cpp:function can't parse multiple signatures
The python domain allows multiple signatures to be grouped as follows:
.. py:function:: start(x) end(x)
The corresponding formulation in the C++ domain does not parse:
.. cpp:function:: iterator begin() iterator end()
In the general case, doing this correctly for C++ might be undecidable, due to cases like this:
.. cpp:function:: T& vector<T>::operator(size_t loc) const T& vector<T>::operator(size_t loc) const
where it's ambiguous whether the `const` should be interpreted as a trailing part of the first signature, or the leading part of the second signature. However, it wouldn't be so bad to require an explicit comma between declarations.