Those > can be instantiated a finite number of times and then used like non-templated code.
So you have a C++ file that uses vector<int>, vector<struct c_struct>, vector<CppClass>, vector<DClass>, etc. once and then you can link to them from D code.
The only case where that doesn't work is when you have lots of one-off instantiations, where requiring an instantiation in C++ code for each use in D would get annoying quickly.
Does the D compiler know how to mangle/demangle C++ names?
Do you have to write some kind of D header file for foreign C++ functions? Otherwise, how would D even know about the existence of e.g. vector<int>::push?
So you have a C++ file that uses vector<int>, vector<struct c_struct>, vector<CppClass>, vector<DClass>, etc. once and then you can link to them from D code.
The only case where that doesn't work is when you have lots of one-off instantiations, where requiring an instantiation in C++ code for each use in D would get annoying quickly.