunction)_init_pyside_extension, METH_NOARGS},
-    {nullptr, nullptr}
-};
-
-static safe_globals_struc *init_phase_1(PyMethodDef *init_meth)
-{
-    {
-        auto *p = reinterpret_cast<safe_globals_struc *>
-                                    (malloc(sizeof(safe_globals_struc)));
-        if (p == nullptr)
-            goto error;
-        /*
-         * Initializing module signature_bootstrap.
-         * Since we now have an embedding script, we can do this without any
-         * Python strings in the C code.
-         */
-#ifdef Py_LIMITED_API
-        // We must work for multiple versions, so use source code.
-#else
-        AutoDecRef marshal_module(PyImport_Import(PyName::marshal()));
-        if (marshal_module.isNull())
-            goto error;
-        AutoDecRef loads(PyObject_GetAttr(marshal_module, PyName::loads()));
-        if (loads.isNull())
-            goto error;
-#endif
-        char *bytes_cast = reinterpret_cast<char *>(
-                                       const_cast<unsigned char *>(PySide_SignatureLoader));
-        AutoDecRef bytes(PyBytes_FromStringAndSize(bytes_cast, sizeof(PySide_SignatureLoader)));
-        if (bytes.isNull())
-            goto error;
-#ifdef Py_LIMITED_API
-        PyObject *builtins = PyEval_GetBuiltins();
-        PyObject *compile = PyDict_GetItem(builtins, PyName::compile());
-        if (compile == nullptr)
-            goto error;
-        AutoDecRef code_obj(PyObject_CallFunction(compile, "Oss",
-                                bytes.object(), "(builtin)", "exec"));
-#else
-        AutoDecRef code_obj(PyObject_CallFunctionObjArgs(
-                                loads, bytes.object(), nullptr));
-#endif
-        if (code_obj.isNull())
-            goto error;
-        p->helper_module = PyImport_ExecCodeModule(const_cast<char *>
-                                                       ("signature_bootstrap"), code_obj);
-        if (p->helper_module == nullptr)
-            goto error;
-        // Initialize the module
-        PyObject *mdict = PyModule_GetDict(p->helper_module);
-        if (PyDict_SetItem(mdict, PyMagicName::builtins(), PyEval_GetBuiltins()) < 0)
-            goto error;
-        /*
-         * Unpack an embedded ZIP file with more signature modules.
-         * They will be loaded later with the zipimporter.
-         * Due to MSVC's limitation to 64k strings, we need to assemble pieces.
-         */
-        const char **block_ptr = (const char **)PySide_CompressedSignaturePackage;
-        int npieces = 0;
-        PyObject *piece, *zipped_string_sequence = PyList_New(0);
-        if (zipped_string_sequence == nullptr)
-            return nullptr;
-        for (; **block_ptr != 0; ++block_ptr) {
-            npieces++;
-            // we avoid the string/unicode dilemma by not using PyString_XXX:
-            piece = Py_BuildValue("s", *block_ptr);
-            if (piece == nullptr || PyList_Append(zipped_string_sequence, piece) < 0)
-                goto error;
-        }
-        if (PyDict_SetItemString(mdict, "zipstring_sequence", zipped_string_sequence) < 0)
-            goto error;
-        Py_DECREF(zipped_string_sequence);
-
-        // build a dict for diverse mappings
-        p->map_dict = PyDict_New();
-        if (p->map_dict == nullptr)
-            goto error;
-
-        // build a dict for the prepared arguments
-        p->arg_dict = PyDict_New();
-        if (p->arg_dict == nullptr
-            || PyObject_SetAttrString(p->helper_module, "pyside_arg_dict", p->arg_dict) < 0)
-            goto error;
-
-        // build a dict for assigned signature values
-        p->value_dict = PyDict_New();
-        if (p->value_dict == nullptr)
-            goto error;
-
-        // PYSIDE-1019: build a __feature__ dict
-        p->feature_dict = PyDict_New();
-        if (p->feature_dict == nullptr
-            || PyObject_SetAttrString(p->helper_module, "pyside_feature_dict", p->feature_dict) < 0)
-            goto error;
-
-        // This function will be disabled until phase 2 is done.
-        p->finish_import_func = nullptr;
-
-        // Initialize the explicit init function.
-        AutoDecRef init(PyCFunction_NewEx(init_meth, nullptr, nullptr));
-        if (init.isNull()
-            || PyDict_SetItemString(PyEval_GetBuiltins(), init_meth->ml_name, init) != 0)
-            goto error;
-
-        return p;
-    }
-error:
-    PyErr_Print();
-    Py_FatalError("could not initialize part 1");
-    return nullptr;
-}
-
-static int init_phase_2(safe_globals_struc *p, PyMethodDef *methods)
-{
-    {
-        PyMethodDef *ml;
-
-        // The single function to be called, but maybe more to come.
-        for (ml = methods; ml->ml_name != nullptr; ml++) {
-            PyObject *v = PyCFunction_NewEx(ml, nullptr, nullptr);
-            if (v == nullptr
-                || PyObject_SetAttrString(p->helper_module, ml->ml_name, v) != 0)
-                goto error;
-            Py_DECREF(v);
-        }
-        PyObject *bootstrap_func = PyObject_GetAttrString(p->helper_module, "bootstrap");
-        if (bootstrap_func == nullptr)
-            goto error;
-        // The return value of the bootstrap function is the loader module.
-        PyObject *loader = PyObject_CallFunction(bootstrap_func, const_cast<char *>("()"));
-        if (loader == nullptr)
-            goto error;
-        // now the loader should be initialized
-        p->pyside_type_init_func = PyObject_GetAttrString(loader, "pyside_type_init");
-        if (p->pyside_type_init_func == nullptr)
-            goto error;
-        p->create_signature_func = PyObject_GetAttrString(loader, "create_signature");
-        if (p->create_signature_func == nullptr)
-            goto error;
-        p->seterror_argument_func = PyObject_GetAttrString(loader, "seterror_argument");
-        if (p->seterror_argument_func == nullptr)
-            goto error;
-        p->make_helptext_func = PyObject_GetAttrString(loader, "make_helptext");
-        if (p->make_helptext_func == nullptr)
-            goto error;
-        p->finish_import_func = PyObject_GetAttrString(loader, "finish_import");
-        if (p->finish_import_func == nullptr)
-            goto error;
-        return 0;
-    }
-error:
-    PyErr_Print();
-    Py_FatalError("could not initialize part 2");
-    return -1;
-}
-
-static int _fixup_getset(PyTypeObject *type, const char *name, PyGetSetDef *new_gsp)
-{
-    /*
-     * This function pre-fills all fields of the new gsp. We then
-     * insert the changed values.
-     */
-    PyGetSetDef *gsp = type->tp_getset;
-    if (gsp != nullptr) {
-        for (; gsp->name != nullptr; gsp++) {
-            if (strcmp(gsp->name, name) == 0) {
-                new_gsp->set = gsp->set;
-                new_gsp->doc = gsp->doc;
-                new_gsp->closure = gsp->closure;
-                return 1;  // success
-            }
-        }
-    }
-    PyMemberDef *md = type->tp_members;
-    if (md != nullptr)
-        for (; md->name != nullptr; md++)
-            if (strcmp(md->name, name) == 0)
-                return 1;
-    // staticmethod has just a `__doc__` in the class
-    assert(strcmp(type->tp_name, "staticmethod") == 0 && strcmp(name, "__doc__") == 0);
-    return 0;
-}
-
-static int add_more_getsets(PyTypeObject *type, PyGetSetDef *gsp, PyObject **doc_descr)
-{
-    /*
-     * This function is used to assign a new `__signature__` attribute,
-     * and also to override a `__doc__` or `__name__` attribute.
-     */
-    assert(PyType_Check(type));
-    PyType_Ready(type);
-    PyObject *dict = type->tp_dict;
-    for (; gsp->name != nullptr; gsp++) {
-        PyObject *have_descr = PyDict_GetItemString(dict, gsp->name);
-        if (have_descr != nullptr) {
-            Py_INCREF(have_descr);
-            if (strcmp(gsp->name, "__doc__") == 0)
-                *doc_descr = have_descr;
-            else
-                assert(false);
-            if (!_fixup_getset(type, gsp->name, gsp))
-                continue;
-        }
-        AutoDecRef descr(PyDescr_NewGetSet(type, gsp));
-        if (descr.isNull())
-            return -1;
-        if (PyDict_SetItemString(dict, gsp->name, descr) < 0)
-            return -1;
-    }
-    PyType_Modified(type);
-    return 0;
-}
-
-////////////////////////////////////////////////////////////////////////////
-//
-// Augmenting builtin types with a __signature__ attribute.
-//
-// This is a harmless change to Python, similar like __text_signature__.
-// We could avoid it, but then we would need to copy quite some module
-// initialization functions which are pretty version- and word size
-// dependent. I think this little patch is the lesser of the two evils.
-//
-// Please note that in fact we are modifying 'type', the metaclass of all
-// objects, because we add new functionality.
-//
-// Addendum 2019-01-12: We now also compute a docstring from the signature.
-//
-
-// keep the original __doc__ functions
-static PyObject *old_cf_doc_descr = nullptr;
-static PyObject *old_sm_doc_descr = nullptr;
-static PyObject *old_md_doc_descr = nullptr;
-static PyObject *old_tp_doc_descr = nullptr;
-static PyObject *old_wd_doc_descr = nullptr;
-
-static int handle_doc_in_progress = 0;
-
-static PyObject *handle_doc(PyObject *ob, PyObject *old_descr)
-{
-    init_module_1();
-    init_module_2();
-    AutoDecRef ob_type_mod(GetClassOrModOf(ob));
-    const char *name;
-    if (PyModule_Check(ob_type_mod))
-        name = PyModule_GetName(ob_type_mod);
-    else
-        name = reinterpret_cast<PyTypeObject *>(ob_type_mod.object())->tp_name;
-    if (handle_doc_in_progress || name == nullptr
-        || strncmp(name, "PySide2.", 8) != 0)
-        return PyObject_CallMethodObjArgs(old_descr,
-                                          PyMagicName::get(),
-                                          ob, nullptr);
-    handle_doc_in_progress++;
-    PyObject *res = PyObject_CallFunction(
-                        pyside_globals->make_helptext_func,
-                        const_cast<char *>("(O)"), ob);
-    handle_doc_in_progress--;
-    if (res == nullptr) {
-        PyErr_Print();
-        Py_FatalError("handle_doc did not receive a result");
-    }
-    return res;
-}
-
-static PyObject *pyside_cf_get___doc__(PyObject *cf) {
-    return handle_doc(cf, old_cf_doc_descr);
-}
-
-static PyObject *pyside_sm_get___doc__(PyObject *sm) {
-    return handle_doc(sm, old_sm_doc_descr);
-}
-
-static PyObject *pyside_md_get___doc__(PyObject *md) {
-    return handle_doc(md, old_md_doc_descr);
-}
-
-static PyObject *pyside_tp_get___doc__(PyObject *tp) {
-    return handle_doc(tp, old_tp_doc_descr);
-}
-
-static PyObject *pyside_wd_get___doc__(PyObject *wd) {
-    return handle_doc(wd, old_wd_doc_descr);
-}
-
-// the default setter for all objects
-static int pyside_set___signature__(PyObject *op, PyObject *value)
-{
-    // By this additional check, this function refuses write access.
