Re: [boost] [smart_ptr] !defined(BOOST_NO_CXX11_SMART_PTR) does notimply !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)

Subject: Re: [boost] [smart_ptr] !defined(BOOST_NO_CXX11_SMART_PTR) does notimply !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
From: Peter Dimov (lists_at_[hidden])
Date: 2013-02-08 10:36:46

Michel Morin wrote:

> `!defined(BOOST_NO_CXX11_SMART_PTR)` does not necessarily mean that
> the compiler support of rvalue references is available. For example,

How could the standard library have std::unique_ptr without the compiler 
supporting rvalue references?

> when I use shared_ptr (on trunk) with clang + libc++ in a C++03 mode,
> I get warnings something like
>
>   boost/smart_ptr/shared_ptr.hpp:556:51:
>   warning: rvalue references are a C++11 extension [-Wc++11-extensions]
>     shared_ptr & operator=( std::unique_ptr<Y, D> && r )

Looks like rvalue references are available, but as an extension.