building from source with libc++

[Mojca Miklavec]

On 2 April 2017 at 00:55, db wrote:
> What I would like to know is though, how is MP team's view on legacy OS versions — I do know that it's focusing on 10.9+ supported systems, as stated in the homepage, and that here and there software is still being patched for the former and binaries still produced, but for lack of a somewhat official notice of support, I'd appreciate the views of its members.

You would probably get many slightly different answers here and
different developers go to different (or no) efforts in making sure
that older OSes are supported.

"Officially" nobody is required to make special efforts to ensure that
a package is working on anything but the macOS versions supported by
Apple.

Practically:
- nobody is actively or intentionally breaking backward compatibility
- we still make efforts to make sure that at least the MacPorts base
compiles everywhere and that at least gcc & clang (plus some others)
work
- many developers either have no access or no motivation (or neither)
to spend additional effort to come up with workarounds for older OS
versions themselves when new software gets released
- but we generally accept patches
- I would say that still we have a surprisingly good coverage for old OSes

The biggest dealbreaker in my opinion is that we still didn't decide
how to patch base to distinguish between libstdc++ vs. libc++ builds
and then start a buildbot and distribute packages for libc++ for
10.6-10.8. That would make an enormous difference (but the longer we
wait, the less relevant support for ancient OSes will be and the less
motivation there will be to actually deploy code).

When upstream drops support for a certain OS in the sense that they
require a newer API, there's literally nothing we can do other than
perhaps installing an older version of the same software. Usually the
biggest problem is C++11 nowadays and libc++ usually helps there, it's
just that most developer don't have resources to actually test
packages on older boxes.

We lack manpower to even keep existing packages updated for the latest
OS, so we cannot afford maintaining separate branches of Portfiles for
older OSes (which would probably be the right thing to do if we had
unlimited resources).

Mojca