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

[Andrzej Krzemienski]

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.

Thanks, that should be sufficient. Even restricting it to VC 14.0 would be OK. STL