How to reliable detect a MacPorts-ported compiler?

[Rainer Müller]

On 2015-09-07 02:46, Jeffrey Walton wrote:
> We have some users reporting issues under MacPort-ported compilers
> (specifically, Issue 37664, https://trac.macports.org/ticket/37664).
> 
> How do I reliably detect a MacPorts-ported compiler?

Wouldn't it be more correct to detect gcc on OS X as apparently this
feature is not supported no matter where the compiler comes from?

Rainer