-    // We consider both nullptr and Py_None as not been written.
-    AutoDecRef has_val(get_signature_intern(op, nullptr));
-    if (!(has_val.isNull() || has_val == Py_None)) {
-        PyErr_Format(PyExc_AttributeError,
-                     "Attribute '__signature__' of '%.50s' object is not writable",
-                     Py_TYPE(op)->tp_name);
-        return -1;
-    }
-    int ret = value == nullptr ? PyDict_DelItem(pyside_globals->value_dict, op)
-                               : PyDict_SetItem(pyside_globals->value_dict, op, value);
-    Py_XINCREF(value);
-    return ret;
-}
-
-static PyGetSetDef new_PyCFunction_getsets[] = {
-    {const_cast<char *>("__doc__"), (getter)pyside_cf_get___doc__},
-    {const_cast<char *>("__signature__"), (getter)pyside_cf_get___signature__,
-                                          (setter)pyside_set___signature__},
-    {nullptr}
-};
-
-static PyGetSetDef new_PyStaticMethod_getsets[] = {
-    {const_cast<char *>("__doc__"), (getter)pyside_sm_get___doc__},
-    {const_cast<char *>("__signature__"), (getter)pyside_sm_get___signature__,
-                                          (setter)pyside_set___signature__},
-    {nullptr}
-};
-
-static PyGetSetDef new_PyMethodDescr_getsets[] = {
-    {const_cast<char *>("__doc__"), (getter)pyside_md_get___doc__},
-    {const_cast<char *>("__signature__"), (getter)pyside_md_get___signature__,
-                                          (setter)pyside_set___signature__},
-    {nullptr}
-};
-
-static PyGetSetDef new_PyType_getsets[] = {
-    {const_cast<char *>("__doc__"), (getter)pyside_tp_get___doc__},
-    {const_cast<char *>("__signature__"), (getter)pyside_tp_get___signature__,
-                                          (setter)pyside_set___signature__},
-    {nullptr}
-};
-
-static PyGetSetDef new_PyWrapperDescr_getsets[] = {
-    {const_cast<char *>("__doc__"), (getter)pyside_wd_get___doc__},
-    {const_cast<char *>("__signature__"), (getter)pyside_wd_get___signature__,
-                                          (setter)pyside_set___signature__},
-    {nullptr}
-};
-
-////////////////////////////////////////////////////////////////////////////
-//
-// get_signature  --  providing a superior interface
-//
-// Additionally to the interface via __signature__, we also provide
-// a general function, which allows for different signature layouts.
-// The "modifier" argument is a string that is passed in from 'loader.py'.
-// Configuration what the modifiers mean is completely in Python.
-//
-
-static PyObject *get_signature_intern(PyObject *ob, PyObject *modifier)
-{
-    if (PyType_IsSubtype(Py_TYPE(ob), &PyCFunction_Type))
-        return pyside_cf_get___signature__(ob, modifier);
-    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
-        return pyside_sm_get___signature__(ob, modifier);
-    if (Py_TYPE(ob) == PepMethodDescr_TypePtr)
-        return pyside_md_get___signature__(ob, modifier);
-    if (PyType_Check(ob))
-        return pyside_tp_get___signature__(ob, modifier);
-    if (Py_TYPE(ob) == &PyWrapperDescr_Type)
-        return pyside_wd_get___signature__(ob, modifier);
-    return nullptr;
-}
-
-static PyObject *get_signature(PyObject * /* self */, PyObject *args)
-{
-    PyObject *ob;
-    PyObject *modifier = nullptr;
-
-    init_module_1();
-
-    if (!PyArg_ParseTuple(args, "O|O", &ob, &modifier))
-        return nullptr;
-    if (Py_TYPE(ob) == PepFunction_TypePtr)
-        Py_RETURN_NONE;
-    PyObject *ret = get_signature_intern(ob, modifier);
-    if (ret != nullptr)
-        return ret;
-    Py_RETURN_NONE;
-}
-
-static PyObject *_init_pyside_extension(PyObject * /* self */, PyObject * /* args */)
-{
-    init_module_1();
-    init_module_2();
-    Py_RETURN_NONE;
-}
-
-////////////////////////////////////////////////////////////////////////////
-//
-// This special Type_Ready does certain initializations earlier with
-// our new version.
-//
-
-#ifndef _WIN32
-////////////////////////////////////////////////////////////////////////////
-// a stack trace for linux-like platforms
-#include <stdio.h>
-#if defined(__GLIBC__)
-#  include <execinfo.h>
-#endif
-#include <signal.h>
-#include <stdlib.h>
-#include <unistd.h>
-
-void handler(int sig) {
-#if defined(__GLIBC__)
-    void *array[30];
-    size_t size;
-
-    // get void *'s for all entries on the stack
-    size = backtrace(array, 30);
-
-    // print out all the frames to stderr
-#endif
-    fprintf(stderr, "Error: signal %d:\n", sig);
-#if defined(__GLIBC__)
-    backtrace_symbols_fd(array, size, STDERR_FILENO);
-#endif
-    exit(1);
-}
-
-////////////////////////////////////////////////////////////////////////////
-#endif // _WIN32
-
-static int PySide_PatchTypes(void)
-{
-    static int init_done = 0;
-
-    if (!init_done) {
-        AutoDecRef meth_descr(PyObject_GetAttrString(
-                                    reinterpret_cast<PyObject *>(&PyString_Type), "split"));
-        AutoDecRef wrap_descr(PyObject_GetAttrString(
-                                    reinterpret_cast<PyObject *>(Py_TYPE(Py_True)), "__add__"));
-        // abbreviations for readability
-        auto md_gs = new_PyMethodDescr_getsets;
-        auto md_doc = &old_md_doc_descr;
-        auto cf_gs = new_PyCFunction_getsets;
-        auto cf_doc = &old_cf_doc_descr;
-        auto sm_gs = new_PyStaticMethod_getsets;
-        auto sm_doc = &old_sm_doc_descr;
-        auto tp_gs = new_PyType_getsets;
-        auto tp_doc = &old_tp_doc_descr;
-        auto wd_gs = new_PyWrapperDescr_getsets;
-        auto wd_doc = &old_wd_doc_descr;
-
-        if (meth_descr.isNull() || wrap_descr.isNull()
-            || PyType_Ready(Py_TYPE(meth_descr)) < 0
-            || add_more_getsets(PepMethodDescr_TypePtr,  md_gs, md_doc) < 0
-            || add_more_getsets(&PyCFunction_Type,       cf_gs, cf_doc) < 0
-            || add_more_getsets(PepStaticMethod_TypePtr, sm_gs, sm_doc) < 0
-            || add_more_getsets(&PyType_Type,            tp_gs, tp_doc) < 0
-            || add_more_getsets(Py_TYPE(wrap_descr),     wd_gs, wd_doc) < 0
-            )
-            return -1;
-#ifndef _WIN32
-        // We enable the stack trace in CI, only.
-        const char *testEnv = getenv("QTEST_ENVIRONMENT");
-        if (testEnv && strstr(testEnv, "ci"))
-            signal(SIGSEGV, handler);   // install our handler
-#endif // _WIN32
-        init_done = 1;
-    }
-    return 0;
-}
-
-static void init_module_1(void)
-{
-    static int init_done = 0;
-
-    if (!init_done) {
-        pyside_globals = init_phase_1(init_methods);
-        if (pyside_globals != nullptr)
-            init_done = 1;
-    }
-}
-
-static int PySide_BuildSignatureArgs(PyObject *obtype_mod, const char *signatures[])
-{
-    init_module_1();
-    AutoDecRef type_key(GetTypeKey(obtype_mod));
-    /*
-     * PYSIDE-996: Avoid string overflow in MSVC, which has a limit of
-     * 2**15 unicode characters (64 K memory).
-     * Instead of one huge string, we take a ssize_t that is the
-     * address of a string array. It will not be turned into a real
-     * string list until really used by Python. This is quite optimal.
-     */
-    AutoDecRef numkey(Py_BuildValue("n", signatures));
-    if (type_key.isNull() || numkey.isNull()
-        || PyDict_SetItem(pyside_globals->arg_dict, type_key, numkey) < 0)
-        return -1;
-    /*
-     * We record also a mapping from type key to type/module. This helps to
-     * lazily initialize the Py_LIMITED_API in name_key_to_func().
-     */
-    return PyDict_SetItem(pyside_globals->map_dict, type_key, obtype_mod) == 0 ? 0 : -1;
-}
-
-static PyMethodDef signature_methods[] = {
-    {"get_signature", (PyCFunction)get_signature, METH_VARARGS,
-        "get the __signature__, but pass an optional string parameter"},
-    {nullptr, nullptr}
-};
-
-static void init_module_2(void)
-{
-    static int init_done = 0;
-
-    if (!init_done) {
-        // Phase 2 will call __init__.py which touches a signature, itself.
-        // Therefore we set init_done prior to init_phase_2().
-        init_done = 1;
-        init_phase_2(pyside_globals, signature_methods);
-    }
-}
-
-static PyObject *_address_to_stringlist(PyObject *numkey)
-{
-    ssize_t address = PyNumber_AsSsize_t(numkey, PyExc_ValueError);
-    if (address == -1 && PyErr_Occurred())
-        return nullptr;
-    char **sig_strings = reinterpret_cast<char **>(address);
-    PyObject *res_list = PyList_New(0);
-    if (res_list == nullptr)
-        return nullptr;
-    for (; *sig_strings != nullptr; ++sig_strings) {
-        char *sig_str = *sig_strings;
-        AutoDecRef pystr(Py_BuildValue("s", sig_str));
-        if (pystr.isNull() || PyList_Append(res_list, pystr) < 0)
-            return nullptr;
-    }
-    return res_list;
-}
-
-static PyObject *PySide_BuildSignatureProps(PyObject *type_key)
-{
-    /*
-     * Here is the second part of the function.
