Merge branch 'coleb-python35_dtor_exception_fix'

* coleb-python35_dtor_exception_fix:
  Add test case for Python 3.5 assertion with a pending StopIteration
  Amend python_destructor_exception runtime test
  Call PyErr_WriteUnraisable if a destructor sets a Python exception (-builtin)
  Extended zjturner's changes to encompass all function dispatch and use PyErr_WriteUnraisable to handle exceptions during __del__.
  Python - Save and restore exception state before calling destroy.

Examples/test-suite/python/Makefile.in

@@ -58,6 +58,7 @@ CPP_TEST_CASES += \
 	primitive_types \
 	python_abstractbase \
 	python_append \
+	python_destructor_exception \
 	python_director \
 	python_docstring \
 	python_nondynamic \

Examples/test-suite/python/python_destructor_exception_runme.py

@@ -0,0 +1,64 @@
+import python_destructor_exception
+from StringIO import StringIO
+import sys
+
+def error_function():
+    python_destructor_exception.ClassWithThrowingDestructor().GetBlah()
+
+def runtest():
+    attributeErrorOccurred = False
+    try:
+        error_function()
+    except AttributeError, e:
+        attributeErrorOccurred = True
+    return attributeErrorOccurred
+
+def test1():
+    stderr_saved = sys.stderr
+    buffer = StringIO()
+    attributeErrorOccurred = False
+    try:
+        # Suppress stderr while making this call to suppress the output shown by PyErr_WriteUnraisable
+        sys.stderr = buffer
+
+        attributeErrorOccurred = runtest()
+    finally:
+        sys.stderr.flush()
+        sys.stderr = stderr_saved
+
+    assert attributeErrorOccurred
+    assert buffer.getvalue().count("I am the ClassWithThrowingDestructor dtor doing bad things") >= 1
+
+class VectorHolder(object):
+    def __init__(self, v):
+        self.v = v
+    def gen(self):
+        for e in self.v:
+            yield e
+
+# See issue #559, #560, #573 - In Python 3.5, test2() call to the generator 'gen' was
+# resulting in the following (not for -builtin where there is no call to SWIG_Python_CallFunctor
+# as SwigPyObject_dealloc is not used):
+#
+# StopIteration
+#
+# During handling of the above exception, another exception occurred:
+# ...
+# SystemError: <built-in function delete_VectorInt> returned a result with an error set
+
+def addup():
+    sum = 0
+    for i in VectorHolder(python_destructor_exception.VectorInt([1, 2, 3])).gen():
+        sum = sum + i
+    return sum
+
+def test2():
+    sum = addup()
+
+    if sum != 6:
+        raise RuntimeError("Sum is incorrect")
+
+# These two tests are different are two different ways to recreate essentially the same problem
+# reported by Python 3.5 that an exception was already set when destroying a wrapped object
+test1()
+test2()

Examples/test-suite/python_destructor_exception.i

@@ -0,0 +1,19 @@
+/* File : example.i */
+%module python_destructor_exception
+%include exception.i
+
+%exception ClassWithThrowingDestructor::~ClassWithThrowingDestructor()
+{
+  $action
+  SWIG_exception(SWIG_RuntimeError, "I am the ClassWithThrowingDestructor dtor doing bad things");
+}
+
+%inline %{
+class ClassWithThrowingDestructor
+{
+};
+
+%}
+
+%include <std_vector.i>
+%template(VectorInt) std::vector<int>;

Lib/python/builtin.swg

@@ -9,9 +9,17 @@ SWIGINTERN void					\
 wrapper##_closure(PyObject *a) {		\
     SwigPyObject *sobj;				\
     sobj = (SwigPyObject *)a;			\
-    Py_XDECREF(sobj->dict);	                \
+    Py_XDECREF(sobj->dict);			\
     if (sobj->own) {				\
+	PyObject *val = 0, *type = 0, *tb = 0;	\
+	PyErr_Fetch(&val, &type, &tb);		\
 	PyObject *o = wrapper(a, NULL);		\
+	if (!o) {				\
+	    PyObject *deallocname = PyString_FromString(#wrapper); \
+	    PyErr_WriteUnraisable(deallocname);	\
+	    Py_DECREF(deallocname);		\
+	}					\
+	PyErr_Restore(val, type, tb);		\
 	Py_XDECREF(o);				\
     }						\
     if (PyType_IS_GC(a->ob_type)) {		\
@@ -64,7 +72,7 @@ wrapper##_closure(PyObject *a, PyObject *b, PyObject *c) {	\
 
 #define SWIGPY_TERNARYCALLFUNC_CLOSURE(wrapper)			\
 SWIGINTERN PyObject *						\
-wrapper##_closure(PyObject *callable_object, PyObject *args, PyObject *) {	\
+wrapper##_closure(PyObject *callable_object, PyObject *args, PyObject *) { \
     return wrapper(callable_object, args);			\
 }
 
@@ -124,7 +132,7 @@ wrapper##_closure(PyObject *a, Py_ssize_t b) {		\
     return result;					\
 }
 
-#define SWIGPY_FUNPACK_SSIZEARGFUNC_CLOSURE(wrapper)		\
+#define SWIGPY_FUNPACK_SSIZEARGFUNC_CLOSURE(wrapper)	\
 SWIGINTERN PyObject *					\
 wrapper##_closure(PyObject *a, Py_ssize_t b) {		\
     PyObject *arg, *result;				\

Lib/python/pyrun.swg

@@ -536,16 +536,32 @@ SwigPyObject_dealloc(PyObject *v)
     if (destroy) {
       /* destroy is always a VARARGS method */
       PyObject *res;
+
+      /* PyObject_CallFunction() has the potential to silently drop
+         the active active exception.  In cases of unnamed temporary
+         variable or where we just finished iterating over a generator
+         StopIteration will be active right now, and this needs to
+         remain true upon return from SwigPyObject_dealloc.  So save
+         and restore. */
+      
+      PyObject *val = NULL, *type = NULL, *tb = NULL;
+      PyErr_Fetch(&val, &type, &tb);
+
       if (data->delargs) {
-	/* we need to create a temporary object to carry the destroy operation */
+        /* we need to create a temporary object to carry the destroy operation */
-	PyObject *tmp = SwigPyObject_New(sobj->ptr, ty, 0);
+        PyObject *tmp = SwigPyObject_New(sobj->ptr, ty, 0);
-	res = SWIG_Python_CallFunctor(destroy, tmp);
+        res = SWIG_Python_CallFunctor(destroy, tmp);
-	Py_DECREF(tmp);
+        Py_DECREF(tmp);
       } else {
-	PyCFunction meth = PyCFunction_GET_FUNCTION(destroy);
+        PyCFunction meth = PyCFunction_GET_FUNCTION(destroy);
-	PyObject *mself = PyCFunction_GET_SELF(destroy);
+        PyObject *mself = PyCFunction_GET_SELF(destroy);
-	res = ((*meth)(mself, v));
+        res = ((*meth)(mself, v));
       }
+      if (!res)
+        PyErr_WriteUnraisable(destroy);
+
+      PyErr_Restore(val, type, tb);
+
       Py_XDECREF(res);
     } 
 #if !defined(SWIG_PYTHON_SILENT_MEMLEAK)