id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8625	Add function to indicate if `swap` is no-throw	Daryle Walker	joseph.gauterin	"While writing a library for Boost, I found the need for this function:

{{{
    #include <utility>

    //! Detect if a type's swap (found via ADL for
    //! non-built-ins) throws.
    template < typename T, typename U = T >
    inline constexpr
    bool  is_swap_nothrow() noexcept
    {
        using std::swap;

        return noexcept( swap(std::declval<T &>(),
         std::declval<U &>()) );
    }
}}}

while writing my container's swap.  You would probably use the macros for ""inline,"" ""constexpr,"" operator ""noexcept,"" and the ""noexcept"" flag, but the function is pretty much useless unless all of those features are fully defined.  The function has to be shielded from pre-C++11 compiles, of course.
"	Feature Requests	new	Boost 1.55.0	swap	Boost 1.55.0	Optimization		swap noexcept