shiboken: Fix __doc__ setter for derived types

This setter makes sure that __doc__ for derived SbkObject types
behaves like a data descriptor.

Change-Id: I4ca1d4a224755304d9a9223b9fd6244af94d981f
Fixes: PYSIDE-1177
Task-number: PYSIDE-908
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

4 files changed, 34 insertions, 3 deletions

diff --git a/sources/shiboken2/libshiboken/basewrapper.cpp b/sources/shiboken2/libshiboken/basewrapper.cpp
index 1960e5932..961c6c739 100644
--- a/sources/shiboken2/libshiboken/basewrapper.cpp
+++ b/sources/shiboken2/libshiboken/basewrapper.cpp
@@ -99,12 +99,38 @@ static SelectableFeatureHook SelectFeatureSet = nullptr;
 
 static PyObject *Sbk_TypeGet___dict__(PyTypeObject *type, void *context);   // forward
 
+static int
+check_set_special_type_attr(PyTypeObject *type, PyObject *value, const char *name)
+{
+    if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
+        PyErr_Format(PyExc_TypeError,
+                     "can't set %s.%s", type->tp_name, name);
+        return 0;
+    }
+    if (!value) {
+        PyErr_Format(PyExc_TypeError,
+                     "can't delete %s.%s", type->tp_name, name);
+        return 0;
+    }
+    return 1;
+}
+
+// PYSIDE-1177: Add a setter to allow setting type doc.
+static int
+type_set_doc(PyTypeObject *type, PyObject *value, void *context)
+{
+    if (!check_set_special_type_attr(type, value, "__doc__"))
+        return -1;
+    PyType_Modified(type);
+    return PyDict_SetItem(type->tp_dict, Shiboken::PyMagicName::doc(), value);
+}
+
 // PYSIDE-908: The function PyType_Modified does not work in PySide, so we need to
 // explicitly pass __doc__. For __signature__ it _did_ actually work, because
 // it was not existing before. We add them both for clarity.
 static PyGetSetDef SbkObjectType_Type_getsetlist[] = {
     {const_cast<char *>("__signature__"), (getter)Sbk_TypeGet___signature__},
-    {const_cast<char *>("__doc__"),       (getter)Sbk_TypeGet___doc__},
+    {const_cast<char *>("__doc__"),       (getter)Sbk_TypeGet___doc__, (setter)type_set_doc},
     {const_cast<char *>("__dict__"),      (getter)Sbk_TypeGet___dict__},
     {nullptr}  // Sentinel
 };
diff --git a/sources/shiboken2/libshiboken/sbkstaticstrings.cpp b/sources/shiboken2/libshiboken/sbkstaticstrings.cpp
index 9dd98eef3..602c0619b 100644
--- a/sources/shiboken2/libshiboken/sbkstaticstrings.cpp
+++ b/sources/shiboken2/libshiboken/sbkstaticstrings.cpp
@@ -78,8 +78,10 @@ namespace PyMagicName {
 // exported:
 STATIC_STRING_IMPL(class_, "__class__")
 STATIC_STRING_IMPL(dict, "__dict__")
+STATIC_STRING_IMPL(doc, "__doc__")
 STATIC_STRING_IMPL(ecf, "__ecf__")
 STATIC_STRING_IMPL(file, "__file__")
+STATIC_STRING_IMPL(get, "__get__")
 STATIC_STRING_IMPL(members, "__members__")
 STATIC_STRING_IMPL(module, "__module__")
 STATIC_STRING_IMPL(name, "__name__")
diff --git a/sources/shiboken2/libshiboken/sbkstaticstrings.h b/sources/shiboken2/libshiboken/sbkstaticstrings.h
index ebb64579c..df0c683b0 100644
--- a/sources/shiboken2/libshiboken/sbkstaticstrings.h
+++ b/sources/shiboken2/libshiboken/sbkstaticstrings.h
@@ -64,8 +64,10 @@ namespace PyMagicName
 {
 LIBSHIBOKEN_API PyObject *class_();
 LIBSHIBOKEN_API PyObject *dict();
+LIBSHIBOKEN_API PyObject *doc();
 LIBSHIBOKEN_API PyObject *ecf();
 LIBSHIBOKEN_API PyObject *file();
+LIBSHIBOKEN_API PyObject *get();
 LIBSHIBOKEN_API PyObject *members();
 LIBSHIBOKEN_API PyObject *module();
 LIBSHIBOKEN_API PyObject *name();
diff --git a/sources/shiboken2/libshiboken/signature.cpp b/sources/shiboken2/libshiboken/signature.cpp
index e4dc27ea7..e2c02a196 100644
--- a/sources/shiboken2/libshiboken/signature.cpp
+++ b/sources/shiboken2/libshiboken/signature.cpp
@@ -731,8 +731,9 @@ handle_doc(PyObject *ob, PyObject *old_descr)
         name = reinterpret_cast<PyTypeObject *>(ob_type_mod.object())->tp_name;
     if (handle_doc_in_progress || name == nullptr
         || strncmp(name, "PySide2.", 8) != 0)
-        return PyObject_CallMethod(old_descr, const_cast<char *>("__get__"),
-            const_cast<char *>("(O)"), ob);
+        return PyObject_CallMethodObjArgs(old_descr,
+                                          Shiboken::PyMagicName::get(),
+                                          ob, nullptr);
     handle_doc_in_progress++;
     PyObject *res = PyObject_CallFunction(
                         pyside_globals->make_helptext_func,