2016-02-18 23:03 GMT+01:00 Stephan T. Lavavej
Hi,
A user reported a bug (VSO#191303/Connect#2351203, see [1]) using Boost.Optional with MSVC 2015 Update 2. The original test case involved a minor bug in VC's tuple, which I'll look into fixing in the future (specifically, N-tuples recursively construct (N - 1)-tuples, in a way that's visible to overload resolution). However, there is also a bug in boost::optional.
Hi, I have created a ticket abut this problem: https://svn.boost.org/trac/boost/ticket/12002 Frankly, I do not know how to implement it in a portable way (considering older compilers) without type trait boost::is_constructible. I am currently blocked on it: https://svn.boost.org/trac/boost/ticket/12003. As an aside, the "prevent_binding" stuff should probably be expressed as a
SFINAE constraint, not a static_assert.
About this remark, I am not sure. I understand that you want the constructors to be SFINAE-friendly, but at the same time I would loose the opportunity to convey a text message to the user-programmers, as to what the problem is. Now I do it with the static_assert. I wish I had the feature "delete for a reason" Optional::Optional(R&&r) = delete("because it would cause..."); Regards, &rzej