SignalInstance: Fix more very old errors due to unlucky exposure

SignalInstance unfortunately can be created directly without
a calling Signal. This is an old design error that cannot easily
be reverted because that is now the API.

Fixed by printing "(no signature)":
* print(SignalInstance())    # prints "(no signature)"
Fixed by producing a runtime error:
* SignalInstance().connect(lambda: None)
* SignalInstance().disconnect()
* SignalInstance().emit()

Thanks to <bers bers> who reported them all.

Task-number: PYSIDE-79
Change-Id: I92598d963b9796453fbd17c1526a674fa007e5e8
Pick-to: 6.4
Reviewed-by: Adrian Herrmann <adrian.herrmann@qt.io>
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>

1 files changed, 14 insertions, 1 deletions

diff --git a/sources/pyside6/libpyside/pysidesignal.cpp b/sources/pyside6/libpyside/pysidesignal.cpp
index 291de73d8..17071cd1d 100644
--- a/sources/pyside6/libpyside/pysidesignal.cpp
+++ b/sources/pyside6/libpyside/pysidesignal.cpp
@@ -185,7 +185,8 @@ static PyObject *signalInstanceRepr(PyObject *obSelf)
     auto *self = reinterpret_cast<PySideSignalInstance *>(obSelf);
     auto *typeName = Py_TYPE(obSelf)->tp_name;
     return Shiboken::String::fromFormat("<%s %s at %p>", typeName,
-                                        self->d->signature.constData(), obSelf);
+                                        self->d ? self->d->signature.constData()
+                                                : "(no signature)", obSelf);
 }
 
 static PyMethodDef SignalInstance_methods[] = {
@@ -436,6 +437,10 @@ static PyObject *signalInstanceConnect(PyObject *self, PyObject *args, PyObject
         return nullptr;
 
     PySideSignalInstance *source = reinterpret_cast<PySideSignalInstance *>(self);
+    if (!source->d) {
+        PyErr_Format(PyExc_RuntimeError, "cannot connect uninitialized SignalInstance");
+        return nullptr;
+    }
     Shiboken::AutoDecRef pyArgs(PyList_New(0));
 
     bool match = false;
@@ -552,6 +557,10 @@ static int argCountInSignature(const char *signature)
 static PyObject *signalInstanceEmit(PyObject *self, PyObject *args)
 {
     PySideSignalInstance *source = reinterpret_cast<PySideSignalInstance *>(self);
+    if (!source->d) {
+        PyErr_Format(PyExc_RuntimeError, "cannot emit uninitialized SignalInstance");
+        return nullptr;
+    }
 
     // PYSIDE-2201: Check if the object has vanished meanwhile.
     //              Tried to revive it without exception, but this gives problems.
@@ -625,6 +634,10 @@ static PyObject *signalInstanceGetItem(PyObject *self, PyObject *key)
 static PyObject *signalInstanceDisconnect(PyObject *self, PyObject *args)
 {
     auto source = reinterpret_cast<PySideSignalInstance *>(self);
+    if (!source->d) {
+        PyErr_Format(PyExc_RuntimeError, "cannot disconnect uninitialized SignalInstance");
+        return nullptr;
+    }
     Shiboken::AutoDecRef pyArgs(PyList_New(0));
 
     PyObject *slot = Py_None;