Re: [boost] [optional] optional(Expr&&) is insufficiently constrained

Subject: Re: [boost] [optional] optional(Expr&&) is insufficiently constrained
From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2016-02-19 12:48:07

2016-02-19 2:54 GMT+01:00 Stephan T. Lavavej <stl_at_[hidden]>:

> [Andrzej Krzemienski]
> > I have created a ticket abut this problem:
> > https://svn.boost.org/trac/boost/ticket/12002
>
> Thanks!
>
> > 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.
>
> The simplest solution would be to add the additional constraint when
> Boost.Config tells you that a modern is_constructible is available. (Older
> toolsets will lack the intense metaprogramming that makes this constraint
> necessary in the first place.)

I have implemented a temporary patch: the constructor is SFINAE-friendly,
but only on the latest compilers (MSVC 12.0).
It is available for tests in the develop branch.

Regards,
&rzej