Phew, a lot of classes were affected by this. The rationale for the
changes are as follows:
- When a type X declares any constructor, the default constructor is
not declared, so there is no need for X() = delete there. In fact,
there is brutal difference between those two: deleted members
participate in overload resolution, but not-declared members do not!
- When a type X wants to be non-copyable (e.g. to be only movable, like
threads, unique_ptrs, and so on), you can either do it by inheriting
from boost::noncopyable (the old way), or better declare both (!) the
copy constructor _and_ the copy assignment operator as deleted:
X(X const&) = delete;
X& operator=(X const&) = delete;
We had tons of types with deleted copy constructors that were lacking
a corresponding deleted copy assignment operator, making them still
copyable and you wouldn't even notice (read: scary)!
References:
- http://accu.org/content/conf2014/Howard_Hinnant_Accu_2014.pdf
- http://www.boost.org/doc/libs/master/libs/core/doc/html/core/noncopyable.html
Note: I know, I'm quoting Hinnant's extraordinary slides a lot, but
getting the sematic right here is so incredibly important.
And includes the optional header that was transitively included by the
spirit header before. Hopefully this will speed up compile times, as the
RouteParameters header is used in a lot of translation units.
