LLVM's bazel build has changed a bit, so this updates the tree for that.
LLVM is also moving `llvm::Optional` to match the standard API, but it seemed simpler to just switch to `std::optional`.
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
I'm treating my PR to mypy bazel integration as dead in the water. Abandoning that approach, this seems to work reasonably well as a replacement. It's actually a slightly newer version of mypy too -- the bazel integration was stuck on an old version.
Note I don't think we're losing much: we shouldn't be writing too much python.
Moves common script logic into utils.py (not a great name, but couldn't come up with better). This is in particular to make the buildifier.py script really trivial, allowing that pre-commit to be easily added. However, scripts have also been diverging on how we find bazel, so I'm trying to unify that.
The advantage of reimplementing buildifier's pre-commit is that (a) we can now run buildifier server-side, and (b) we can stop advising installing it manually. Then the only Linux-specific package manager is Cargo, which is only used for watchman, which is optional -- so stop highlighting Linux-specific package managers in the tool instructions.
Chandler CarruthandJon Ross-Perkins
Jon Meow
