Hello, I am appending Python dict objects to a C++ vector of structs. If it is done implicitly (calling v.push_back(dict_object)), Cython creates C++ code that does not compile. If dict_object has been cdef'd to be of the struct type, everything works. I am using version cf75e9eb7e from the master branch. Here is the code for reproducing the problem # cythonbug.pyx from libcpp.vector cimport vector ctypedef struct test_struct: int a int b def main(): cdef vector[test_struct] test_vector # cdef test_struct dict_object # Uncommenting this avoids the bug dict_object = {"a": 0, "b": 1} test_vector.push_back(dict_object) # end cythonbug.pyx The C++ output from "cython --cplus cythonbug.pyx" contains the statement "__pyx_t_9cythonbug_test_struct;" which GCC complains about: "error: declaration does not declare anything [-fpermissive]". Best wishes, Joonas Paalasmaa