[tex-live] Platform & library check on macOS during TL 2018 installation

[Tom Kacvinsky]

> On Mar 18, 2018, at 18:39:29, Karl Berry <karl at freefriends.org> wrote:
> 
>    Dear Norbert,
> 
> Norbert is not the only one who works on the installer :).
> 
>    would it be possible for the
>    installer to check if the system is darwin10, and if so, check whether
>    libc++ is present on the system, and if not, print an error saying
>    that it cannot proceed unless the user installs the library?
> 
> Anything is possible. The question is, how do we check whether libc++ is
> present? We can't try to link with it, that would lead to far more
> complications. What file location(s) should we check?

One option I see is an application that is run during the installation
process that uses dlopen() to try to load libc++.  This will use the 
predefined system locations.  A problem is if DYLD_LIBRARY_PATH is also
set when this program is invoked.

Tried to find a symbol to call to get the version information, but no joy.
> 
> I assume checking for "darwin10" means checking that
> sw_vers -productVersion returns 10.10?
> 
>    We have various options in principle:
> 
> I agree that all of these other options are worse, except perhaps simply
> giving up.  I find these constantly proliferating special cases for Macs
> highly unfortunate. -k
>