Add unit test for cpp iteration over attribute of temporary object

tests/run/cpp_iterators.pyx

@@ -11,6 +11,10 @@ cdef extern from "cpp_iterators_simple.h":
         double* begin()
         double* end()
 
+    cdef cppclass HasIterableAttribute:
+        vector[int] vec
+        HasIterableAttribute()
+
 def test_vector(py_v):
     """
     >>> test_vector([1, 2, 3])
@@ -177,3 +181,21 @@ def test_iteration_from_function_call():
         print(i)
     for i in make_vec3():
         print(i)
+
+cdef HasIterableAttribute get_has_iterable_attribute():
+    return HasIterableAttribute()
+
+def test_iteration_from_function_call_attribute():
+    """
+    >>> test_iteration_from_function_call_attribute()
+    1
+    2
+    3
+    1
+    2
+    3
+    """
+    for i in HasIterableAttribute().vec:
+        print(i)
+    for i in get_has_iterable_attribute().vec:
+        print(i)

tests/run/cpp_iterators_simple.h

+#include <vector>
+
 class DoublePointerIter {
 public:
     DoublePointerIter(double* start, int len) : start_(start), len_(len) { }
@@ -8,3 +10,9 @@ private:
     int len_;
 };
 
+class HasIterableAttribute {
+public:
+    std::vector<int> vec;
+    HasIterableAttribute() : vec({1, 2, 3}) {}
+};
+