Fix python/c++ conversion for boost::optional<T>

Setters for types wrapped in boost::optional, such as item_t::note were
broken, e.g. setting a note on a transaction resulted in garbled data
that would cause Python to throw utf-8 errors when retrieving the note.

(But setters that accessed strings directly, e.g. "payee" on a transaction
worked fine.)

This change alters the from-python conversion for optional-wrapped
types based on the example at
https://stackoverflow.com/questions/36485840/wrap-boostoptional-using-boostpython
and a test case to verify the behavior.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/pyutils.h b/src/pyutils.h
index 6c9675b7..7bc0d0af 100644
--- a/src/pyutils.h
+++ b/src/pyutils.h
@@ -88,13 +88,14 @@ struct register_optional_to_python : public boost::noncopyable
     {
       using namespace boost::python::converter;
 
-      void * const storage =
-        reinterpret_cast<rvalue_from_python_storage<T> *>(data)->storage.bytes;
+      const T value = typename boost::python::extract<T>(source);
 
-      if (data->convertible == source)      // == None
+      void * storage = ((rvalue_from_python_storage<boost::optional<T>>*) data)->storage.bytes;
+
+      if (source == Py_None)      // == None
         new (storage) boost::optional<T>(); // A Boost uninitialized value
       else
-        new (storage) boost::optional<T>(*reinterpret_cast<T *>(data->convertible));
+        new (storage) boost::optional<T>(value);
 
       data->convertible = storage;
     }