[RFC] Clang-formatting all of libc++ once and for all

[cjdb]

@ldionne

I actually believe that clang-formatting the whole codebase in one go is the best course of action to address all of these concerns. Indeed, the alternative is to incrementally clang-format the code base like we’ve been doing, but this has worse effects in the long run on the above points.

Agreed. However, I will caution against doing this right now, as there are certain bugs in clang-format that we’ll need to deal with because they hurt readability quite a lot. Perhaps it’s worth prioritising addressing these bugs as a matter of libc++?

Does there need to be a discussion about the contents of our format style, or are we rolling with what’s already there?

We should also adopt a policy on how often we want to run clang-format project-wide. I raise this because clang-format frequently adds new features, and it may occasionally be beneficial to adopt some. Sometimes the changes are small, but other times they can be far-reaching.