standard way to require c++11?

[Michael Dickens]

On Fri, Mar 20, 2015, at 04:38 AM, Chris Jones wrote:
> Using Macports gcc you will still have the problem of mixing different 
> C++ runtimes, the macports stdlibc++ used by the gcc ports, and the 
> system one. They are not the same and if you try use at the same time 
> ports built with the normal compiler, to yours, problems can happen.

I appreciate your concern, Chris. And, I agree in a general sense: in my
experience, mixing C++ runtime libraries results in failures & is
frustrating as a user and developer. That said, I think that the current
way we've determined (discussions here and on IRC) of forcing a C++11
compiler should work for the vast vast majority of users, because it
uses GCC when the C++ runtime is libstdc++ and Clang when libc++ -- so,
we're -not- mixing C++ runtime libraries any more than normal for those
platforms. This mixing will not work in extreme cases, but I expect
there to be very few such cases if any -- and, mostly developers testing
odd combinations of OSX and C++ runtime support. Hence, I'm not
concerned any more than usual about mixing the C++ runtime libraries in
these few, specific ports that will use and require C++11 support. I
will start pushing this style of forcing C++11 into a few ports that I
maintain & don't work on 10.8 and prior & we'll see if I get any failure
reports back; I doubt I will. - MLD