Why does macports require a migration across major version bumps?

[Joshua Root]

On 2017-8-30 11:01 , Eitan Adler wrote:
> What is the underlying reason to require a reinstall across major
> versions? I did something silly/stupid/smart  and removed the check
> from libexec/macports/lib/macports1.0/macports.tcl and just did 'sudo
> port upgrade outdated' to rebuild the world. It got about 90% of the
> way through and only errored on a few expected
> broken-for-other-reasons ports.
> 
> Obvious I'm down the deep hole of unsupported actions but I'm curious
> about what gets missed when someone does this?

It's the same reason there are separate installers per OS version in the 
first place: Many features are detected at configure time. If the same 
features are not available at runtime, stuff breaks.

It's possible that nothing relevant changes between certain major OS 
versions. It definitely does between others.

If we were able to detect all features at runtime, we could have a 
single (base) build that would work on all supported OS versions. All 
the many ports that detect features at configure time would still need 
to be reinstalled of course.

- Josh