check for os and xcode version

[Helmut K. C. Tessarek]

On 2017-10-05 21:46, Joshua Root wrote:
> Well, it depends on the nature of the problem. Newer versions of Xcode
> routinely break some C++ code by shipping a newer clang++ which complies
> more closely with the C++ standards, for example, and that's not really
> something that Apple should fix, since the code was really incorrect all
> along.

In such a case I totally agree with you.

> What kind of breakage are we talking about exactly?

Please have a look at the following thread (takes 2 minutes):

https://groups.google.com/forum/#!topic/tmux-users/ct7nAv8cYm4

So, basically, everything is fine on my machine, since I'm running
10.11.6. The next guy runs 10.12.6 (or 10.13) and Xcode 9 and all of a
sudden it blows up.

> Doing a quick grep of the ports tree, the first few examples I see are
> libgcrypt, lua-md5, libunwind, and apr.

awesome, thanks.

Cheers,
 K. C.

-- 
regards Helmut K. C. Tessarek              KeyID 0xF7832007C11F128D
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