boost::python::objects::iterator_range::next::operator() might return reference to temporary object about python

[BorisSchaeling]

Here is a test case (rename test.txt to test.cpp):

test.txt

Run this Python code for a crash:

import test
v = test.vector()
for i in v.range:
  print(i)

If you change this line in test.txt:

typedef const value_type& reference;

to:

typedef const value_type reference;

it all works (operator() now doesn't return a reference to something in a temporary object anymore but a copy).