This code:

pybind11::object func = ...;
pybind11::dict d = func.attr("__class__").attr("__dict__");

compiles for MSVC and clang (and works as expected) but causes a compiler error for gcc 6 and gcc 7 complaining about not being able to convert a str_attr_accessor to a dict. I'm not sure if I'm trying to do the right thing here, so this might not be a real issue, just my ignorance.