-     * This part will be called on-demand when needed by some attribute.
-     * We simply pick up the arguments that we stored here and replace
-     * them by the function result.
-     */
-    init_module_2();
-    if (type_key == nullptr)
-        return nullptr;
-    PyObject *numkey = PyDict_GetItem(pyside_globals->arg_dict, type_key);
-    AutoDecRef strings(_address_to_stringlist(numkey));
-    if (strings.isNull())
-        return nullptr;
-    AutoDecRef arg_tup(Py_BuildValue("(OO)", type_key, strings.object()));
-    if (arg_tup.isNull())
-        return nullptr;
-    PyObject *dict = PyObject_CallObject(pyside_globals->pyside_type_init_func, arg_tup);
-    if (dict == nullptr) {
-        if (PyErr_Occurred())
-            return nullptr;
-        // No error: return an empty dict.
-        if (empty_dict == nullptr)
-            empty_dict = PyDict_New();
-        return empty_dict;
-    }
-    // We replace the arguments by the result dict.
-    if (PyDict_SetItem(pyside_globals->arg_dict, type_key, dict) < 0)
-        return nullptr;
-    return dict;
-}
-
-static int _finish_nested_classes(PyObject *dict);
-static int _build_func_to_type(PyObject *obtype);
-
-static int PySide_FinishSignatures(PyObject *module, const char *signatures[])
-{
-    /*
-     * Initialization of module functions and resolving of static methods.
-     */
-    const char *name = PyModule_GetName(module);
-    if (name == nullptr)
-        return -1;
-
-    // we abuse the call for types, since they both have a __name__ attribute.
-    if (PySide_BuildSignatureArgs(module, signatures) < 0)
-        return -1;
-
-    /*
-     * Note: This function crashed when called from PySide_BuildSignatureArgs.
-     * Probably this was too early.
-     *
-     * Pep384: We need to switch this always on since we have no access
-     * to the PyCFunction attributes. Therefore I simplified things
-     * and always use our own mapping.
-     */
-    PyObject *key, *func, *obdict = PyModule_GetDict(module);
-    Py_ssize_t pos = 0;
-
-    while (PyDict_Next(obdict, &pos, &key, &func))
-        if (PyCFunction_Check(func))
-            if (PyDict_SetItem(pyside_globals->map_dict, func, module) < 0)
-                return -1;
-    if (_finish_nested_classes(obdict) < 0)
-        return -1;
-    // The finish_import function will not work the first time since phase 2
-    // was not yet run. But that is ok, because the first import is always for
-    // the shiboken module (or a test module).
-    if (pyside_globals->finish_import_func == nullptr) {
-        assert(strncmp(name, "PySide2.", 8) != 0);
-        return 0;
-    }
-    AutoDecRef ret(PyObject_CallFunction(
-        pyside_globals->finish_import_func, const_cast<char *>("(O)"), module));
-    return ret.isNull() ? -1 : 0;
-}
-
-static int _finish_nested_classes(PyObject *obdict)
-{
-    PyObject *key, *value, *obtype;
-    PyTypeObject *subtype;
-    Py_ssize_t pos = 0;
-
-    if (obdict == nullptr)
-        return -1;
-    while (PyDict_Next(obdict, &pos, &key, &value)) {
-        if (PyType_Check(value)) {
-            obtype = value;
-            if (_build_func_to_type(obtype) < 0)
-                return -1;
-            // now continue with nested cases
-            subtype = reinterpret_cast<PyTypeObject *>(obtype);
-            if (_finish_nested_classes(subtype->tp_dict) < 0)
-                return -1;
-        }
-    }
-    return 0;
-}
-
-static int _build_func_to_type(PyObject *obtype)
-{
-    /*
-     * There is no general way to directly get the type of a static method.
-     * On Python 3, the type is hidden in an unused pointer in the
-     * PyCFunction structure, but the Limited API does not allow to access
-     * this, either.
-     *
-     * In the end, it was easier to avoid such tricks and build an explicit
-     * mapping from function to type.
-     *
-     * We walk through the method list of the type
-     * and record the mapping from static method to this type in a dict.
-     * We also check for hidden methods, see below.
-     */
-    auto *type = reinterpret_cast<PyTypeObject *>(obtype);
-    PyObject *dict = type->tp_dict;
-    PyMethodDef *meth = type->tp_methods;
-
-    if (meth == nullptr)
-        return 0;
-
-    for (; meth->ml_name != nullptr; meth++) {
-        /*
-         * It is possible that a method is overwritten by another
-         * attribute with the same name. This case was obviously provoked
-         * explicitly in "testbinding.TestObject.staticMethodDouble",
-         * where instead of the method a "PySide2.QtCore.Signal" object
-         * was in the dict.
-         * This overlap is also found in regular PySide under
-         * "PySide2.QtCore.QProcess.error" where again a signal object is
-         * returned. These hidden methods will be opened for the
-         * signature module by adding them under the name
-         * "{name}.overload".
-         */
-        PyObject *descr = PyDict_GetItemString(dict, meth->ml_name);
-        PyObject *look_attr = meth->ml_flags & METH_STATIC ? PyMagicName::func()
-                                                           : PyMagicName::name();
-        int check_name = meth->ml_flags & METH_STATIC ? 0 : 1;
-        if (descr == nullptr)
-            return -1;
-
-        // We first check all methods if one is hidden by something else.
-        AutoDecRef look(PyObject_GetAttr(descr, look_attr));
-        AutoDecRef given(Py_BuildValue("s", meth->ml_name));
-        if (look.isNull()
-            || (check_name && PyObject_RichCompareBool(look, given, Py_EQ) != 1)) {
-            PyErr_Clear();
-            AutoDecRef cfunc(PyCFunction_NewEx(
-                                meth, reinterpret_cast<PyObject *>(type), nullptr));
-            if (cfunc.isNull())
-                return -1;
-            if (meth->ml_flags & METH_STATIC)
-                descr = PyStaticMethod_New(cfunc);
-            else
-                descr = PyDescr_NewMethod(type, meth);
-            if (descr == nullptr)
-                return -1;
-            char mangled_name[200];
-            strcpy(mangled_name, meth->ml_name);
-            strcat(mangled_name, ".overload");
-            if (PyDict_SetItemString(dict, mangled_name, descr) < 0)
-                return -1;
-            if (meth->ml_flags & METH_STATIC) {
-                // This is the special case where a static method is hidden.
-                AutoDecRef special(Py_BuildValue("(Os)", cfunc.object(), "overload"));
-                if (PyDict_SetItem(pyside_globals->map_dict, special, obtype) < 0)
-                    return -1;
-            }
-            if (PyDict_SetItemString(pyside_globals->map_dict, mangled_name, obtype) < 0)
-                return -1;
-            continue;
-        }
-        // Then we insert the mapping for static methods.
-        if (meth->ml_flags & METH_STATIC) {
-            if (PyDict_SetItem(pyside_globals->map_dict, look, obtype) < 0)
-                return -1;
-        }
-    }
-    return 0;
-}
-
-int InitSignatureStrings(PyTypeObject *type, const char *signatures[])
-{
-    auto *ob_type = reinterpret_cast<PyObject *>(type);
-    int ret = PySide_BuildSignatureArgs(ob_type, signatures);
-    if (ret < 0) {
-        PyErr_Print();
-        PyErr_SetNone(PyExc_ImportError);
-    }
-    return ret;
-}
-
-void FinishSignatureInitialization(PyObject *module, const char *signatures[])
-{
-    /*
-     * This function is called at the very end of a module initialization.
-     * We now patch certain types to support the __signature__ attribute,
-     * initialize module functions and resolve static methods.
-     *
-     * Still, it is not possible to call init phase 2 from here,
-     * because the import is still running. Do it from Python!
-     */
-    if (   PySide_PatchTypes() < 0
-        || PySide_FinishSignatures(module, signatures) < 0) {
-        PyErr_Print();
-        PyErr_SetNone(PyExc_ImportError);
-    }
-}
-
-void SetError_Argument(PyObject *args, const char *func_name)
-{
-    /*
-     * This function replaces the type error construction with extra
-     * overloads parameter in favor of using the signature module.
-     * Error messages are rare, so we do it completely in Python.
-     */
-    init_module_1();
-    init_module_2();
-    AutoDecRef res(PyObject_CallFunction(pyside_globals->seterror_argument_func,
-                                         const_cast<char *>("(Os)"), args, func_name));
-    if (res.isNull()) {
-        PyErr_Print();
-        Py_FatalError("seterror_argument did not receive a result");
-    }
-    PyObject *err, *msg;
-    if (!PyArg_UnpackTuple(res, func_name, 2, 2, &err, &msg)) {
-        PyErr_Print();
-        Py_FatalError("unexpected failure in seterror_argument");
-    }
-    PyErr_SetObject(err, msg);
-}
-
-/*
- * Support for the metatype SbkObjectType_Type's tp_getset.
- *
- * This was not necessary for __signature__, because PyType_Type inherited it.
- * But the __doc__ attribute existed already by inheritance, and calling
- * PyType_Modified() is not supported. So we added the getsets explicitly
- * to the metatype.
- */
-
-PyObject *Sbk_TypeGet___signature__(PyObject *ob, PyObject *modifier)
-{
-    return pyside_tp_get___signature__(ob, modifier);
-}
-
-PyObject *Sbk_TypeGet___doc__(PyObject *ob)
-{
-    return pyside_tp_get___doc__(ob);
-}
-
-PyObject *GetFeatureDict()
-{
-    init_module_1();
-    return pyside_globals->feature_dict;
-}
-
-} //extern "C"
diff --git a/sources/shiboken2/libshiboken/signature.h b/sources/shiboken2/libshiboken/signature.h
index c5f515a7f..b77cc0f4c 100644
--- a/sources/shiboken2/libshiboken/signature.h
+++ b/sources/shiboken2/libshiboken/signature.h
@@ -40,8 +40,6 @@
 #ifndef SIGNATURE_H
 #define SIGNATURE_H
 
-#include "sbkpython.h"
-
 extern "C"
 {
 
diff --git a/sources/shiboken2/libshiboken/signature/signature.cpp b/sources/shiboken2/libshiboken/signature/signature.cpp
new file mode 100644
index 000000000..76a71b00b
--- /dev/null
+++ b/sources/shiboken2/libshiboken/signature/signature.cpp
@@ -0,0 +1,479 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+////////////////////////////////////////////////////////////////////////////
+//
+// signature.cpp
+// -------------
+//
+// This is the main file of the signature module.
