> > 1) For N2235, use __cpp_constexpr (emphasizing the new keyword)
> > For N3652, use __cpp_constexpr_statements (emphasizing that this is an
> > extension of __cpp_constexpr, and that the primary change is that it
> permits
> > almost any statements in constexpr functions)

I like this idea, but I'm somewhat concerned about the ambiguity of "constexpr statements", especially since "constexpr" can't be applied to a statement.

I'm tempted to suggest __cpp_constexpr_iteration. Iteration seems to have been one of the strongest motivations for the change.

If we don't do it that way, I guess my next preference would be __cpp_constexpr_2014, or some variation thereof, and use just __cpp_constexpr for the C++11 feature.

I note that no one has (yet) specifically argued that the difference between C++11 and C++14 in this area is subtle or minor -- that being the criterion I would prefer for using a different macro value, instead of a different name.

Clark