Update Protobuf to 3.11.3

[Yannic]

No description provided.

[lberki]

(I'll hold off reviewing this until #10648 lands)

[philwo]

I think all dependencies of this are merged now!

[Yannic]

We're mostly there! #10723 adds a patch for Protobuf to use the existing references for zlib, six, guava, ... When that landed, I'll rebase this PR (already verified locally that it works) and merge, and as a last change we get to delete the vendored version of Protobuf 😃.

[philwo]

Hi @Yannic,

just saw the failed tests here with this message:

ERROR: Analysis of target '//a:c' failed; build aborted: no such package '@bazel_skylib//lib': java.io.IOException: Error downloading [https://github.com/bazelbuild/bazel-skylib/archive/0.9.0.tar.gz] to /var/lib/buildkite-agent/.cache/bazel/_bazel_buildkite-agent/ec321eb2cc2d0f8f91b676b6d4c66c29/sandbox/linux-sandbox/2733/execroot/io_bazel/_tmp/53cf69ace19a0796fc4537030d753e89/root/917143f2cfdfb15433399b1574e0bac0/external/bazel_skylib/0.9.0.tar.gz: Unknown host: github.com

You can fix this with a little tweak:

• Add @bazel_skylib//:WORKSPACE to the test_repos filegroup in src/BUILD.
• Add bazel_skylib to the repos array in testenv.sh.

Then it should work!

[Yannic]

@philwo Thanks! That fixed the skylib error. Unfortunately, there is a new error because of zlib being referenced as @io_bazel//third_party/zlib and I can't seem to figure out how to fix that.

[philwo]

Mhm... yeah, I'm not sure how to solve that. What's the reason that we're patching the references to @zlib and @six in protobuf's BUILD file via https://github.com/bazelbuild/bazel/blob/master/third_party/protobuf/3.11.3.patch?

If we change this: https://github.com/bazelbuild/bazel/blob/master/WORKSPACE#L59-L62 to:

local_repository(
    name = "six",
    path = "./third_party/py/six/",
)

and add one for zlib:

local_repository(
    name = "zlib",
    path = "./third_party/zlib/",
)

Maybe it works?

[Yannic]

Finally figured it out. I think the problem was actually that bash didn't like the use of ` in a comment.

Also, I'm not sure why, but adding local_repository(name = "zlib, path = "...") prohibits from building //third_party/zlib (did you mean @zlib//), while new_local_repository(name = "zlib, path = "...", build_file = ".../BUILD") doesn't. I find that very confusing.

[philwo]

@Yannic We're done!! 🎉

Thank you so much for this contribution and your hard work through the little issues and blockers :)