+// It contains the most important functions and avoids confusion
+// by moving many helper functions elsewhere.
+//
+// General documentation can be found in `signature_doc.rst`.
+//
+
+#include "basewrapper.h"
+#include "autodecref.h"
+#include "sbkstring.h"
+#include "sbkstaticstrings.h"
+#include "sbkstaticstrings_p.h"
+
+#include "signature_p.h"
+#include <structmember.h>
+
+using namespace Shiboken;
+
+extern "C"
+{
+
+static PyObject *CreateSignature(PyObject *props, PyObject *key)
+{
+    /*
+     * Here is the new function to create all signatures. It simply calls
+     * into Python and creates a signature object directly.
+     * This is so much simpler than using all the attributes explicitly
+     * to support '_signature_is_functionlike()'.
+     */
+    return PyObject_CallFunction(pyside_globals->create_signature_func,
+                                 const_cast<char *>("(OO)"), props, key);
+}
+
+PyObject *GetClassOrModOf(PyObject *ob)
+{
+    /*
+     * Return the type or module of a function or type.
+     * The purpose is finally to use the name of the object.
+     */
+    if (PyType_Check(ob)) {
+        // PySide-928: The type case must do refcounting like the others as well.
+        Py_INCREF(ob);
+        return ob;
+    }
+    if (PyType_IsSubtype(Py_TYPE(ob), &PyCFunction_Type))
+        return _get_class_of_cf(ob);
+    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
+        return _get_class_of_sm(ob);
+    if (Py_TYPE(ob) == PepMethodDescr_TypePtr)
+        return _get_class_of_descr(ob);
+    if (Py_TYPE(ob) == &PyWrapperDescr_Type)
+        return _get_class_of_descr(ob);
+    Py_FatalError("unexpected type in GetClassOrModOf");
+    return nullptr;
+}
+
+PyObject *GetTypeKey(PyObject *ob)
+{
+    assert(PyType_Check(ob) || PyModule_Check(ob));
+    /*
+     * Obtain a unique key using the module name and the type name.
+     *
+     * PYSIDE-1286: We use correct __module__ and __qualname__, now.
+     */
+    AutoDecRef module_name(PyObject_GetAttr(ob, PyMagicName::module()));
+    if (module_name.isNull()) {
+        // We have no module_name because this is a module ;-)
+        PyErr_Clear();
+        module_name.reset(PyObject_GetAttr(ob, PyMagicName::name()));
+        return Py_BuildValue("O", module_name.object());
+    }
+    AutoDecRef class_name(_get_qualname(ob));
+    if (class_name.isNull()) {
+        Py_FatalError("Signature: missing class name in GetTypeKey");
+        return nullptr;
+    }
+    return Py_BuildValue("(OO)", module_name.object(), class_name.object());
+}
+
+static PyObject *empty_dict = nullptr;
+
+PyObject *TypeKey_to_PropsDict(PyObject *type_key, PyObject *obtype)
+{
+    PyObject *dict = PyDict_GetItem(pyside_globals->arg_dict, type_key);
+    if (dict == nullptr) {
+        if (empty_dict == nullptr)
+            empty_dict = PyDict_New();
+        dict = empty_dict;
+    }
+    if (!PyDict_Check(dict))
+        dict = PySide_BuildSignatureProps(type_key);
+    return dict;
+}
+
+static PyObject *_GetSignature_Cached(PyObject *props, PyObject *func_kind, PyObject *modifier)
+{
+    // Special case: We want to know the func_kind.
+    if (modifier) {
+#if PY_VERSION_HEX >= 0x03000000
+        PyUnicode_InternInPlace(&modifier);
+#else
+        PyString_InternInPlace(&modifier);
+#endif
+        if (modifier == PyMagicName::func_kind())
+            return Py_BuildValue("O", func_kind);
+    }
+
+    AutoDecRef key(modifier == nullptr ? Py_BuildValue("O", func_kind)
+                                       : Py_BuildValue("(OO)", func_kind, modifier));
+    PyObject *value = PyDict_GetItem(props, key);
+    if (value == nullptr) {
+        // we need to compute a signature object
+        value = CreateSignature(props, key);
+        if (value != nullptr) {
+            if (PyDict_SetItem(props, key, value) < 0)
+                // this is an error
+                return nullptr;
+        }
+        else {
+            // key not found
+            Py_RETURN_NONE;
+        }
+    }
+    return Py_INCREF(value), value;
+}
+
+PyObject *GetSignature_Function(PyObject *obfunc, PyObject *modifier)
+{
+    // make sure that we look into PyCFunction, only...
+    if (Py_TYPE(obfunc) == PepFunction_TypePtr)
+        Py_RETURN_NONE;
+    AutoDecRef obtype_mod(GetClassOrModOf(obfunc));
+    AutoDecRef type_key(GetTypeKey(obtype_mod));
+    if (type_key.isNull())
+        Py_RETURN_NONE;
+    PyObject *dict = TypeKey_to_PropsDict(type_key, obtype_mod);
+    if (dict == nullptr)
+        return nullptr;
+    AutoDecRef func_name(PyObject_GetAttr(obfunc, PyMagicName::name()));
+    PyObject *props = !func_name.isNull() ? PyDict_GetItem(dict, func_name) : nullptr;
+    if (props == nullptr)
+        Py_RETURN_NONE;
+
+    int flags = PyCFunction_GET_FLAGS(obfunc);
+    PyObject *func_kind;
+    if (PyModule_Check(obtype_mod))
+        func_kind = PyName::function();
+    else if (flags & METH_CLASS)
+        func_kind = PyName::classmethod();
+    else if (flags & METH_STATIC)
+        func_kind = PyName::staticmethod();
+    else
+        func_kind = PyName::method();
+    return _GetSignature_Cached(props, func_kind, modifier);
+}
+
+PyObject *GetSignature_Wrapper(PyObject *ob, PyObject *modifier)
+{
+    AutoDecRef func_name(PyObject_GetAttr(ob, PyMagicName::name()));
+    AutoDecRef objclass(PyObject_GetAttr(ob, PyMagicName::objclass()));
+    AutoDecRef class_key(GetTypeKey(objclass));
+    if (func_name.isNull() || objclass.isNull() || class_key.isNull())
+        return nullptr;
+    PyObject *dict = TypeKey_to_PropsDict(class_key, objclass);
+    if (dict == nullptr)
+        return nullptr;
+    PyObject *props = PyDict_GetItem(dict, func_name);
+    if (props == nullptr)
+        Py_RETURN_NONE;
+    return _GetSignature_Cached(props, PyName::method(), modifier);
+}
+
+PyObject *GetSignature_TypeMod(PyObject *ob, PyObject *modifier)
+{
+    AutoDecRef ob_name(PyObject_GetAttr(ob, PyMagicName::name()));
+    AutoDecRef ob_key(GetTypeKey(ob));
+
+    PyObject *dict = TypeKey_to_PropsDict(ob_key, ob);
+    if (dict == nullptr)
+        return nullptr;
+    PyObject *props = PyDict_GetItem(dict, ob_name);
+    if (props == nullptr)
+        Py_RETURN_NONE;
+    return _GetSignature_Cached(props, PyName::method(), modifier);
+}
+
+////////////////////////////////////////////////////////////////////////////
+//
+// get_signature  --  providing a superior interface
+//
+// Additional to the interface via `__signature__`, we also provide
+// a general function, which allows for different signature layouts.
+// The `modifier` argument is a string that is passed in from `loader.py`.
+// Configuration what the modifiers mean is completely in Python.
+//
+
+PyObject *get_signature_intern(PyObject *ob, PyObject *modifier)
+{
+    if (PyType_IsSubtype(Py_TYPE(ob), &PyCFunction_Type))
+        return pyside_cf_get___signature__(ob, modifier);
+    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
+        return pyside_sm_get___signature__(ob, modifier);
+    if (Py_TYPE(ob) == PepMethodDescr_TypePtr)
+        return pyside_md_get___signature__(ob, modifier);
+    if (PyType_Check(ob))
+        return pyside_tp_get___signature__(ob, modifier);
+    if (Py_TYPE(ob) == &PyWrapperDescr_Type)
+        return pyside_wd_get___signature__(ob, modifier);
+    return nullptr;
+}
+
+static PyObject *get_signature(PyObject * /* self */, PyObject *args)
+{
+    PyObject *ob;
+    PyObject *modifier = nullptr;
+
+    init_module_1();
+
+    if (!PyArg_ParseTuple(args, "O|O", &ob, &modifier))
+        return nullptr;
+    if (Py_TYPE(ob) == PepFunction_TypePtr)
+        Py_RETURN_NONE;
+    PyObject *ret = get_signature_intern(ob, modifier);
+    if (ret != nullptr)
+        return ret;
+    Py_RETURN_NONE;
+}
+
+PyMethodDef signature_methods[] = {
+    {"get_signature", (PyCFunction)get_signature, METH_VARARGS,
+        "get the __signature__, but pass an optional string parameter"},
+    {nullptr, nullptr}
+};
+
+////////////////////////////////////////////////////////////////////////////
+//
+// Argument Handling
+// -----------------
+//
+// * PySide_BuildSignatureArgs
+//
+// Called during class or module initialization.
+// The signature strings from the C modules are stored in a dict for
+// later use.
+//
+// * PySide_BuildSignatureProps
+//
+// Called on demand during signature retieval. This function calls all the way
+// through `parser.py` and prepares all properties for the functions of the class.
+// The parsed properties can then be used to create signature objects.
+//
+
+static int PySide_BuildSignatureArgs(PyObject *obtype_mod, const char *signatures[])
+{
+    init_module_1();
+    AutoDecRef type_key(GetTypeKey(obtype_mod));
+    /*
+     * PYSIDE-996: Avoid string overflow in MSVC, which has a limit of
+     * 2**15 unicode characters (64 K memory).
+     * Instead of one huge string, we take a ssize_t that is the
+     * address of a string array. It will not be turned into a real
+     * string list until really used by Python. This is quite optimal.
+     */
+    AutoDecRef numkey(Py_BuildValue("n", signatures));
+    if (type_key.isNull() || numkey.isNull()
+        || PyDict_SetItem(pyside_globals->arg_dict, type_key, numkey) < 0)
+        return -1;
+    /*
+     * We record also a mapping from type key to type/module. This helps to
+     * lazily initialize the Py_LIMITED_API in name_key_to_func().
