Add yapf and clang-format to formatter

[vmax]

//tools:formatter currently relies on yapf and clang-format being available on the user's system.
We should make a BUILD target that will make bazel download them, and then add them to runtime_deps of //tools:formatter, so that they're available to the tool to use.

[NikleshPhabiani]

I would want to try out this one.

[oferb]

Ok, go ahead :)

[vmax]

@NikleshPhabiani for reference, you can have a look at how //tools:protoc is implemented. Remember it should work at both platforms (Linux/macOS). Ping me if you need any help 🙂

[NikleshPhabiani]

@vmax . Actually, I did happen to look at how //tools:protoc is implemented a few days back and looked something that would help me out in this issue but haven't looked at it lately. Thanks a lot for the update. Yes, will definitely let you know if I need any help.

[NikleshPhabiani]

A snippet for installation of clang-format on macOS:

platform=$(uname)

if [ "$platform" == "Darwin" ]; then
  mkdir -p ./clang-format
  curl 'http://releases.llvm.org/6.0.0/clang+llvm-6.0.0-x86_64-apple-darwin.tar.xz' -o './clang-format/clang-format.tar.xz'
  tar xvfj clang-format/clang-format.tar.xz -C ./clang-format
  rm -f ~/bin/clang-format
  ln -s $(pwd)/$(find clang-format | grep bin/clang-format$) ~/bin/clang-format
fi

Reference Link

Is this fine or is something else expected? The other relevant files will be changed but this is just a snippet for installation on the system. Also, which binary from the releases needs to be used for installation on Linux? Thanks.

[oferb]

So the idea is to have bazel get the binary. That way no setup step is needed from the developer.
If you look at https://github.com/google/startup-os/blob/master/tools/BUILD#L36
It uses protoc_bin which is defined in WORKSPACE.

Ohh, and when we say linux, we actually mean Ubuntu :) so "Clang for Ubuntu 16.04".

[oferb]

Hey, how's it going?

[NikleshPhabiani]

Hey. Sorry, couldn't work on this during the week. I will get this done early in the weekend. Oh ok, got it. Thanks a lot. One doubt. What would be the SHA-256 code for these? I couldn't figure out a way yet to retrieve a tag for each.

[oferb]

That's fine, just checking.
About SHA-256, we use this:
https://github.com/google/startup-os/blob/master/WORKSPACE#L1-L2
Thanks again!

[vmax]

@NikleshPhabiani One more SHA-256 tip: if you don't specify it, bazel will print it out on building the target that depends on that archive

[NikleshPhabiani]

Thanks a lot for all the help. I have a doubt regarding YAPF. The release does not have separate versions for Linux and macOS. Is it platform independent and linked directly to Python? Kindly let me know what needs to be done with respect to YAPF.

[vmax]

@NikleshPhabiani it'll be great to use it as http_archive together with writing custom BUILD file with py_binary target in it

[oferb]

clang-format is now fully added. Thanks Niklesh! Do you want to continue this task for YAPF?
I believe that YAPF is platform-independent.

[NikleshPhabiani]

Actually, I am extremely tied up for sometime with university coursework and interviews. Hence, won't be able to pick this up atleast for a couple of days.

[oferb]

That's fine. I created an issue just for yapf #304
You're welcome to take a look, but just know that the python task is a P3 (lower priority), since we don't currently use python. There's other issues that are good first good issue (although you're not a first contributor anymore ;) you're welcome to take a look.

More details about P3 and other priorities: https://developers.google.com/issue-tracker/concepts/issues