[clang] [SystemZ][z/OS] Add visibility features for z/OS (eg. _Export, pragma export) (PR #111035)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

There seems to be a LOT of added complexity for the `#pragma export`, to the point that I'm not sure of the value compared to the keyword, and if we're going to keep it, we need to spend quite a bit more time on it.

As far as the keyword itself, I think there are quite a few more diagnostics we should look at, particularly for 'completeness'.  I don't really like the error that is being diagnosed (just 'cannot be qualified'), as that is really quite vague.  We need to try harder on that.


https://github.com/llvm/llvm-project/pull/111035