[clang] [clang-tools-extra] [lldb] [llvm] [SystemZ][z/OS] Propagate IsText parameter to open text files as text (PR #107906)

[kadir çetinkaya via cfe-commits]

kadircet wrote:

thanks a lot for the swift response!

I can see how none of these implementations are not using those flags _today_, but we're changing the observable behavior for them as well, and if some of those implementations decides to give meaning to these flags, it might be impossible to keep it working. Especially because we're not clearly defining the semantics around how callers are going to figure those bits out.

So I am wondering:
- if we can make these changes in a very limited way, e.g. just in https://github.com/llvm/llvm-project/blob/main/llvm/lib/Support/Unix/Path.inc#L972-L1118. We already have lots of `__MVS__` specific regions in there. that's also the "right" layer if you want to perform syscalls.
- if we need to make those changes in the VFS interfaces indeed, can you provide the rationale explaining that need and what the new semantics mean both for implementors of the interface and the callers of it?

https://github.com/llvm/llvm-project/pull/107906