How to handle ports that are still broken because of the icu upgrade

[Joshua Root]

On 2019-10-25 16:27 , Mojca Miklavec wrote:
> I'm not sure if it falls into this category, but the most annoying
> problem for me has been clang-9.0 on legacy systems. It depends on
> libxml2 which is broken due to icu update, but I cannot rebuild
> libxml2 because the compiler is broken. I thought that bootstrapping
> was supposed to address this, but apparently it doesn't.

The clang_dependency portgroup allows using the newer clangs iff they
are already installed. That strategy breaks down if the compiler is
installed but broken.

Either the circular dependency should not be allowed at all, or it
should check not only that the compiler is present but also that it is
working.

It's worth noting that the buildbot will never run into this problem
because it deactivates all installed ports between builds.

- Josh