proto_library does not document its implicit dependency on @com_google_protobuf//:protoc

[endobson]

I'm attempting to use proto_library and getting the following error message.

ERROR: /Users/endobson/proj/bes-example/BUILD:1:1: every rule of type proto_library implicitly depends upon the target '@com_google_protobuf//:protoc', but this target could not be found because of: no such package '@com_google_protobuf//': The repository could not be resolved.

The documentation of proto_library has no mention of this implicit dependency so I need to go into the bazel repo to find out how that repo does it and mimic that. This dependency should be mentioned in the documentation and a recommended solution should be provided.

[aj-michael]

I agree the documentation should be improved, however if you're still stuck, there is a guide to setting up the protobuf dependencies here: https://blog.bazel.build/2017/02/27/protocol-buffers.html

[martinw1982]

Tried doing this now and given that the blogpost is more than a year old, there is quite some additional work needed on Bazel V 0.21, which is hard for a newbie to figure out:

First I got build:
aborted: no such package '@com_google_protobuf//': The native http_archive rule is deprecated. load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive") for a drop-in replacement.

Next up:
The value 'REPOSITORY_NAME' has been removed in favor of 'repository_name()', please use the latter (https://docs.bazel.build/versions/master/skylark/lib/native.html#repository_name). You can temporarily allow the old name by using --incompatible_package_name_is_a_function=false

When adding the flag the build succeeded, but obviously it's suboptimal if I have to specify this flag every time.

How do I reference a newer version of the protobuf library? Also, would it be possible to have a documentation page describing the up-to-date steps to avoid people getting stuck?

[jin]

@martinw1982 check out this comment (#6984 (comment)) for instructions to use protobuf 3.6.1.3, which includes the fix for the REPOSITORY_NAME incompatible change issue.

[jin]

Also created a PR to update the blogpost with the minimum version required: https://github.com/bazelbuild/bazel-blog/pull/146/files?short_path=bde5ec7#diff-bde5ec77860ad065de8fd8ab1862de03

[martinw1982]

Thanks Jin, this worked like a charm!

[RezaMehrabian]

I agree the documentation should be improved, however if you're still stuck, there is a guide to setting up the protobuf dependencies here: https://blog.bazel.build/2017/02/27/protocol-buffers.html

I have the same problem but I did not get how I can fix it by your suggested link. Could you explain more?

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