Build Failure on ports-10.10_x86_64: ixion

[Joshua Root]

Ryan Schmidt wrote:
> On Jan 26, 2021, at 13:41, Andrew Udvare wrote:
> 
>> Might this be fixed by a -std= flag? I don't get this error on Big Sur.
> 
> The error is:
> 
> model_context.cpp:20:39: error: unknown type name 'nullptr_t'; did you mean 'std::nullptr_t'?
> 
> Maybe the error message is right and it should be using "std::nullptr_t" instead of "nullptr_t" (or "using namespace std", though this is not recommended).

It definitely should be using std::nullptr_t. To (reliably) get 
nullptr_t in the global namespace, you have to include <stddef.h>, which 
is deprecated in C++. The right way is to include <cstddef> which puts 
the declarations in the std namespace.

- Josh