[cfe-dev] RFC: Removing clang-cl's /fallback option

[Zachary Henkel via cfe-dev]

No objections from the Microsoft Office team.

-----Original Message-----
clang-cl's /fallback option was added back in 2013 [1] as part of bringing up clang's native Windows support.

Since then, the Windows support has become quite stable, and I'm not aware of anyone using /fallback anymore. In Chromium we stopped using it in 2015 [2].

While /fallback doesn't require a lot of code, it does add a bit of complexity to the driver (for example it added a special type of Job), and I worry about the code rotting since it's not getting updated to handle new flags.

So, are there any objections to removing the /fallback mode? My proposal is to put a note in the upcoming Clang 12 release, and then delete the code after the branch point, meaning it would be gone in Clang 13.

Please let me know what you think.

Thanks,
Hans