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

Subject: Re: [boost] [optional] optional(Expr&&) is insufficiently constrained
From: Stephan T. Lavavej (stl_at_[hidden])
Date: 2016-02-18 20:54:14

[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.)

STL