[smart_holder] RuntimeError: Invalid return_value_policy for shared_ptr

[jakobandersen]

While trying to convert from Boost.Python I ran into the lifetime issue raised, e.g., in #2839, so I am using the smart_holder branch.
A minimal test case can be found at https://github.com/jakobandersen/pyTest/tree/pybind, with the central part at https://github.com/jakobandersen/pyTest/blob/pybind/libpytest.cpp#L42.

Essentially I have a custom function class which can be derived in Python. The problem is occurs when the function takes a std::shared_ptr as argument and is called from C++. When using PYBIND11_OVERRIDE_PURE_NAME to implement the call back to the Python implementation it will call the override with the default return_value_policy, which seems to be automatic_reference.
This gives the exception RuntimeError: Invalid return_value_policy for shared_ptr..
Expanding the macro and giving automatic as policy makes it work as intended (as done in https://github.com/jakobandersen/pyTest/blob/pybind/libpytest.cpp#L58).

Am I missing something in the setup? Is this manual hax to make it work correct?

[jakobandersen]

A simpler minimal case than above:

class C {
	C(int data);
public:
	int data;
public:
	static std::shared_ptr<C> make(int data) {
		return std::shared_ptr<C>(new C(data));
	}
};

void trigger() {
	auto l = py::list();
	auto c = C::make(42);
	l.append(c); // throws RuntimeError: Invalid return_value_policy for shared_ptr.
}

I'm not sure if this intersects the same code as the original example.

[jakobandersen]

As noted in #3012, the original issue seems fixed in the smart_holder branch, but the second issue is still present.

[rwgk]

Hi @jakobandersen, echoing @rhaschke 's request: #3012 (comment)

That would help us working on the issue together.

BTW: I will respond to PRs much faster, I just don't have the free bandwidth to pay much attention to the pybind11 github issues.

[jakobandersen]

Hi @jakobandersen, echoing @rhaschke 's request: #3012 (comment)

That would help us working on the issue together.

Sure, I started working in #3039, at least for adding tests for the cases I ran into and see if a simple change works out.

[jakobandersen]

Fixed via #3039.