+     */
+    return PyDict_SetItem(pyside_globals->map_dict, type_key, obtype_mod) == 0 ? 0 : -1;
+}
+
+PyObject *PySide_BuildSignatureProps(PyObject *type_key)
+{
+    /*
+     * Here is the second part of the function.
+     * This part will be called on-demand when needed by some attribute.
+     * We simply pick up the arguments that we stored here and replace
+     * them by the function result.
+     */
+    init_module_2();
+    if (type_key == nullptr)
+        return nullptr;
+    PyObject *numkey = PyDict_GetItem(pyside_globals->arg_dict, type_key);
+    AutoDecRef strings(_address_to_stringlist(numkey));
+    if (strings.isNull())
+        return nullptr;
+    AutoDecRef arg_tup(Py_BuildValue("(OO)", type_key, strings.object()));
+    if (arg_tup.isNull())
+        return nullptr;
+    PyObject *dict = PyObject_CallObject(pyside_globals->pyside_type_init_func, arg_tup);
+    if (dict == nullptr) {
+        if (PyErr_Occurred())
+            return nullptr;
+        // No error: return an empty dict.
+        if (empty_dict == nullptr)
+            empty_dict = PyDict_New();
+        return empty_dict;
+    }
+    // We replace the arguments by the result dict.
+    if (PyDict_SetItem(pyside_globals->arg_dict, type_key, dict) < 0)
+        return nullptr;
+    return dict;
+}
+//
+////////////////////////////////////////////////////////////////////////////
+
+static int PySide_FinishSignatures(PyObject *module, const char *signatures[])
+{
+    /*
+     * Initialization of module functions and resolving of static methods.
+     */
+    const char *name = PyModule_GetName(module);
+    if (name == nullptr)
+        return -1;
+
+    // we abuse the call for types, since they both have a __name__ attribute.
+    if (PySide_BuildSignatureArgs(module, signatures) < 0)
+        return -1;
+
+    /*
+     * Note: This function crashed when called from PySide_BuildSignatureArgs.
+     * Probably this was an import timing problem.
+     *
+     * Pep384: We need to switch this always on since we have no access
+     * to the PyCFunction attributes. Therefore I simplified things
+     * and always use our own mapping.
+     */
+    PyObject *key, *func, *obdict = PyModule_GetDict(module);
+    Py_ssize_t pos = 0;
+
+    while (PyDict_Next(obdict, &pos, &key, &func))
+        if (PyCFunction_Check(func))
+            if (PyDict_SetItem(pyside_globals->map_dict, func, module) < 0)
+                return -1;
+    if (_finish_nested_classes(obdict) < 0)
+        return -1;
+    // The finish_import function will not work the first time since phase 2
+    // was not yet run. But that is ok, because the first import is always for
+    // the shiboken module (or a test module).
+    if (pyside_globals->finish_import_func == nullptr) {
+        assert(strncmp(name, "PySide2.", 8) != 0);
+        return 0;
+    }
+    AutoDecRef ret(PyObject_CallFunction(
+        pyside_globals->finish_import_func, const_cast<char *>("(O)"), module));
+    return ret.isNull() ? -1 : 0;
+}
+
+////////////////////////////////////////////////////////////////////////////
+//
+// External functions interface
+//
+// These are exactly the supported functions from `signature.h`.
+//
+
+int InitSignatureStrings(PyTypeObject *type, const char *signatures[])
+{
+    auto *ob_type = reinterpret_cast<PyObject *>(type);
+    int ret = PySide_BuildSignatureArgs(ob_type, signatures);
+    if (ret < 0) {
+        PyErr_Print();
+        PyErr_SetNone(PyExc_ImportError);
+    }
+    return ret;
+}
+
+void FinishSignatureInitialization(PyObject *module, const char *signatures[])
+{
+    /*
+     * This function is called at the very end of a module initialization.
+     * We now patch certain types to support the __signature__ attribute,
+     * initialize module functions and resolve static methods.
+     *
+     * Still, it is not possible to call init phase 2 from here,
+     * because the import is still running. Do it from Python!
+     */
+    if (   PySide_PatchTypes() < 0
+        || PySide_FinishSignatures(module, signatures) < 0) {
+        PyErr_Print();
+        PyErr_SetNone(PyExc_ImportError);
+    }
+}
+
+void SetError_Argument(PyObject *args, const char *func_name)
+{
+    /*
+     * This function replaces the type error construction with extra
+     * overloads parameter in favor of using the signature module.
+     * Error messages are rare, so we do it completely in Python.
+     */
+    init_module_1();
+    init_module_2();
+    AutoDecRef res(PyObject_CallFunction(pyside_globals->seterror_argument_func,
+                                         const_cast<char *>("(Os)"), args, func_name));
+    if (res.isNull()) {
+        PyErr_Print();
+        Py_FatalError("seterror_argument did not receive a result");
+    }
+    PyObject *err, *msg;
+    if (!PyArg_UnpackTuple(res, func_name, 2, 2, &err, &msg)) {
+        PyErr_Print();
+        Py_FatalError("unexpected failure in seterror_argument");
+    }
+    PyErr_SetObject(err, msg);
+}
+
+/*
+ * Support for the metatype SbkObjectType_Type's tp_getset.
+ *
+ * This was not necessary for __signature__, because PyType_Type inherited it.
+ * But the __doc__ attribute existed already by inheritance, and calling
+ * PyType_Modified() is not supported. So we added the getsets explicitly
+ * to the metatype.
+ */
+
+PyObject *Sbk_TypeGet___signature__(PyObject *ob, PyObject *modifier)
+{
+    return pyside_tp_get___signature__(ob, modifier);
+}
+
+PyObject *Sbk_TypeGet___doc__(PyObject *ob)
+{
+    return pyside_tp_get___doc__(ob);
+}
+
+PyObject *GetFeatureDict()
+{
+    init_module_1();
+    return pyside_globals->feature_dict;
+}
+
+} //extern "C"
diff --git a/sources/shiboken2/libshiboken/signature_doc.rst b/sources/shiboken2/libshiboken/signature/signature_doc.rst
index cb9041d0c..f3dc652b6 100644
--- a/sources/shiboken2/libshiboken/signature_doc.rst
+++ b/sources/shiboken2/libshiboken/signature/signature_doc.rst
@@ -73,7 +73,7 @@ It calls ``GetSignature_Function`` which returns the signature if it is found.
 Why this Code is Fast
 ---------------------
 
-It costs a little time (maybe 6 seconds) to run througs every single signature
+It costs a little time (maybe 6 seconds) to run through every single signature
 object, since these are more than 25000 Python objects. But all the signature
 objects will be rarely accessed but in special applications.
 The normal case are only a few accesses, and these are working pretty fast.
diff --git a/sources/shiboken2/libshiboken/signature/signature_extend.cpp b/sources/shiboken2/libshiboken/signature/signature_extend.cpp
new file mode 100644
index 000000000..1490a6003
--- /dev/null
+++ b/sources/shiboken2/libshiboken/signature/signature_extend.cpp
@@ -0,0 +1,294 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+////////////////////////////////////////////////////////////////////////////
+//
+// signature_extend.cpp
+// --------------------
+//
+// This file contains the additions and changes to the following
+// Python types:
+//
+//     PyMethodDescr_Type
+//     PyCFunction_Type
+//     PyStaticMethod_Type
+//     PyType_Type
+//     PyWrapperDescr_Type
+//
+// Their `tp_getset` fields are modified so support the `__signature__`
+// attribute and additions to the `__doc__` attribute.
+//
+
+#include "autodecref.h"
+#include "sbkstring.h"
+#include "sbkstaticstrings.h"
+#include "sbkstaticstrings_p.h"
+
+#include "signature_p.h"
+
+using namespace Shiboken;
+
+extern "C" {
+
+typedef PyObject *(*signaturefunc)(PyObject *, PyObject *);
+
+static PyObject *_get_written_signature(signaturefunc sf, PyObject *ob, PyObject *modifier)
+{
+    /*
+     * Be a writable Attribute, but have a computed value.
+     *
+     * If a signature has not been written, call the signature function.
+     * If it has been written, return the written value.
+     * After __del__ was called, the function value re-appears.
+     *
+     * Note: This serves also for the new version that does not allow any
+     * assignment if we have a computed value. We only need to check if
+     * a computed value exists and then forbid writing.
+     * See pyside_set___signature
+     */
+    PyObject *ret = PyDict_GetItem(pyside_globals->value_dict, ob);
+    if (ret == nullptr)
+        return ob == nullptr ? nullptr : sf(ob, modifier);
+    Py_INCREF(ret);
+    return ret;
+}
+
+PyObject *pyside_cf_get___signature__(PyObject *func, PyObject *modifier)
+{
+    init_module_2();
+    return _get_written_signature(GetSignature_Function, func, modifier);
+}
+
+PyObject *pyside_sm_get___signature__(PyObject *sm, PyObject *modifier)
+{
+    init_module_2();
+    AutoDecRef func(PyObject_GetAttr(sm, PyMagicName::func()));
+    if (Py_TYPE(func) == PepFunction_TypePtr)
+        return PyObject_GetAttr(func, PyMagicName::signature());
+    return _get_written_signature(GetSignature_Function, func, modifier);
+}
+
+PyObject *pyside_md_get___signature__(PyObject *ob_md, PyObject *modifier)
+{
+    init_module_2();
+    AutoDecRef func(name_key_to_func(ob_md));
+    if (func.object() == Py_None)
+        return Py_None;
+    if (func.isNull())
+        Py_FatalError("missing mapping in MethodDescriptor");
+    return pyside_cf_get___signature__(func, modifier);
+}
+
+PyObject *pyside_wd_get___signature__(PyObject *ob, PyObject *modifier)
+{
+    init_module_2();
+    return _get_written_signature(GetSignature_Wrapper, ob, modifier);
+}
+
+PyObject *pyside_tp_get___signature__(PyObject *obtype_mod, PyObject *modifier)
+{
+    init_module_2();
+    return _get_written_signature(GetSignature_TypeMod, obtype_mod, modifier);
+}
+
+////////////////////////////////////////////////////////////////////////////
+//
+// Augmenting builtin types with a __signature__ attribute.
+//
+// This is a harmless change to Python, similar like __text_signature__.
+// We could avoid it, but then we would need to copy quite some module
+// initialization functions which are pretty version- and word size
+// dependent. I think this little patch is the lesser of the two evils.
+//
+// Please note that in fact we are modifying 'type', the metaclass of all
+// objects, because we add new functionality.
