stdx::optional<T> uses quite elaborate std::enable_if_t magic to decide
whether the argument passed to its constructor should be used for a call
T constructor or stdx::optional<T> constructor.
Apparently, with GCC 6.2 having T constructor which accepts any type
confuses that magic and we end up with compile errors.
The solution is to have from_range() method that replaces that
constructor from range. There is also constructor that creates a key
from std::vector<bytes> so that code generated by IDL works as it did
before.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
Message-Id: <1474550971-15309-1-git-send-email-pdziepak@scylladb.com>