[boost] [config] std::unique_ptr, std::ref detection?

Subject: [boost] [config] std::unique_ptr, std::ref detection?
From: Peter Dimov (pdimov_at_[hidden])
Date: 2012-02-28 11:20:27

Suppose I want to implement a shared_ptr constructor taking std::unique_ptr. 
To avoid breaking pre-C++11 compilers, I need to, at least, know whether 
<memory> contains std::unique_ptr. (I'd also like to know if there's 
std::ref in <functional> because the specification of the constructor uses 
it.) But the config library doesn't seem to provide a way. There's no macro 
for std::unique_ptr, and there's no macro for "generic C++11 compiler and 
library".