+//
+// Addendum 2019-01-12: We now also compute a docstring from the signature.
+//
+
+// keep the original __doc__ functions
+static PyObject *old_cf_doc_descr = nullptr;
+static PyObject *old_sm_doc_descr = nullptr;
+static PyObject *old_md_doc_descr = nullptr;
+static PyObject *old_tp_doc_descr = nullptr;
+static PyObject *old_wd_doc_descr = nullptr;
+
+static int handle_doc_in_progress = 0;
+
+static PyObject *handle_doc(PyObject *ob, PyObject *old_descr)
+{
+    init_module_1();
+    init_module_2();
+    AutoDecRef ob_type_mod(GetClassOrModOf(ob));
+    const char *name;
+    if (PyModule_Check(ob_type_mod))
+        name = PyModule_GetName(ob_type_mod);
+    else
+        name = reinterpret_cast<PyTypeObject *>(ob_type_mod.object())->tp_name;
+    if (handle_doc_in_progress || name == nullptr
+        || strncmp(name, "PySide2.", 8) != 0)
+        return PyObject_CallMethodObjArgs(old_descr,
+                                          PyMagicName::get(),
+                                          ob, nullptr);
+    handle_doc_in_progress++;
+    PyObject *res = PyObject_CallFunction(
+                        pyside_globals->make_helptext_func,
+                        const_cast<char *>("(O)"), ob);
+    handle_doc_in_progress--;
+    if (res == nullptr) {
+        PyErr_Print();
+        Py_FatalError("handle_doc did not receive a result");
+    }
+    return res;
+}
+
+static PyObject *pyside_cf_get___doc__(PyObject *cf)
+{
+    return handle_doc(cf, old_cf_doc_descr);
+}
+
+static PyObject *pyside_sm_get___doc__(PyObject *sm)
+{
+    return handle_doc(sm, old_sm_doc_descr);
+}
+
+static PyObject *pyside_md_get___doc__(PyObject *md)
+{
+    return handle_doc(md, old_md_doc_descr);
+}
+
+PyObject *pyside_tp_get___doc__(PyObject *tp)
+{
+    return handle_doc(tp, old_tp_doc_descr);
+}
+
+static PyObject *pyside_wd_get___doc__(PyObject *wd)
+{
+    return handle_doc(wd, old_wd_doc_descr);
+}
+
+// the default setter for all objects
+static int pyside_set___signature__(PyObject *op, PyObject *value)
+{
+    // By this additional check, this function refuses write access.
+    // We consider both nullptr and Py_None as not been written.
+    AutoDecRef has_val(get_signature_intern(op, nullptr));
+    if (!(has_val.isNull() || has_val == Py_None)) {
+        PyErr_Format(PyExc_AttributeError,
+                     "Attribute '__signature__' of '%.50s' object is not writable",
+                     Py_TYPE(op)->tp_name);
+        return -1;
+    }
+    int ret = value == nullptr ? PyDict_DelItem(pyside_globals->value_dict, op)
+                               : PyDict_SetItem(pyside_globals->value_dict, op, value);
+    Py_XINCREF(value);
+    return ret;
+}
+
+static PyGetSetDef new_PyCFunction_getsets[] = {
+    {const_cast<char *>("__doc__"), (getter)pyside_cf_get___doc__},
+    {const_cast<char *>("__signature__"), (getter)pyside_cf_get___signature__,
+                                          (setter)pyside_set___signature__},
+    {nullptr}
+};
+
+static PyGetSetDef new_PyStaticMethod_getsets[] = {
+    {const_cast<char *>("__doc__"), (getter)pyside_sm_get___doc__},
+    {const_cast<char *>("__signature__"), (getter)pyside_sm_get___signature__,
+                                          (setter)pyside_set___signature__},
+    {nullptr}
+};
+
+static PyGetSetDef new_PyMethodDescr_getsets[] = {
+    {const_cast<char *>("__doc__"), (getter)pyside_md_get___doc__},
+    {const_cast<char *>("__signature__"), (getter)pyside_md_get___signature__,
+                                          (setter)pyside_set___signature__},
+    {nullptr}
+};
+
+static PyGetSetDef new_PyType_getsets[] = {
+    {const_cast<char *>("__doc__"), (getter)pyside_tp_get___doc__},
+    {const_cast<char *>("__signature__"), (getter)pyside_tp_get___signature__,
+                                          (setter)pyside_set___signature__},
+    {nullptr}
+};
+
+static PyGetSetDef new_PyWrapperDescr_getsets[] = {
+    {const_cast<char *>("__doc__"), (getter)pyside_wd_get___doc__},
+    {const_cast<char *>("__signature__"), (getter)pyside_wd_get___signature__,
+                                          (setter)pyside_set___signature__},
+    {nullptr}
+};
+
+int PySide_PatchTypes(void)
+{
+    static int init_done = 0;
+
+    if (!init_done) {
+        AutoDecRef meth_descr(PyObject_GetAttrString(
+                                    reinterpret_cast<PyObject *>(&PyString_Type), "split"));
+        AutoDecRef wrap_descr(PyObject_GetAttrString(
+                                    reinterpret_cast<PyObject *>(Py_TYPE(Py_True)), "__add__"));
+        // abbreviations for readability
+        auto md_gs = new_PyMethodDescr_getsets;
+        auto md_doc = &old_md_doc_descr;
+        auto cf_gs = new_PyCFunction_getsets;
+        auto cf_doc = &old_cf_doc_descr;
+        auto sm_gs = new_PyStaticMethod_getsets;
+        auto sm_doc = &old_sm_doc_descr;
+        auto tp_gs = new_PyType_getsets;
+        auto tp_doc = &old_tp_doc_descr;
+        auto wd_gs = new_PyWrapperDescr_getsets;
+        auto wd_doc = &old_wd_doc_descr;
+
+        if (meth_descr.isNull() || wrap_descr.isNull()
+            || PyType_Ready(Py_TYPE(meth_descr)) < 0
+            || add_more_getsets(PepMethodDescr_TypePtr,  md_gs, md_doc) < 0
+            || add_more_getsets(&PyCFunction_Type,       cf_gs, cf_doc) < 0
+            || add_more_getsets(PepStaticMethod_TypePtr, sm_gs, sm_doc) < 0
+            || add_more_getsets(&PyType_Type,            tp_gs, tp_doc) < 0
+            || add_more_getsets(Py_TYPE(wrap_descr),     wd_gs, wd_doc) < 0
+            )
+            return -1;
+        init_done = 1;
+    }
+    return 0;
+}
+
+} // extern "C"
diff --git a/sources/shiboken2/libshiboken/signature/signature_globals.cpp b/sources/shiboken2/libshiboken/signature/signature_globals.cpp
new file mode 100644
index 000000000..6af64682e
--- /dev/null
+++ b/sources/shiboken2/libshiboken/signature/signature_globals.cpp
@@ -0,0 +1,295 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+////////////////////////////////////////////////////////////////////////////
+//
+// signature_global.cpp
+//
+// This file contains the global data structures and init code.
+//
+
+#include "autodecref.h"
+#include "sbkstring.h"
+#include "sbkstaticstrings.h"
+#include "sbkstaticstrings_p.h"
+
+#include "signature_p.h"
+
+using namespace Shiboken;
+
+extern "C" {
+
+static const char *PySide_CompressedSignaturePackage[] = {
+#include "embed/signature_inc.h"
+    };
+
+static const unsigned char PySide_SignatureLoader[] = {
+#include "embed/signature_bootstrap_inc.h"
+    };
+
+static PyObject *_init_pyside_extension(PyObject * /* self */, PyObject * /* args */)
+{
+    init_module_1();
+    init_module_2();
+    Py_RETURN_NONE;
+}
+
+// This function will be inserted into __builtins__.
+static PyMethodDef init_methods[] = {
+    {"_init_pyside_extension", (PyCFunction)_init_pyside_extension, METH_NOARGS},
+    {nullptr, nullptr}
+};
+
+static safe_globals_struc *init_phase_1(PyMethodDef *init_meth)
+{
+    {
+        auto *p = reinterpret_cast<safe_globals_struc *>
+                                    (malloc(sizeof(safe_globals_struc)));
+        if (p == nullptr)
+            goto error;
+        /*
+         * Initializing module signature_bootstrap.
+         * Since we now have an embedding script, we can do this without any
+         * Python strings in the C code.
+         */
+#ifdef Py_LIMITED_API
+        // We must work for multiple versions, so use source code.
+#else
+        AutoDecRef marshal_module(PyImport_Import(PyName::marshal()));
+        if (marshal_module.isNull())
+            goto error;
+        AutoDecRef loads(PyObject_GetAttr(marshal_module, PyName::loads()));
+        if (loads.isNull())
+            goto error;
+#endif
+        char *bytes_cast = reinterpret_cast<char *>(
+                                       const_cast<unsigned char *>(PySide_SignatureLoader));
+        AutoDecRef bytes(PyBytes_FromStringAndSize(bytes_cast, sizeof(PySide_SignatureLoader)));
+        if (bytes.isNull())
+            goto error;
+#ifdef Py_LIMITED_API
+        PyObject *builtins = PyEval_GetBuiltins();
+        PyObject *compile = PyDict_GetItem(builtins, PyName::compile());
+        if (compile == nullptr)
+            goto error;
+        AutoDecRef code_obj(PyObject_CallFunction(compile, "Oss",
+                                bytes.object(), "(builtin)", "exec"));
+#else
+        AutoDecRef code_obj(PyObject_CallFunctionObjArgs(
+                                loads, bytes.object(), nullptr));
+#endif
+        if (code_obj.isNull())
+            goto error;
+        p->helper_module = PyImport_ExecCodeModule(const_cast<char *>
+                                                       ("signature_bootstrap"), code_obj);
+        if (p->helper_module == nullptr)
+            goto error;
+        // Initialize the module
+        PyObject *mdict = PyModule_GetDict(p->helper_module);
+        if (PyDict_SetItem(mdict, PyMagicName::builtins(), PyEval_GetBuiltins()) < 0)
+            goto error;
+        /*
+         * Unpack an embedded ZIP file with more signature modules.
+         * They will be loaded later with the zipimporter.
+         * Due to MSVC's limitation to 64k strings, we need to assemble pieces.
