Re: [Boost-users] boost::proto user guide - compile error creating a lazy function

Eric Niebler writes:

The reason is because in the second invocation, the template argument T is deduced to be "B const", and an rvalue can bind to a const lvalue reference. In the first invocation, T is deduced to "B" and an rvalue cannot bind to a non-const lvalue reference.

HTH,

Thanks again, Eric. This is really helpful.