[clang] [llvm] [Driver] Add option to select compiler-rt arch suffix (PR #89775)

[Paul T Robinson via cfe-commits]

pogo59 wrote:

My understanding is that this change never had a proper Discourse RFC, which means it was quite possible for vendors not to have noticed it. Certainly I (on behalf of Sony) was not aware, and I make some effort to keep an eye on things. There is no good reason to suppose Visual Studio will adopt the change if they are unaware of it.

I understand that @tru has adopted the new style downstream for their internal use. The argument I am hearing here is that you are _requiring_ all downstream Windows users to do the same, because otherwise their builds will start failing (as our internal builds have done). But, despite that requirement, it appears that the Windows _default_ is to build with the old style. This is at best an inconsistency, and at worst really broken. I can see a few ways to fix it.

1. Windows does not adopt the new style. The build default remains as it is, and there is a Windows exception to match the AIX exception as seen in this patch. If someone wants to change to the new style for their own downstream use, as @tru has, they need to deal with it themselves.
2. Windows _fully_ adopts the new style. The build default changes, there is no Windows exception. I have not run the experiment, but if this had been done, probably I never would have noticed.
3. Windows stays as it is. The build defaults to old style, but for those who choose to adopt the new style, we add a driver option so the compiler knows something is different.


https://github.com/llvm/llvm-project/pull/89775