+         */
+        const char **block_ptr = (const char **)PySide_CompressedSignaturePackage;
+        int npieces = 0;
+        PyObject *piece, *zipped_string_sequence = PyList_New(0);
+        if (zipped_string_sequence == nullptr)
+            return nullptr;
+        for (; **block_ptr != 0; ++block_ptr) {
+            npieces++;
+            // we avoid the string/unicode dilemma by not using PyString_XXX:
+            piece = Py_BuildValue("s", *block_ptr);
+            if (piece == nullptr || PyList_Append(zipped_string_sequence, piece) < 0)
+                goto error;
+        }
+        if (PyDict_SetItemString(mdict, "zipstring_sequence", zipped_string_sequence) < 0)
+            goto error;
+        Py_DECREF(zipped_string_sequence);
+
+        // build a dict for diverse mappings
+        p->map_dict = PyDict_New();
+        if (p->map_dict == nullptr)
+            goto error;
+
+        // build a dict for the prepared arguments
+        p->arg_dict = PyDict_New();
+        if (p->arg_dict == nullptr
+            || PyObject_SetAttrString(p->helper_module, "pyside_arg_dict", p->arg_dict) < 0)
+            goto error;
+
+        // build a dict for assigned signature values
+        p->value_dict = PyDict_New();
+        if (p->value_dict == nullptr)
+            goto error;
+
+        // PYSIDE-1019: build a __feature__ dict
+        p->feature_dict = PyDict_New();
+        if (p->feature_dict == nullptr
+            || PyObject_SetAttrString(p->helper_module, "pyside_feature_dict", p->feature_dict) < 0)
+            goto error;
+
+        // This function will be disabled until phase 2 is done.
+        p->finish_import_func = nullptr;
+
+        // Initialize the explicit init function.
+        AutoDecRef init(PyCFunction_NewEx(init_meth, nullptr, nullptr));
+        if (init.isNull()
+            || PyDict_SetItemString(PyEval_GetBuiltins(), init_meth->ml_name, init) != 0)
+            goto error;
+
+        return p;
+    }
+error:
+    PyErr_Print();
+    Py_FatalError("could not initialize part 1");
+    return nullptr;
+}
+
+static int init_phase_2(safe_globals_struc *p, PyMethodDef *methods)
+{
+    {
+        PyMethodDef *ml;
+
+        // The single function to be called, but maybe more to come.
+        for (ml = methods; ml->ml_name != nullptr; ml++) {
+            PyObject *v = PyCFunction_NewEx(ml, nullptr, nullptr);
+            if (v == nullptr
+                || PyObject_SetAttrString(p->helper_module, ml->ml_name, v) != 0)
+                goto error;
+            Py_DECREF(v);
+        }
+        PyObject *bootstrap_func = PyObject_GetAttrString(p->helper_module, "bootstrap");
+        if (bootstrap_func == nullptr)
+            goto error;
+        // The return value of the bootstrap function is the loader module.
+        PyObject *loader = PyObject_CallFunction(bootstrap_func, const_cast<char *>("()"));
+        if (loader == nullptr)
+            goto error;
+        // now the loader should be initialized
+        p->pyside_type_init_func = PyObject_GetAttrString(loader, "pyside_type_init");
+        if (p->pyside_type_init_func == nullptr)
+            goto error;
+        p->create_signature_func = PyObject_GetAttrString(loader, "create_signature");
+        if (p->create_signature_func == nullptr)
+            goto error;
+        p->seterror_argument_func = PyObject_GetAttrString(loader, "seterror_argument");
+        if (p->seterror_argument_func == nullptr)
+            goto error;
+        p->make_helptext_func = PyObject_GetAttrString(loader, "make_helptext");
+        if (p->make_helptext_func == nullptr)
+            goto error;
+        p->finish_import_func = PyObject_GetAttrString(loader, "finish_import");
+        if (p->finish_import_func == nullptr)
+            goto error;
+        return 0;
+    }
+error:
+    PyErr_Print();
+    Py_FatalError("could not initialize part 2");
+    return -1;
+}
+
+#ifndef _WIN32
+////////////////////////////////////////////////////////////////////////////
+// a stack trace for linux-like platforms
+#include <stdio.h>
+#if defined(__GLIBC__)
+#  include <execinfo.h>
+#endif
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static void handler(int sig) {
+#if defined(__GLIBC__)
+    void *array[30];
+    size_t size;
+
+    // get void *'s for all entries on the stack
+    size = backtrace(array, 30);
+
+    // print out all the frames to stderr
+#endif
+    fprintf(stderr, "Error: signal %d:\n", sig);
+#if defined(__GLIBC__)
+    backtrace_symbols_fd(array, size, STDERR_FILENO);
+#endif
+    exit(1);
+}
+
+////////////////////////////////////////////////////////////////////////////
+#endif // _WIN32
+
+safe_globals pyside_globals = nullptr;
+
+void init_module_1(void)
+{
+    static int init_done = 0;
+
+    if (!init_done) {
+        pyside_globals = init_phase_1(init_methods);
+        if (pyside_globals != nullptr)
+            init_done = 1;
+
+#ifndef _WIN32
+        // We enable the stack trace in CI, only.
+        const char *testEnv = getenv("QTEST_ENVIRONMENT");
+        if (testEnv && strstr(testEnv, "ci"))
+            signal(SIGSEGV, handler);   // install our handler
+#endif // _WIN32
+
+    }
+}
+
+void init_module_2(void)
+{
+    static int init_done = 0;
+
+    if (!init_done) {
+        // Phase 2 will call __init__.py which touches a signature, itself.
+        // Therefore we set init_done prior to init_phase_2().
+        init_done = 1;
+        init_phase_2(pyside_globals, signature_methods);
+    }
+}
+
+} // extern "C"
diff --git a/sources/shiboken2/libshiboken/signature/signature_helper.cpp b/sources/shiboken2/libshiboken/signature/signature_helper.cpp
new file mode 100644
index 000000000..7e92a9861
--- /dev/null
+++ b/sources/shiboken2/libshiboken/signature/signature_helper.cpp
@@ -0,0 +1,364 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+////////////////////////////////////////////////////////////////////////////
+//
+// signature_helper.cpp
+// --------------------
+//
+// This file contains assoerted helper functions that are needed,
+// but it is not helpful to see them all the time.
+//
+
+#include "autodecref.h"
+#include "sbkstring.h"
+#include "sbkstaticstrings.h"
+#include "sbkstaticstrings_p.h"
+
+#include "signature_p.h"
+
+using namespace Shiboken;
+
+extern "C" {
+
+// Helper for __qualname__ which might not always exist in Python 2 (type).
+PyObject *_get_qualname(PyObject *ob)
+{
+    // We support __qualname__ for types, only.
+    assert(PyType_Check(ob));
+    PyObject *name = PyObject_GetAttr(ob, PyMagicName::qualname());
+    if (name == nullptr) {
+        PyErr_Clear();
+        name = PyObject_GetAttr(ob, PyMagicName::name());
+    }
+    return name;
+}
+
+static int _fixup_getset(PyTypeObject *type, const char *name, PyGetSetDef *new_gsp)
+{
+    /*
+     * This function pre-fills all fields of the new gsp. We then
+     * insert the changed values.
+     */
+    PyGetSetDef *gsp = type->tp_getset;
+    if (gsp != nullptr) {
+        for (; gsp->name != nullptr; gsp++) {
+            if (strcmp(gsp->name, name) == 0) {
+                new_gsp->set = gsp->set;
+                new_gsp->doc = gsp->doc;
+                new_gsp->closure = gsp->closure;
+                return 1;  // success
+            }
+        }
+    }
+    PyMemberDef *md = type->tp_members;
+    if (md != nullptr)
+        for (; md->name != nullptr; md++)
+            if (strcmp(md->name, name) == 0)
+                return 1;
+    // staticmethod has just a `__doc__` in the class
+    assert(strcmp(type->tp_name, "staticmethod") == 0 && strcmp(name, "__doc__") == 0);
+    return 0;
+}
+
+int add_more_getsets(PyTypeObject *type, PyGetSetDef *gsp, PyObject **doc_descr)
+{
+    /*
+     * This function is used to assign a new `__signature__` attribute,
+     * and also to override a `__doc__` or `__name__` attribute.
+     */
+    assert(PyType_Check(type));
+    PyType_Ready(type);
+    PyObject *dict = type->tp_dict;
+    for (; gsp->name != nullptr; gsp++) {
+        PyObject *have_descr = PyDict_GetItemString(dict, gsp->name);
+        if (have_descr != nullptr) {
+            Py_INCREF(have_descr);
+            if (strcmp(gsp->name, "__doc__") == 0)
+                *doc_descr = have_descr;
+            else
+                assert(false);
+            if (!_fixup_getset(type, gsp->name, gsp))
+                continue;
+        }
+        AutoDecRef descr(PyDescr_NewGetSet(type, gsp));
+        if (descr.isNull())
+            return -1;
+        if (PyDict_SetItemString(dict, gsp->name, descr) < 0)
+            return -1;
+    }
+    PyType_Modified(type);
+    return 0;
+}
+
+static PyObject *get_funcname(PyObject *ob)
+{
+    PyObject *func = ob;
+    if (Py_TYPE(ob) == PepStaticMethod_TypePtr)
+        func = PyObject_GetAttr(ob, PyMagicName::func());
+    else
+        Py_INCREF(func);
+    PyObject *func_name = PyObject_GetAttr(func, PyMagicName::name());
+    Py_DECREF(func);
+    if (func_name == nullptr)
+        Py_FatalError("unexpected name problem in compute_name_key");
+    return func_name;
+}
+
+static PyObject *compute_name_key(PyObject *ob)
+{
+    if (PyType_Check(ob))
+        return GetTypeKey(ob);
+    AutoDecRef func_name(get_funcname(ob));
+    AutoDecRef type_key(GetTypeKey(GetClassOrModOf(ob)));
+    return Py_BuildValue("(OO)", type_key.object(), func_name.object());
+}
+
+static int build_name_key_to_func(PyObject *obtype)
+{
+    auto *type = reinterpret_cast<PyTypeObject *>(obtype);
+    PyMethodDef *meth = type->tp_methods;
+
+    if (meth == nullptr)
+        return 0;
+
+    AutoDecRef type_key(GetTypeKey(obtype));
+    for (; meth->ml_name != nullptr; meth++) {
+        AutoDecRef func(PyCFunction_NewEx(meth, obtype, nullptr));
+        AutoDecRef func_name(get_funcname(func));
+        AutoDecRef name_key(Py_BuildValue("(OO)", type_key.object(), func_name.object()));
+        if (func.isNull() || name_key.isNull()
+            || PyDict_SetItem(pyside_globals->map_dict, name_key, func) < 0)
+            return -1;
+    }
+    return 0;
+}
+
+PyObject *name_key_to_func(PyObject *ob)
+{
+    /*
+     * We build a mapping from name_key to function.
