Re: [Boost-users] [MPL] HAS_XXX gives the wrong answer after "enable_if" on incomplete type in GCC 4.6/7

I've run into an unexpected behaviour, and I'm not sure if the compiler has a bug, if Boost.MPL has a bug, or if I have the wrong expectations. I am using Boost v1.49.0, but I also tested r82084 of the Boost trunk.

I'm not sure which is the case either, but notice that a simple workaround is to define f after traitor_1 is complete (you can still *declare* f where you do now). This is not an unreasonable requirement, because the body of f performs a traitor_1 -> C conversion, for which it needs to instantiate the constructor of C, for which it needs to instantiate has_traitor<traitor_1>, which only gives accurate results if traitor_1 is complete. Regards, Nate