+     * This could also be computed directly, but the Limited API
+     * makes this impossible. So we always build our own mapping.
+     */
+    AutoDecRef name_key(compute_name_key(ob));
+    if (name_key.isNull())
+        Py_RETURN_NONE;
+
+    PyObject *ret = PyDict_GetItem(pyside_globals->map_dict, name_key);
+    if (ret == nullptr) {
+        // do a lazy initialization
+        AutoDecRef type_key(GetTypeKey(GetClassOrModOf(ob)));
+        PyObject *type = PyDict_GetItem(pyside_globals->map_dict,
+                                        type_key);
+        if (type == nullptr)
+            Py_RETURN_NONE;
+        assert(PyType_Check(type));
+        if (build_name_key_to_func(type) < 0)
+            return nullptr;
+        ret = PyDict_GetItem(pyside_globals->map_dict, name_key);
+    }
+    Py_XINCREF(ret);
+    return ret;
+}
+
+PyObject *_get_class_of_cf(PyObject *ob_cf)
+{
+    PyObject *selftype = PyCFunction_GET_SELF(ob_cf);
+    if (selftype == nullptr) {
+        selftype = PyDict_GetItem(pyside_globals->map_dict, ob_cf);
+        if (selftype == nullptr) {
+            // This must be an overloaded function that we handled special.
+            AutoDecRef special(Py_BuildValue("(OO)", ob_cf, PyName::overload()));
+            selftype = PyDict_GetItem(pyside_globals->map_dict, special);
+            if (selftype == nullptr) {
+                // This is probably a module function. We will return type(None).
+                selftype = Py_None;
+            }
+        }
+    }
+
+    PyObject *obtype_mod = (PyType_Check(selftype) || PyModule_Check(selftype))
+                           ? selftype
+                           : reinterpret_cast<PyObject *>(Py_TYPE(selftype));
+    Py_INCREF(obtype_mod);
+    return obtype_mod;
+}
+
+PyObject *_get_class_of_sm(PyObject *ob_sm)
+{
+    AutoDecRef func(PyObject_GetAttr(ob_sm, PyMagicName::func()));
+    return _get_class_of_cf(func);
+}
+
+PyObject *_get_class_of_descr(PyObject *ob)
+{
+    return PyObject_GetAttr(ob, PyMagicName::objclass());
+}
+
+PyObject *_address_to_stringlist(PyObject *numkey)
+{
+    /*
+     * This is a tiny optimization that saves initialization time.
+     * Instead of creating all Python strings during the call to
+     * `PySide_BuildSignatureArgs`, we store the address of the stringlist.
+     * When needed in `PySide_BuildSignatureProps`, the strings are
+     * finally materialized.
+     */
+    ssize_t address = PyNumber_AsSsize_t(numkey, PyExc_ValueError);
+    if (address == -1 && PyErr_Occurred())
+        return nullptr;
+    char **sig_strings = reinterpret_cast<char **>(address);
+    PyObject *res_list = PyList_New(0);
+    if (res_list == nullptr)
+        return nullptr;
+    for (; *sig_strings != nullptr; ++sig_strings) {
+        char *sig_str = *sig_strings;
+        AutoDecRef pystr(Py_BuildValue("s", sig_str));
+        if (pystr.isNull() || PyList_Append(res_list, pystr) < 0)
+            return nullptr;
+    }
+    return res_list;
+}
+
+static int _build_func_to_type(PyObject *obtype)
+{
+    /*
+     * There is no general way to directly get the type of a static method.
+     * On Python 3, the type is hidden in an unused pointer in the
+     * PyCFunction structure, but the Limited API does not allow to access
+     * this, either.
+     *
+     * In the end, it was easier to avoid such tricks and build an explicit
+     * mapping from function to type.
+     *
+     * We walk through the method list of the type
+     * and record the mapping from static method to this type in a dict.
+     * We also check for hidden methods, see below.
+     */
+    auto *type = reinterpret_cast<PyTypeObject *>(obtype);
+    PyObject *dict = type->tp_dict;
+    PyMethodDef *meth = type->tp_methods;
+
+    if (meth == nullptr)
+        return 0;
+
+    for (; meth->ml_name != nullptr; meth++) {
+        /*
+         * It is possible that a method is overwritten by another
+         * attribute with the same name. This case was obviously provoked
+         * explicitly in "testbinding.TestObject.staticMethodDouble",
+         * where instead of the method a "PySide2.QtCore.Signal" object
+         * was in the dict.
+         * This overlap is also found in regular PySide under
+         * "PySide2.QtCore.QProcess.error" where again a signal object is
+         * returned. These hidden methods will be opened for the
+         * signature module by adding them under the name
+         * "{name}.overload".
+         */
+        PyObject *descr = PyDict_GetItemString(dict, meth->ml_name);
+        PyObject *look_attr = meth->ml_flags & METH_STATIC ? PyMagicName::func()
+                                                           : PyMagicName::name();
+        int check_name = meth->ml_flags & METH_STATIC ? 0 : 1;
+        if (descr == nullptr)
+            return -1;
+
+        // We first check all methods if one is hidden by something else.
+        AutoDecRef look(PyObject_GetAttr(descr, look_attr));
+        AutoDecRef given(Py_BuildValue("s", meth->ml_name));
+        if (look.isNull()
+            || (check_name && PyObject_RichCompareBool(look, given, Py_EQ) != 1)) {
+            PyErr_Clear();
+            AutoDecRef cfunc(PyCFunction_NewEx(
+                                meth, reinterpret_cast<PyObject *>(type), nullptr));
+            if (cfunc.isNull())
+                return -1;
+            if (meth->ml_flags & METH_STATIC)
+                descr = PyStaticMethod_New(cfunc);
+            else
+                descr = PyDescr_NewMethod(type, meth);
+            if (descr == nullptr)
+                return -1;
+            char mangled_name[200];
+            strcpy(mangled_name, meth->ml_name);
+            strcat(mangled_name, ".overload");
+            if (PyDict_SetItemString(dict, mangled_name, descr) < 0)
+                return -1;
+            if (meth->ml_flags & METH_STATIC) {
+                // This is the special case where a static method is hidden.
+                AutoDecRef special(Py_BuildValue("(Os)", cfunc.object(), "overload"));
+                if (PyDict_SetItem(pyside_globals->map_dict, special, obtype) < 0)
+                    return -1;
+            }
+            if (PyDict_SetItemString(pyside_globals->map_dict, mangled_name, obtype) < 0)
+                return -1;
+            continue;
+        }
+        // Then we insert the mapping for static methods.
+        if (meth->ml_flags & METH_STATIC) {
+            if (PyDict_SetItem(pyside_globals->map_dict, look, obtype) < 0)
+                return -1;
+        }
+    }
+    return 0;
+}
+
+int _finish_nested_classes(PyObject *obdict)
+{
+    PyObject *key, *value, *obtype;
+    PyTypeObject *subtype;
+    Py_ssize_t pos = 0;
+
+    if (obdict == nullptr)
+        return -1;
+    while (PyDict_Next(obdict, &pos, &key, &value)) {
+        if (PyType_Check(value)) {
+            obtype = value;
+            if (_build_func_to_type(obtype) < 0)
+                return -1;
+            // now continue with nested cases
+            subtype = reinterpret_cast<PyTypeObject *>(obtype);
+            if (_finish_nested_classes(subtype->tp_dict) < 0)
+                return -1;
+        }
+    }
+    return 0;
+}
+
+} // extern "C"
diff --git a/sources/shiboken2/libshiboken/signature/signature_p.h b/sources/shiboken2/libshiboken/signature/signature_p.h
new file mode 100644
index 000000000..9444f3e9b
--- /dev/null
+++ b/sources/shiboken2/libshiboken/signature/signature_p.h
@@ -0,0 +1,106 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SIGNATURE_IMPL_H
+#define SIGNATURE_IMPL_H
+
+#include "signature.h"
+
+extern "C" {
+
+// signature_globals.cpp
+
+typedef struct safe_globals_struc {
+    // init part 1: get arg_dict
+    PyObject *helper_module;
+    PyObject *arg_dict;
+    PyObject *map_dict;
+    PyObject *value_dict;       // for writing signatures
+    PyObject *feature_dict;     // registry for PySide.support.__feature__
+    // init part 2: run module
+    PyObject *pyside_type_init_func;
+    PyObject *create_signature_func;
+    PyObject *seterror_argument_func;
+    PyObject *make_helptext_func;
+    PyObject *finish_import_func;
+} safe_globals_struc, *safe_globals;
+
+extern safe_globals pyside_globals;
+extern PyMethodDef signature_methods[];
+
+void init_module_1(void);
+void init_module_2(void);
+
+// signature.cpp
+
+PyObject *GetTypeKey(PyObject *ob);
+
+PyObject *GetSignature_Function(PyObject *, PyObject *);
+PyObject *GetSignature_TypeMod(PyObject *, PyObject *);
+PyObject *GetSignature_Wrapper(PyObject *, PyObject *);
+
+PyObject *get_signature_intern(PyObject *ob, PyObject *modifier);
+PyObject *PySide_BuildSignatureProps(PyObject *class_mod);
+PyObject *GetClassOrModOf(PyObject *ob);
+
+// signature_extend.cpp
+
+PyObject *pyside_cf_get___signature__(PyObject *func, PyObject *modifier);
+PyObject *pyside_sm_get___signature__(PyObject *sm, PyObject *modifier);
+PyObject *pyside_md_get___signature__(PyObject *ob_md, PyObject *modifier);
+PyObject *pyside_wd_get___signature__(PyObject *ob, PyObject *modifier);
+PyObject *pyside_tp_get___signature__(PyObject *obtype_mod, PyObject *modifier);
+
+int PySide_PatchTypes(void);
+PyObject *pyside_tp_get___doc__(PyObject *tp);
+
+// signature_helper.cpp
+
+PyObject *_get_qualname(PyObject *ob);
+int add_more_getsets(PyTypeObject *type, PyGetSetDef *gsp, PyObject **doc_descr);
+PyObject *name_key_to_func(PyObject *ob);
+PyObject *_get_class_of_cf(PyObject *ob_cf);
+PyObject *_get_class_of_sm(PyObject *ob_sm);
+PyObject *_get_class_of_descr(PyObject *ob);
+PyObject *_address_to_stringlist(PyObject *numkey);
+int _finish_nested_classes(PyObject *dict);
+
+} // extern "C"
+
+#endif // SIGNATURE_IMPL_H